Cranial Nerves Examination and common pathologies Agata Plonczak - - PowerPoint PPT Presentation

Cranial Nerves

Examination and common pathologies

Agata Plonczak

Tuesday Jan 15th 2013

Approach to Examination

Where is the lesion? Cranial nerves can be affected as single nerves or in groups There are 12 cranial nerves arising from the brainstem

The olfactory (I) nerve

• Sensory nerve conveying the sense of smell

Brainstem –anterior view

The olfactory (I) nerve -examination

• Rarely performed
• Ask patient if they noticed any change of smell

1.Check nasal passages clear 2.Ask pt to close eyes and shut one nostril with one finger 3.Use common, easily recognizable, non-irritant substance eg orange, coffee

CN I –abnormal findings

Anosmia usually due to nasal rather than neurological disease Olfactory nerve is vulnerable as it passes through cribriform plate May occur in Parkinson’s or Huntington’s diease

The optic (II) nerve

• Sensory nerve conveying the sense of vision from

the retina

The optic (II) nerve -anatomy

The optic (II) nerve -examination

• 1. Visual acuity
• 2. Visual fields including sensory inattention
• 3. Colour vision
• 4. Pupillary responses
• 5. Fundoscopy

Visual acuity

• Sharpness, clarity of vision
• Assessed formally using a Snellen chart
• In good light patient should stand 6m away from

chart

• Number above each line =distance from which a

person with normal sight should be able to read from

• Indicate results as: distance from chart/distance it

should be read eg. 6/24 (normal vision = 6/6)

Visual acuity cont.

• If the patient can’t read any letters, record if they

can:

• Count Fingers held in front of their face
• See Hand Movements
• Perceive Light
• Record as: CF, HM, PL or NPL

Visual fields

• Normal visual field extends 160 degrees horizontally

and 130 degrees vertically

• Blind spot is located 15 degrees to the temporal side
• f the visual fixation
• Test by confrontation
• Sit 1 metre apart at the same level, ask patient to

keep looking into your eyes

• Start with sensory inattention

Visual field defects

Pupillary responses

• Autonomic nervous system and integrity of iris

determine the size of resting pupil

• Parasympathetic fibres

pupillary constriction

• Sympathetic fibres

pupillary dilatation

Pupillary responses –examination

• Examine for shape and symmetry in good light
• Ask patient to fix the eyes on a distant point ahead
• Bring a bright light from the side to shine on the

pupil

• Look for direct and consensual light reflex (+/-

RAPD)

• Test accomodation

The oculomotor (III), trochlear (IV) and abducens (VI) cranial nerves

• CN III supplies the levator palpebrae superioris which opens

the upper eyelid as well as all extraocular muscles but SOL and LR

• In addition it carries parasympathetic fibres causing

constriction of the pupil

• CN IV superior oblique
• CN VI lateral rectus

Brainstem –anterior view

CN III, IV and VI –examination

• Inspect the position of eyelids
• Ask the patient to follow your index finger in vertical,

horizontal and oblique planes avoiding extremes of gaze, drawing an imaginary H line in front of them

• Ask for any diplopia
• Examine for saccadic eye movements

CN III, IV, VI –abnormal findings

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Horner’s syndorme

Interuption of sympathetic nerve suppy to the iris 1.Miosis 2.Enopthalmos (sunken eyes) 3.Ptosis 4.Ipsilateral anhidrosis Causes: demyelination, vascular disease, Pancoast tumour , syringomyelia, carotid aneurysm

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Complete ptosis associated with widely dilated pupil, eye paralysed with outward and downward deviation Causes: mononeuritis multiplex, posterior communicating artery aneurysm, midbrain lesion

CN IV and VI palsies

Trochlear nerve palsy: rare in isolation, diplopia on looking down and in often noticed on walking down stairs, compensated for by turning of head Abducens nerve palsy: loss of eye abduction, horizontal diplopia on looking out, often false localising sign!!!

Nystagmus

• Involuntary, often jerky eye oscillations
• ≤ 2 beats and at extremes of gaze normal

Horizontal: Often due to vestibular or cerebellar lesions If more in whichever eye abducting can be due to MS: -INO If associated with deafness, tinnitus: Meniere’s If varies with head position: consider BPPV Vertical: ask neurologist

CN IV and VI palsies

Trochlear nerve palsy: rare in isolation, diplopia on looking down and is often noticed on walking down stairs, compensated for by turning of head Abducens nerve palsy: loss of eye abduction, horizontal diplopia on looking out, often false localising sign!!!

Trigeminal (V) nerve

• Sensory: somatic sensation to face
• Motor: muscles of mastication (masseters, temporalis,

pterygoids)

• Corneal reflex
• Jaw jerk

Brainstem –anterior view

Trigeminal (V) nerve -examination

• Sensory: assess light touch for each branch, choose 3 spots on each

side (ie forehead, cheek and mid-way along jaw) + test pin-prick sensation

• Motor: ask patient to clench their teeth and feel for muscle bulk
• Corneal reflex: look for direct and consensual blinking
• Jaw jerk: normal response: absent or just present

?

Trigeminal (V) nerve –abnormal findings

• Sensory lesions are much more common than

motor

• Absent corneal reflex may be the first sign of
• pthalmic Herpes
• Brisk jaw jerk occurs with bilateral upper motor

neurone lesions above the pons

Facial (VII) nerve

Facial (VII) nerve -examination

• Ask patient to raise their eyebrows
• Ask the patient to show their teeth
• Next close eyes against resistance
• Then blow out cheeks
• Taste can be tested with sweet/salt solutions, rarely

done

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Facial (VII) nerve

• As forehead has bilateral innervation in the brain,
• nly lower 2/3 is affected in UMN lesions but ALL

side of the face in LMN lesions.

• LMS: Bell’s palsy, polio, otitis media, skull fracture,

acoustic neuroma, Herpes Zoster

• UMN: tumour, stroke

Vestibulocochlear (VIII) nerve

• Auditory –sense of hearing
• Labirynthine –sense of balance

Vestibulocochlear (VIII) nerve -examination

• 1. Simple test of hearing
• Whisper a number into patient’s ear and ask to repeat, repeat with other ear
• 2. Rinne’s test
• tap a 512Hz tuning fork.

Compare subjective loudness when held close to external auditory meatus vs when base applied to mastoid

• 3. Weber’s test:
• tap a 512 tuning fork

hold against vertex of forehead at midline

Assessment of tuning fork tests

Condition Rinne’s Weber’s Normal hearing positive Heard in midline Conductive deficit negative Heard louder on affected side Sensory deficit positive Heard louder on non- affected side

Glosopharyngeal (IX) and vagus (X) nerves

Glosopharyngeal:

• Sensation to posterior 1/3 of the tongue
• Motor to stylopharyngeus
• Autonomic to the parotid gland

Vagus:

• Autonomic: parasympathetic innervation to heart, lungs, foregut
• Motor to larynx, soft palate, pharynx
• Sensory to dura matter of posterior cranial fossa, small parts of external

ear

Brainstem –anterior view

CN IX and X -examination

• 1. Soft palate: observe uvula; will deviate away from

lesion (CN X)

• 2. Speech: listen for dysphonia
• 3. Cough
• 4. Test swallow –terminate if any signs of aspirating
• 5. Gag reflex: produces elevation of the palate.

!unpleasant, don’t test unless you suspect a CN IX

• r X lesion.

Common causes of CN IX and X lesions

Unilateral of IX and X Skull base tumours, fractures Lateral medullary syndrome Recurrent laryngeal Lung cancer Thyroid surgery Bilateral X Progressive bulbar palsy Psedudobulbar palsy (CVA, MS)

Accessory (XI) nerve

Motor to the trapezius and sternocledomastoid muscles Note that each cerebral hemisphere controls the ipsilateral sternocleidomastoid and contralateral trapezius

Brainstem –anterior view

Accessory (XI) nerve -examination

Inspection: face the patient to inspect for wasting or hypertrophy; stand behind the patient to inspect for wasting or assymetry of trapezius Testing power:

Accessory (XI) nerve –abnormal findings

Surgery in the posterior triangle of the neck Local invasion by tumour Wasting and weakness of trapezius characteristic of dystrophia myotonica Head drop may be seen in myasthenia and motor neurone disease

Hypoglossal (XII) nerve

Innervates the muscles of the tongue Inspect the tongue for wasting and fasciculations Ask the patient to protrude the tongue. If there is a unilateral lesion the tongue will deviate towards the side of the lesion

Brainstem –anterior view

Thank you

Any questions?