Vestibular Flashcards
what stimulates the vestibular system
linear/angular acceleration of head
what does vestibular stimulation cause to happen
clear vision with head movement
facilitate postural reflexes
orient body/head to vertical
types of input in the vestibular system
visual
vestibular
proprioceptive
what are the two areas that the sensory input in the vestibular system go to
vestibular nuclear complex
cerebellum
what makes up the peripheral vestibular system
inner ear
CN8 until brainstem
central vestibular system
nuclei and tracts in brain cortex
cerebellum
brainstem
what is not a part of the peripheral vestibular system
cochlea
what detects angular motion
semicircular canals
what are the names of the semicircular canals
anterior
posterior
horizontal
what is the ampula
enlargement at the end of each SCC
what are the otolith organs? what is another name for them
utricle and saccule
aka vestibule
what do the otolith organs detect
linear acceleration
static tilt of head
how are the canals oriented
orthogonal
- in the plane as the opposite canal on the other side
how are conjugate canals aligned
in optimal pulling directions of extraocular muscles
what is within the bony labyrinth
membranous labyrinth filled with endolymphatic fluid
hair cells
where are hair cells
cupula of the ampullae, utricle, saccule
how does endolymph fluid flow? what does this do?
opposite the direction of canal movement
deflects the ampulla’s cupula
where does vestibular nuclei relay info to
cerebellum
cerebral cortex
spinal cord
oculomotor muscles
what is abnormal vor sign on the head impulse test
eyes do not stay on target and need a saccade back to the target
describe nystagmus naming
fast phase
with specific direction, intensity and shape
what does the direction of nystagmus indicate
which inner ear and which structure is dysfunctioning
what nystagmus suggests a central origin
pure vertical
pure torsional
direction changing
how can nystagmus be changed
lighting in a room
- light = suppression of nystagmus because eyes can fixate on a target
- dark = eyes cannot fixate on a target
what mostly causes dizziness
peripheral causes
what causes vestibular system dysfunction
abnormal firing rate between L and R peripheral vestibular apparatus
impaired processing within CNS
damage to CNS
symptoms of vestibular system dysfunction
sensation of motion (vertigo)
oscillopsia
dysequilibrium
motion sensitivity
what are two things that indicate a central lesion other than nystagmus
lack of oscillopsia
severe headache
what are the peripheral causes of vestibular dysfunction
BPPV
vestibular neuritis/neuroma
meniere’s disease
ototoxicity
what are the central causes of vestibular dysfunction
stroke
MS
neoplasms
what medical diagnoses result in vestibular hypofunction
vestibular neuritis
acoustic neuroma
meniere’s
ototoxicity
what is BPPV
episodic, intense vertigo related to a change in head position
what causes BPPV
otoconia becoming loose, clumping together and moving into SCC
which canal does otoconia most typically move into
posterior
what are symptoms of BPPV
brief episodes of vertigo (<60s) precipitated by head movement
will nystagmus be seen with BPPV
yes
what is the main cause of vestibular neuritis
upper respiratory infection
gastritis
symptoms of vestibular neuritis
sudden onset 1-2 days, residual symptoms with head motion
vertigo
nausea
vomiting
intense dysequilibrium
oscillopsia
sings of vestibular neuritis
nystagmus
abnormal VOR gain
– unilateral vestibular hypofunction
what medical treatments are there for vestibular neuritis
anti-emetics, histamines, cholinergics
steroids
prognosis of vestibular neuritis
6 weeks to 3 months
what is acoustic neuroma
benign tumor within schwann cells of vestibular nerve sheath
s/s of acoustic neuroma
hearing loss
dizziness
imbalance
– gradual onset / worsen as tumor grows
medical management of acoustic neuroma
surgery
what is meniere’s disease
malabsorption of endolymph fluid – increased fluid volume
s/s of meniere’s
fullness feeling
tinnitus
fluctuating vertigo
hearing loss
imbalance
episodic - minutes to hours
medical treatment of meniere’s
diuretics
diet-sodium restriction
shunt or ablation of vestibular nerve
where is the damage from ototoxicity
bilaterally
s/s of ototoxicity
impaired VOR
oscillopsia
dizziness
imbalance
signs of central disorder
dysarthria
nystagmus
disequillibrium
what can be used to test vestibular system
video nystagmography
electronystagmography
what is computerized dynamic posturography
assessment of ability to maintain upright posture during various environmental conditions
evaluation of somatosensory and visual influences on posture/equilibrium
does computerized dynamic posturography diagnose peripheral vs central causes
no
assesses one’s ability to integrate various sensory inputs to maintain postural control
