Cranial nerve findings/questions

Question 1

Causes nystagmus

Answer 1

HORIZONTAL

• Vestibular lesion. Fast phase away from the side of the lesion
• Cerebellar lesion- unilateral Dx= fast phase to lesion. Drift to midline with fast phase in direction of gaze= Gaze evoked. A/W Dysarthria, limb ataxia, hyper/hypometric saccades
• INO- nystagmus in abducting eye, with failure of adduction on affected side. If young- MS, if older- brain stem infarct

VERTICAL Brain Stem Lesion Toxic

Question 2

Causes pupillary constriction

Answer 2

Horner’s syndrome,
Argyll Robertson pupil,
Pontine lesion (often bilateral and reactive to light),
narcosis, pilocarpine drops, old age

AR pupil- no react to light, react to accomodation. cause= syphilis, diabetes, alcohol

Question 3

Causes pupillary dilatation

Answer 3

third nerve lesion, Adies pupil, Iridectomy/lens impant/iritis, post trauma, deep coma, cerebral death, congenital, mydriatics

Question 4

Visual field defect location

Answer 4

Central scotoma= retina optic nerve= monocular vision Bitemporal hemianopia= optic chiasm homonymous hemianopia (away from lesion)= optic tract/radiations

Question 5

Causes papilloedema

Answer 5

• Space occupying lesion or retro bulbar mass - Hydrocephalus (Associated with large ventricles) – obstructive (tumour), or communicating (tumour, papilloma, meningitis - Idiopathic intracranial hypertension- idiopathy, OCP, addisons, drugs, lateral sinus thrombus, head trauma - Hypertension - Central retinal vein thrombosis - Cerebral venous sinus thrombosis - High cerebrospinal fluid protein level (GBS)

Question 6

Causes optic atrophy

Answer 6

• Chronic papilloedema or optic neuritis - Optic nerve pressure or division - Glaucoma - Ischaemia - Familial- retinitis pigmentosa, lebers disease, freidreichs ataxia

Question 7

Causes optic neuropathy

Answer 7

• MS - Toxic- ethambutol, chloroquine, nicotine, alcohol - Metabolic- B12 deficiency - Ischaemia- DM, temporal arteritis, atheroma - Familial- lebers disease - Infective- infectious mononucleosis

Question 8

Causes ptosis with normal pupils

Answer 8

Senile, Myotonic dystrophy Fascioscapulohumeral dystrophy Ocular myopathy- e.g. mitochondrial myopathy Thyrotoxic myopathy Myasethnia gravus Botulism, snake bite Congenital Fatigue

Question 9

Causes ptosis with contrsicted pupil

Answer 9

Horners syndrome Tabes dorsalis

Question 10

Causes ptosis with dilated pupil

Answer 10

third nerve lesion

Question 11

Features third nerve palsy

Answer 11

Ptosis Divergent strabismus (eye ‘down and out’)- limited adduction and elevation Dilated pupil (unreactive)

Question 12

Causes third nerve palsy

Answer 12

Central -Vascular (e..g brain stem infarct) -Tumour -Demyelination (rare) -Trauma -Idiopathic Peripheral -Compressive lesions- aneurysm, tumour - Infarction- diabetes mellitus, arteritis (pupil usually spared - Trauma -Cavernous sinus lesions

Question 13

Features sixth nerve palsy

Answer 13

Failure of lateral movement. +/- convergent strabismus (in) Diplopia- worst by looking to affected side

Question 14

Causes sixth nerve palsy

Answer 14

Bilateral- head trauma, wernickes encephalopathy, raised ICP, mononeuritis multiplex Unilateral -Central- vascular, tumour, wernicke’s encephalopathy, MS (rare) -Peripheral- diabetes, other vascular lesions, trauma, idiopathic, raised ICP

Question 15

Causes fifth (trigeminal) nerve palsy

Answer 15

-central (pons, medulla, upper cervical cord)- vascular, tumour, syringobulbia, multiple sclerosis -posterior fossa- aneurysm, tumour (acoustic neuroma), chronic meningitis -Trigeminal ganglion (petrous temporal bone)- meningioma, # -Cavernous sinus (a/w 3rd, 4th and 6th nerve palsies)- aneurysm, thrombosis, tumour -Other- sjogrens syndrome, SLE, toxins, idiopathic Hints -all 3 divisions- ganglion or sensory root. -one division postganglionic lesion -loss pain preserved soft touch-brain stem or upper cervical cord lesion -soft touch lost, pain preserved- pontine nucleus lesion

Question 16

Causes seventh (facial nerve) palsy

Answer 16

Upper motor neurone lesion (supranuclear)- vascular, tumour FOREHEAD SPARED Lower motor neurone lesion- FOREHEAD INVOLVED - Pontine- often a/w 5th and 6th nerve palsy= Vascular, tumour, syringobulbia, multiple sclerosis -Posterior fossa- Acoustic neuroma, meningioma - Petrous temporal bone- Bells palsy, ramsay hunt syndrome, otitis media, fracture - Parotid- Tumour, sarcoid Bilateral Guillain Barre syndrome Bilateral parotid disease (e.g. sarcoidosis) Mononeuritis multiplex (rare) (myopathy and NMJ defects can cause bilateral facial weakness)

Question 17

Causes sensorineural hearing loss

Answer 17

Degeneration (presbycusis), Trauma (high noise exposure, fracture of petrous temporal bone etc) Toxic (aspirin, EOTH, streptomycin) Infection- congenital rubella syndrome, congenital syphilis Tumour (acoustic neuroma) Brain stem lesions Vascular disease of the internal auditory artery

Question 18

Causes 9th (glossopharyngeal) and 10th (vagus) nerve pasly

Answer 18

Central -Vascular (E.g. lateral medullary infarction due to vertebral or posterior inferior cerebellar artery disease), tumour, syringobulbia, motor neurone disease (vagus only) Peripheral- posterior fossa -Aneurysm, tumour, chronic meningitis, Guillain Barre syndrome (vagus only)

Question 19

Causes 12th (hypoglossal) nerve palsy

Answer 19

Upper motor neurone lesion- vascular, motor neurone disease, tumour, multiple sclerosis NOTE: bilateral UMN lesion of 9th, 10th, 12th nerves= pseudobulbar palsy Lower motor neurone lesion- unilateral -Central- vascular (thrombosis of vertebral artery), motor neurone disease, syringobulbia -Peripheral (posterior fossa)- aneurysm, tumour, chronic meningitis, trauma, Arnold-chiari malformation, fracture/tumour of base of skull Lower motor neurone lesion- bilateral -Motor neurone disease, Arnold chiari malformation, Guillain barre syndrome, polio

Question 20

Causes multiple cranial nerve palsies

Answer 20

Think cancer first Nasopharyngeal carcinoma Chronic meningitis (e.g. carcinoma, tuberculosis, sarcoidosis) Guillain Barre syndrome (spares CN 1, 2, 8) including miller fischer variant (ataxia, areflexia, and ophthalmoplegia) Brain stem lesions- usually vascular disease causing crossed sensory or motor paralysis (e.g. CN signs on one side, contralateral long tract signs). Gliomas in brain stem can cause similar signs Arnold chiari malformation Trauma Lesion of base of skull (e.g. pagets disease, large meningioma, metastasis) Rarely mononeuritis multiplex (e.g. DM)

Question 21

Causes horners (ptosis, miosis, anhidrosis)

Answer 21

• Carcinoma of ling apex- likely squamous cell - Neck- thyroid malignancy, trauma - Carotid arterial lesion (carotid aneurysm or dissection, pericarotid tumour, cluster headache - Brain stem lesions- vascular disease (especially lateral medullary syndrome), syringobulbia, tumour - Retro-orbital lesions - Syringomyelia

Question 22

5 broad causes dysarthria

Answer 22

• Upper motor neurone (pseudobulbar) - Lower motor neurone (bulbar) - Cerebellar - Movement- PD, HD - Muscle Cerebellar- slurred/scanning (irregular, staccato) Pseudobulbar palsy- slow, hesitant, hollow sounding w harsh, strained voice Bulbar- nasal speech with imprecise articulation Motor neurone can be mixed

Question 23

Expressive aphasia- description, location

Answer 23

• Slow and non fluent - Broca’s- frontal gyrus

Question 24

Receptive aphasia- - description, location

Answer 24

• Fluent but content poor - Wernicke’s- temporal gyrus