Cranial Nerve Examination

MRCS Part B OSCE Revision

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Cranial Nerve Examination

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Cranial Nerves
‘I’m now going to test the nerves in your head.’
Position: Raise bed. Sit patient up at 90. ‘I’d like you to sit up straight now.’

CNI Olfactory
‘Have you noticed any change in your sense of smell?’

CNII Optic
‘Do you have any problems with your vision? Do you wear glasses?’

Acuity – With glasses on have patient read your badge or a newspaper. ‘I’d like you to read my badge.’
[If available use a Snellen chart (hand-held charts can be positioned 14 inches from patient)]

Pupil Accommodation
- ‘I’m going to shine a light you’re your eyes. Could you look at the curtain.’ Shine pen torch onto patient’s eye noting both direct pupil (the pupil onto which the light source is shining) response and consensual pupil (the pupil of the other eye) response. Test for relative afferent papillary defect (RAPD) by swinging the light source between the eyes.

Visual Fields – Sit opposite patient approximately arm length apart. Gross defects - ‘can you see all of my face?’
Ask patient to look directly at you (‘look at my nose’) and raise your arms to upper edge of your own visual fields. Move a finger and ask patient to identify which hand is moving while keeping focused on you. Do same for lower edge. This tests for inattention.
Individual eyes – ‘Can you cover your right eye with your right hand please. I’d like you to keep looking at my nose and tell me when you see my finger come into view.’
Close eye opposite to patient’s closed eye. Move finger to edge of your own field of vision and, with the patient looking directly at you, move your finger into your field of vision. Map out field of vision for each eye. Can also use a hat-pin instead of finger.
[Fundoscopy: Use left eye to look through fundoscope at patient’s left eye and right eye for right. Ask patient to look at object over your shoulder. Using as small a light source as possible approach from 15 to elicit white reflex then move in. Examine optic disc, macula and retinal vessels.]

CNIII Occulomotor, CN IV Trochlear & CN VI Abducens
Test convergence by asking patient to look at a distant object and then quickly looking at your finger.
‘Can you look at the curtain and now look at my finger.’
Occular Movements: ‘I would like you to keep your head still and use only your eyes to follow my finger.’ Place hand on patients chin to stop them turning their head. Move finger laterally in ‘H’ pattern then back to centre and in towards patient’s nose. ‘Did you have any double vision’

CNV Trigeminal
Test sensory branches ophthalmic, maxillary, mandibular.
Sensory branches: ‘I’d like you to close your eyes. I’m going to touch your face and I would like you to say ‘Yes’ when you can feel me touching.’ Touch on either side of forehead, cheek and chin (vary timing of touches).
Motor branches: ‘Can you clench your teeth and open your jaw.’ Test power by feeling over masseter muscle.

CNVII Facial
Test motor branches by asking the patient to raise their eyebrows, scrunch up their eyes, puff out their cheeks, show their teeth and whistle. Test power by applying resistance.

CN VIII Auditory
‘Do you have any trouble with your hearing or your balance?’
‘I’m going to whisper in your ear. I’d like you to repeat back to me what I said.’ Rustle fingers/cover opposite ear.
[Weber’s Test: 512Hz tuning fork on forehead/vertex. In sensorineural deafness sound localises to unaffected ear, in conductive to the affected ear and remains midline if hearing is normal (or bilat sensorineural).
Rinne Test: 512Hz tuning fork place in the same line as the meatus (air conduction) and then on the mastoid bone (bone conduction). Ask ‘which is louder?’ Rinne +ve AC>BC in sensorineual hearing loss and normal ear. SNAC-rip Sensorineural loss and normal ears air conduction is better – rinne positive. Rinne –ve BC>AC conductive hearing loss.]


CNIX Glossopharyngeal & CNX Vagus
‘Open your mouth and say ‘ahh’. Uvula moves to side opposite to lesion
‘Do you have any problem swallowing?’

XII Hypoglossal
‘Stick out your tongue’
Tongue deviates to the side of the lesion

CNXI Accessory
Trapezii: ‘Shrug your shoulders. And stop me pushing them down.’
Sternocleidomastoid: ‘Turn your head to the left/right and stop me pushing.’

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