Cranial Nerves Examination

Introduction

Aim: to perform a screening test of the main functions of the cranial nerves. Position : Sitting over the edge of the bed/on a chair is ideal.

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Inspection

In the face, look for:

- Ptosis
- Pupillary inequality
- Facial asymmetry
- Skin (erythema, sweating, scars, etc.)

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I

Olfactory

- Ask about recent changes in sense of smell/taste.

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II

Optic

- Acuity (one eye at a time with Snellen chart & accommodation [also III])
- Fields
- Reflexes
- Opthalmoscopy (fundoscopy)

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III/IV/VI

Oculomotor/Trochlear/Abducens

- Eye movements (move your finger slowly and smoothly in a 'H' shape and ask the patient to follow)
- Ask about double vision (diplopia), look for nystagmus

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V

Trigeminal

- Facial sensation in the three branches (ophthalmic, maxillary, mandibular)
- Muscles of mastication

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VII

Facial

- Look for facial weakness/asymmetry/loss of forehead creases
- Upper motor neurone lesions = forehead crease sparing (bilateral innervation) - Raise eyebrows
- Screw up eyes
- Puff cheeks out
- Grin (show teeth)

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VIII

Vestibulocochlear

- Whisper in one ear while occluding/distracting the other
- Rimes/Weber test with tuning fork

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IX/X

Glossopharyngeal/Vagus

- Say 'ahh' and look for uvula deviation (away from side of lesion)
- Swallowing problems
- Gag reflex (not in routine examination)

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XI

Accessory

- Shrug shoulders against resistance (trapezius)
- Turn head to side against resistance (sternocleidomastoid) - weakness in turning head right is due to left sided muscle weakness

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XII

Hypoglossal

- Fasciculations/wasting of tongue as it rests in mouth - lower motor neurone signs
- Stick tongue out/move side to side ? look for deviation (towards side of lesion)

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