ca review on cns

7/31/2019 CA Review on Cns

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I. NEUROANATOMY


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Anatomy and Physiology

Gross anatomy

The nervous system is divided into the central

and peripheral nervous system

The Central nervous system consists of the

BRAIN and the Spinal Cord

The peripheral nervous system consists of theSpinal nerves and the cranial nerves


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BRAIN

The Brain is divided into 3 major areas:

1. Cerebrum

2. Brain Stem3. Cerebellum


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BRAIN- 1. Cerebrum

The largest part of the brain. Composed of:

2 hemispheres- the right and left, and the basal

ganglia.

The hemisphere is connected by corpus callosum, aband of fibers.

Each hemisphere is divided into 4 lobes.


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The 4 Lobes of the CEREBRUM

1. Frontal Lobe Largest lobe

location: frontof the skull.

contains theprimary motor cortexand responsible

for functions related to motor activity.

The left frontal lobe containsBrocas area(controlthe ability to produce spoken words)

The frontal lobecontrols higher intellectualfunction, awareness of self, and autonomic

responses related to emotions.


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2. Parietal

Sensory lobe

location: near the crown of the head.Contains theprimary sensory cortex.

One of its major function is to process sensory inputsuch asposition sense, touch, shape, and consistency

of objects.3. TemporalLocation: around the temples.

Contains theprimary auditory cortex.

Wernickes area is located on left temporal lobe. Contains the interpretative area where auditory, visual and

somatic input are integrated into thought and memory


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Lobes-cont.

4. Occipital

Location: lower back of the head

Contains theprimary visual cortex

Function: responsible for visual

interpretation.


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THE 4 LOBES

Frontal- motor /controlshigher intellectualfunction, awareness ofself, and autonomicresponses related toemotions.

Parietal- sensory

Temporal-auditory(Wernickes); Containsthe interpretative areawhere auditory, visualand somatic input areintegrated into thoughtand memory

Occipital-visual


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Structure of the Brain


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BRAIN-2. Brain Stem Consist of the midbrain, pons, and medulla oblongata.

Midbrain

-connects the pons and the cerebellum with the cerebralhemisphere, it contains sensory and motor pathways

-center for auditory and visual reflexes

Pons-connects the two halves of the cerebrum

- involved in the integration of movements in the right and leftsides of the body, and the transmission of motor informationfrom the higher brain areas and the spinal cord to the

cerebellum.medulla oblongata

- involved in the respiration, circulation, gastrointestinalfunctioning, coughing, sneezing, and swallowing.


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BRAIN-3. Cerebellum

Location: base of the brain.

Responsible for coordination, balance and

posture.

Damage to the cerebellum can resultinataxia, a

condition characterized by drunken-like

movements, severe tremors, and loss of

balance.


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Structures Protecting the Brain

The brain is contained in the rigid skull, whichprotects it from injury.

The meninges(fibrous connective tissuesthat cover the brain and the spinal cord)

provide protection, support and nourishmentto the brain and the spinal cord.

Layers of the meninges:

1.dura mater

2.arachnoid

3.pia mater.


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CSF

CSF- provide a cushion, provide nutrition,maintain normal ICP, remove metabolic waste.

Composition colorless, odorless fluid containing

glucose, electrolytes, oxygen, water, small amountof carbon monoxide and few leukocytes.

Produced in the choroid plexus of the ventricles.


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BLOOD SUPPLY TO THE CNS

1/3 of the cardiac output

From 2 vertebral artery and one internal

carotid arteries

Circle of willis


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Spinal Cord

Approximately 45 cm long (18 inches) long.

Acts as apassageway for condition of

sensory information from the periphery

of the body to the brain (via afferent

nerve fibers).

Serve as the connection between the brain and

the periphery.Mediates the reflexes.


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Spinal Nerves Spinal nerves

31 pairs 8 cervical, 12 thoracic, 5 lumbar

5 sacral, 1 coccygeal

Two roots

Ventral root (motor)

Carry impulses from the spinal cord to themuscles

Dorsal root (sensory)

Carry impulses from sensory receptors to thebody of the spinal cord

Then to brain for interpretation

Initiate a reflex response

Dermatome distribution


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Cranial Nerves

12 pairs

emerge from theundersurface of the brain.

Cranial nerve conductsimpulses (motor andsensory information)between the brain andvarious structures of thehead, neck, thoracic cavityand abdominal cavity.

IOlfactory nerve

IIOptic nerve

IIIOculomotor nerve

IVTrochlear nerve

VTrigeminal nerve

VIAbducens nerve

VIIFacial nerve VIIIAcoustic/Vestibulococ

hlear

IXGlossopharyngeal

nerve

XVagus nerve XIAccessory nerve

XIIHypoglossal nerve


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Autonomic Nervous System

Contains motor neurons that regulate

visceral organs & innervate ( supply

nerves to ) smooth & cardiac muscles& the glands


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TWO PARTS OF ANS

1. sympathetic nervous system

Controls the fight or flight response

2. parasympathetic nervous systrem

Maintains the baseline of the body functions

Resposible for the rest & digest response


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the NEURON or NERVE CELL is the nervous systems

fundamental unitthis highly specialized conductor cell receives and

transmits electrochemical nerve impulses

delicate, threadlike nerve fibers called

AXONS & DENDRITES extend from thecell body & transmit signals

Axons carry impulses away from the

cell body;dendrites carry impulses to the

cell body


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Each neuron communicates with each

other to a specific target tissue through

neurotransmitters

These neurotransmitters are produced

& stored in the synaptic vesicles;theyenable conduction of impulses across the

synaptic cleft

The action of neurotransmitters is to

potentiate, terminate or modulate a

specific action & can either excite orinhibit the target cells activity.

MAJOR NEUROTRANSMITTERS:

1. Acetycholine

2. Serotonin

3. Dopamine4. Norepinephrine

5. Gamma-aminobutyric acid (GABA)

6. Enkephalin,endorphin


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II. NEUROLOGICAL ASSESSMENTS


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NEUROLOGICAL ASSESSMENT

I. Mental Status: Reveals cerebral function (intellectual and

affective) Major areas of assessment:

a. Languageb. Orientationc. Memory d. Attention span

e. Calculation

Level of consciousness


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A. Language

Aphasia

inability to express oneself by speech,

writing or comprehend spoken or writtenlanguage due to disease of cerebral cortex

Two Categories:1. Sensory or receptive aphasia

2. Motor or expressive aphasia


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1. Sensory/receptive aphasia

- loss of ability to comprehend written orspoken words

Two types:a. Auditory aphasia unable to understand

symbolic content associated with sounds

b. Visual aphasia unable to understand printed

or written figures


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2. Motor/ expressive aphasia

- loss of power to express oneself by writing,making signs or speaking

How to assess language deficits: Point to common objects and name them

Read some words and match printed and writtenwords with pictures

Respond to verbal/written commands


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Speech Patterns:

- pace, clarity, spontaneity

Abnormalities:

a. Perseveration

- repeating the same response as differentquestions are asked

b. Paraphasia- speech appropriately expressed but containsincorrect words


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B. Orientation 3 spheres

C. Memory

- Listen for lapses of memory

- If problems are present:

Three categories of memory:

1. Immediate recall

N: can repeat series of 5

8 digits in sequenceand 4 6 digits in reverse order


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C. Memory

2. Recent memory

- Ask to recall the events of the day- Recall information given early in the

interview

- Provide 3 facts to recall (color, object,address), then ask later


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C. Memory

3. Remote memory

- Previous illness or surgery (years ago), birthday,

anniversaryD. Attention Span

- Tests the ability to concentrate

(alphabet, count backward from 100)


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E. Calculation

- Serial seven or serial three test

N: can complete serial seven in 90 secondswith 3 or less errors


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Mental status

Utilize the Glasgow Coma Scale

An easy method of describing mental status

and abnormality detection

Tests 3 areas- eye opening, verbal response

and motor response

Scores are evaluated- range from 3-15

NoZERO score


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Glascow Coma Scale

Score BEST response

in each category

Highest score = 15

(normal)

Lowest score = 3

(deep coma)

Eye OpeningSpontaneous

To Voice

To Pain

None

Best VerbalOriented

Confused

Inappropriate Words

Incomprehensible Sounds

None

Best MotorObeys Commands

Localizes Pain

Withdraws to Pain

Flexion to Pain (decorticate)

Extension to Pain (decerebrate)None

4

3

2

1

5

4

3

2

1

65

4

32

1


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Altered Level of Consciousness (LOC)

Confusion

Delirium

Impaired ability to think clearly

Disturbed ability to perceive, respond to, and

remember current stimuli

Disorientation Functional in activities of daily living (ADLs)

Motor restlessness

Increased disorientation

Transient hallucinations

Delusions possible

Requires some assistance with ADLs

can result from destruction of the brain stem or its reticular formation of ascending

nerves, or from other structural, metabolic, or psychogenic disturbances.


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Altered Arousal/Level of Consciousness (LOC)

cont.

Obtundation

Stupor

Coma

Decreased alertness

Psychomotor retardation

Requires complete assistance with ADLs

Arousable but not alert

Severe disorientation

Little or no spontaneous activity

Unarousable

Unresponsive to external stimuli or internal needs

Determination commonly documented usingGlasgow Coma Scale score


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Altered Movement

Involves certain neurotransmitters (ex. dopamine)

Hyperkinesia- excessive movement

Hypokinesia- decreased movement

Marked byparesis- partial loss of motor function and

muscle power; commonly described as weakness;

can result from destruction of upper & lower motor

neurons


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Cranial Nerve Function

Assess cranial nerve function.


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CRANIAL NERVESCranial Nerves

I olfactory smell

II optic vision

III oculomotor Most eye movt, pupillary constriction, upper eyelid elevation

IV trochlear Down & in down movt

V trigeminal Chewing, corneal reflex, face & scalp sensations

VI abducent Lateral eye movement

VII facial Expressions in forehead

VIII acoustic Hearing & balance

IX glossopharynge

al

Swallowing, salivating, taste

X vagus Swallowing, gag reflex, talking, sensations of the throat, larynx & abdl viscera,activities of thoracic & abdl viscera, e.g. HR, & peristalsis

XI accessosy Shoulder movt, head rotation

XII hypoglossal Tongue movt


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Cranial Nerve Function: Cranial Nerve

1- Olfactory

Check first for the patency of the nose

Instruct to close the eyes

Occlude one nostrils at a time

Hold familiar substance and asks for the

identification

Repeat with the other nostrils

PROBLEM- ANOSMIA- loss of smell


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2- Optic

Check the visual acuity with the use of the

Snellen chart

Check for visual field by confrontation test

Check for pupillary reflex- direct and

consensual


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Snellen chart


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3, 4 and 6

Assess simultaneously the movement of the

extra-ocular muscles

Deviations:

Opthalmoplegia- inability to move the eye in a

direction

Diplopia- complaint of double vision


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C i l N F i C i l N


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5 -trigeminal

Sensory portion- assess for sensation of the

facial skin

Motor portion- assess the muscles of

mastication

Assess corneal reflex

C i l N F i C i l N


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7 -facial

Sensory portion- prepare salt, sugar, and

vinegar. Place each substance in the anterior

two thirds of the tongue, rinsing the mouth

with water

Motor portion- ask the client to make facial

expressions, ask to forcefully close the eyelids


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Cranial Nerve Function: Cranial Nerve 8- vestibulo-

auditory

Test patients hearing acuity

Observe for nystagmus and disturbed balance


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Cranial Nerve Function: Cranial Nerve 9-

glossopharyngeal

Together with Cranial nerve 10vagus

Assess for gag reflex

Watch the soft palate rising after instructing

the client to say AH

The posterior one-third of the tongue is

supplied by the glossopharyngeal nerve

C i l N F ti C i l N


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11- accessory

Press down the patients shoulder while he

attempts to shrug against resistance

C i l N F ti C i l N


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12- hypoglossal

Ask patient to protrude the tongue and note

for symmetry

3. Motor System Function


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3. Motor System FunctionAssess muscle size (inspect and palpate) tone, and strength;

assess symmetry differences between right and left side; balance

and coordination.

Altered Muscle Tone

Hypotonia- severely reduced degree oftension or resistance to movement in a muscle

Hypertonia- marked increase in a muscle

tension and decreased ability of a muscle tostretch


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MUSCLE GRADING

5- Normal-Complete range of motion against gravity with full resistance

4- Good

-Complete range of motion against gravity with some resistance

3- Fair

-Complete range of motion against gravity2- Poor

-Complete range of motion against gravity eliminated

1- Trace

-Evidence of slight contractility. No joint motion.

0- ZeroNo evidence of contractility


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4.Sensory FunctionTest for:

superficial tactile sensation superficialand deep pressure pain

thermal sensitivity

sensitivity to vibration point localization.

Reflexes

Evaluate deep and superficial reflexes(biceps, triceps, patellar, ankle reflexes)and abnormal reflexes (Babinskis reflex).


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4.Sensory Function

Primary Sensory Functions Always with the persons eyes closed

Vision, hearing, smell, taste and facial sensations

Part to be Assess Hands

Lower arms

Abdomen

Feet

Lower legs


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4.Sensory Function

Primary Sensory Functions Superficial touch

Use a cotton wisp

Have the person point to the area touched

Superficial pain

Sharp and dull sensations

Allow 2 seconds between each stimulus

Temperature and deep pressure ONLY TESTED when superficial pain sensation is not

intact


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4.Sensory Function

Primary Sensory Functions

Vibration

Place stem of tuning fork against bony prominences

Begin distally

Sites

Sternum

Finger wrist elbow - shoulder

Toes ankle shin

Position of joints (great toes, one finger on each hand) Up

Down


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4.Sensory Function

Cortical Sensory Functions

Always with the persons eyes closed

Stereognosis

Ability to identify a familiar object by touch andmanipulation

Tactile agnosia: inability to recognize objects

Graphesthesia

With a blunt pen, draw a letter or number on the palm

Should be readily recognized


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4.Sensory Function

Cortical Sensory Functions

Point location

Touch an area of the body and ask the person to point

to where you have touched This is being tested the same time as superficial touch

Extinction phenomenon

Simultaneously touch one or both sides of the body

Ask the person to point to where you have touched


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4.Sensory Function

Cortical Sensory Functions Two-point discrimination

Use two pointed objects, alternate touching skin withone or two points

Find the distance at which the person can no longerdiscriminate 2 points

Fingertips 2 - 8 mm

Toes 3 - 8 mm

Palms 8-12 mm Forearms 40 mm

Upper arms and thighs 75 mm


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Proprioception/Cerebellar Function

Proprioception

The sensation of position and muscular activity

originating from within the body which provides

awareness of posture, movement, and changes inequilibrium

Test

Coordination and Fine Motor Skills

Balance


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Coordination and Fine Motor Skills Rapid rhythmic alternating movements

Have seated person alternately pronate and supinatehands, patting knees, and gradually increasing speed

OR Have person touch thumb to each finger on the same

hand sequentially from index to little finger and back,gradually increasing speed

person should be able to do these movementssmoothly, maintaining rhythm, with increasing speed

Observe for slow, stiff, non-rhythmic, or jerkymovements


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Accuracy of movement

Finger-to-finger test with persons eyes open Movements should be rapid, smooth, and accurate

Consistent past pointing may indicate cerebellar impairment

Finger to nose test with persons eyes closed

Movement should be smooth, accurate, and rapid

Heel-to-shin with person supine, sitting, or standing

Should move heel from knee up and down the shin in a

straight line, without irregular deviations to the side


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Balance: Equilibrium

Romberg test Have person stand with arms at side and feet together

Have person perform initially with eyes open and then with

eyes closed

Stand close to prevent falls

person should maintain position with eyes open or closed for

20 seconds with only minimal swaying

If the Romberg is positive (i.e. there is significant swaying or

the person has to take a step to maintain/regain balance) DO

NOT DO OTHER TESTS OF BALANCE
http://www.webster.edu/~davittdc/ear/romberg/romberg.mov


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III.DIAGNOSTIC TEST


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DIAGNOSTIC TESTS

EEG - Graphic record of the electrical activity generated in the brain. EEG is a useful test for diagnosing and evaluating seizure

disorders, coma, or organic brain syndrome.

Nursing implication: Withhold medications that may interfere with the results-

anticonvulsants, sedatives and stimulants Wash hair thoroughly before procedure

Explain the procedure, assure the client he/she will not receiveelectrical shock.

The nurse needs to check doctors order regarding the administration

of antiseizure medication prior to testing. Withhold tranquillizer and stimulants for 24 to 48 hours.

Inform the client that the standard EEG takes 45 to 60 minutes and 12hours for sleep EEG.


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DIAGNOSTIC TESTS


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DIAGNOSTIC TESTS

CT scanVisualize sections of the spinal cord as well as intracranial contents

The injection of a water-soluble iodinated contrast into thesubarachnoid space through lumbar puncture helps

noninvasive and painless

has a high degree of sensitivity for detecting lesions.Use of xray beams cross section

Use : to identify intracranial tumor, hemorrhage, cerebral atrophy,calcification, edema, infarction, congenital abnormality.

With radiation risk If contrast medium will be used- ensure consent, assess for

allergies to dyes and iodine or seafood, flushing and metallictaste are expected as the dye is injected

DIAGNOSTIC TESTS


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MRI

Uses magnetic waves

Patients with pacemakers, orthopedic

metal prosthesis and implanted metal

devices cannot undergo this procedure


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DIAGNOSTIC TESTS

Cerebral arteriographyIs an x-ray study of the cerebral circulation with a contrastagent injected into a selected artery (femoral)

Visualize aneurysm

Nursing considerationNote allergies to dyes, iodine and seafood

Ensure consentKeep patient at rest after procedure

Maintain pressure dressing or sandbag overpunctured site


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Lumbar Puncture

is a procedure to collect cerebrospinal fluid tocheck for the presence of disease or injury.

A spinal needle is inserted, usually between the3rd and 4th lumbar vertebrae in the lower spine.Once the needle is properly positioned in the

subarachnoid space (the space between the spinalcord and its covering, the meninges), pressures canbe measured and fluid can be collected for testing.

DIAGNOSTIC TESTS


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DIAGNOSTIC TESTS

Lumbar puncture

Nursing considerations

Ensure consent, determine ability to lie stillContraindicated in patients with increased

ICP

Keep flat on bed after procedureIncrease fluid intake after procedure


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