(45) Vertigo Flashcards
the saccade = fast or slow component of nystagmus
fast
if the nystgmus in to the right, which direction is the slow component? what direction would the individual perceive the room to be spinning?
slow phase = left so room spins from left to right
**recall, you only can process visual info in slow phase bc fast is too quick and you just see a blur/blinded
a right beating nystagmus indicates a dysfunction in what side of the vestibular system?
left vestibular
rotation about the y axis is called
pitch
**movement like slow pitch softball
rotation about the X axis
yaw
rotation about the x axis
roll
structures that detect linear accelerations within a plane
utricle = horizontal sacculus = vertical
structures that detect rotational acceleration or deceleration
ampulla with 3 semicircular canals
which structure of the vestibualr system in in parallel with the ground when standing
utricle
how does distortion of hair cell lead to an electrical signal?
distortion opens K+ channel–> K+ in and depolarizes cell –> voltage gated Ca channels open –> influx of Ca signals release of glu/asp –> active afferent half of bipolar cells in scarpas ganglia –> efferent half of biolar cells go to brainstem as vestibular nerve
**reversed bc influx of Ca acitvates K+ efflux pumps
in the ____ the kinocillia are directed away from the striola and in the ____ are directed toward the striola
away = sacculus toward = uricle
if you jerk head to the left and you want your eyes to remain in the middle which sides of the vesitbular system will be activated or inhibited?
left active and right inhibited semicircular canals
what is the VOR?
vestibular ocular reflex. keeps eyes midline when jerk head to side
which semicircular canal is likely to become obstructed by otoliths?
posterior
slow phase nystagmus is (away from or towards) the side of the lesion
towards
explain the results of ice calorics in a person in a true coma (but still has intact brain stem)
eyes will look in the direction of the ear that was irrigated (i.e. irrigate left ear and eyes will look right) this is bc you KO left vestubualr system so the right takes over and pushes eyes to left
explain the results of ice calorics in a person in a pshycogenic coma (but still has intact brain stem)
will get fast saccades (nystagmus) towards the opposite side of the irrigation /away from irrigated side
COWS
purpose of using frenzel lenses
eliminate visual fixation to reveal compensated nystagmus
head shaking maneruver with left beading nystamus = lesion on what side of the vestibule system
left
to perform the Dix maneuver and maximally simulate the left posterior canal, how would you have to position the head when you lie the person back?
turn the head to the left
eye movements expected with dix hallpike when right posterior canal is affected by BPPV
upbeat (when looking left)
a person with vestibular neuritis will have gait that causes the person to walk (towards or away from) the affected ear
towards
how can person receive temporary relief from vestibular neuritis
ice calorics in UNAFFECTED ear
