vestibular Flashcards
vestibular system functions
- stabilizing visual images on the fovea of he retina during head movements
- maintaining postural stability
- providing information for spatial orientation
3 semicircular canals
structures here
- ampulla
- cupula (have the hair cells here)
otolith organs
saccule and utricle
vertical linear acc.
saccular excitation
horizontal linear acc.
utricle excitation
VOR
maintain stability of an image on the fovea of the retina during rapid head movements. VOR must generate rapid compensatory movements in the direction opposite the head rotation
VOR gain
eyes and head move in opposite directions with equal velocity
VOR phase
the amplitude relationship between eye and head.
should represent an equal but opposite head and eye relationship
vertigo a
an illusion of movement
oscillopsia
subjective experience of motion of objects in the visual environment that are known to be stationary
vertigo lasting for seconds to minutes think
BPPV
vertigo lasting for hours think
Menier’s
vertigo lasting for days think
vestibular neuronitis or think migraine associated
DHI
functional
emotional
physical components
nystagmus
primary indicator for central vs. peripheral lesions
peripheral vs. central nystagmus
peripheral: will attenuate, torsional upbeats
central: will not attenuate, vertical upbeats
neuritis
sudden onset of vertigo and nausea
severe for 3-4 days (unilateral)
labyrinthitis
due to infection, inflammation of SCC, will hae pain and hearing loss (unilateral)
menier’s disease
increase in endolymph volume causing labyrinthine distension/rupture
fullness in ears, loss of hearing, tinnitus, vertigo
lasts 2-4 hours, episodic unilateral, common
perilymphatic fistula
a passage between perilymph and middle ear (uncommon)
aoustic neuroma
CN 8-vestibulocochlear tumor, progressive unilateral hearing loss, tinnitus, mild disequilibrium
bilateral vestibular loss
usually due to meningitis, DM, ototoxic drugs (irreversible)
central vertigo
caused by CVA, HI, cerebellum involved usually, constant dizziness, spontaneous
mal de barquement, migraine, anxiety, cervical
non-vestibular causes of dizziness/imbalance
