cranial nerve pathologies

Question 1

describe 3rd nerve palsy

Answer 1

can be caused by life threatening things

ptosis, eye out and down and pupil is dilated = compressive CNS palsy - mydriasis because of the loss of PNS stimulation to sphincter pupillae muscle

it is ischemic if the pupil isnt effected - DM/hypertension

Question 2

causes of 3rd nerve palsy

Answer 2

Posterior communicating aneursym

raised ICP

Pupil spared in medical causes: Vascular, Diabetes

Question 3

signs of horner’s syndrome

Answer 3

Ptosis

Anhidrosis (no sweat on one side of the face)

Miosis (pupil constriction)

(because of disruption in SNS supply)

might have resp symptoms - pancoasts tumour in lung can effet SNS

Question 4

cause of bilateral ptosis

Answer 4

M gravis

Question 5

possible cause of unilateral ptosis with normal pupil

Answer 5

hereditory and not pathological

Question 6

describe 6th nerve palsy

Answer 6

cannot abduct

weakness of lateral rectus muscle

esotropia - eye point inwards when looking ahead

Question 7

causes of 6th nerve palsy

Answer 7

vascular

MS

tumour

Question 8

summarise visual field defects

Answer 8

afferent CN2 - tumour/MS = full loss of vision on one side

at optic chiasm = temporal loss - above pit gland so probably pit tumour is cause = bitemperal hemianopia

homonymous hemianopia - stroke - further back in brain on contralateral side

Question 9

herpes and trigeminal nerve

Answer 9

unilateral vesicular rash

opthalmic branch of the trigeminal nerve

neuropathic pain

Question 10

describe trigeminal neuraligia

Answer 10

electric shock pain

worse when you brush hair or eat

cause is unknown - maybe compression by bv

give anti-seizure med

surgery between BV and nerve

Question 11

summarise facial nerve lower motor neuron lesions

Answer 11

bells palsy - complete facial paralysis, comes in 2-3 days, can be EBV/herpes reactivation - give steroids and cover the eye - they cant close it

ramsey hunt syndrome - zoster infection - look for vesicular rash in the ear

lyme disease - bacterial infection by ticks - give AB

facial paralysis is ipsilateral

Question 12

UMN lesion for facial nerve

Answer 12

stroke, demyelination (MS), tumour

spare forehead - raise eyebrows fine

onset in minutes

contralateral droopy face

Question 13

why is UMN lesions forehead sparing for facial nerve

Answer 13

nucleus controlling upper part of face has bilateral UMN innervation

by LMN there is only one nerve supplying forehead

Question 14

if eye cant move laterally

Answer 14

CN6 lesion

Question 15

if eye cant move inferiorly when facing medially

Answer 15

CN4 lesion

Question 16

if majority of eye movements are impaired and eye lies at rest out and down

Answer 16

CN3 lesion

Question 17

if there is dramatically abnormal eye movements not fitting a single nerve lesion

Answer 17

complex opthalmoplegia - M gravis, graves, mitochondrial/brainstem lesion