22. Vestibular System Flashcards
what causes vestibular symptoms?
a mismatch of firing of the canal functional pairs
what is the most common peripheral vestibular dysfunction
which canal does this happen the most?
BPPV
PSCC
what is BPPV
otoconia become dislodged from utricle or saccule and are displacced in the SCC
BPPV:
the displaced _______ affect the flow of the _________ within the canal. leads to the defection of the ________, leading to a nerve signal and vertigo
the displaced otoconia affect the flow of the endolymph within the canal. leads to the defection of the cupula, leading to a nerve signal and vertigo
causes of BPPV
idiopathic, head trauma, inflammation, ischemia, pressure changes
risk factors for BPPV
age, female, VitD def, HTN, migraine, hyperlipidema
symptoms of BPPV
brief spells of vertigo with changes in head position against gravity
clear sign of BPPV
nystagmus is upbeat for PSCC
- named by torsion or rotary component which indicates if it is R or L PSCC
which is more commom: cupulolithiasis or canalithiasis
canalithiasis
Cupulolithiasis:
otoconia fall off and adhere to _______, making cupula denser than surrounding
__________ onset of vertigo
__________ vertigo/nystagmus at provoking position
otoconia fall off and adhere to cupula, making it denser than surrounding
immediate onset of vertigo
persistent vertigo/nystagmus at provoking position
canalithiasis:
otoconia fall off otolith and are free floating in _____________ of PSCC
_______ onset of vertigo/nystagmus
___________ intensity of nystagmus/vertigo, diminishes after 1 minute of provocation
otoconia fall off otolith and are free floating in long arm of PSCC
latent onset of vertigo/nystagmus
fluctuating intensity of nystagmus/vertigo, diminishes after 1 minute of provocation
both nystagmus for cupulolithiasis and canalithiasis are
upbeat and rotary R/L for PSCC
inflammation of the inner ear
vestibular labyrinthitis
inflammation of the vestibular nerve
neuritis
which inflammatory vestibular issue has hearing loss?
labyrinthitis, and it has tinnitus
main cause of neuritis and labyrinthitis
viral infection (98%), also head trauma
symptoms of neuritis and labyrinthitis
sudden onset of vertigo/vomiting
how long does symptoms of neuritis and labyrinthitis last
3-7 days with residual balance and dizziness lasting 1-2 wks
what is the hallmark of neuritis and labyrinthitis?
direction fixed of nystagmus and if it occurs in 1st, 2nd. 3rd degrees of gaze
damage to inner ear or vestibular nerve that results in diminished or weaker neurological signal
peripheral vestibular hypofunction
causes of peripheral vestibular hypofunction
neuritis, labyrinthitis, meniere’s disease, acoustic neuroma, some medications
symptoms of peripheral vestibular hypofunction
affects VOR and VSR
postural and gait instability
movement dizziness, motion sensitivity, foggy headedness
what is tinnitus
ringing in the ear
before diagnosis of vestibular neuritis/labyrinthitis, what should you do first?
rule out central causes!
types of central vestibular dysfunction
stroke
tumor
MS lesions
degenerative neuro conditions
vestibular migraine
persistent postural positional dizziness
mal de debarquement
anything affecting central vestibular connection in brain or brainstem!
signs of vestibular dysfunction
nystagmus and oscillopsia
non voluntary rhythmic oscillations of eyes with clearly defined fast and slow components beating in opposite directions
nystagmus
physiologic nystagmus
induced by a normal stimuli
pathologic nystagmus
abnormal, appears with or without stimulation; 4 types
4 types of pathologic nystagmus
spontaneous
positional
gaze evoked
congenital
T or F: peripheral vestibular hypofunction is unilateral
F: can be unilateral or bilateral
spontaneous nystagmus
due to central or peripheral vestibular problempo
positional nystagmus
can be paroxysmal or static
2 types: torsional or downbeat
torsional/rotary nystagmus points to what diagnosis?
peripheral (BPPV) or brainstem dysfunction
downbeat/upbeat nystagmus points to what diagnosis?
central (cerebellar) dysfunction or peripheral (but not BPPV)
gaze evoked nystagmus
eyes drift toward center, constant corrective saccades to reset gaze
congenital nystagmus
since birth or infancy (types of central vestibular dysfunction)
mal de debarquement
feeling like you’re moving even though you are still- perceptual issues
what phase is nystagmus named for? what is the exception?
fast phase
exception is BPPV, named for direction or rotary torsion towards side of lesion
nystagmus causes by peripheral will present as..
a mix of torsion vertically and rotary
peripheral vestibular nystagmus slow phases is caused by
VOR
periphreal vestibular nystagmus fast phase is caused
corrective saccades
nystagmus caused by CNS lesions
smooth pursuit and saccades- points to cerebellum and brainstem lesions
what can suppress nystagmus
if the patient can fixate on a target
nystagmus is best examined by
Frenzel/ Infrared Goggles!
central nystagmus looks like: (4 points)
directional changing
vertical
not affected by fixation
constant
alexander’s law
peripheral vestibular issues
gaze towards fast phases increases intensity
sensory for postural control involves
observing availability and accuracy of sensory info
three sensory systems for postural control
vision
somatosensory
vestibular
posture control, motor output is based on (3 things)
anticipatory mechanisms, automatic motor strategies, and motor pathways
what is the fastest of the 3 senses
somatosensory system
somatosensory system provides information about
support system via pressure receptors
body position and movement via muscle/joint receptors
what are the 3 conscious proprioceptive senses
kinesthesia
joint position sense
sense of resistance
functions of the vestibular system (3)
oculomotor control
gaze stability
VOR
oculomotor control includes what 3 cranial nerves?
oculomotor, trochlear, abducens
jobs of the CNS
provides CNS info
VOR
internal reference to determine appropriateness/accuracy of external sensory info
postural stability
selection of sensory strategy for postural control depends on (3 things)
availability of information within individual
accuracy of info within environment
motor strategy used to control balance
what are the components of the peripheral vestibular system
semi circular canals
otoliths
what are the otolith organs
utricle
saccule
what are the components of the central vestibular system
CN 8
vestibular nuclei
motor pathways
cerebellum
which part of the vestibular system can we address as PTs?
peripheral
movement that bends hair towards the kinocilium causes
activation
movement that bends hair away from the kinocilium causes
deactivation
T or F: activation of hair cells is gravity dependent
True
T or F: semicircular canals sense angular velocity/speed
F: semicircular canals sense angular acceleration
“YAW” axis
is what motion and includes what semicircular canal?
shaking head NO
horizontal canal
“PITCH” axis
is what motion and includes what semicircular canals?
shaking head YES
posterior and anterior canals
“ROLL” axis
is what motion and includes what semicircular canals?
rolling head side to side (ear to shoulder)
anterior and posterior canals
if turning head to right:
endolymph moves ______
exciting the _____
hyperpolarizing the _____
endolymph moves left
exciting the right
hyperpolarizing the left
ampulla at the base of canal contains _______ with hair cells
cupula
utricle senses
horizontal movement
saccule senses
vertical movement
lateral vestibular nuclei are the origin of what tract
lateral vestibulospinal tract
medial vestibular nuclei are the origin of what tract
medial vestibulospinal tract
superior vestibular nuclei is the relay center for what
ocular reflexes
inferior vestibular nuclei is the 2nd origin of what tract?
medial vestibulospinal tract
cerebellum role in vestibular
monitors and fine tunes the vestibular reflexes
maintains gaze stability during head motion thus controlling eye-head coordination
VOR
maintains head and body equilibrium by facilitating or inhibiting skeletal muscle activity thus controlling coordination for balance
vestibulo spinal reflex
reflex output to motor cells
signals head position on body; maintains gaze stability; taught as substitution for VOR when VOR absent
cervical ocular reflex COR
input from otoliths; output to eye muscles
controls horizontal and vertical eye movements via linear VOR
otolith-ocular reflex