Neuro E2- CN disorders

What CN’s does the sense of smell depend on?

CN 1 and portions of CN V

Qualitative odor sensations are mediated by _____

CN I

Somatosensory overtones (warmth, coolness, sharpness, tingling & irritation) are mediated by ____

ophthalmic & maxillary divisions of CN V

What is the absent sense of smell?

anosmia

What is an abnormally intense smell?

hyperosmia

What is the hallucination of fecal odor known as?

Cacosmia

Which is more common- primary disorders of CN I or secondary dysfunction of CN I?

secondary

Where is there a high concentration of photoreceptors (rods/cones)?

fovea

Describe the pupillary pathway

light impulse travels up optic nerve → divides at chasm → arrive at pretectal nucleus → efferent signals sent via CN III → direct & consensual constriction

What does a sudden onset of blindness imply?

vascular event

What does a slow evolution of visual complaints imply?

inflammatory or neoplastic disease

What do transient or recurrent visual symptoms imply?

ischemia, embolic, MS, or myasthenia gravis

What is the inability to maintain conjugate gaze?

diplopia

What u/l loss of vision that resolves w/in ~20 minutes due to decreased blood flow to the retina (likely from embolism)?

transient monocular vision loss (TMVL)

What else is TMVL known as?

amaurosis fugax, optic neuritis, giant cell arteritis

What condition would a patient experience gray-black curtain that gradually descends in one eye, or blurring/fogging/dimming of vision?

TMVL

What do patients with TMVL also need to be evaluated for?

TIA/stroke

What is inflammation of the optic nerve that causes u/l vision loss, scotomata on visual field testing, & pupils that are slow to react?

optic neuritis

What is the treatment for optic neuritis?

steroids

What is inflammation of the external carotid artery at the superficial temporal artery that can extend to the ophthalmic artery, leading to blindness?

giant cell / temporal arteritis

What patients would likely hav optic neuritis?

MS patients aged 15-50

Who is giant cell arteritis MC in?

> 50 y/o (mean age is 70)

What condition?

• pain over scalp at temporal artery w/ dec pulse or nodules

• jaw pain/stiffness when chewing

• pale optic disc

• elevated ESR > 50 mm/hr

• dx w/ temporal artery bx

Giant cell arteritis

What is the treatment for giant cell/temporal arteritis?

urgent prednisone burst to avoid vision loss, slowly taper over several months

What condition?

• afferent pupillary defect & defective sensory system

• pupils dilate instead of constricting with direct light

• consensual reflex present (both eyes dilate)

• disease oof retina or optic nerve

Marcus gunn pupil

What condition?

• sign of increased ICP

• usually b/l (binocular vision disorder)

• HA, N/V, other neuro dysfunction

• urgent search for cause (HTN emergency, mass, etc)

Papilledema

What is the MC pituitary tumor?

prolactinoma

What condition?

• tumor press on optic chiasm → gradual bitemporal hemianopsia

• other sx: HA, galactorrhea, amenorrhea, acromegaly

• Dx: MRI & prolactin levels

pituitary tumor

What is the treatment for pituitary tumors?

surgical excision & bromocriptine

Which condition is diplopia, ptosis, dilation of pupil, & fixed position of eye downward and outward?

CN III palsy

What should all patients with new-onset CN III palsy with pupillary involvement be presumed to have until proven otherwise with expeditious MRA?

cerebral artery aneurysm (emergency if HA present)

In what patients is pupil-sparing CN III palsy most common in?

older patients (>50) due to diabetes related vascular infarction (or HTN)

What is the workup for pupil-sparing CN III palsy?

MRI & neuro referral to r/o aneurysm; usually resolves w/in 3 mos

What is unequal pupil sizes?

anisocoria

identifying abnormal pupil in aniscocoria

What condition is the interruption of cervical sympathetic nerves to the eye that causes ptosis, miosis, & anhidrosis on the involved side of face (also dilation lag or delayed eyelid elevation)?

Horner’s syndrome

How do you confirm the diagnosis of Horner’s syndrome?

Cocaine drop test / topical cocaine test

How does the cocaine drop test (topical cocaine test) work?

blocks reuptake of NE at sympathetic nerve synapse → causes pupillary dilation in eyes w/ intact innervation to increase degree of anisocoria(no effect in eyes w/ impaired innervation)

positive = anisocoria ≥ 0.8 mm

What all can be done for the workup of Horner’s syndrome?

cocaine test, CT/MRI, angiography (think lung tumor or carotid artery aneurysm)

Ptosis of the eyelid on the side of the small pupil indicates what condition?

horner’s syndrome

Ptosis of the eyelid on the side of the large pupil indicates what condition?

CN III palsy

What condition?

• pupil accommodates to near vision but does NOT react to light directly or consensually

• assoc w/ CNS syphillis, etc

argyll-robertson pupil

What condition is a tonic pupil with parasympathetic denervation that constricts poorly to light but reacts better to accommodation?

Adie’s pupil

What condition?

• anisocoria more in dark (small pupil abnormal)

• dilation lag, ptosis

• cocaine test → small pupil does not dilate

Horner’s Syndrome

What condition?

• anisocoria more in dark (small pupil abnormal)

• cocaine test → both pupils dilate symmetrically

Physiologic anisocoria

What condition?

• anisocoria more in light (large pupil abnormal)

• sluggish to light, light near dissociation, isolated

• 0.1% Pilocarpine → large pupil constricts

Adie’s tonic pupil

What condition?

• anisocoria more in light (large pupil abnormal)

• ptosis / ophthalmoplegia

CN III palsy

What condition?

• anisocoria more in light (large pupil abnormal)

• sluggish to light, light near dissociation, isolated

• 0.1% pilocarpine → large pupil does not constrict

pharmacologic anisocoria

What is the MCC of vertical diplopia?

CN IV palsy

What condition?

• (vertical) diplopia

• eye deviates upward and slightly medially

• MCC- blunt head trauma (other- microvascular infarct d/t DM, neoplasms, inflammation, infx)

CN IV palsy

What condition?

• affected eye adducted at rest & cannot abduct

• MCCs: basal intracranial neoplasms, trauma, microvascular dz

CN VI palsy

What is bilateral CN VI palsy a sign of?

increased ICP (get urgent head CT)

What in the MCC of unilateral CN VI palsy in elderly?

microvascular infarction second to DM

What is a more common cause of CN VI palsy in children & young adults?

tumor

What is another name for trigeminal neuralgia?

Tic Douloureux

What condition?

• microvascular compression of sensory fibers of trigeminal root by a blood vessel (usually superior cerebellar artery)

• lancinating pain in distribution of 1+ branches of CN V (lower 2/3 of face)

• very painful sharp electric spasms lasting s-mins, usually around eye, cheek, lower face

• can be triggered by touch, draft of air, or sounds & pain occurs while brushing teeth/chewing, drinking, eating, shaving

Trigeminal neuralgia

What are treatment options of trigeminal neuralgia?

usually spontaneous recovery; can tx w/ carbamazepine, phenytoin, baclofen, gabapentin

What is another name for idiopathic facial nerve palsy?

Bell’s palsy

What condition?

• possibly d/t reactivation of HSV

• u/l facial paresis, prodromal aural pain, numbness in affected region, auditory hyperacusis, impaired taste on anterior 2/3 of tongue

• sx divello over 1-3 days

Idiopathic facial nerve palsy

What is the treatment for Bell’s palsy?

complete spontaneous recover in most

prednisone burst & taper; acyclovir

no improvement & complete paralysis → ENT referral

What does facial paralysis with spared forehead muscles indicate?

central lesion (storke in one cerebral hemisphere)

What condition?

• HSV re-eruption along CN VII

• prodrome of pain, facial weakness, vesicular rash (in ear), dec hearing on affected side, N, loss of balance

• MRI & NCV → inflammation & damage to CN VII

Ramsay-hunt syndrome

What is the treatment for Ramsey hunt syndrome?

antivirals (acyclovir), steroids, & pain control

What kind of hearing loss?

• affects external auditory canal or middle ear

• weber lateralize to side of lesion

• rinne: BC>AC on side of lesion

conductive hearing loss

What kind of hearing loss?

• lesions affecting inner ear or CN VIII

• weber materializes away from lesion

• rinne: AC > BC (both decreased) on side of lesion

sensorineural hearing loss

A diminished gag reflex & disturbed swallowing indicates what palsy?

CN IX

Asymmetric rise of uvula indicates what palsy?

CN X

Flaccid paralysis of tongue w/ atrophy & speech difficulties indicates what palsy?

CN XII

In a patient s/p stroke affecting the left CN IX, which direction would the uvula be deviated?

towards the right (the normal/strong side bc this side of the palate is pulled up higher)

In right CN XII dysfunction, which way will the tongue deviate?

towards the right (the paralyzed side because of weakened genioglossus muscle)

What is the MCC of injury to spinal accessory nerve?

medical procedures involving head and neck

What would injury to CN XI cause?

drooping shoulder, muscle atrophy, weak/limited elevation of arm/shoulder, shoulder pain and scapula (shoulder blade) winging

What medications can cause taste loss?

ACE inhibitors

What nerve is affected if there is altered sense of taste with somatosensory sensations (hot peppers)?

CN V

When would taste be lost on anterior 2/3 of tongue?

bell’s palsy

When would taste be loss on posterior 1/3 tongue?

CN IX dysfunction