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CHAPTER -3

REVIEW OF LITERATURE

The experience of being human is imbedded in the sensory events of everyday

life. Sensation is the common language by which we share the experience of being

human; it provides common ground for understanding and it is so intimate and

personal that we use it to define our individuality; the term sensory integration was

first used by Ayres in 1963 [9], this complex process of organizing sensation from

the body and the environment for sensory integration occurs in the central nervous

system and is generally thought to take place in the mid-brain and brainstem levels

in complex interactions of the portions of the brain responsible for such things as

coordination, attention, arousal levels, autonomic functioning, emotions, memory,

and higher level cognitive functions. Williamson and Anzalone [10] identified five

interrelated components that help to explain how sensory integration occurs. The

components are sensory registration, orientation, interpretation, organization of a

response, execution of a response.

3.1 COMPONENTS OF SENSORY INTEGRATION

We all receive information from our senses through touch, body position,

movement, sight, hearing, taste, and smell. These senses work together, each sense

works with the others to form a composite picture of which we are physically, where

we are, and what is going on around us. The dynamic interactions of the various

sensory systems forms a complete picture of self and environment which enables

people to remain correctly oriented and to respond to task demands in an appropriate

way. In order to achieve developmental milestones, children must first be able to

intake sensory input, process it, and then respond appropriately within seconds. For

most of us, effective sensory integration occurs automatically and subconsciously

without effort. Each sensory system has its own specific receptor that specializes in

optimal responses to a specific type of sensation and our brain must organize this

information so that we can successfully function in day-to-day life, including home,

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school, play, work and during social interactions [11]. Some of the basic senses

which help to function successfully in day to day activities. These are

1. Tactile or somatosensory system- sense of touch

2. Visual system- sense of sight

3. Auditory system- sense of hearing

4. Gustatory system- sense of taste

5. Olfactory system- sense of smell

6. Vestibular system– sense of balance

7. Proprioception system- sense of body position

Tactile system:

The tactile system is the first sensory system to function in utero, and it

mediates our first experiences in this world. The sensation of touch is, in fact, the

“oldest and most primitive expressive channel” [12] and it is a primary system for

“making contact” with the external world [13]. It Provides information about touch,

size, shape, and texture of objects, and it is important for developing body awareness

and planning motor actions. Tactile receptors are found throughout the skin and are

activated by externally applied stimuli such as touch, pressure, pain and temperature.

Tactile system has several different functions. There is an ongoing interaction

between the two major divisions of the body’s tactile system: the dorsal column

medial lemniscal and the anterolateral systems. The dorsal column medial lemniscal

system carries discriminative touch (specifically two point discrimination),

conscious proprioception, touch pressure, and vibration for the body. It plays a

major role in the development of praxis. Wall [14] identified an expanded role for

the dorsal medial lemniscal system that is particularly pertinent to development of

praxis. He identified deficits in motor performance, especially voluntary exploratory

movements, and deficits in attention, orientation and, anticipation with dorsal

column lesion. The anterolateral system is composed of spinothalamic,

spinoreticular, and spinotectal pathways. It is a nonspecific, protective system that

can produce sympathetic arousal. It is also a diffuse system that directs input into the

reticular formation, and it is responsible for body sensations of pain, temperature,

and crude touch which play a major role in tactile defensive responses, such as

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aversive response to light touch that results from overarousal. Adequate functioning

of both major division of tactile system is necessary for appropriate sensory

integration. Problems in interpreting tactile input may result in difficulties in the

end-products, such as touch discrimination or praxis[15].

Auditory system:

The auditory system is also one of the newer sensory mechanisms in central

nervous system. It processes sound primarily for communication, but also as a

means of environmental orientation. The direction, distance and quality of sound all

contribute to the ability to orient within our environment from an auditory

perspective. The auditory receptor is divided into three sections: the outer, middle,

and inner ear. Through these three components, airwaves are transformed into

pressure waves within a fluid system. The pressure waves displace hair cells located

in the inner ear and this action fires the nerve cells. The outer ear consists of the

auricle, the ear canal, and the ear drum. The middle ear is a chamber that contains

three small bones (malleus, incus, stapes) and two small muscles (tensor tympani

and stapedius). The cochlea is shaped like a snail with several chambers inside. The

movement of fluid within these chambers allows displacement of hair cells. When

the hair cells are displaced, the auditory nerves fire. Specific hair cells are

responsible for specific sounds, and fire specific nerve cells [16].

Gustatory system & Olfactory system:

The gustatory (taste) system is responsible for our sense of taste. The

gustatory information travels from the sensory receptors in the tongue to the portions

of the brainstem where the information is relayed to the thalamus. The thalamus is

responsible for sending the information to the appropriate location on the

somotosensory cortex, which maps the mouth and tongue. Additionally, gustatory

information reaches both the hypothalamus and the cortical taste area in the inferior

frontal gyrus [16]. The Olfactory (smell) system responds to odors in the

environment. The process of smell is a complicated one, beginning with the intake

of substance by the olfactory epithelium in the top portion of the nasal cavity. The

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olfactory system is a very sensitive system, even more sensitive than its chemical

counterpart, the gustatory system. With specific connections to the limbic system,

the olfactory system has the potential to establish memories and associations of our

roles as children and adults [16].

Proprioception system:

Proprioception is the understanding of where the joints and muscles are in

space. Sherrington [17] defined proprioception as perception of joint and body

movement as well as position of the body segments in space, it helps in spatial

orientation of our bodies in space, the rate and timing of our movement, the force of

our muscle exerting, and the speed of our muscle being stretched [18,19,20].

Proprioceptors include the muscle spindles, the golgi tendon organs, and

mechanoreceptors of the skin. The muscle spindle is a small muscle fiber

surrounded by connective tissue that is housed within a fleshy part of a muscle belly.

These encapsulated fibers are dispersed throughout the muscle belly so that they

may respond to any changes in muscle integrity. The golgi tendon organ is located

within the tendons at the end of each muscle belly [16]. Proprioceptors work in

conjunction with the vestibular system to give a sense of balance and position in

space. All muscles and joints are involved in process; however, the neck joints and

the proximal limb joints, such as shoulders and hips, are of primary importance and

give the most feedback to CNS. Proprioception is a powerful system therapeutically

[15].

Visual system:

The visual system is one of the most advanced sensory systems in human

organism. Although cell clusters from early in fetal life, this system becomes most

functional in postnatal period [21]. This system is critical in recognizing shapes,

colors, letters, words, and numbers. It is also important in social interactions, such as

reading body language and other non-verbal cues. The visual system guides and

monitors our movement. There are more fibers in optic nerve than in all sensory

tracts in the entire length of the spinal cord [22]. Because of its anatomical

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organization from the front to back of the cortex, it also provides an excellent

vehicle for localization of central nervous system problems. The retina is the

receptor mechanism of visual system. The retinal cells operate to maximize the

reception of both light and color and the pathways of visual input travel from the

front of the cortex to the back; the other sensory system ascend from the receptor

site to the cortex. The visual and vestibular systems work together to produce visual

perception and perceptual motor integration skills [16].

Vestibular system :

The vestibular system is fundamental for all our actions. This system is

traditionally viewed as having a role, along with the visual system and

proprioception, in three major functions: subjective awareness of body position and

movement in space; postural tone and equilibrium; and stabilization of eyes in space

during head movements (compensatory eye movements) [13]. The vestibular

receptors are hair cells (cristae) located within the semicircular canals, the utricle,

and the saccule of the vestibular labyrinth. The semicircular canals are angular

accelerometers that detect changes in the direction and rate of angular acceleration

or deceleration of the head. Angular acceleration of the head results in rotary head

movements. Within each vestibular apparatus are three semicircular canals,

endolymphfilled ducts oriented at right angles to each other so that they represent all

three planes in space. When the head is tilted forward 300 .the horizontal canal is

oriented in the horizontal plane, and the two vertical canals are vertical and oriented

at right angles to each other. The hairs of the cristae ampullaris of the semicircular

canals project into the cupula, a gelatinous wedge that is free to move like a

swinging door within the endolymph. When the head moves (accelerates), the

inertia of the endolymph causes it to lag behind head movement. The result is

displacement of the cupula and bending of the hairs in the direction opposite head

movement. When head movement stops (decelerates), the inertia of the endolymph

causes the cupula to “keep going”. The result is displacement of the cupula and

bending of the hairs in the same direction that the head had been moving. Several

seconds after the head stops moving, or after it has rotated at a constant velocity for

several seconds, the endolymph “catches up” and the cupula and the hairs return to

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their normal resting positions. Because the hair cells in each pair of canals are

maximally stimulated by head rotation in the same plane, the hair cells are able to

detect movement of the head in the three orthogonal (right angle) planes of three

dimensional space. The most efficient stimuli to the semicircular canals are angular,

transient (short-term), and fast (high –frequency) head movements of at least 20 per

second; when the head moves at slower speeds, the endolymph,cupula, and hair cells

all move at the same speed as the head [1,23,24]

The utricle is a linear accelerometer that detects linear head movement and

head tilt. The utricle is located in the horizontal plane when the head is erect, and

the hair cells in each quadrant of the utricle are systematically oriented in a different

direction. Embedded in a gelatinous layer over the hair cells are calcium carbonate

formation called otoliths, which are denser than the surrounding endolymph. As the

head moves, the force of gravity and linear acceleration act on this otolithic

membrane to displace the hairs of the hair cells. Those hair cells that are aligned in

the direction of gravitational pull, head tilt, or linear acceleration are maximally

stimulated. Thus, systematic variation in the orientation of the utricular hair cells

results in the utricle also being able to detect head movement or head tilt (position)

in the three orthogonal planes of three-dimensional space [1,23,24].

The literature concluded that each sensory system has specific functions and

it help to function successfully in day to day activities.

3.2 VESTIBULAR SYSTEM-MEDIATED POSTURAL AND OCULAR

RESPONSES

The response that are elicited as a result of utricular or semicircular canal

stimulation “act on antigravity extensor muscles so as to elicit compensatory

head,trunk, and limb movements, which serve to oppose head perturbations, postural

sway, or tilt” [1]. Utricular input, conveyed primarily via the lateral vestibular spinal

pathway to limb and upper-trunk alpha and gamma motorneurons, result in

ipsilateral facilitation of extensor muscles and inhibition of flexor muscles.

Semicircular canal inputs are conveyed primarily via the medial vestibulospinal

pathway to axial alpha and gamma motorneurons, and result in bilateral facilitation

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of neck and upper-trunk muscles. Utricular inputs elicit more sustained postural

responses, whereas semicircular canal input elicit more transient or phasic

equilibrium responses[1,23,24].

More specifically, transient or angular head movements that stimulate the

semicircular canals result in phasic stabilization of the head and upper trunk in the

upright position, phasic extension of the weight bearing limbs on the side toward

which the individual is rotating or tilting (downhill side), phasic flexion of the

weight bearing limbs on the contralarteral (uphill) side and phasic compensatory

abduction and extension of nonweight bearing limbs.

Sustained head tilt or linear head movements that stimulate the utricle result

in tonic extension of the downhill weight bearing limbs (support reaction),

maintained flexion of the uphill weight bearing limbs, maintained compensatory

abduction and extension of the non-weight bearing limbs and maintained

stabilization of the head and upper trunk in the upright position [1,23,24].

Vestibular-ocular responses are compensatory in nature. These are vestibular

nystagmus or vestibule ocular reflex (VOR) and Optokinetic afternystagmus

(OKAN). Vestibular nystagmus consists of compensatory slow phase eye

movements in one direction followed by saccadic fast-phase eye movements in the

other direction. There are two types of vestibular nystagmus, (i) perrotary

nystagmus, which occurs during rotation, and (ii) postrotary nystagmus, which

occurs following rotation. During perrotary nystagmus, when the head moves in one

direction, the eyes move “slowly” in the opposite direction to compensate for the

head movement. These compensatory slow phase eye movements of vestibular

nystagmus function to stabilize the visual images on the retina when the head

moves. Because these relatively slow compensatory eye movements in one

direction are followed by quick saccadic eye movements (fast-phase) in the opposite

direction. Vestibular nystagmus is characterized by rhythmic, back- and-forth eye

movements. During angular acceleration of the head, the speed of the slow-phase

eye movements increases as the speed of head movement increases. However,

when the speed of rotation remains contant,slow-phase eye velocity of perrotary

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nystagmus does not remain constant. Instead, after about 2 seconds, it gradually

declines until the eyes stop moving. When the rotation is suddenly stopped,

nystagmus is induced in the opposite direction; this is referred to as postrotary

nystagmus. Postrotary nystagmus slow-phase eye velocity continues at a fairly

steady rate for about 2 seconds the gradually declines to zero.

The time course of perrotary and postrotary nystagmus is usually described

in terms of the duration of nystagmus and the time constant of slow phase eye

velocity decay. The time constant is a measure of how fast the slow phase eye

velocity declines from peak velocity to about two-thirds of the initial peak slow-

phase eye velocity [25].

Many individuals have had the experience of sitting a parked car and

perceiving the sensation that the car in which they are sitting was moving forward

when the car that was parked next to them backed out. This illusion of self

movement in one direction, induced by movement of the visual surround (moving

car) in the opposite direction, is called circularvection. When the visual surround

appears to “move” (called optokinetic stimulation), as it does when we ride in a car

or when we turn our heads in space, slow phase eye movements are generated that

attempt to track the “movement” of the visual surround. As with vestibular

nystagmus, they are followed by saccadic fast phase eye movements in the opposite

direction. These eye movements are called optokinetic nystagmus. Within seconds

after initiation of optokinetic stimulation, one begins to feel, and appropriately so, as

though he or she is moving (circularvection). Optokinetic nystagmus is initiated

simultaneously with the onset of optokinetic stimulation, continues as long as there

is relative movement of the visual surround. However, optokinetic nystagmus also

persists after the termination of optokinetic stimulation, that is, after the visual

surround stops “moving” and there is no longer a moving visual surround for the

eyes to track. This response is termed optokinetic afternystagmus (OKAN).

The literature concluded that vestibular-ocular responses plays important

role during movement activities.

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3.3 CEREBELLAR VESTIBULAR (CV) EXPLANATION TO

VESTIBULAR FUNCTIONING

Levinson [26] did a study to find out cerebellar vestibular explanation for

fear and phobia. Neurological and electronystagmographic evidence of CV

dysfunction were analyzed for anxiety and related symptoms with responses of

4000 learning disability children, adolescents and adults. The results found that

64.6% had fear/phobia and females were significantly more predisposed. Children

with mixed handedness were significantly related to fear of heights, reduced

vestibular or asymmetric vestibular functioning. Adults had a higher incidence of

the specific fear/phobia characterizing agrophobia than children and adolescents.

Levinson [27] conducted study to determine cerebellar vestibular

predisposition to anxiety disorder. CV dysfunction was analyzed by using

neurological and electronystagmographic examination for 402 subjects with various

anxiety symptoms. The results revealed that 94% evidenced CV dysfunction on the

basis of 2 or more abnormal neurological or ENG parameters per subjects. This

suggests that anxiety disorders regards less of surface description and DSM III R

category have a common denominator with varying symptoms shaping mechanism

and that this denominator is significantly CV based.

Levinson [28] conducted a study to identify cerebellar-vestibular basis for

learning disability (LD) in children, adolescents and adults. Neurological and

electronystagmographic (ENG) parameters were used to identity cerebral vestibular

dysfunction. 4,000 patients with learning disabilities were included for the study and

1465 or 36.6% were children, 1156 or 28.9% adolescents, and 1379 or 34.5% adults.

He used set of diagnostic methods and criteria to determine the incidence of CV-

dysfunction in this diverse sample was statistically equivalent to that reported by

neurologists and neurotologists in a prior "blind" analysis of 115 dyslexic children.

The results revealed that more than 94% of both the learning disabled and the

dyslexic samples showed two or more abnormal neurological or ENG parameters

indicating a CV-dysfunction. This study concluded that learning disabilities and

dyslexia may be cerebellar-vestibular-based and reflect a single disorder and that the

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varying academic, speech, concentration, activity, and related symptoms

characterizing learning disabled persons seem to be shaped by a diverse group of

cerebellar-vestibular-determining mechanisms rather than distinct

neurophysiological disorders. Cerebellar-vestibular dysfunctioning and learning

disabilities may secondarily elicit altered and/or compensatory cerebral processing

and dominance mechanisms.

The literature revealed that there is strong relationship between cerebellar-

vestbular function, fear and phobia.

3.4 THE INFLUENCE OF VESTIBULAR SYSTEM IN

MOTOR,LANGUAGE AND BEHAVIOUR DEVELOPMENT

Redfern, Furman & Jacob [29] conducted a study to analyze the postural

sensitivity to moving visual environments in patients with anxiety disorders.

Twenty-one patients with generalized anxiety without panic and 38 patients with

panic and agoraphobia were compared to 22 healthy controls. Space and Motion

Discomfort (SMD) was evaluated in all subjects through the questionnaire. Subjects

stood on a force platform that was either fixed or rotating with the subject during

exposure to a sinusoidally moving visual surround. The results showed that SMD

was a predictor of sway response in the patients. Patients with high SMD swayed

significantly more than both controls and anxiety patients with low SMD. These

results indicate that patients with anxiety disorders, particularly those with SMD,

are more visually dependent for balance.

Jacob, Redfern and Furman [30] conducted a study to examine psychiatric

correlates of vestibular/balance dysfunction in patients with anxiety disorders and

the specific nature of the correlated vestibular abnormalities. The following four

psychiatric variables were considered for this study: anxiety disorder versus normal

control status, panic disorder versus non-panic anxiety disorder diagnosis, presence

or absence of comorbid fear of heights, and degree of space and motion discomfort

(SMD). In their study, 104 subjects were recruited. Twenty nine psychiatrically

normal individuals and 75 psychiatric patients with anxiety disorders. Anxiety

patients were assigned to four subgroups depending on whether or not they had

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panic disorder and co-morbid fear of heights. Subjects were examined for abnormal

unilateral vestibular hypo function on caloric testing indicative of peripheral

vestibular dysfunction, asymmetric responses on rotational testing as an indicator of

an ongoing vestibular imbalance and balance function using Equitest dynamic

posturography (EDP) as an indicator of balance control. The results showed that

Rotational test was not significantly related to any of the psychiatric variables. The

presence of either panic attacks or fear of heights increased the probability of

having caloric hypofunction in a non-additive fashion. SMD and anxiety responses

were independently associated with abnormal balance. This study concluded that

patients with anxiety disorders, higher SMD is indicative of somatosensory

dependence in the control of balance. The absence of both panic and fear of heights

reduces the probability of having peripheral vestibular dysfunction.

Jacob, Furman, Durrant and Turner [31] conducted a study to identify the

prevalence of such findings in panic disorder with and without agoraphobia and to

distinguish whether vestibular dysfunction was associated with specific symptom.

Audiological and vestibular tests were administered to 30 patients with

uncomplicated panic disorder, 29 patients with panic disorder with moderate to

severe agoraphobia, 27 patients with anxiety, 13 patients with deperessive disorders

and 45 normal subjects. Investigators were blind to subjects' diagnostic group.

Quantitative measures of subjects' discomfort with space and motion and of the

frequency of certain symptoms between and during panic attacks were obtained.

Anxiety state levels were measured during the vestibular tests. The results indicated

that vestibular abnormalities were common in all the groups but most prevalent in

the patients with panic disorder with moderate to severe agoraphobia. Vestibular

dysfunction was associated with space and motion discomfort and with frequency

of vestibular symptoms between, but not during, panic attacks. There were no major

differences between the two panic groups in anxiety levels during vestibular testing.

There were no significant differences between groups on the audiological

component of the test battery.

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Bart et al [32] conducted a study to identify balance-anxiety co- morbidity.

Children with balance dysfunction were compared to normally balanced controls on

anxiety and self-esteem. Children with balance dysfunction were assigned to either

balance training or a waiting-list control. Training consisted of 12 weekly sessions

of balance treatment. Anxiety and self-esteem were tested before and after

treatment/waiting. The results found that signi�cantly higher anxiety and lower self-

esteem in the balance dysfunction group compared to the normally balance children.

Balance treatment improved balance performance, reduced anxiety, and increased

self-esteem relative to the control waiting list group. The findings of this study

confirmed that co-morbidity between balance and anxiety disorders in children.

Erez et.al [33] proposed a study on balance dysfunction in childhood anxiety.

The study was conducted for a small sample diagnosed for general or separation

anxiety disorder and a control group of normal children. The result predicts that

anxiety disorder may be an off shot of lasting balance dysfunction.

Stins et al [34] examined the spatio-temporal structure of the centre of

pressure (COP) fluctuations in children with elevated levels of anxiety and a group

of typically developing children (TDC) while maintaining quiet stance on a force

plate in various balance challenging conditions. Balance was challenged by adopting

sensory manipulations (standing with eyes closed and/or standing on a foam surface)

and using a cognitive manipulation (dual-tasking). The results indicated that postural

performance was strongly influenced by the sensory manipulations, and hardly by

the cognitive manipulation. They also found that children with anxiety had overall

more postural sway, and that their postural sway was overall less complex than sway

of typically developing children. The postural differences between groups were

present even in the simple baseline condition, and the group differences became

larger with increasing task difficulty. This study concluded that the pattern of

postural sway suggests that balance is overall less stable and more attention

demanding in children with anxiety than typically developing children.

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Balaban & Thayer [35] examined the neurologic bases of links between

balance control and anxiety based upon neural circuits that are shared by pathways

that mediate autonomic control, vestibulo-autonomic interactions, and anxiety. The

parabrachial nucleus (PBN) is a site of convergence of vestibular information

processing and somatic and visceral sensory information processing in pathways that

appear to be involved in avoidance conditioning, anxiety, and conditioned fear.

Monoaminergic influences on these pathways are potential modulators of both

effects of vigilance and anxiety on balance control and the development of anxiety

and panic. This neurologic schema provides a unifying framework for investigating

the neurologic bases for co-morbidity of balance disorders and anxiety.

Balaban [36] has conducted a study to identify neurological bases for the

close association between balance control and anxiety. New data suggest that a

vestibulo-recipient region of the parabrachial nucleus (PBN) contains cells that

respond to body rotation and position relative to gravity. The PBN, with its

reciprocal relationships with the extended central amygdaloid nucleus, infralimbic

cortex, and hypothalamus, appears to be an important node in a primary network

that processes convergent vestibular, somatic, and visceral information processing to

mediate avoidance conditioning, anxiety, and conditioned fear responses.

Noradrenergic and serotonergic projections to the vestibular nuclei also have parallel

connections with anxiety pathways. The coeruleo-vestibular pathway originates in

caudal locus coeruleus (LC) and provides regionally specialized noradrenergic input

to the vestibular nuclei, which likely mediate effects of alerting and vigilance on the

sensitivity of vestibulo-motor circuits. Both serotonergic and nonserotonergic

pathways from the dorsal raphe nucleus and the nucleus raphe obscurus also project

differentially to the vestibular nuclei, and 5-HT(2A) receptors are expressed in

amygdaloid and cortical targets of the PBN. It is proposed that the dorsal raphe

nucleus pathway contributes to both (a) a tradeoff between motor and sensory

(information gathering) aspects of responses to self-motion and (b) a calibration of

the sensitivity of affective responses to aversive aspects of motion.

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Furman & Jacob [37] studied association between dizziness and anxiety in

otoneurological setting. Because dizziness often is situation specific, concepts of

space and motion sensitivity (SMS), space and motion discomfort (SMD), and space

and motion phobia (SMP) are needed to understand the interface. They developed

framework involving several categories of interactions between balance and

psychiatric disorders. The first category is that of dizziness caused by psychiatric

disorder (psychiatric dizziness), including hyperventilation-induced dizziness during

panic attacks. The second category involves chance co-occurrence of a psychiatric

disorder and a balance disorder in the same patient. The third category involves

problematic coping with balance symptoms (psychiatric overlay). The fourth

category provides psychological explanations for the relationship between anxiety

and balance disorders, including somatopsychic and psychosomatic relationships.

The final category, neurological linkage, focuses on the overlap in the neurological

circuitry involved in balance disorders and anxiety disorders.

Gordon J. G. Asmundson [38] conducted a study to find the relationship

between panic disorder and vestibular disturbance. This relationship has been

examined from two distinct perspectives, including: (a) the assessment of vestibular

dysfunction in patients with panic disorder; and (b) the evaluation of panic

symptomatology in patients with vestibular disturbance. Consequently, this review

focuses primarily on the literature pertaining to vestibular symptoms in patients

with panic disorder and panic symptomatology in patients with vestibular

complaints.

Jacob [39] reviewed the interrelationship between panic disorder and

vestibular function. There is a possibility of both somatopsychic and psychosomatic

interactions between panic and the vestibular system. Another possibility is that

vestibular dysfunction could be associated with certain mental disorders, including

panic disorder, as a nonspecific marker. Somatopsychic interactions are suggested

by findings of high prevalence of vestibular dysfunction in selected patients with

panic disorder, by the occurrence of "space and motion phobia" in patients with

panic disorder, and by the report of anxiety and pseudoagoraphobia in some patients

with a primary complaint of vertigo. Psychosomatic influences include symptoms of

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dizziness and increased sensitivity of the vestibular system due to anxiety or

hyperventilation. Vestibular dysfunction as a nonspecific marker is discussed in the

context of a review of studies of the vestibular system in schizophrenia. This review

concluded that further research is needed to establish the specificity of vestibular

dysfunction for panic disorder.

Vaillancourt and Bélanger [40] reviewed the literature on the association

between panic disorder with or without agoraphobia and vestibular dysfunction.

Various researches concluded that these conditions are encountered in high

proportions in psychiatric samples and in patients consulting for equilibrium

problems. Three models have endeavored to hypothesize the mechanisms underlying

this co-occurrence. Agoraphobic avoidance and high anxiety level seem to be

characteristics of individuals affected by both conditions. Furthermore, vestibular

dysfunctions appear to be predicted by individuals feeling uncomfortable in

situations characterized by spatial and/or motor particularities. Further studies

should try to better understand people with both panic disorder and dysfunctions of

the equilibrium system. These individuals who suffer from both conditions may

avoid activities that particularly call upon the equilibrium system, such as walking

on uneven surfaces or undertaking some forms of transportation. The cognitive

substrates pertaining to the feared consequences of the physical symptoms may also

differentiate this group from uncomplicated anxiety disorder patients.

Tecer, Tukel,Erdamar,Sunay [41] conducted a study to investigate

audiovestibular function in patients with pani disorder and healthy subjects. Clinical

otoneurological examination, pure tone audiometry, tympanometry, and

electronystagmography (ENG) were done for 34 panic disorder patients and 20

healthy control subjects. All patients were evaluated with the Panic and

Agoraphobia Scale (PAS), the Hamilton Anxiety Rating Scale (HARS), the

Hamilton Depression Rating Scale (HDRS), and the State-Trait Anxiety Inventory

(STAI). The results found that abnormal responses were more prevalent in panic

disorder patients compared to healthy controls on vestibular testing. The presence

of agoraphobia in panic disorder patients did not make a significant difference on

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vestibular test results. The only variable that may be a predictor of vestibular

abnormalities in panic disorder patients was found to be dizziness between attacks.

Jacob,Furman,Durrant and Turner [42] conducted a study to examine

sensory integration of spatial information in agoraphobia. Computerized dynamic

posturography was used to examine balance performance in patients with panic

disorder with agoraphobia, uncomplicated panic disorder, nonpanic anxiety

disorders, and depression without anxiety, as well as healthy subjects for

comparison. The posturography procedure included six sensory conditions in which

visual and proprioceptive balance information was manipulated experimentally by

permutations of sway-referencing the support surface or the visual surround or by

having patients close their eyes. The results showed that agoraphobics had impaired

balance when proprioceptive balance information was minimized by sway-

referencing the support surface. This study concluded that agoraphobics rely on

proprioceptive cues for maintenance of upright balance.

Redfern, Yardley & Bronstein [43] discussed the impact of vision on

balance and orientation in patients with vestibular disorders and in anxiety patients

with Space and Motion Discomfort (SMD). When the vestibular system is impaired,

vision has a greater influence on standing postural control, resulting in greater sway

when individuals are presented with erroneous or conflicting visual cues. Thus,

while specific vestibular deficits are not always directly associated with SMD, data

regarding the impact of vision on balance suggest that some patients with SMD may

have an underlying balance disorder.

Cherng Chen, & Su [44] conducted study to find vestibular system in

performance of standing balance of children and young adults under altered sensory

conditions. Inputs from the visual, somatosensory and vestibular systems must be

integrated efficiently to activate appropriate motor responses in maintaining optimal

balance. This study examined the standing balance of 17 children (7 to 10 years old)

and 17 young adults (19 to 23 years old) as a function of sensory organization,

sensory system efficiency, and postural strategy adopted. Tests of standing balance

were administered under six sensory conditions created by simultaneous alteration

26

of the visual (full, occluded, or sway-referenced) and the somatosensory inputs

(fixed-foot or compliant-foot support). The sway area and the sway amplitude of the

center of pressure were measured and analyzed. Three findings are notable. The

function of sensory organization for balance control was poorer for the children than

the young adults. The functional efficiency of the somatosensory and the visual

systems of children has developed to the young adult level, but that of the vestibular

system has not. There was no difference between children and young adults in hip

control, but there was in ankle control when the vestibular input was the only

reliable source of sensory input. These results suggest that the functional efficiency

of the vestibular system in children 7 to 10 years of age may still be developing.

This study concluded that poor vestibular function affects balance.

Mark S. Redfern et al [45] carried out to find the impact of vision on balance

and orientation in patients with vestibular disorders and in anxiety patients with

space and motion discomfort (SMD). When the vestibular system is impaired,

vision has a greater influence on standing postural control, resulting in greater sway

when individuals are presented with erroneous or conflicting visual cues. Patients

with anxiety disorders that include SMD also have been shown to have increased

postural sway in conflicting visual environments, similar to patients with vestibular

disorders. Thus, while specific vestibular deficits are not always directly associated

with SMD, data regarding the impact of vision on balance suggest that some

patients with SMD may have an underlying balance disorder.

Bremmer et al., [46] analyzed visual – vestibular interactive responses in the

macaque ventral intraparietal area (VIP). Self-motion detection requires the

interaction of a number of sensory systems for correct perceptual interpretation of a

given movement and an eventual motor response. Parietal cortical areas are thought

to play an important role in this function. They have identified for the first time the

presence of vestibular sensory input to this area and described its interaction with

somatosensory and visual signals, via extracellular single-cell recordings in awake

head-fixed animals. Visual responses were driven by large field stimuli that

simulated either backward or forward self-motion (contraction or expansion stimuli,

respectively), or movement in the front parallel plane (visual increments moving

27

simultaneously in the same direction). The associated visual responses were always

codirectional with the vestibular on-direction, i.e. noncomplementary.

Somatosensory responses were in register with the visual preferred direction, either

in the same or in the opposite direction, thus signaling translation or rotation in the

horizontal plane. These results, taken together with data on responses to optic flow

stimuli obtained in a parallel study, strongly suggest an involvement of area VIP in

the analysis and the encoding of self-motion.

Hallam and Stephens [47] examined a study on the relation between

vestibular dysfunction and behavior. A standardized test of psychopathology was

administered to tinnitus sufferers some of whom also complained of dizziness. It

was predicted that the complaint of dizziness would be associated with higher

scores on the anxiety scales and this was confirmed. Subjects complaining of

dizziness obtained much higher scores on ‘phobic’ and ‘somatic’ anxiety scales in

particular. However, the complaint of dizziness was completely uncorrelated with

objective assessments of balance and there was no effect of balance, objectively

assessed, in moderating the association between the complaint of dizziness and

‘anxiety’. The results highlight the complex relationship between vestibular

dysfunction and complaint behavior.

Slavil & Ayres [48] examined the effectiveness of vestibular stimulation on

eye contact. Five autistic boys ages 5-1 to 5-10 were included to determine whether

stimulation of the macular receptors of the inner ear through linear motion

influences the boys' eye contact with the investigators. The duration of eye contact

was measured during linear motion on a motor-driven oscillator and on two hand-

operated swings and compared to the duration of eye contact when the macular

receptors were not stimulated. Four of the five boys showed longer eye contact

while on the motor driven oscillator (p less than .0005), and two of these also

showed longer contact when on a manually operated swing (p less than .025). The

fifth child resisted the use of the oscillator and did not show longer eye contact

while on it (p greater than .05), but did so when on two different swings (p less than

.005).The results of this conclude that there is close relationship between vestibular

system and eye contact.

28

Weeks [49] conducted study with the effects of vestibular stimulation on

human development and function are reviewed. Studies are included that relate to

changes in the vestibule-occular reflex with age, effects of vestibular stimulation on

smiling, crying, general activity and visual attentiveness of infants; and studies

show that typical sequel to vestibular stimulation are reduced following long term

stimulation. Implication of this result with vestibular based therapy will improve as

occupational therapists become more aware of related research.

Cook [50] conducted study to examine the role of the vestibular system in

balance and coordination problems found in motor-impaired, learning-disabled

(LD) children. Vestibulo-ocular reflex (VOR) and vestibulo-spinal tests (moving

platform posturography) were performed on 15 learning disabled and 54 normal

children. Twelve LD children had normal VOR scores suggesting normal peripheral

vestibular inputs. All 15 LD children had abnormal posturography. Motor-impaired

LD children could not appropriately integrate vestibular information with visual and

somatosensory inputs for postural orientation. Results suggest that the best

discriminator of abnormal sensorimotor function in LD children are posturography

trials requiring orientation to gravity despite absent or inaccurate visual and

somatosensory cues, rather than traditionally relied on VOR and Romberg tests.

Ottenbacher [51] conducted study identify neurobehavioral functions of the

vestibulo-proprioceptive system that would aid the clinician in evaluating vestibular

processing dysfunction in Vestibulo-proprioceptive function were subjected to

multiple regression analysis. Data analysis revealed that four variables shared

significant variance with Southern California Postrotary Nystagmus Test scores. It is

suggested that these variables can provide additional information in evaluating

vestibular processing dysfunction in learning-disabled children.

Lackner, Dizio [52] analyzed the interaction of vestibular, proprioceptive,

and haptic contributions to spatial orientation. The control and perception of body

orientation and motion are sub served by multiple sensory and motor mechanisms

ranging from relatively simple, peripheral mechanisms to complex ones involving

29

the highest levels of cognitive function and sensory-motor integration. Vestibular

contributions to body orientation and to spatial localization of auditory and visual

stimuli have long been recognized. These contributions are reviewed here along with

new insights relating to sensory-motor calibration of the body gained from space

flight, parabolic flight, and artificial gravity environments. Recently recognized

contributions of proprioceptive and somatosensory signals to the appreciation of

body orientation and configuration are described.

Horak, Cook, Crowe & Black [53] determined whether vestibular loss can

account for deficits in motor co- ordination by documenting vestibular status and

motor proficiency of 30 hearing impaired and 15 motor impaired Learning Disabled

(LD) children. Vestibular loss was differentiated from sensory organization deficits

by of Vestibular Ocular Reflex (VOR) and postural orientation results, which were

compared with 54 normal individuals aging 7- 12 years. Reduced or absent

vestibular function in 20 hearing impaired children did not affect the development of

motor proficiency, except in specific balance activities. However, widespread

deficits in motor proficiency were seen sensory organization deficits in LD group

and in three hearing impaired children.

Kokubun [54] conducted a study to investigate the differences in standing

broad jump performance between two task conditions (with and without goal) and to

clarify the relation of verbal behavior regulation to this difference in children with

intellectual disability. The subjects were 30 children with intellectual disability with

an average age of 16.2 years. In the without-goal condition, subjects were instructed

to jump as far as possible. In the with-goal condition, on the other hand, subjects

were given a goal set 20 cm away from the distance of the first trial in the without-

goal condition and instructed to jump for the goal. Verbal behavior regulation ability

was measured by three tasks on Garfield's motor impersistence test: keeping eyes

closed, protruding tongue with eyes open and keeping mouth open. The mean

performance of the with-goal condition was 108 cm, while that of the without-goal

condition was 102 cm. Behavior regulation score was found to be significantly

related to the condition difference. It was more effective to demonstrate the goal

when the behavior regulation abilities of the children were lower, but giving the

30

children a goal was not effective for subjects with Down's syndrome. Children with

Down's syndrome were considered to have a deficiency in the motor ability itself,

not in the system for expressing the motor ability.

Clark ,et al., [55] had done a research to identify relationship between

vestibular stimulation and gross motor skills in infants. Mild semicircular canal

stimulation was given for 2 days per week for 4 weeks. The gross motor ability of

each child was assessed before and after the 4-week period. The results revealed that

vestibular stimulation effected a significant improvement in gross motor skills.

Ottenbacher [56] conducted a systematic review to determine various forms

of sensory stimulation to improve the neuromotor development of high-risk infants

and developmentally delayed children. The applied clinical research using vestibular

stimulation activities with healthy human infants, infants at risk, and young children

with developmental delay disorders is reviewed. The literature discussed indicates

that controlled vestibular stimulation has had positive effects on arousal level, visual

exploratory behavior, motor development, and reflex integration. They also

conducted a study on the effect of a program of controlled vestibular stimulation on

the gross motor, and reflex development of 38 severely and profoundly retarded,

nonambulatory, developmentally delayed children were investigated. Data analysis

revealed that subjects receiving a combined program of sensor motor therapy and

controlled vestibular stimulation make significantly greater gains on measures of

reflex integration, gross motor, and fine motor development than control subjects

receiving a progression of normal motor development and appeared to be related to

the age of subjects and to the presence or absence of identifiable neuromotor

spasticity.

Sallustro and Atwell [57] conducted a study to identify effectiveness of self

stimulation for normal motor development. Five hundred and twenty five normal

children were included for the study. Children who persistently displayed such self

stimulatory behaviors would be reported as developmentally more advanced than

“non-self-stimulators”. Body rocking was the earliest to appear and most prevalent

of the habits. Head banging and head rolling had roughly the same prevalence and

31

age of onset. Comparisons of “self-stimulators” with “non-self-stimulators” yielded

no significant effects for birth order. A comparison of the ages at which 12

“milestones” first appeared supported the hypothesis of developmental precocity for

the body rockers and the head bangers, but not for the head rollers.

Yardley & Redfern [58] reviewed the evidence for three mechanisms

whereby psychological factors may aggravate dizziness and retard recovery from

balance disorders. Firstly, avoidance of activities and environments that provoke

symptoms are the common behavioral responses to dizziness. Secondly, anxiety

arousal and hyperventilation might be the responses induced by balance disorder.

Thirdly, attention and cognitive load may influence the central processing of

information required for perception and control of orientation.

Kramer, Deitz & Crowe [59] described and compared the postrotatory

nystagmus(PRN) response of 26 pre - school children enrolled in mental health

programs with 26 preschool children enrolled in project head start, non - mental

health program. The Southern California Postrotatory Nystagmus Test (SPRNT) was

administered to all subjects. Scores of children enrolled in mental health program

were significantly lower than the children enrolled in project head start. Variances of

the group were not statistically significant. Results of the study suggested that the

hypoactive postrotatory nystagmus may be a characteristic of children with

emotional disturbances.

Magrun et.al [60] conducted a study to determine relationship between

vestibular stimulation and language development. Five primary trainable mentally

deficient groups and five developmentally retarded preschoolers group were

recruited for the study. Subjects received vestibular stimulation prior to a free play

situation and were monitored for spontaneous recognizable language use. The

results revealed that there is increase in spontaneous verbal language use for both

groups immediately after the stimulation periods, and suggest vestibular stimulation

as an effective nonverbal intervention method for the facilitation of spontaneous

language.

32

MacLeane and Baumeister [61] conducted a study to identify relationship

between vestibular stimulation, motor development and stereotyped movements.

Semicircular canal stimulation was given to four developmentally delayed children

to facilitate their motor and reflex development. Each of the children also exhibited

abnormal stereotyped movements. Semicircular canal stimulation was provided by

rotating the children in a motor-driven chair at a velocity of about 17 rpm for 10

minutes daily over a period of 2 weeks. Standard motor and reflex measures were

taken before, during, and after the rotation treatment period. Daily observations were

made of the children's stereotyped movements. Over the course of the study all of

the children showed motor and reflex changes that were attributable to the vestibular

stimulation. In addition, some evidence was obtained linking changes in stereotypic

responding to the vestibular stimulation.

Bonadonna [62] conducted a study to measures the effect of a vestibular

stimulation program on the stereotypic rocking behavior. Vestibular stimulation was

given for three severely mentally retarded persons within both experimental and

natural settings. A multiple baseline design was used. Results indicated a

statistically significant reduction of both frequency and duration of rocking behavior

directly after receiving vestibular stimulation and 1 hour after stimulation. The

rocking behavior remained reduced after 6 days without the vestibular stimulation

program. It was concluded that vestibular stimulation resulted in a reduction of the

stereotypic rocking behavior of these subjects.

The literature concluded that vestibular stimulation plays vital role in

motor,language and behaviour development

3.5 VISUAL – VESTIBULAR INTERACTION

Mario & Henrietta [63] have conducted a study to determine Visual-

Vestibular Interaction Hypothesis for the Control of Orienting Gaze Shifts by Brain

Stem OmniPauseNeurons(OPNs) and they found that simulated performance reveals

that a weighted sum of three signals: gaze motor error, head velocity, and eye

33

velocity, hypothesized as inputs to OPNs, successfully reproduces diverse

behaviorally observed eye-head movements.

Brandt, Bartenstein, Janek and Dietrich [64] have conducted a study to

determine visual motion stimulation deactivates the parieto-insular vestibular cortex.

Ten normal subjects participated and positron emission tomography (PET) scan is

used. Results shown that there was a positive correlation between the perceived

intensity of circularvection and relative changes in regional cerebral blood flow in

parietal and occipital areas. Further, these findings support a new functional

interpretation: reciprocal inhibitory visual-vestibular interaction as a multisensory

mechanism for self-motion perception. Inhibitory visual- vestibular interaction might

protect visual perception of self-motion from potential vestibular mismatches caused

by involuntary head accelerations during locomotion, and this would allow the

dominant sensorial weight during self-motion perception to shift from one sensory

modality to the other.

Allum, Graf, Dichgans and Schmidt [65] have conducted a study to find out

visual –vestibular interaction in vestibular nuclei of the gold fish. A relaxed,

unanaesthetized gold fish subject is included. They show three different response

profiles, classified A, B or C, based on the neuron's discharge rate: increasing,

decreasing or remaining constant once surround motion is maintained at constant.

Responses to body rotation in the light were found to linearly combine the weighted

vestibular and optokinetic responses so that accurate velocity information is

available for sensory and motor functions independent of the neuron is vestibular (I,

II) or optokinetic (A, B, C) response type. The principle of this visual-vestibular

interaction is discussed with respect to multisensory processing within the vestibular

nuclei.

Rosander and Von Hofsten [66] have conducted a study to determine the

development of visual and vestibular control of smooth gaze adjustments

longitudinally in 3 to 18 week old infants. Electro-OculoGraphy (EOG) and an

optoelectronic system are used to measure eye and head movements. Results shown

that the vestibular control of smooth gaze adjustment functions earlier than the

34

visual control. At two months, the visual control improves dramatically and at 3–

4 months head participation increases considerably. The eye gain in the Vestibulo

Ocular Reflex Inhibition (VORINHIB) condition could be well predicted by vector

addition of the eye position signals in the Opto Kinetic Response (OKR) and Visual

– Vestibular Ocular Reflex (VVOR) conditions.

Baloh, Honrubia, Yee and Jacobson [67] conducted a study to determine

vertical visual- vestibular interaction in normal human subjects. Ten normal human

subjects participated. A magnetic search coil technique is used. Results shown that

there was no significant difference (p > 0.05) between the mean gains of up and

down slow eye movements induced by vestibular, visual or visual-vestibular

stimulation in the group of normal subjects.

Hayashi, Uwa Nobuaki & Ando [68] have conducted a study to determine

the basic Property of Yawing Sensation in Visual-vestibular Interaction and they

found that visual image information was predominant when the visual image was

presented and the body acceleration was less than 0.1 deg/s'2'. They also found that

in the case of opposite direction between body rotation and visual image rotation,

the estimated magnitude of a body rotation increased with the acceleration of visual

image when the vestibular acceleration was between 0.1 deg/s'2' and 1.0 deg/s'2'.

These experimental findings can be used to develop a simulator or a display, which

can effectively produce a rotational sensation of the body.

Cynthia, Kim and Amit [69] have conducted a study to measure the postural

stability in children with Autism Spectrum Disorder (ASD) compared with children

with typical neurodevelopment and to measure the relative contributions of the

visual, somatosensory, and vestibular afferent systems in each group. Eight boys

with ASD and 8 age, race, and gender matched controls participated in this study.

Force platform technology with customized software is used to measure postural

sway. Results shown that Children with ASD had significantly larger sway areas

under all test conditions in which afferent input was modified. These results are

consistent with a deficit in the integration of visual, vestibular, and somatosensory

input to maintain postural orientation.

35

Leah , Bradford, McFadyen, & Timothy inglis [70] have conducted a study

to determine the interaction between visual and vestibular information during the

transition from quiet standing to the completion of a forward step. Six subjects

participated. Galvanic vestibular stimulation is used. . The results suggest that the

importance of visual and vestibular information varies depending on the phase of the

task. In addition, the different integration between visual and vestibular input during

quiet standing suggests a dual role for vestibular information. They propose that

vestibular information in quiet standing has a role in maintaining whole body

postural stability, as well as playing an integral role in the alignment of the body

segments in preparation for proper movement execution. Vision was demonstrated

to differentially attenuate these responses based on the phase of the task. Thus,

visual and vestibular information appear to be integrated differently across the

different phases of a forward-stepping task.

Martin Sanz, Guzman, Cerveron and Baydal [71] have conducted a study to

determine the analysis of the interaction of visual and vestibular influences on

postural control. A normal and pathological vestibular group subjects are included.

A dynamometric platform and scalogram are used. Results shown that in both

groups, parameters showed higher values when proprioceptive and visual system

were altered. A pattern of visual dependence was identified in both groups.

Wenzel [72] has conducted a study to find out the development of parachute

reaction as a visual vestibular response. A normal and statomotorically retarded

infants participated. It is concluded that the parachute reaction results from a

combined visuo -vestibular mechanism of interaction in connection with sufficient

kinesthetic experience in visuo-motor behavior.

Cooper & Pivik [73] have conducted a study to determine abnormal visual-

vestibular interaction and smooth pursuit tracking in psychosis and implications for

cerebellar involvement. Twenty-three actively ill psychotic patients and 23 remitted

psychotic patients and normal controls (23 with no history of psychiatric illness)

participated. Standardized clinical electronystagmographic (ENG) procedures were

used, together with electrographic measures to assess visual fixation and level of

36

arousal. Results shown that during the light condition previous findings of impaired

smooth pursuit tracking and reduced fixation suppression in actively psychotic

patients were replicated. These patients also exhibited hyperactive -responsive

vestibulo-ocular responses. Remitted patients' performance levels on test measures

fell between those of controls and actively ill patients on the majority of response

measures. However, remitted patients were found to have impaired smooth pursuit

tracking and failure of fixation suppression relative to controls. The dark testing

condition effected a normalization of several patient-control differences, including

smooth pursuit tracking and the elimination of vestibular hyper responsiveness. In

many respects, the present results parallel findings of eye movement aberrations in

cerebellar patients. These similarities include evidence of an intact but

hyperresponsive vestibular system, the normalization of previously disordered

pursuit tracking during dark testing, the failure of fixation suppression, and the

decrease in this measure during dark conditions. These findings suggest that

cerebellar dysfunction may contribute to irregularities in smooth pursuit tracking

and fixation suppression found in psychotic patients.

Baloh, Jenkins, Honrubia, Yee and Lau [74] have conducted a study to

determine the visual – vestibular interaction in cerebellar atrophy. Ten patients with

cerebellar atrophy and 10 normal subjects using (1) constant velocity optokinetic

stimulation, (2) sinusoidal rotation in the dark and (3) sinusoidal rotation in the light

with a surrounding fixed optokinetic drum were participated. ElectroOculoGraphy

(EOG) is used to calculate the gain (maximum slow component velocity/maximum

head or drum velocity) of induced nystagmus. Optokinetic nystagmus (OKN) was

abnormal in seven patients and the average optokinetic gain in the patients was

significantly (p < 0.01) less than that of the normal group. Three patients with

"clinically pure" cerebellar atrophy had increased vestibular responses, and one

patient with clinical signs of peripheral neuropathy had decreased responses,

probably due to associated vestibular nerve disease. The average vestibulo-ocular

reflex (VOR) gain in patients did not differ significantly from controls (p > 0.05).

Three patients had normal vestibular and optokinetic responses when tested

independently, but had abnormal visual-vestibular interaction. These patients

probably had selective disorders of the midline cerebellar pathways that mediate

37

visual-vestibular interaction. By studying each system, both independently and

during interaction, all patients were identified as abnormal, and a more precise

anatomic localization of the atrophy was obtained.

Walter and Werner Wihmann [75] have conducted a study to determine

oculomotor disturbances during visual-vestibular interaction in Wallenberg’s lateral

medullary syndrome (WLMS). Nine patients with Wallenberg’s lateral medullary

syndrome participated. Magnetic Resonance Imaging (MRI) is used. . The following

conclusions are made. (1) The spontaneous drift that is dependent on eye position is

mostly created by ‘ocular lateropulsion’, that is, a tonic bias within the oculomotor

system, which may have several sources. (2) The abnormalities and asymmetries of

oculomotor responses during visual-vestibular stimulation cannot solely be

explained by this spontaneous drift and its interaction with otherwise normal eye

movements. Instead, structures and pathways are damaged in Wallenberg's

syndrome, which mediates visual and/or motor signals important for the cerebellar

control of visually guided slow eye movements. (3) Damage to these pathways

occurs in the lateral medulla, as the MRI findings show that in most patients, the

cerebellum is rarely involved, but no definite conclusion can be made as to which of

the fibres traveling in the inferior peduncle to the cerebellum may be interrupted.

Eyeson-annan, Peterken, Brown and Atchison [76] have conducted a study to

determine the relative importance of visual and vestibular information in the

etiology of Motion Sickness (MS). Twenty – two Subjects participated. Results

shown that Visual stimuli produced more symptoms of MS than vestibular stimuli

when only visual or vestibular stimuli were used (ANOVA: F = 7.94, df = 1, 21 p =

0.01), but there was no significant difference in MS production when combined

visual and vestibular stimulation were used to produce the Coriolis effect or pseudo-

Coriolis effect (ANOVA: F = 0.40, df = 1, 21 p = 0.53). This was further confirmed

by examination of the order in which the symptoms occurred and the lack of a

correlation between previous experience and visually induced MS. It is concluded

that Visual information is more important than vestibular input in causing MS when

these stimuli are presented in isolation. In conditions where both visual and

vestibular information are present, cross coupling appears to occur between the

38

pseudo-Coriolis is effect and the Coriolis is effect, as these two conditions are not

significantly different in producing MS symptoms.

Demer [77] has conducted a study to determine visual – vestibular

interaction with low vision Acquired ImmunoDeficiency Syndrome (AIDS). The

effect of telescopic spectacles on vertical Visual Vestibular Ocular Reflex (VVOR)

will be quantitatively characterized in the physiologic range of active and passive

head velocities and frequencies, in normally sighted and low vision adults. This

data will enhance basic understanding of human vertical eye movements, and

provide clinical insight into an important problem in clinical low vision.

The literature concluded that visual-vestibular interaction is essential for

righting and equilibrium reactions.

3.6 SENSORY PROCESSING DISORDER (SPD)

Sensory Processing (SP) refers to the way that sensory information e.g.

visual, auditory, vestibular or proprioceptive stimuli is managed in the cerebral

cortex and brainstem for the purpose of enabling adaptive responses to the

environment and engagement in meaningful daily life activities [78]. SP theory

suggests that optimal functioning in daily environments requires efficient reception

and integration of incoming sensory stimuli. Adaptive behaviour, learning and

coordinated movement are considered products of effective sensory integration

[79,80].

Sensory Processing Disorder (SPD) is the impairment in detecting,

modulating, interpreting, or responding to sensory stimuli [81,82]. Some of the

documented manifestations of sensory processing deficits include hyperactivity,

distractibility, social difficulties, learning difficulties, poor organizational skills, and

behavioral difficulties [82]. Bundy [82, 83] found that boys with Sensory

Processing Disorder (SPD) engaged in less social play out-doors and that their

Preschool Play Scale (PPS) [84, 85] scores were lower than that of boys who were

typically developing. Moreover, school environments contain physical and social

39

stimuli that frequently cause these children significant distress [86,87]. While

Parents may struggle with issues long before children enter school, problems

stemming from sensory processing may become more apparent once a child enters a

day-care or school environment. Sensory problems may persist into adulthood, with

related social and emotional difficulties [88]. The lack of ability to play successfully

with peers is proposed to be related to a lack of full participation in sensory and

motor play from which cognitive and social skills emerge and develop [86]. The

fear, anxiety, or discomfort that accompanies everyday situations may significantly

disrupt daily routines in the home environment. There is a relation between sensory

processing disorders and atypical behaviors ranging from mild disruptions in infant

self-regulation [89,90] to severe behavior problems associated with Pervasive

Developmental Disorders such as Fragile X Syndrome [91], Cerebral Palsy [92], and

Autism Spectrum Disorders [93].

A recent study comparing Sensory responses have also been shown to

fluctuate such that both hyper and hypo-responsiveness to sensory stimuli can occur

in the same individual [94,95,96,97]. Further, findings from six studies, which

specifically compared the SP patterns of individuals with autism or another

pervasive developmental disorder (PDD) with controls, all revealed the presence of

significantly different SP profiles for individuals with autism/PDD and

developmental disabilities [98-102]. These findings suggest that SP dysfunction is a

feature of autism and developmental disabilities.

Disorders of SP in children are increasingly discussed in the literature [86].

Dunn [103] proposed a model for classifying patterns of dysfunction in SP

according to individuals’ behavioural response to stimuli and neurological

thresholds, describing four patterns of SP dysfunction: Low Registration, Sensation

Seeking, Sensory Sensitivity and Sensation Avoiding. Unusual responses to sensory

stimuli and SP difficulties exhibited by individuals with autism and developmental

disabilities have been widely documented [95,104]. Abnormalities have been

reported to occur across all sensory domains, including tactile, vestibular, auditory

and visual [105,106] and in the absence of known peripheral dysfunction such as a

visual or hearing loss [94].

40

Dunn [107] proposed that there is an interaction between neuroscience and

behavioral concepts, such that the neuroscience concepts can help us interpret young

children’s behavior and performance. Neurological thresholds indicate the amount

of stimuli needed for the nervous system to notice or react to stimuli.

Central Nervous System (CNS) is complex; none of its system contains only

habituation or only sensitization patterns. In order to produce functional behaviors,

the CNS must modulate information by creating a continuous interchange among

habituation and sensitization. Young children who have high neurological thresholds

react less readily to stimuli or take a longer time to react; the mechanisms of

habituation support high thresholds. When young children have low thresholds

neurons trigger more readily and, therefore cause more frequent reactions to stimuli

in the environment[103].

3.1 Proposed working model for sensory processing

Neurological thresholdcontinuum

Behavior Response Continuum

Responds in

ACCORDANCE with

Threshold

Responds to

COUNTERACT the

Threshold

HIGH (Habituation) Poor Registration Sensory Seeking

LOW Sensitivity to stimuli Sensation avoiding

The literature concluded that children with sensory processing impairments

has wide range of neurobehavioural difficulties, including problems with motor

coordination,language, visual perceptual skills, attention, learning and emotional

regulation.

3.7 SENSORY MODULATION DISORDER (SMD)

Sensory modulation refers to as a specific component of sensory integration,

it is the capacity to regulate and organize the degree, intensity, and nature of

responses to sensory input in a graded and adaptive manner [108]

41

Sensory Modulation Disorders (SMD) is impairments in regulating the

degree, intensity and nature of responses to sensory input, resulting in considerable

problems with daily roles and routine. Behavioral patterns demonstrated by

individuals with sensory modulation dysfunction include hyper-responsivity, also

referred to as “sensory defensiveness”, hypo-responsitivity or “sensory dormancy”

as well as patterns of fluctuating responsivity [108].

Some theorists have proposed that the relationship between hyper and hypo-

responsivity is best conceptualized not as a continuum but as part of a

multidimensional phenomenon that represents the interaction between an individuals

neurological threshold and behaviour response tendencies [103], or between internal

factors (i.e., attention, emotion, & sensation) and external factors (i.e., culture,

environment and relationship and task) [109]. This may be reflected by they fact

that these children’s behaviour are not consistent from day to day or even for the

same input, which has led theorists to believe that behaviour are part of a unified

underlying sensory modulation dysfunction. Sensory modulation disorder includes

three subtypes

(i) Sensory Overresponsivity (SOR):

Children with SOR respond to sensation faster with more intensity.

Overresponsivity may occur in only one sensory system (eg; tactile defensiveness)

or in multiple sensory systems (eg; sensory defensiveness). Behaviors in SOR range

from active, negative, impulsive, or aggressive responses to more passive

withdrawal or avoidance of sensation. Sympathetic nervous system activation is a

marker of SOR, which may result in exaggerated, fight, flight and fright or freeze

response [110]. The emotional responses include irritability, moodiness,

inconsolability, or poor socialization.

42

(ii) Sensory Underresponsivity (SUR):

Children with SUR do not respond to sensory stimuli in their environments.

They appear nor to detect incoming sensory information. This lack of initial

awareness may lead to apathy, lethargy, and a seeming lack of inner drive to initiate

socialization and exploration. Children with SUR are often labeled “lazy” or

“unmotivated”[111]

(iii) Sensory seeking/ Craving (SS):

Children with SS crave an unusual amount or type of sensory input and seem

to have an insatiable desire for sensation. They energetically engage in actions that

add more intense sensations to their bodies in many modalities (eg spicy food, loud

noises, visually stimulating objects, constant spinning). Active SS often lead to

socially unacceptable or unsafe behaviour, including constant moving, “crashing and

bashing”, “bumping and jumping”, impulsiveness, carelessness, and overexpression

of affection. They are frequently labeled “troublemakers,” “risk-takers”, “bad”, and

“dangerous”[111].

Parham and Mailloux [112] list five key limitations commonly demonstrated

by children with disturbances in sensory modulation:

1. Decreased social skills and participation in play

2. Disturbance in self confidence and self esteem

3. Difficulty with daily life skills and at school

4. Anxiety disturbances in attention and disturbances in the ability to

regulate reaction to others

5. Disturbances in skill development

This section reviewed about classification of sensory modulation disorder

and characteristics of children with sensory modulation problems.

43

3.8 PHYSIOLOGICAL RESPONSE IN CHILDREN WITH SENSORY

PROCESSING PROBLEM

Reynolds , Lane , Gennings [113] conducted a study to determine if sensory

overresponsivity (SOR) is a moderating condition impacting the activity of the

Hypothalamic Pituitary Adrenal (HPA) Axis in children with ADHD.Participants

were children with (n = 24) and without ADHD (n = 24). Children in the ADHD

group were divided into SOR (ADHDs) and non-SOR (ADHDt) groups using the

Sensory Over-Responsivity Inventory. All children participated in the Sensory

Challenge Protocol. Salivary cortisol was used as a measure of HPA activity. The

results of this study premise that SOR may be a moderating variable used to create

subgroups in diagnostic populations such as ADHD.

Lane , Reynolds, and Thacker [114] analyzed sensory overresponsivity and

ADHD by using electrodermal responses, cortisol, and anxiety.Deficits in sensory

modulation have been linked clinically with impaired attention, arousal, and

impulsivity for years, but a clear understanding of the relationship between sensory

modulation disorders and attention deficit hyperactivity disorder (ADHD) has

proven elusive. Our preliminary work suggested that patterns of salivary cortisol and

electrodermal responsivity to sensation may be linked to different groups of children

with ADHD; those with and without sensory over-responsivity (SOR). They

examined neuroendocrine, electrodermal and behavioral characteristics and sought

to predict group membership among 6- to 12-year-old children with ADHD and

SOR (ADHDs), ADHD and no SOR (ADHDt), and typicals (TYP). Behavioral

questionnaires were completed to document SOR and anxiety. Lab testing used a

Sensory Challenge Protocol (SCP) with concurrent electrodermal measurement and

the collection of cortisol prior to and following the SCP. Results suggest that ADHD

should be considered in conjunction with anxiety and sensory responsivity.

Gavin, et al., [115] did a study to determine whether children with sensory

processing disorder (SPD) differ from typically developing children on a

neurophysiological measure, the P300 component of event-related potentials

produced in response to brief auditory stimulation. They used

44

electroencephalographic measures (i.e., N200 and P300 components) to examine

auditory processing in 20 children with SPD and 71 typically developing children,

ages 5–10 yr. Children with SPD demonstrated significantly smaller P300

amplitudes and shorter N200 latencies than typically developing children. Brain

activity correctly distinguished children with SPD from typically developing

children with 77% accuracy. They concluded that children with SPD display unique

brain processing mechanisms compared with typical children.

Schaaf, et al., [116] conducted a pilot study to examine the role of

parasympathetic nervous system in children with disturbances in sensory processing.

A sample of 15 children, 9 with disturbances in sensory processing and 6 typically

developing children were recruited for the study. Heart period data were

continuously collected for a period of 2 minute baseline and also during

administration of 15 minute sensory challenge protocol. Groups were compared on

vagal tone index, heart period and heart rate using two-tailed, independent sample t-

tests. Results showed that children with disturbance in sensory processing had

significantly lower vagal tone than the typically developing children.

The literature concluded that children with sensory processing disorder

display unique brain processing mechanisms compared with typically developing

children.

3.9 ̀ SENSORY PROCESSING ABILITIES IN CHILDREN WITH AND

WITHOUT VARIOUS DISABILITIES

Su, et al., [117] did a study to compare stance control between children with

sensory modulation disorder and typically developing children in various visual and

somato sensory conditions. Thirty one children were recruited for this study which

included 17 children with SMD and 14 matched typically developing children. The

sensory profile was used to screen for Sensory Modulation problems, which were

further confirmed by measures of electrodermal response(EDR) and the evaluation

of Sensory Processing(SP). Stance parameter for an assessment of postural stability

was obtained with a dual-axis accelerometer on the lumbar area. The results for

stance showed a greater body sway in SMD group than in control group.

45

Gal, Dyck, & Passmore [118] conducted a study to find out association

between the severity of Sensory Processing Disorders (SPD) and the severity of

sensory modulation . The Short Sensory Pro�le (SSP) and the Stereotyped and Self-

Injurious Movements Interview were administered to children with autism,

intellectual disability, visual impairment, and hearing impairment and to typically

developing children. The results showed that SPD predicted the severity of SM in all

samples and accounted for differences in sensory modulation between the groups.

Other differences in the severity of sensory modulation were the result of diagnosis

and the interaction between diagnosis and an intellectual disability. They concluded

that SPD may be a source of sensory modulation, but functional connections

between these phenomena will need to be tested in future research.

Brown & Dunn [119] conducted a study to determine the relationship

between sensory processing and context for children with autism. Teachers and

parents of 49 students with autism completed the Sensory Profile School

Companion, and Sensory Profile. The avoiding quadrant score coefficient and the

seeking quadrant score coefficient were statistically significant with good and fair

correlations. The results suggest that sensory processing patterns have both universal

qualities and context-specific qualities in children with autism and this study provide

initial evidence that sensory processing and context for children with autism are

related.

John & Mervis [120] conducted a study on sensory modulation impairments

in children with Williams Syndrome (WS). They hypothesized that children with

Williams Syndrome (WS) would demonstrate symptoms of poor sensory

modulation. Parents of 78 children with WS aged 4-10 years completed Short

Sensory Profile (SSP). The results indicated that most children were classified as

having definite sensory modulation issues and children in the high impairment group

demonstrated poorer adaptive functioning, executive functioning, more problem

behaviors, and more difficult temperaments than children in the low impairment

group.

46

Newmeyer, Aylward, Akers, Ishikawa, Grether, Grauw, Grasha & White

[121] conducted a study to compare the results of the Sensory Profile in children

with a specific type of speech-sound disorder, Childhood Apraxia of Speech (CAS),

and to explore the relationship between sensory processing and sound-production

deficits. Thirty-eight children aged 3 to 10 years with suspected CAS were

evaluated. The results indicated that there is a difference for these children in

several factor clusters when compared to typical peers from the normative

population of the Sensory Profile and children with suspected CAS may present with

differences in sensory processing in addition to speech impairment.

Bharadwaj, Daniel, & Matzke [122] did a study to examine Sensory-

Processing Disorder (SPD) in children with cochlear implants and explored

the relationship between SPD and duration of hearing loss or duration of

cochlear implant use. Caregivers of 30 children completed the Sensory Profile

Questionnaire (SPQ). Seventy percent of the children showed “at-risk” or

“different” behaviors in one or more of five categories of the SPQ: auditory, visual,

vestibular, tactile, and oral processing. No noteworthy relationships surfaced

between duration of deafness or duration of cochlear implant use and the atypical

behaviors identified. To validate these findings further, Post Rotary Nystagmus

(PRN) testing and Miller’s Assessment for Preschoolers (MAP) were administered

to a subset of children. PRN was atypical in all 6 children tested. MAP findings

revealed atypical sensory processing in 4 of the 6 children. Findings suggested that

children with cochlear implants may be at risk for SPD.

Lane, et al., [123] investigated the specific patterns of sensory processing in

children with Autism Spectrum Disorders (ASD). A sample of 54 children

diagnosed as ASD was included. Model-based cluster analysis revealed three

distinct sensory processing subtypes in autism. These subtypes were differentiated

by taste and smell sensitivity and movement-related sensory behavior. Further,

sensory processing subtypes predicted communication competence and maladaptive

behavior. They concluded that this finding lay the foundation for the generation of

more specific hypotheses regarding the mechanisms of sensory processing

47

dysfunction in autism, and support the continued use of sensory-based interventions

in the remediation of communication and behavioral difficulties in autism.

Galvin, Froude & Imms [124] did a study to find out the sensory processing

abilities in children with sustained Traumatic Brain Injuries (TBI). A descriptive

study design with convenience sampling of 20 children of 3 to 10 age, who were

admitted to a Pediatric Neurosurgical Unit were included in the study. Information’s

provided by caregivers regarding their child’s sensory processing abilities were

collected using Sensory Profile. Proportionally more children with TBI than children

in the normative sample demonstrated behaviors outside of the typical range in all

sections of the Sensory Profile except for oral sensory processing. These findings

strongly support the need to include evaluation of sensory processing in any clinical

assessment of children who have sustained TBI.

Engel-Yegar, Shani-Adir, Sophia Raiber & Aharon Kessel [125] conducted a

study to compare the sensory modulation abilities of children with Allergic Rhinitis

(AR) to healthy peers. 28 children with moderate/severe persistent AR and healthy

children, aged 4–11 years, participated in this study. Sensory modulation abilities

were assessed using the Short Sensory Profile (SSP). Children with rhinitis showed

significantly worse sensory modulation abilities than in healthy children. The

highest percentage of children with rhinitis showed deficiencies in the Taste/Smell

Sensitivity and Low Energy/Weak SSP sections. The results indicate that children

with allergic rhinitis (AR) may suffer from sensory modulation deficiencies.

Ben-Sassan, et al., [126] did a study to identify extreme sensory modulation

behaviors in Toddlers with Autism Spectrum Disorder(ASD). Parent’s report of 101

toddlers with ASD was compared with 100 chronologically matched typically

developing toddlers and in additional 99 mental age matched toddlers. Measures

included were Infant/Toddler sensory profile, Infant/Toddler-Social Emotional

Assessment, Autism Diagnostic Review Revised and Autism Observation Schedule-

Generic. Results showed that toddlers with ASD were more distinct from typically

developing groups in their high frequency of under-responsive and avoiding

48

behaviors and their low frequency of seeking. There were significant associations

across sensory parent report measures within ASD group.

Engel, et al., [127] conducted a study to characterize the Sensory Processing

of children with Atopic Dermatitis(AD) as expressed in daily living. Patients with

AD (n=53) and healthy children (n=61), aged 3 to 10 years, participated in this

study. The severity of the disease was assessed using the Severity Scoring of AD

(SCORAD) score. The Sensory Processing was assessed using the Short Sensory

Profile. The results indicated that Children with AD demonstrated higher sensory

sensitivity than the control group except in vestibular sensation.

Pfeiffer, Kinnealey, & Reed [128] conducted a study to determine

relationships between dysfunction in sensory modulation, symptoms of affective

disorders, and adaptive behaviors in children and adolescents with Asperger’s

disorder. Parents of 50 children and adolescents between 6 to 17 years of age

diagnosed with Asperger’s disorder based on the Diagnostic and Statistical Manual

of Mental Disorders-IV criteria were included. They completed the (a) Sensory

Pro�le for children 6 to 10 years of age or the Adolescent/Adult Sensory Pro�le for

adolescents 11 to 17 years of age; (b) the Adaptive Behavior Assessment System:

Parent Version; (c) Revised Children’s Manifest Anxiety Scale Adapted Parent’s

Version; and (d) the Children’s Depression Inventory Adapted Parent’s Version.

The results indicated that there were signi�cantly strong positive correlations

between sensory defensiveness & anxiety and depression & hyposensivity in

children and adolescents with Asperger’s disorder. The data supports positive

relationships between anxiety and sensory defensiveness in all age ranges.

Rogers, Hepburn & Wehner, [129] conducted a study to find the parent

reports of sensory symptoms in toddlers with autism and other developmental

disorders. The Short Sensory Profile was used to assess parental report of sensory

reactivity across four groups of young children (n = 102). The groups were autism (n

= 26), fragile X syndrome (n = 20), developmental disabilities of mixed etiology (n

= 32), and typically developing children (n = 24). Groups were compared on overall

mental age (x = 22 months), and clinical groups were compared on chronological

49

age (x = 31 months). The results indicated that neither overall developmental level

nor IQ was related to abnormal sensory reactivity in children with autism or general

developmental disorders. However, abnormal sensory reactivity had a significant

relationship with overall adaptive behavior.

Dunn & Bennett [130] conducted a study to compare the sensory responses

of children with Attention Deficit Hyperactivity Disorder (ADHD) and children

without disabilities on the Sensory Profile. Parents of 70 children 3 to 15 years old

with a primary diagnosis of ADHD and parents of children without disabilities

matched by age and gender completed the Sensory Profile. Children with ADHD

differed significantly from children without disabilities in their sensory

responsiveness. The results indicate that Sensory Profile can contribute to diagnostic

and program planning processes and increase understanding of the nature of the

disorder of ADHD.

Watling, Deitz, & White [102] did a study to describe the sensory-based

behaviors of young children with autism as reported by their parents on the Sensory

Profile. Factor scores of children with autism were compared with those of children

without autism. The Sensory Profile questionnaire was completed by parents of 40

children with and without autism, 3 to 6 years of age. It was found that the

performance of children with autism was significantly different from children

without autism on 8 of 10 factors. Factors where differences were found included

Sensory Seeking, Emotionally Reactive, Low Endurance/Tone, Oral Sensitivity,

Inattention/ Distractibility, Poor Registration, Fine Motor/Perceptual, and others.

Findings from the study suggest that young children with autism have deficits in a

variety of sensory processing abilities as measured by the Sensory Profile.

Cosbey, Johnston & Dunn [131] conducted a study about the impact of

Sensory Processing Disorders (SPD) on children’s social participation. Two groups

of children with ages 6–9: (1) children with SPD and (2) their typically developing

peers participated in a structured interview to report their social participation

patterns, including activity patterns and social networks. A parent and teacher

questionnaire was used to triangulate the data gathered from the children. Results

50

revealed that the 2 groups of children demonstrated generally similar patterns of

activity preferences and use of free time but had significant differences in areas

related to intensity and enjoyment of involvement and in their social networks.

Williams, et al., [132] conducted a systematic review to identify relationship

between toe walking and sensory processing dysfunction. Forty-nine articles were

reviewed, predominantly sourced from peer reviewed journals. Five contemporary

texts were also reviewed. The literature styles consisted of author opinion pieces,

letters to the editor, clinical trials, case studies, classification studies,

poster/conference abstracts and narrative literature reviews. Literature was assessed

and graded according to level of evidence. They found that four contemporary texts

and one conference abstract discussed about relationship between toe walking and

sensory processing dysfunction and concluded that further investigation of this

relationship would be advantageous to confirm the hypothesis.

Schoen, Miller, Green & Nielsen [133] conducted a study to compare the

physiological and behavioral differences in sensory processing of children with

autism spectrum disorder and sensory modulation disorders. The Short Sensory

Profile was provided a measure of sensory-related behaviors. Physiological arousal

and sensory reactivity were lower in children with ASD whereas reactivity after

each sensory stimulus was higher in SMD, particularly to the first stimulus in each

sensory domain. The results indicated that both clinical groups had significantly

more sensory-related behaviors than typically developing children, with contrasting

profiles and ASD group had more taste/smell sensitivity and sensory under-

responsivity while the SMD group had more atypical sensory seeking behavior.

Franklin, Deitz, Jirkowic & Astley [134] conducted a study on children with

Fetal Alcohol Spectrum Disorders (FASD) and examined the relationship between

sensory processing and behavior. Outcomes on Short Sensory Profile (SSP) and

Child Behavior Checklist (CBCL) for children (n=44), of ages 5 to10 years, were

assessed and compared with retrospective data analysis. The results indicated that a

high portion of children demonstrated deficits in sensory processing and problem

51

behaviors when measured by SSP and CBCL. Moreover correlation between SSP

and CBCL total scores was significant.

Ashburner, Ziviani & Rodger [135] conducted a study to explore the

association between sensory processing and classroom emotional, behavioral and

educational outcomes of children with Autism Spectrum Disorder (ASD). Twenty

eight children with ASD (with average- range IQ ) were compared with 51 age –

gender – matched typically developing peer on sensory processing and educational

outcomes. They found that a pattern of auditory filtering difficulties, sensory under

responsiveness and sensory seeking was associated with academic

underachievement in children with ASD. Children who have difficulty processing

verbal instructions in noisy environments and who often focus sensory seeking

behavior appear more likely to underachieve academically.

Baker,et al., [136] did a study to examine the relationship between Sensory

Processing(SP) Patterns and Behavioural Responsiveness in Autistic Disorder.

Children diagnosed with Autistic disorder were recruited from the Early Intervention

Research Program (EIRP) for children with autism at Flinders University, South

Australia. They used Short Sensory Profile and Vineland Adaptive Behaviour Scales

(VABS)-Interview Edition and Developmental Behaviour Checklist—Parent (DBC-

P). They concluded that there is significant relationship between SP patterns and

social, emotional and behavioural function in children with Autistic Disorder.

Dunn, [107] gave a lecture regarding sensations of everyday life with

Empirical, Theoretical and Pragmatic consideration. This lecture reviews sensory

processing literature, including neuroscience and social science perspectives.

Introduced in Dunn’s Model of Sensory processing, and the evidence supporting this

model is summarized. Specifically, using Sensory Profile questionnaires (i.e., items

describing responses to sensory events in daily life; persons mark the frequency of

each behavior), person’s birth to 90 years of age demonstrate four sensory

processing patterns: sensory seeking, sensory avoiding, sensory sensitivity, and low

registration. These patterns are based on a person’s neurological thresholds and self-

regulation strategies. Psychophysiology studies verify these sensory processing

52

patterns; persons with strong preferences in each pattern also have unique patterns of

habituation and responsivity in skin conductance. Studies also indicate that persons

with disabilities respond differently than peers on these questionnaires, suggesting

underlying poor sensory processing in certain disorders, including autism, attention

deficit hyperactivity disorder, developmental delays, and schizophrenia. The author

proposes relationships between sensory processing and temperament and personality

traits. The four categories of temperament share some consistency with the four

sensory processing patterns described in Dunn’s model. As with temperament, each

person has some level of responsiveness within each sensory processing preference

The author suggests that one’s sensory processing preferences simultaneously reflect

his or her nervous system needs and form the basis for the manifestation of

temperament and personality.

The literature concluded that there is significant relationship between

sensory processing patterns and social, emotional and behavioural function in

children.

3.10 THE IMPACT OF SENSORY PROCESSING DISORDER ON

PERFORMANCE AREAS OF CHILDREN

Bagby, Dickie, & Baranek, [137] did a study to find out how sensory

experiences of children with and without autism affect family occupations. They

found that children’s sensory experiences affect family occupations in three ways:

(1) what a family chooses to do or not do; (2) how the family prepares; and (3) the

extent to which experiences, meaning, and feelings are shared.

Reynolds, et al., [138] conducted a Pilot study to examine the Activity

Participation, Sensory Responsiveness and competence in children with high

functioning Autism Spectrum Disorders. This pilot study explored activity patterns

in children with and without ASD and examined the role of sensory responsiveness

in determining children’s level of competence in activity performance. Twenty six

children with high functioning ASD and twenty six typically developing children 6-

12 years old were assessed using the sensory profile and the child behavior

53

checklist. Children demonstrating more frequent Sensory sensitivity and sensory

avoiding had significantly lower competence scores than the children with fewer

behaviors in these domains suggesting that sensory responsiveness may impact the

ability to participate successfully.

Koeng & Rudney [139] carried out a study to find out the performance

challenges for children and Adolescents with difficulty in processing and integrating

sensory information. A systematic review of the literature related to performance

difficulties for children and adolescents with sensory processing and integrating

sensory information was completed in this study. The review focused on functional

performance difficulties that these children may exhibit in areas of occupation

including play and leisure, social participation, activities of daily living,

instrumental activities of daily living, rest and sleep, education and work. The

results suggest that children and adolescents with difficulty in processing and

integrating sensory information do exhibit functional performance difficulties in key

areas of occupation.

Shum & Pang [140] conducted a comparative study to examine the standing

balance performance and sensory organization of balance control in children with

ADHD -Combined type (ADHD-C) and typically developing children. They

included 43 school aged children with ADHD-C and 50 age and sex matched

typically developing children. Sensory organization of standing balance was

evaluated using Sensory Organization Tests (SOT). In addition to the composite

equilibrium score, somatosensory, vestibular and visual ratios, which were indicator

of the ability of the child to use information from the respective sensory systems to

maintain balance, were computed. They concluded that children with ADHD-C had

significant deficits in standing balance performance in all conditions that included a

disruption of sensory signals. The visual system tends to be more involved in

contributing to the balance deficits in children with ADHD-C than the

somatosensory and vestibular system.

54

Jasmin. et al., [141] did a study to determine impact of sensori motor

abilities on Daily Living Skills(DLS) of pre school children with Autism Spectrum

Disorder(ASD). Thirty Five children, 3-4 years of age were recruited and assessed

with a battery of diagnostic and clinical tests. Results indicated that children exhibits

atypical sensory responses, very poor motor & daily living skills and sensory

avoiding, an excessive reaction to sensory stimuli, fine motor skills were highly

correlated with DLS.

Bar-Shalita, et al., [142] conducted a study in children with sensory

modulation disorder and the risk factors of these children for participation in daily

life activities. Participation in childhood daily functional performance was examined

in 78 children: Children with Sensory Modulation Disorder (n=44) and children

without sensory modulation disorder (n=33). The results indicate that Children with

SMD scored significantly lower on all three participation scales than the control

group. A high correlation was observed between level of activity performance of the

Participation in Childhood Occupations Questionnaire (PICO-Q) and the SSP, a

moderate correlation was observed between the Enjoyment of Performance of the

PICO-Q and the SSP and a low correlation was observed between Frequency of

Performance of the PICO-Q and the SSP.

Bundy, Shia, Qi, & Miller, [79] investigated the influence of Sensory

Processing Dysfunction (SPD) in playfulness. Twenty children with SPD and 20

children who were typically developing took the Short Sensory Pro�le (SSP) and

Test of Playfulness (ToP). Results indicated that sensory modulation affect

playfulness and Correlations among ToP and SSP ranged from .36 to .72; ToP and

SIPT, from –0.1 to –0.46.

Baranek.,et al., [94] conducted a study to examine sensory processing and its

relationship to occupational performance in children with fragile X syndrome

(FXS). Fifteen school-aged boys with full-mutation FXS were assessed with three

occupational performance measures (School Function Assessment, Vineland

Adaptive Behavior Scales, play duration) and three sensory processing measures

(Sensory Pro�le, Tactile Defensiveness and Discrimination Test–Revised, Sensory

55

Approach–Avoidance Rating). Results showed that avoidance of sensory

experiences (internally controlled) was associated with lower levels of school

participation, self-care & play and aversion to touch from externally controlled

sources was associated with a trend toward greater independence in self-care—

opposite of expectations.

This section concluded that sensory processing affects academic

performance, playfulness and social participation.

3.11 PREVALENCE OF SENSORY PROCESSING DISORDERS

Ben-Sasson, et al., [143] conducted a study in elementary school children to

find out the prevalence of Sensory Over Responsivity (SOR) behaviors and their

relation to social-emotional problems and competence. Nine hundred and twenty

children, aged 7 to 11 years were participated in the study. Sixteen percent of

parents reported that at least 4 tactile or auditory sensations bothered their children.

Parents of children with elevated SOR in school age reported high frequencies of

early and co-occurring internalizing, externalizing and disregulation problems, and

lower levels of concurrent adaptive social behaviors.

Ahn, & Miller [144] did a study to systematically examine estimated rates of

sensory processing disorders using survey data. Parents of incoming kindergartners

from one suburban U.S. public school district were surveyed using the Short

Sensory Pro�le, a parent-report screening tool that evaluates parents’ perceptions of

functional correlates of sensory processing disorders (McIntosh, Miller, Shyu, &

Dunn, 1999a). A total of 703 completed surveys were returned, which represents

39% of the kindergarten enrollment (n = 1,796) in the district for the 1999–2000

school year. Of the 703 children represented by the surveys, 96 children (13.7% of

703) met criteria for sensory processing disorders based upon parental perceptions.

A more conservative prevalence estimate of children having sensory processing

disorders based on parental perceptions was calculated by assuming that all non-

respondents failed to meet screening criteria. This cautious estimate suggests that

based on parents’ perceptions, 5.3% (96 of 1796) of the kindergarten enrollment met

screening criteria for sensory processing disorders. These percentages are consistent

56

with hypothesized estimates published in the literature. Findings suggest a need for

rigorous epidemiological studies of sensory processing disorders.

This section concluded that prevalence of sensory processing disorder is

increased in kindergarten school.

3.12 GRAVITATIONAL INSECURITY IN DEVELOPMENTAL

DISABILITIES

Ayres [2] recognized a subgroup of learning disability children who exhibit

excessive emotional reaction in response to movements or changes in position. She

confirmed that this type of child feels “fear, anxiety and agony whenever he is in a

position to which he is not accustomed or when he tries to assume a position or

when someone else tries to control his movement or position”. She labeled this

excessive emotional reaction to changes in position or movement called

Gravitational Insecurity. She acknowledged other indications which included fear

of falling, fear of inverted head position, inability to jump or have the feet leave off

the ground, reluctance to lie supine in a horizontal position and dislike of certain

everyday activities like walking over bumpy ground, climbing stairs, stepping over

objects, leaning backwards, riding in cars etc.

Ayres and Tickle [145] studied the hyper responsitivity to touch and

vestibular stimuli as a predictor of positive response to sensory integration by

autistic children. Ten autistic children of age group 3.6 years to 13 years were

evaluated in regard to the hypo, hyper and normal response to visual, auditory,

tactile, vestibular, proprioceptive, olfactory and gustatory stimuli. The results

suggested that tactile defensiveness, avoidance of movement, gravitational

insecurity and orienting response to air puff were good respondents

Steinberg and Rendle - Short [146] studied vestibular processing dysfunction

in children with mild neurological impairments. Twenty five subjects were recruited

for the study. Four subjects demonstrated extreme fear during the nystagmus that

they were unable to be tested further. The results suggested that the group of mildly

impaired children with hypo nystagmus consistently failed to react efficiently to

57

nonlinear movement through space and were unable to respond appropriately to

gravity.

Lee and Aronson [147] conducted a ‘moving room’ study to evaluate the

postural changes in response to the horizontal movement of the walls within their

visual fields. Three subjects in the group became so distressed when the room was

moved that they were unable to continue participation in the study. The study results

concluded that since the subjects had appeared quite content during the pretest

period, their distress was presumably due to their instability when the room was

moved.

Weisberg [148] examined the autonomic nervous system responses of a

matched group of four normal and four developmentally delayed, gravitationally

insecure preschooler to auditory and gravitational stimuli. The results were

determined that developmentally delayed children had higher resting and

sympathetic states than the normal children as measured by Galvanic Skin Response

(GSR). Also the delayed children had higher mean skin temperature during

sympathetic arousal states.

The literature concluded that gravitational insecurity is commonly seen in

learning disability, Autism and attention deficit children.

3.13 GRAVITATIONAL INSECURITY ASSESSMENT

May Benson & Koomar [8] developed an observational assessment of

gravitational insecurity (GI) and examined its preliminary reliability and validity

evidence. The GI Assessment consisted of 15 activities with three behaviour

categories —avoidance, emotional, and postural responses—were scored for each

activity. Eighteen Gravitational Insecurity children, ages 5-10 years and a matched

group of children who were typically developing. Forty-eight preschoolers who

were typically developing, ages 2–4 years, were examined for developmental trends.

The results showed that significant differences were found between GI group and

typically developing children group. Discriminant analysis classified 83% of the

gravitationally insecure group and 100% of the typical group. Further stepwise

discriminant analysis revealed that 9 items were sufficient to discriminate two group

58

of children. Emotional response and behavioural response has more discriminant

power than avoidance behaviour. Finally GI assessment was revised from 15 items

to 9 items with two behavioural categories-emotional responses and postural

responses. Interrater reliability for the total test was .79. Performance of preschool

children on GI assessment suggested a developmental age trend.

The GI Assessment is a promising clinical tool for objectively identifying

children with gravitational insecurity.GI assessment(revised version) is time

consuming and it has to be refined [8]. Hence current study was carried out to refine

Gravitational Insecurity assessment among Indian children and examined reliability

and validity.