vestibular Flashcards
(38 cards)
3 components of the vestibular system
peripheral sensory apparatus, Central nervous system processor, mechanism for motor output (sensory input=motor output)
peripheral sensory apparatus of the vestibular system
motion sensors sending info to CNS on head angular velocity and linear acceleration, position of the spine relative to the head, spatial orientation WRT gravity, sense of self motion. combines visual and proprioceptive input in response to balance tasks.
otolith organs
utricle and saccule
semicircular canals
superior, posterior, horizontal coplanar pairs close to planes of extra ocular muscles. provide input about head angular velocity. enables VOR to generate an eye mvmt to match head mvmt.
central nervous system processor
vestibular nuclear complex (pons), cerebellum, monitored by vestibule cortex (right perisylvian area)
motor output of vestibular system
ocular mm. and SC. 3 reflexes: VOR (1&2), VCR, VSR
VOR
vestibulo-ocular reflex: eye stability with head movement. 1-head moves, finger stationary. 2-head and finger move in opposite directions. test vertical, horizontal, diagonal, sitting, standing, walking.
VSR
vestibulospinal reflex: compensatory body movements to prevent falls
VCR
vestibulocolic reflex: stabilization of the head by the neck
Labyrinth
in the inner ear. membranous labyrinth is surrounded by bony labyrinth. consists of the otolith organs and the semicircular canals.
otconia
calcium carbonate crystals in the otoliths that deflect the hair cells of the otoliths
cupula
located in the ampullae of each of the semicircular canals. hair cells within the cupula sense fluid moving over the hair cells and send the message to the brain thru the vestibulocochlear nerve. (CN 8)
boney labyrinth
3 semicircular canals, cochlea, vestibule, perilymph
membranous labyrinth
suspended in boney labyrinth. consists of 5 sensory organs: membranous portion of semi-circular canals, otolith organs (utricle and saccule), ampullae
BPPV treatment
CRM/Epley manouver-canalith repositioning manouver. specifically works for Posterior semi-circular canal BPPV. causes otoconia to flow back into the otoliths. if not resolved w/ 3 reps probably not the posterior SSC.
brandt-Daroff exercises
BPPV treatment home exercises. side-lying–>sitting–>opposite side-lying. rapid movement till nystagmus is gone, rest 30 seconds. sit up for 30 sec. and go other way. 5-20 times, 3-4/day
liberatory manouver
go to provoking side first and rest for 2-3 minutes. move rapidly up to sitting and directly to the other side and maintain 2-3 minutes.
vestibular neuronitis
acute unilateral idiopathic vestibulopathy. acute onset, peaks at 24 hours, lasts 3-4 days. no hearing loss. viral infections. symptoms may remain after infection clears.
labyrinthitis
viral or bacterial. acute onset hearing loss, vertigo, N&V. 3-4 days. hearing loss and vertigo can persist.
meniere’s disease
episodic vertigo, hearing loss, sea shell tinnitus/aural fullness. pathologic increase in endolymph, changes K balance btw end and perilymph. treat w/ Na restriction, surgery (resections and shunts), vestibular rehab
ototoxicity
bilat. irreversible vestibular loss. permanent destruction of the peripheral vestibular apparatii. caused by ototoxic drugs crossing the blood perilymph carrier. tx: compensation via increased use of other balance modalities.
acoustic neuroma
progressive unilateral loss of vest. fxn, hearing, tinnitus. vertigo in 20-25% of cases. schwannoma of vestibular nerve.
trauma effects on vest. system
dislodging of otoconia, temporal or labyrinthine fx, BPPV with other central findings, central and peripheral vestibular findings.
central vestibular finidings
trauma, demyelination, tumor, ischemia, degeneration of central structures. tx more difficult but still efficacious. often assoc. w/ mult. co-morbidities
