Cranial Nerves examination Flashcards by

Where is the most likely place of lesion for a RAPD (relative afferent pupillary defect)

lesion of the optic nerve (between the retina and the optic chiasm

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Both pupils constrict to light regardless of which pupil is illuminated. In RADP however, the … is damaged meaning whatever light the dominant eye is exposed to determines both pupil size.

CN 2 Optic nerve

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How does RAPD manifest itself?

inappropriate pupillary dilation with light shining on.

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How would a CN 3 lesion manifest itself? (3)

Ptosis
Dilated pupil
Eye out and downwards pointing

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The … muscle is responsible for ptosis and it is innervated by CN …

levator palpebrae superioris

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CN3 (via Edinger-Westphal–>ciliary ganglion; parasympathetic) controls accomodation via … muscles and pupillary constriction via … muscle.

Ciliary muscles

Sphincter pupillae

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how would a trochlear nerve lesion present

Diplopia on looking down and in.

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How do you remember the muscles innervated by CN4 and CN6

SO4LR6

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CN3 lesion presents how

Horizontal diplopia on looking outwards

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Horizontal nystagmus indicates … lesion

vestibular

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Nystagmus can be normal in which 2 circumstances

2 or less oscillations

at the extremes of gaze

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Acute horizontal nystagmus is present when pointed towards or away from the lesion??

Away

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Chronic vestibular horizontal nystagumus is present when the eyes point…

Towards the lesion

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Cerebellar lesion nystagmus will present with uni or bilateral lesion

Unilateral lesion

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Cerebellar lesions present with nystagmus towards/away from affected side

Towards

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How would Foramen Magnum lesions present ocularly

Downbeat nystagmus

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Upbeat nystagmus is indicative of lesions of (2)

Midbrain

Base of 4th ventricle

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What may also be present if ocular problems are present with tinnitus or deafness

CN 8 lesion (a peripheral cause)

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How would you check pterygoids (CN5)

Opening jaw against resistance (jaw deviates to weak side)

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how would you check masseters

Clench (feel for mass)

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CN7 UMN lesions are represents in which 3rds of the face

The lower 2/3s on the contralateral side

What is the result of the forehead having bilateral representation in the brain?

UMNL are only represented in the lower 2/3s of the face. (unless bilateral identical lesions - Low % chance!!)

IN CN7 LMN lesions what parts of the face will be affected

Ipsilateral full 3/3s of face.

Describe Bell’s Sign

upgaze on attempted eye closure

When would you see bell's sign

Facial nerve palsy (e.g. Bells)

What 2 non-facial questions could you ask to elucidate any CN7 palsys

Troubled by loud noises | noticed any change in taste

Why might a patient with a CN7 palsy have noticed a change in taste.

The chorda tymapani (a branch of 7) supplies the anterior 2/3s of tongue

Why might a patient with a CN7 palsy be troubled by loud noises

Prevents excessive movement of stapes. Reduced amplitude, dampens noise.

What is the mneumonic to remember Rinnes test.

SNAC-RIP

In what circumstances would air conduction>bone conduction (2)

Normal | Sensorineural hearing loss (SNHL)

In severe sensorineural hearing loss bone conduction is ... than air conduction. Outline the pathophysiology.

> | Other cochlea picks up sound via conduction

If sound is similar in both ears when performing Webers test what can this mean (2)

Normal | Bilateral SNHL

In conductive hearing loss on which side would the sound localise during Webers

Affected (because the ambient noise in the room is masked so it sounds louder)

In SNHL hearing loss on which side would the sound localise during Webers

Contralateral

Vagus nerve lesions cause the ... to be pulled ... from the side of the lesion

palate (look at uvula) away

The tongue is innervated by CN... and deviates .... the side of the palsy

12 | Towards

What are the 3 ∆∆ of bilateral ptsosis

Myasthenia gravis Myotonic dystrophy congenital

What are the 3 ∆∆ of unilateral ptosis

Horners syndrome Congenital CN 3 palsy

What cranial nerves can Pagets disease of the bone affect (3)

V VII VIII

What is the most common CN to be affected in Pagets

8 | 50% get hearing loss

Which 4 cranial nerves pass along the lateral wall of the cavernous sinus

III IV V (V1 and V2 only)

Which CN runs with the internal carotid artery through the cavernous sinus centre

Abducens

What would be the motor nerves affected in a cavernous sinus thrombosis.

III IV VI* *most common

How might a cavernous sinus thrombosis present in sensory terms?

V1 and V2 pain (most frequently ophthalmic)

Which reflex may be lost in a cavernous sinus thrombosis

Corneal reflex

A cavernous sinus thrombosis may a present with what general clinical signs on top of motor and sensory signs (3)

Proptosis peri-orbital oedema headache

Syringobulbia: what would be the signs/symptoms you'd expect in VIII affection

Vertigo/nystagmus

Syringobulbia: what would be the signs/symptoms you'd expect in V affection

pain or sensory loss

What CN a part of a 'Bulbar Palsy'

9,10,11,12

In syringobulbia which CN nerve is specifically spared