Cranial Nerve examination

Olfactory Nerve I

Scratch and sniff, improve - get them to smell smth

used in head injuries, neurodegenerative diseases

Optic nerve II

- Acuity - what size letter can you identify
• Fields - each eye separately. Look - ask which hand is moving
• Colour vision -
• Pupil-light reflex.
Ophthalmoscopy - look at optic nerve and retina

assess pupil size, symmetry and shape

oculomotor III, Trochlear IV and Abducens VI

• Pupils
§ Size and symmetry
§ Light and accommodation

ptosis

extra-ocular eye move
§ Range of movements
§ Double vision
§ Speed of movements

see how their eyes move
assess for abnormalities of eye movements which may be caused by underlying cranial nerve palsy

Trigeminal V

Assess the sensory component of V1, V2 and V3 by testing light touch and pinprick sensation across regions of the face supplied by each branch:

Forehead (lateral aspect): ophthalmic (V1)
Cheek: maxillary (V2)
Lower jaw (avoid the angle of the mandible as it is supplied by C2/C3): mandibular branch (V3)

Motor assessment
- strength
- jaw jerk reflex
- corneal reflex

Facial VII

- asymmetry
- Movement --> UMN syndrome, LMN syndrome
- sensation --> taste 2/3 anterior

Vestibulocochlear VIII

Hearing --> deafness, Webers/Rinne's

(Webers - Tap a 512Hz tuning fork and place in the midline of the forehead. The tuning fork should be set in motion by striking it on your knee)

(Rinne's - Place a vibrating 512 Hz tuning fork firmly on the mastoid process)

Balance --> hallpike's
Inspection of EAMs

Glossopharyngeal (CN IX) and vagus (CN X) nerves

voice -
swallow and cough
palatal movement
gag reflex
Ask the patient to open their mouth and inspect the soft palate and uvula:

Accessory nerve (CN XI)

inspect for evidence sternocleidomastoid or trapezius muscle wasting.

strength --> Ask the patient to raise their shoulders and resist you pushing them downwards: this assesses the trapezius muscle

Hypoglossal nerve (CN XII)

Inspection - LMN signs
movement

unilateral weakness

1. Ask the patient to open their mouth and inspect the tongue for wasting and fasciculations at rest (minor fasciculations can be normal).

2. Ask the patient to protrude their tongue and observe for any deviation (which occurs towards the side of a hypoglossal lesion).

3. Place your finger on the patient’s cheek and ask them to push their tongue against it. Repeat this on each cheek to assess and compare power (weakness would be present on the side of the lesion).