Cranial nerves

Question 1

3 parts of brainstem?

Answer 1

midbrain, pons, medulla

Question 2

example of disease in which lesion is in the brainstem?

Answer 2

MS- may also affect optic tract

Question 3

example of disease in which lesion at NMJ?

Answer 3

myasthenia gravis: AI destruction of end-plate ACh receptors by autoantibodies

Question 4

what can be given to treat myasthenia gravis?

Answer 4

AChesterase inhibitors e.g. neostigmine- more ACh around to bind to end-plate receptors so less likely that autoantibodies will bind so less receptors destroyed

Question 5

how is 1st cranial nerve tested for?

Answer 5

ask patient if they have noticed any changes in their sense of smell, can test ability of each nostril to distinguish smells e.g. peppermint- left nostril supplied by L olfactory nerve, R by R nerve, but patient may think that they can smell fine if sense of smell only lost from inside 1 nostril

Question 6

how is 2nd cranial nerve tested for?

Answer 6

visual acuity: snellen chart, test each eye separately
visual fields: movement of finger from side
pupils: size, shape, symmetry, pupillary response to light- sensory limb= optic nerve, motor limb= oculomotor, and accomodation reflex
opthalmoscopy- view optic disc- pale or swollen- papilloedema?

remember to check if patient normally wears glasses, can ask to put these on if so.

Question 7

how are 3rd, 4th and 6th cranial nerve tested for?

Answer 7

eye movements- H shape with finger

Question 8

characteristics of oculomotor nerve palsy?

Answer 8

down and out eye, dilated pupil (mydriasis), ptosis (full), loss of accomodation reflex, loss of pupillary reflex

Question 9

common infection of the trigeminal nerve and how does this occur?

Answer 9

Shingles- herpes-zoster infection
Reactivation of the latent varicella-zoster virus in dorsal root ganglia, possible as a result of a compromised IS e.g. on corticosteroids. Virus causes chickenpox, and then remains latent in the body located in the dorsal root ganglion= location of cell body of 1st order afferent neurones in acsedning tracts of somatosensory system.

Question 10

causes of space occupying lesions (SOLs)?

Answer 10

tumour
abscess
aneurysm
cyst
chronic SD haematoma
granuloma

Question 11

signs of SOLs?

Answer 11

headaches- worse on walking and lying down
vomiting
seizures
irritability
papilloedema

Question 12

functions of frontal lobe?

Answer 12

memory

voluntary movements

Question 13

functions of parietal lobe?

Answer 13

speech

Question 14

functions of temporal lobe?

Answer 14

sound awareness

Question 15

functions of occipital lobe?

Answer 15

interpretation of visual stimuli

Question 16

clinical presentation of SOL in frontal lobe?

Answer 16

hemiparesis
dysphasia
personality change

Question 17

what is guillain barre syndrome?

Answer 17

IS attack on part of peripheral nervous system

Question 18

pathophysiology of Parkinson’s?

Answer 18

degeneration of dopaminergic neurones in substantia nigra pars compacta

Question 19

3 cardinal signs of Parkinson’s disease?

Answer 19

resting tremor
bradykinesis
muscular rigidity

Question 20

causes of bilateral hemianopia?

Answer 20

optic chiasm compression e.g. pituitary adenoma and ICA aneurysm

Question 21

what is a homonymous hemianopia and what are its causes?

Answer 21

1/2 of visual field lost in each eye which is contralateral to the side of lesion. Lesions lie beyond chiasm in tracts, radiation, or occipital cortex e.g. stoke, tumour, abscess

Question 22

causes of nystagmus?

Answer 22

involuntary eye oscillations, often jerky.
vestibular lesion- acute- nystagmus away from lesion, chronic=towards
cerebellar lesion- if unilateral, nystagmus is towards affected side
MS
up and down nystagmus- maybe midbrain lesion

Question 23

causes of optic neuritis?

Answer 23

pain on movement of eye, loss of central vision
demyelination e.g. MS
syphilis- can also cause poster column degenerative changes, leading to loss of fine touch and conscious proprioception- causes +ve Romberg sign and sensory ataxia.

Question 24

causes of papilloedema (swollen optic disc)

Answer 24

tumour
abscess
hydrocephalus
idiopathic IC hypertension

Question 25

how might the oculomotor nerve be compressed alone?

Answer 25

``` uncal herniation (part of parahippocampal gyrus) also tumour, and aneurysm of posterior communicating artery along with other nerves e.g. abducens and trochlear- could be cavernous sinus thrombosis and superior orbital fissure lesion. ```

Question 26

which side of the brain is dominant in most people?

Answer 26

left, * write with right hand | so Broca's area and Wernicke's area for speech usually on L side of brain. **visual fields affected?**

Question 27

how can mild ptosis in horner's syndrome be overcome by patient?

Answer 27

if patient looks up

Question 28

what ptosis generally occurs with myasthenia gravis?

Answer 28

bilateral partial ptosis | * contrast to unilateral full ptosis with oculomotor nerve lesion, and unilateral partial ptosis with Horner's syndrome.

Question 29

causes of conductive hearing loss?

Answer 29

``` otitis externa acute otitis media chronic otitis media with effusion foreign body ruptured TM otosclerosis cholesteatoma ```

Question 30

causes of sensori-neural hearing loss?

Answer 30

meniere's disease vestibular schwanoma damage to hair cells by loud noises hair cell death by ototoxic drugs e.g. gentamicin and furosemide

Question 31

what am I looking for on general inspection of pateint?

Answer 31

pain/discomfort facial asymmetry loss of expression muscle wasting

Question 32

what might patient with trochlear nerve palsy complain of?

Answer 32

diplopia (double vision) on looking down and in, often noticed on descending stairs, head tilting compensates for this- head tilted away from side where superior oblique affected.

Question 33

resting gaze of someone with trochlear nerve palsy?

Answer 33

eye slightly elevated | SO normally causes depression when the eye is adducted

Question 34

patient has +ve weber's test in right ear, and +ve rinne's tests in both ears, what type of hearing loss?

Answer 34

left ear sensorineural hearing loss

Question 35

a patient has right ear conductive hearing loss, what would their results be with weber's and rinne's?

Answer 35

``` weber's= sound heard loudest in right ear rinne's= rinne +ve in left ear, and rinne -ve in right ear= sound heard loudest when tuning fork placed on mastoid process compared to when placed just in front of the EAM. ```

Question 36

resting gaze of someone with abducens nerve palsy?

Answer 36

slightly adducted

Question 37

functions of superior oblique muscle?

Answer 37

intorsion of eye when abducted, depression of eye when adducted

Question 38

functions of inferior oblique muscle?

Answer 38

extorsion of eye when abducted, elevation of eye when adducted

Question 39

functions of superior rectus muscle?

Answer 39

elevation of eye when abducted, intorsion of eye when adducted

Question 40

functions of inferior rectus muscle?

Answer 40

depression of eye when abducted, extorsion of eye when adducted

Question 41

problem patient may complain of if abducens nerve palsy?

Answer 41

horizontal double vision (diplopia) when looking outwards

Question 42

if damage to trigeminal nerve, what would happen when patient asked to open their mouth?

Answer 42

jaw would deviate towards side of lesion

Question 43

on asking ptnt to say 'aaahh' what would happen to the uvula if lesion of the left vagus nerve?

Answer 43

palate pulled to normal side, so the right.

Question 44

causes of olfactory nerve lesions?

Answer 44

frontal love tumour meningitis respiratory tract infection, common cold trauma e.g. fracture of cribiform plate of ethmoid bone- would also expect CSF rhinorrhoea smell loss= anosmia

Question 45

causes of monocular blindness?

Answer 45

lesion of 1 eye or optic nerve e.g. MS, giant cell arteritis

Question 46

causes of bilateral blindness?

Answer 46

neurosyphillis

Question 47

causes of optic atrophy (pale optic discs and reduced acuity)?

Answer 47

MS | frontal tumours

Question 48

cause of oculomotor nerve palsy without dilated pupil?

Answer 48

diabetes mellitus | hypertension

Question 49

cause of oculomotor nerve palsy with down+out eye, ptosis AND dilated pupil?

Answer 49

tumour | posterior communicating artery from ICA (anterior circulation to brain) aneurysm

Question 50

causes of damage to just trochlear or abducens nerve alone?

Answer 50

``` trochlear= trauma to orbit abducens= MS, pontine stroke ```

Question 51

what may cause sensory loss in face?

Answer 51

herpes zoster | nasopharyngeal cancer

Question 52

cause of LMN lesion of facial nerve?

Answer 52

bell's palsy skull fracture infection e.g. herpes zoster acoustic neuroma

Question 53

causes of UMN lesion of facial nerve?

Answer 53

stroke | tumour

Question 54

causes of glossopharyngeal, vagus and hypoglossal nerve individual damage?

Answer 54

neck tumours trauma brainstem lesions

Question 55

causes of accessory nerve damage?

Answer 55

trauma tumour stroke polio

Question 56

cause of damage to both IX,X and XI cranial nerves?

Answer 56

jugular foramen lesion

Question 57

what features of parkinson's disease might you see on a patient when doing a cranial nerve examination?

Answer 57

lack of facial expression | as muscles in face become rigid*

Question 58

causes of optic neuritis?

Answer 58

multiple sclerosis | drugs e.g. isoniazid

Question 59

motor component of glossopharyngeal nerve?

Answer 59

supplies stylopharyngeus muscle= elevates pharynx during swallowing and speech

Question 60

skeletal muscles innervated by vagus nerve?

Answer 60

``` cricothyroid intrinsic laryngeal muscles palatopharyngeus salpingopharyngeus 3 constrictors of the pharynx ```