understanding a dizzy adult

8/2/2019 Understanding a Dizzy Adult

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Evaluation of a dizzy adult

Dr. R. Srinivasa Raghavan

Royal National Nose Throat and Ear HospitalLondon


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dizziness

vertigo balance problem

light headed

travel sickness panic attack

disequilibrium dont like turning right quickly

dont like supermarkets any more ?!?!?


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Wanted:

A system that reacts promptly andaccurately to head movements


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Proprioception Labyrinth Visual input

3D movementbalanceGaze stabilisationVestibulo ocular reflex

Graviceptors

Autonomic regulationCircadian rythm
http://www.joelertola.com/tutorials/heart/img/heart.jpg


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Mechanism of rotation detection

semicircular canal Utricle and Saccule


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Transducers


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Push-Pull Principle


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Ambiguity of the otolith system


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6 ways to move

3 Rotations

3 Translations

SCC

Utriculussacculus


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Vestibular system

1) provide general orientation of the bodywith respect to gravity

2) enable balanced locomotion and bodyposition

3) readjust autonomic functions after body

reorientation and4) ensure gaze stabilisation


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Ocular stabilising systems VOR

maintenance of gaze during head movements saccades (350 0 - 600 0 /s)

maintenance of visual target on fovea by either

voluntary effort or involuntary reflex (i.e. fast phaseof nystagmus) smooth pursuit (


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Vestibulo-ocular ReflexVOR:Stabilises images on the retina duringhead movements, by moving the eyesin a direction opposite to that of headmovement

Includes the semicircular canal ocularreflexes and otolith-ocular reflexes.


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Working principle of the VOR for gazestabilization


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Anatomical basis of the VORThree Neuron arc 1st order neurons from

vestibular sensoryapparatus

2nd order neurons fromvestibular nuclei

3 rd order neurons fromexternal ocular motornerve nuclei to theexternal ocular muscles


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Impairment of VOR

Unilateral vestibular damage results in twotypes of abnormality within VOR

Static imbalance -difference in tonic dischargerate between vestibular nuclei on two sides

spontaneous nystagmus

Loss of dynamic sensitivity - during rotationdecreased gain of VOR Oscillopsia

Smith and Curthoys,1988


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Tests for VOR

Head thrust (Halmagyi and Curthoys,1988) Head shaking nystagmus test

Vestibular Dynamic Visual acuity test Calorics


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Head Thrust test

Patient fixates on a target (examinersnose). Eye position observed after rapidthrust of head to right and left. Duringhead thrust toward side of lesion, there iscatch up saccade.


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Head shaking nystagmus test

Patient closes eyes and flexes head downto 30 , then head oscillated 20 times in thehorizontal plane. At the end if VORimpaired, nystagmus to opposite side oflesion.


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Saccades

check saccades i.e fast eye movementslook back and forth between 2 targets andobserve: reaction time (latency) accuracy

velocity


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Saccadic abnormalities:CNS pathology or ocular myopathy

Cerebellar dysmetria under or over-shooting (hypo- or hypermetria)

Internuclear ophthalmoplegia (INO) (failure of ad duction, n ystagmus in ab ductimg eye)

Lesion of parapontine reticular formation (PPRF)(contralateral gaze palsy)

Lesion of frontal cortex (ipsilateral gaze palsy) One and a half syndrome

Failure of conjugate gaze in one direction in INO and other Supranuclear degeneration (Steele-Richardson-Olszewski)

Latency with vertical EM affected before horizontal


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Smooth pursuiti.e tracking eye movements

check in both horizontal and vertical planes

if pursuit is broken, in which direction?


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Abnormalities of smooth pursuit

Horizontal Cerebellum Pons

Parieto-occipital lobe Vertical

Downward: low brainstem Upward: pre-tectal, basal ganglia

Note: age, alcohol, psychotropic medication,anticonvulsants


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Adaptation in vestibular hair cells

It avoids saturation of hair cell responsiveness bylarge or sustained stimuli

It allows a cell to detect small stimuli in thepresence of an enormous background input It places the hair cell bundle in a sensitive region of

its operating domain


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BPPVVestibular neuritis

Herpes zoster oticusMeniere's diseaseLabyrinthine concussionPerilymphatic fistula Semicircular canaldehiscence syndromeCogan's syndrome

Recurrent vestibulopathyVestibular schwannoma (acoustic neuroma)Aminoglycoside toxicityOtitis media

CENTRAL ETIOLOGIESMigrainous vertigoBrainstem ischemiaTIA Wallenberg's syndromeCerebellar infarction and hemorrhageChiari malformation


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BPPVThe dizziness is brief usually seconds, rarely minuteswhen turning in bed or tilting the head

nausea but rarely vomit predictably provoked and continue for weeks or months Episodes may recur.

Diagnosis History Dix-Hallpike positive in only 50 to 80%


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Vestibular Neuritis Rapid onset severe, persistent vertigo (one or two days) Nausea, vomiting and gait instability

spontaneous vestibular nystagmus, a positive head thrust test, and gait instability without a loss of the ability to ambulate

Cerebellar haemorrhage or infarction may be similar


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Meniere's disease Peripheral vestibular disorder Excess endolymphatic fluid pressure episodic inner ear dysfunction spontaneous episodic vertigo minutes to hours unilateral tinnitus, hearing loss, and ear fullness the vertigo is often severe nausea and vomiting and disabling imbalance

The disequilibrium may last for several days Horizontal-torsional nystagmus is typically seenon examination during an attack

C ti il t l l i


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Compensation upon unilateral lesion

Left Vest Nucl Right Vest Nucl


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Prevalence of unexplained symptoms inmedical clinics at UK Teaching Hospital

Clinic Prevalence (95% CI)

ChestCardiologyGastroenterologyRheumatologyNeurologyDentalGynaecology

59% (46-72)56% (46-67)60% (45-73)58% (47-69)55% (45-65)49% (37-61)57% (50-68)

Total 56% (52-60)

Prof. S. Wessely, BMJ. 2001 March 31; 322(7289): 767


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One study showed 20% of consecutivepatients evaluated in a dizziness clinic had

panic disorder(Clark et al 1994)


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Anxiety / panic attacks secondary tovestibular dysfunction

The reported incidence is 15-28%

15% Stein et al 1994 16% Sullivan et al 1993 17.2% Persoona et al 2003 20% Yardley and Beech 2001 20.4% Clark and Leslie 1992 26% Honrubia et al 1996 27.8% Yardly and Masson 1992


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The reported incidence of Depression

secondary to vestibular dysfunction5-38%

5% Sullivan et al 1993 7.1% Yardly and Masson 1992 11% Kroenke et al 1993 11.2% Persoona et al 2003 37.4 % Honrubia et al 1996 38 % Eagger at al 1991


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Vestibular Anxiety and Panic- two types

Primary (early/somatic) hard wired component Immediate somatopsychic response to disorientation Instinctive

Secondary (late/cognitive) Fear (cognition) regarding future attacks of dizziness Its social consequences and disability Worries about illnesses such as tumours/ mental illness

Begins when pt begins to worry about significance of symptoms

Jacob RG et al 2003


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Rehab is the Key to the managementof vestibular imbalance


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Balance-Anxiety Link

Parabrachialnucleus (PBN)network mediatevisceral, vestibularand extra-vestibularinformation

PBN networkgenerate emotional,affective andphysiological

manifestations offear and anxiety

(Balaban and Thayer, 2001)


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1. Prof. Floris Wuyts, Head of the Vestibular Function Lab & Research,University Antwerp (Research co- operation with NASA)

2. Baloh and Honrubia, Clinical Neurophysiology of the Vestibular System,Oxford publication, third edition

3. Clark, D. B., Hirsch, B. E., Smith, M., Furman, J. M. R., & Jacob, R. G.(1994). Panic in otolaryngology patients presenting with dizziness orhearing loss. American Journal of Psychiatry, 151(8), 1223-1225.

4. Prof. S. Wessely, BMJ. 2001 March 31; 322(7289): 767

understanding a dizzy adult

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