Cranial Nerves

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Cranial Nerves

1) Olfactory nerve ->

Has the patient noticed a change in smell recently.

Offer to test with smelling salts

2) Optic nerve ->

- Visual acuity- Check can see (read clock in room). Do you wear contacts or glasses. Keep glasses on. Cover right eye with right hand. Read lowest line on snellen chart. Record right eye VA= R/X where X= lowest line can read. Offer pinhole if needed. If can't see; how many fingers, can you see which hand is waving, can you see light and point to where it is. VA= CF at 1m VA= HM at 1m VA=PL at 1 m

- Visual inattention- sit opposite, both eyes oppen. Hand held halfway between you and patient, point to which finger is moving or both. Test upper and lower fields, looking for neglect.

- Visual Fields - Patient covers one eye, you cover your own mirror image. Patient to look at your nose. Keep their heads and eyes still, testing what they can see without them directly looking at it. Patient to report when they first see the finger pointing in each quadrant. (central vision checking blind spot, red neurotip 4 quadrants patient cover one eye)

- Accomodation both eyes separately- patient look in distance and then at your finger 20 cm away. Both pupils should constrict

- Direct and consensual light reflex- warn shine light in their eye. Patient to look in distance.

- Could offer colour vision ishihara plates (suspicion of optic nerve disease, 24 version. Test plates are 1-24, if can't see test plates stop. record how many out of how many correct. Could check can see red with red neurotip)

- Could offer fundoscopy

3,4,6 Opthalmic Trochlear Abducens ->

- Inspects size of pupils and for ptosis

- Full range of eye movements, pain and double vision. Follow my finger with your eyes without moving your head. ( H draw) If have double vision ask which direction it is worst in.

- Pauses at extremities for nystagmus

5 Trigeminal ->

- Offer corneal reflex and jaw jerk

- Tests sensation of face bilaterally in 3 areas

- Tests strength of masseter and temporalis muscles (fingers sprea). Clench teeth, move jaw side to side. Open jaw against resistance, stop me from closing it.

7 Facial ->

- Inspects face and comments on asymmetry

- Asks about taste (anterior 2/3rds)

- Patient to raise eyebrows, scrunch up eyes, smile, puff out cheeks

8 Vestibulocochlear ->

- Tests hearing using fingers (whisper 21)

- Offers Rinnes and Webers

( 512 small tuning fork, Rinnes on mastoid bone ask when can no longer hear it and then place 2 cm from auditory canal and ask if can hear it. Normal result is air conduction should be better than bone conduction so patient should be able to hear it next to pinna. If can't may be conduction deficit.

Webers test- place on middle of forehead, ask which ear it is louder in. Conduction deficit would go to the bad ear. If normal ear hears the sound louder sensorineural defect.

9, 10 Glossopharyngeal and Vagus ->

- Examines uvula deviation

- Would check gag reflex

11 Accessory->

- Shrugs shoulders against resistance

- Deviates head to left and right against resistance

12- Hypoglossal ->

- Examines for tongue deviation, wasting or fasiculations. Stick it out, wiggle it

- Tests tongue strength by pressing over cheek to test tongue movement

-Optic atrophy-> MS , temporal arteritis, compression (SOL, raised ICP), glaucoma

- Third nerve palsy- down and out. Posterior communicating artery aneurysm. Diabetes, mononeuritis multiplex.

- Sixth nerve palsy- raised ICP, diabetes

- Homonymous hemianopia (stroke, cerebral SOL)

- Bitemporal hemianopia- tunnel vision (optic chiasm) - pituitary tumour, aneurysm

- Central scotoma- MS, temporal arteritis

- Homonymous Quadrantopia-> PITS parietal inferior , temportal superior lesion. (optic radiation)

- Monocular- central retinal arteyry occlusion. Field of vision increased, depth of perception decreased

- Ptosis- myasthenia gravis, myotinic dystrophy

- Unilateral ptosis- third nerve palsy, horners syndrome (pupil constricted)

- Bilateral ptosis- Argyll robertson pupils seen in Tabes Dorsalis. Pupils reduce in size on a near object but do not constrict when exposed to bright light (neuro syphilis)

- Horners syndrome- MS, SOL, Syringomyelia, spondolosis, stroke, pancoast's tumour, cervical rib, carotid artery dissection

- Cavernous sinus thrombosis - 3,4,6, 5a

1- Olfactory nerve problem= trauma , respiratory tract infection, meningitis, frontal lobe tumour

2- Optic nerve problem= scotomas in glaucoma. Monocular blindness in MS, giant cell arteritis. Bilateral blindness in diabetes, MS, neurosyphillis. Bitemporal hemianopia in pituitary adenoma, craniopharyngioma, internal carotid artery aneurysm. Homonymous hemianopia (affects half the visual field contralateral to the lesion in each eye, lesions lie beyond the chiasm in the tracts, radiation or occipital cortex) eg stroke, abscess, tumour. Optic neuritis ( pain on moving eye, loss of central vision, relative afferent pupillary defect, disc swelling from papillitis) caused by demyelination, syphillis, sinusitis.

3- Oculo-motor problem- diabetes, hypertension, giant cell arteritis, syphillis, posterior communicating artery aneurysm (surgery)

4- Trochlear problem- trauma to the orbit

5- Trigeminal problem- sensory - herpes zoster, vestibular schwannoma, nasopharyngeal cancer.

6- Abducens problem- wenicke's encephalopathym pontine stroke (small pupila and quadriparesis)

7- Facial problem- Bells Palsy, polio, otitis media, skull fracture, cerebello-pontine angle tumours, UMN (spares forehead because of its bilateral cortical representation) stroke or tumour

8- Vestibulocochlear problem- Noise damage, pagets disease, mernieres disease, herpes zoster, vestibular schwannoma, brainstem CVA, aminoglycosides

9- Glossopharyngeal Problem- trauma ,brainstem lesions, neck tumour

10- Vagus Problem- trauma, brainstem lesions, neck tumours

11- Accessory Problem- trauma, brainstem lesions, neck tumours

12- Hypoglossal Problem- poli, syringomyelia, tumour,stroke, bulbar palsy, trauma, TB