Neuro Disorders of Equilibrium- lec 5

A generalized whirling sensation in the head associated with light headedness, near-fainting feeling, floating sensation, and confusion is known as _______

dizziness

Dizziness w/ a sense of rotation of self or environment due to a distortion/mismatch of vestibular, visual and somatosensory inputs is known as _____

vertigo

What type of vertigo?

• sudden onset

• N/V

• tinnitus and hearing loss

• horizontal nystagmus that should lessen when gaze is focused

peripheral vestibulopathy

What type of vertigo?

• more gradual progression

• vertical nystagmus

• MRIs are helpful

central origin

How is vertigo diagnosed?

Dix Hallpike maneuver & assess Romberg, gait, nystagmus

Audiologic testing, MRI, CT (indicated w/ persistent sx & suspected CNS dz)

What is the treatment for vertigo?

symptomatic → meclizine, scopolamine

What historical factors are considered concerning?

ataxia, dysarthria (inability to articulate), dysphasia (lack of coordination of speech → implies cortical damage), diplopia, sudden vertigo

What Weber and Rinne results suggest sensorineural hearing loss?

Weber → lateralize away from side of lesion

Rinne → both AC & BC diminished

What do a wide based stance, positive Romberg, staggering/ataxic gait, and ocular abnormalities suggest?

cerebellar involvement

“Overshoot” when the limb is directed at a target (like FTN) is known as _____

terminal dysmetria

A tremor as the limb approaches a target is known as ______

terminal intention tremor

Stimulation of the semicircular canals, with the Dix-Hallpike maneuver, may produce ______

nystagmus

Are the following Dix-Hallpike results peripheral or central?

• 2-20s latent period

• < 1 min duration

• fatiguing w/ repitition

• only one direction (usually rotary)

• severe vertigo

peripheral disorder

Are the following Dix-Hallpike results peripheral or central?

• no latent period

• > 1 min duration

• no fatiguing

• direction may change with head position

• less severe vertigo, sometimes none

central disorder

Stimulating the labyrinth with caloric testing causes _______ if nerve pathways are intact.

vertigo & nystagmus

What kind of testing is this evaluates disorders of vestibule-ocular pathways by instilling cold water into the ear canal?

caloric testing

What is a normal response to caloric testing?

nystagmus w/in 30s

What response to caloric testing would be seen in a patient w/ unilateral vestibular dysfunction?

irrigation of affected side fails to cause nystagmus

What response to caloric testing would you see in an unconscious patient w/ brainstem reflexes intact?

eyes deviate toward irrigated ear

What kind of disorders have the following?

• strength - normal

• atrophy - absent

• intention tremor - present

• true ataxia - present

Cerebellar disorders

What kind of disorder?

• lesions outside of brain

• sudden onset vertigo lasting up to a few days

• intense vertigo sx, marked exacerbation by head movement

• intermittent sx, lasts for brief periods

• produces significant distress

• no neuro exam findings

• ex: BPPV, menieres, acoustic neuroma, med otoxicity

peripheral disorders

what kind of disorder?

• lesion w/in brain

• ataxia, vertigo, nystagmus

• sx presently slowly over several mos

• little or no change in sx w/ head movement

• may have other focal neurological signs

• ex: alcohol intoxication, wenicke’s encephalopathy, MS, TIA/stroke, cerebellar ataxia

central disorders

What condition?

• sudden attacks of rotational vertigo triggered by certain head moments (getting out of bed or laying down)

• due to otolithic material in semicircular canal

• fully resolves b/t episodes

benign paroxysmal positional vertigo (BPPV)

How is BPPV diagnosed?

Dix Hallpike → latency, resolves w/in seconds-minutes, fatigues w/ repetition

What is the treatment for BPPV?

epley maneuver - dislodge otolith from canal

meclizine 25mg PO q4-6h PRN

scopolamine patch 0.5mg QD

What is high endolymph volume causing a membranous labyrinth rupture, which leads to progressive sensorineural hearing loss, seen in Meniere’s disease?

endolymphatic hydrops

What condition?

• common cause of dizziness originating in inner ear; MC only one ear

• onset age 20-50

• endolymphatic hydrops

• acute episodic horizontal / rotary nystagmus & sensorineural hearing loss (low frequency pure tone loss)

• vertigo resolves as hearing loss worsens

Meniere’s Disease

What is the tetrad of menieres disease?

vertigo, hearing loss, tinnitus, aural pressure

what is the treatment for menieres disease?

Lower endolymphatic pressure→ low Na diet (< 2 g/day), diuretics (HCTZ, acetazolamide)

Meclizine/scopolamine

Surgery if severe/drug resistant

what condition?

• benign tumor that arises from sheath of CN VIII in internal auditory canal

• insidious onset hearing loss, tinnitus, HA, vertigo, facial weakness

• unilateral sensorineural hearing loss on exam

acoustic neuroma

what is the best diagnostic study for acoustic neuromas?

MRI w/ constrast

What is the treatment for acoustic neuromas?

excision→ translabyrinthine surgery, craniectomy

What medications are ototoxic?

aminoglycosides & salicylates (ASA)

which aminoglycoside is the worst offender of ototoxicity?

gentamicin

How does alcohol intoxication affect the vestibular system?

unusually sensitive to gravity and position (peripheral system)

What sx are you likely to see after ingesting alcohol?

• positional vertigo w/in 2 hrs

• vertigo and nystagmus, accentuated when eyes closed

• dysarthria, gait ataxia, somnolence & other central/cerebellar sx

What causes wernicke’s encephalopathy?

thiamine deficiency

In what patient population is wernicke’s encephalopathy especially prevalent?

alcoholics

What is the classic triad of wernicke’s encephalopathy?

gait ataxia, ophthalmoplegia, confusion

what should all patients w/ undiagnosed altered mental status, oculomotor disorders, or ataxia receive?

parenteral thiamine

What is the treatment for Wernicke’s Encephalopathy?

thiamine 100mg IV (give BEFORE glucose)

Years of alcohol abuse causes ______

toxic degeneration of purkinje cells → alcoholic cerebellar degeneration

What condition?

• hx of alcohol abuse

• gait ataxia & tremor; evolves gradually

• alcohol related neuropathy

• cognition intact & no nystagmus

• irreversible

alcoholic cerebellar degeneration

What symptom is seen in MS ~10% of the time?

Vertigo

What might an occlusion of cerebellar artery cause?

dizziness or vertigo; may result in cerebellar infarction

what is the most common cerebellar ataxia?

friedreich’s ataxia

What are inherited disorders that cause atrophy of the cerebellum, brainstem & spinal cord that lead to slurring dysarthria, gait ataxia & nystagmus W/O vertigo?

cerebellar ataxias

what condition?

• autosomal recessive; chromosome 9

• presents before 25 (5-15y/o)

• spinal cord becomes thinner, myelin sheath destroyed, & distal axons degenerate due to pathological changes in posterior columns, lateral corticospinal tracts, and peripheral nerves

• brain, cerebellum, brainstem relatively unaffected

• first sx gait ataxia, progresses to arms → sensory loss & weakness later

Friedreichs Ataxia

Which ataxia?

• LE reflexes absent

• sensory loss prominent → joint position & vibration sense impaired

• muscle atrophy; progressive kyphoscoliosis; clubfoot

• positive romberg

• NCV: slowed conduction

• echo: cardiomyopathy

• progression to wheelchair bound in 10-20 years

friedreich’s