exam 2: vestibular review Flashcards
yaw
shaking your head no
on the z axis
pitch
nodding
on the y axis
roll
side bend
moving on the x axis
what three nerves do we find in the ear
vestibular, cochlear nerve and facial nerve are all intertwined
what is the function of the vestibular system
helps detect head position and movement of the head
helps maintain balance
involved in reflexive eye movements
what is the function of the otolith organs
detects static position of the head and linear acc
what is the function of the semicirccular canals
detect the rotational accc of the head
what are the name of the three semicircular canals
superior
horizontal
posterior
what is the ampullae
bulbous chamber at the end of each semicircular canals
this where hair cells are located
what do we find inside the ampullae
cupla
what is the cupula and it function
for a barrier that endolymph cannot pass - the endo distorts the cupula
this bend the hair cells and increase or decrease NT release depending on the direction of the endo flow
when are the horizontal canals horizontal to the ground
when we flex the head forward
what are the two type of otolith organs
saccule and utricle
what direction do the hair cells get excited
when they push towards the kinocilia
what is the otoconia
the sterocilia extend into a gelatinous layer that is covered with the otoconia
otoconia location
on to of hair cell in the utricle and saccule - otolith organs
otocconia and shifting of the head
when we shift our head the otocania shift that hair cells
is there one primary vetsibular cortex in the brain
no vestibular information is spread through the brain
what happen is we have dysregulation of the vestibular system
vertigo
VOR reflex is a connection of what two systems
vestibular system and the ocular system
what is the vestibular ocular reflex
produce eye movement that counters head movements
allows us to focus our gaze on one point even when our head it moving
EX: if we move our head to the right our eye can stay focused on an object
what is gain of VOR
the change in the eye angle divided by the change in the head angle during the head turn
what does a gain of 1.0 mean
meaning there is a compensatory eye velocity equal to the head velocity and in the opposite direction
how much of a gain decrease do we normally see with unilateral labyrinthine lesion
25-50%
which way does nys beat
away from the involved side
what is spontaneous nys
this is when you see nys in the resting posistion
what drives VOR adaptation
rentinal slip
an attempt is made to change the amp or speed of the eye movement to bring the target on the fovea
for vision to be normal what does rentinal slip have be less then
2 deg/secc
what is the center of the vestibular system
vestibular nuclei
otolith organs vs SSC
oto - detect static head position and linear accc
SSC - rot acc of the head
what is the def of retinal slip
the differencce between eye velocity and head velocity
what are included in the vestibular peri organs
3 SSC
2 otolith organs - saccule and utricle
what are the phases nystagmus
slow and fast phase
what does the slow phase of nys reflect
the function of VOR
reflecting the underlying pathology
what does left beating nys mean
fast phase to the left and right ear issue
Fixation suppression of a spontaneous nys is a clue in to what
peripheral vestibular disorder
how do we name torsional nys
named for the direction of the fast phase for the upper pole of the eye
what are the two types of nys
physiological and pathological
what are the three types of physiological nys
vestibular induce
visually induced
extreme endpoint induced
vestibular induced
everyone can prestn with nys depending on the situation - spinning in a chair
caloric
visually indiced
if you count strips this can induce nys
end point induced nys
if you go to the end range of you visual field this can induce nys
Caloric Nystagmus
irrigation of the external ear canal with ice-cold water or warm water for 3 to 5 minutes causes the endolymph to flow in the semicircular ducts.
what are the three type of patho nys
spontaneous
gaze evoked
posiotional
what is spontaneous nys
movement of the eyes without a cognitive, visual or vestibular stimulus
spontaneous nys and fixation
central disorder
there nys does not change with light, focusing does not help
o Brian problem
spontaneous nys and fixation
peripheral disorder
nys stops with fixation
- inner ear problem
does Peri spontaneous change as we look differnt directions with out eye
no - in every direction the nys is the same
unilateral vestibular loss - uni directional problem
Sym gaze evoked diagram presentation
o Center – nothing
o Right – beat right
o Left – beat left
o there is a change in direction without a change in head position
BPPV nys
o This is associated with head movement
o Move the head and the nys changes direction
presentation of Congenital nys
nys at center point
what do you do if you see down beating nys
go see a neurologist
this does not fatigue and is highly unusual
nys with peri issues straight or with torsion
with torsion
is sym gaze evoked nys brain or peri issue
brain problem
there persons head is still and just their eye movements cause the nys
cervico-ocular reflex (COR)
an ocular stabilization reflex that is elicited by rotation of the neck
interact with VOR to drive eye movement based on the cervical
work to prevent visual slip
are smooth pursuits and sacccades effected by vestibular issue
no
they never have to do anything with the inner ear if there is a disorder this is most likely a brain issue
what do smooth pursuit allow the eye to do
allow the eye to track moving object across the visual field without omving the head
what is often the cause to issue with smooth pursuits
cerebellar lesions
what are saccadic eye movements
rapid voluntary movement that allow re-foveation of stationary targets
maintain a visual object on the fovea voluntary or involuntary
what is indicated by issue with smooth pursuit
brian issue
what are possible causes for slow saccades
parkinsons
progressive supernuclear palsy
intranuclear opthamoplagia
drug intoxication
oliviopontocerebellar atrophy
huntingtons chorea
is nys named for its slow or fast phase
fast ohase
what happens to peri vestibular nys with visual fixation
it stops
what happens to a central vestibular nys with visual fixation
the nys does not stop
alexander law - looking in the direction of the the fast phase
looking in direction of fast phase increase the amp and freq of nys
alexander law - looking in the opposite direction of the the fast phase
decrease the amp and freq
what is first degree nys
seen only when we look in the direction of the fast phase of nys
what is 2nd degree nys
nys is present in the primary position (looking forward) and when looking toward the fast phase
what is third degree nys
nys is seen in all direction horizontal
presentation of the person with 3rd nys
they are very sick - just had surgery, just go admitted to the hospital
what does primary gaze mean
neutral - looking straight forward
does central nys change intesity with fixation
no
is peri nys worse or better with fixation
better
what kind of nys do we see with posterior canal BPPV
torsional nystagmus
what is BPPV
the sudden sensation of spinning
