Cranial nerve examination:
CN1: Olfactory
- Block one nostril at a time, use different smells, eg soap / lemon / nothing / perfume
CN2: Ophthalmic
- Acuity: Snellen chart
- Visual fields – equal distance between patient and examiner, use different numbers of fingers.
- Visual acuity – distance is important, one eye at a time.
CN3: Oculomotor
- PLR. Use bright dazzling light.
- Ipsilateral / direct, and contralateral / indirect responses.
- Swinging light response, test for RAPD
- Accommodation: bring finger towards eyes, check for pupil constriction
- Pathologies: DOWN AND OUT
Vasculopathic – diabetic, hypertensive. Aneurysm – aneurysm of internal carotid artery, Tumour – will see
parasympathetic alterations first. Increased intracranial pressure with herniation / displacement
CN3, CN4, CN6: extraocular motor function:
- H pattern
- Nasal side = left of page
Cover-uncover tests for strabismus / tropia / phoria
Inferior oblique
Medial rectus
Superior oblique
Superior rectus
Lateral rectus
Inferior rectus
CN4 pathology: CROSSED EYE
Vasculopathic, Tumour, Congenital, Trauma
CN6 pathology: NASAL UPSHOOT WHEN LOOKING IN
Vasculopathic, Tumour, Increased intracranial pressure – long nerve, has a bend, sensitive to increased pressure.
CN5: Trigeminal
- Motor function: muscles of mastication. Palpate muscles, detect tenderness. Get patient to open
mouth. If weakness in one side, jaw will deviate towards affected side. Can also do clench teeth –
should feel the same
- Touch: divided into crude touch / proprioception vs fine touch / temperature. Also divided into 3
segments of sensation: supra-orbital; between orbit and lips; inferior to lips. Ensure test both
components of touch in all three areas, on both sides. Test within mouth, rostral component of
hard palate.
CN7: Facial
- Smile, grimace / show teeth
- Close eyes hard, raise eyebrows
CN8: Vestibulocochlear
- Hearing – finger rub or “sixty-nine”
CN9: Glossopharyngeal
- Uvula and soft palate should be symmetrical. Will deviate away from weakness
CN10: Vagus
- Look to side, cough: should see movement of larynx. Ask about change of voice.
CN11: Accessory
- Head turn strength: trapezius or sternocleidomastoid muscle
CN12: Hypoglossal
- Tongue protrusion: deviate towards lesion on protrusion, through weakness of affected muscles.