Vestibular Disorders Review Flashcards
what stimulates the vestibular system
linear acceleration
angular acceleration
result of vestibular stimulation
clear vision with head motion
postural reflexes
orientation of body/head to vertical
how is the vestibular system function categorized?
what type of loop is it and what systems are involved?
feed forward loop
- sensory input to the CNS for processing and then motor output
what sensory input is gathered by the vestibular system
motion detection via
visual, vestibular and proprioceptive pathways
in the CNS, where does vestibular information get processed
primary processing center = vestibular nuclear complex
secondary processing center = cerebellum
where in the CNS is the primary processing complex
medulla and pons
integration of information in 1° and 2° processing centers allows for
estimation of head and body orientation
stimulation of a motor response
explain the process of motor output in response to CNS processing
motor neurons stimulate
oculomotor reactions (VOR)
cervical muscle reactions (VCR)
postural muscle reactions (VSR)
explain the VOR
vestibular oculomotor reflex
ocular muscle stimulation that result in eye movement that is equal and opposite of head movement
what is the purpose of VOR
allow for stable vision during head motion
explain the VCR (not tv)
vestibulocollic reflex
cervical muscles activate to counter movement sensed by vestibular apparatus
goal of the VCR
stabilization of the head
explain the VSR
vestibulospinal reflex
postural muscle activation to stabilize the body counteractively
how is the vestibular system divided? where are the respective receptors for each?
peripherally - inner ear
centrally - nuclei and tracts in brain cortex, cerebellum and brainstem
explain the exact location where the peripheral and central portions of the vestibular system divide
peripheral - CN7 until it enters brainstem
within the inner ear, explain the location of the peripheral vestibular system
situated between middle ear and petrous portion of temporal bone
explain the relationship between cochlea and peripheral vestibular system
cochlea is within the inner ear but is not a component of the peripheral vestibular system
the anatomy of peripheral vestibular system is made of
semicircular canals
ampulla
otolith organs
names of semicircular canals? relationship between contralateral sides
anterior
posterior
horizontal
- weird picture of dude flexing, basically saying that anterior of one side and posterior canal of the other will line up with each other and so will the horizontal canals
what do semicircular canals detect
angular motion
ie head flexion, extension, lateral flexion and rotation
anatomy and physiology of the ampulla
enlargements of SCC near utricle
made of hair cells that bend as the head moves, detecting movement
what is another name for the vestibule?
what makes up the vestibule?
otolith organs
utricle and saccule
what do otolith organs detect
linear motion
static tilt of the head
explain static tilt of the head
acceleration of head when in a static position
ex - car accelerating or plane taking off
– otoliths will detect the acceleration even though the head is not moving
what does it mean when canals are described as orthogonal
90° to each other
explain the idea of “push-pull” relationship of SCCs
when angular motion is experienced in conjugate SCCs neural firing will increase in one vestibular nerve and decrease in the other
ie - left rotation will cause left horizontal to fire and right horizontal to inhibit
are semicircular canals oriented within cardinal planes
no
how do conjugate canals positioning relate to extraocular muscles
they are in optimal pulling directions of extraocular muscles
what detects movement within the peripheral vestibular system
hair cells
stereocillia
what surrounds the peripheral vestibular system?
bony labyrinth
what is contained within the bony labyrinth? what is this made of?
membranous labyrinth
endolymph fluid
describe the anatomy within an ampulla
hair cells that are embedded in the crista and covered by a gelatinous capula
explain the heights of different stereocilia and the point of them
tallest - kinocilium
shorter ones - stereocilia
if stereocilia move toward kinocilium then an excitatory signal is sent
–> not sent if moved away from kino
explain direction of endolymph fluid and and canal movement? what is the point of this
endo will flow opposite of canal movement
capula within the ampulla will deflect the steroecilia
excitatory signals will be sent to the brain for sense of processing motion
explain direction of endolymph fluid and and otolith movement? what is the point of this
endolymph will flow opposite of movement
endo will flow towards or away from kinocilium and cause an excitatory or inhibitory response
vestibular nuclei will relay information to which CNS locations
cerebellum
cerebral cortex
spinal cord
oculomotor muscles (CN3,4,6)
explain oculomotor muscles and their relationship with head movement
eyes will move equally and oppositely of head direction
explain VOR in relation to vestibular dysfunction
inability to stabilize gaze via VOR = vestibular dysfunction
abnormal head impulse test result
eyes not staying on target
saccade to target
explain how nystagmus occurs? how is it named?
eye muscle activation in relation to the associated semicircular canals
based upon the fast phase, typically away from the side that is functioning improperly
Central vs Peripheral Nystagmus
central:
pure vertical
pure torsional
direction changing
explain the best practice protocol when testing for nystagmus in relation to lighting
want a darker room with infrared goggles
light will allow the eyes to fixate on a target and suppress nystagmus
what is alexander’s law
nystagmus is direction-fixed during gazing toward center, left and right.
intensity increases in the direction of the fast phase
decreases in the direction of the slow phase
how is dizziness due to vestibular involvement described
sensation that results from the disruption of information from vestibular, visual and somato systems
vestibular system dysfunction occurs due to
abnormal firing rate between contralateral vestibular apparatuses
impaired CNS or its ability to process
signs of vestibular dysfunction
nystagmus
positive special tests
symptoms of vestibular dysfunction
vertigo - sensation of moving
oscillopsia - visual illusion where stationary objects seem to bounce
dysequilibrium
motion sensitivity
how do we quantify symptoms of vestibular dysfunction
description of symptoms
tempo - acute, episodic or chronic
circumstances of symptoms
differentiate peripheral vs central vestibular dysfunction based on
- vertigo
- nausea
- oscillopsia
- dysequilibrium
- vomiting
- headache
vert - both
nausea - both
oscillopsia = central not peripheral
dyseq = both, central more severe
vom = maybe both
HA = central yes
what nerve is associated with oscillopsia
CN 8 = vestibulocochlear
list of peripheral vestibular disorders
BPPV
Vestibular neuritis
acoustic neuroma
meniere’s disease
ototoxicity
central causes of vestibular disorders
stroke
MS
neoplasm
of the peripheral causes of vestibular disorder, what can a PT diagnose
BPPV
others are medical diagnoses that result in vestibular hypofunction
what does BPPV stand for?
benign paroxysmal positional vertigo
cause of BPPV
otoconia in otolith organs become loose, clump together and then move into SCC
how is BPPV described
episodic, intense vertigo related to change in head position
which SCC is otoconia most likely to go into
posterior due to gravity
pathophys of BPPV
otoconia moving into SCC causes endolymph to move
- cascade of events cause the brain to interpret movement of the head and causes sensation of spinning
time related to BPPV episodes of vertigo
<60 seconds
what is vestibular neuritis
viral infection preceeding vestibular symptoms
will travel to vestibular nerve
explain timeline of symptoms associated with vestibular neuritis
sudden onset of vestibular symptoms that lasts 1-2 days
then residual symptoms will resist with head motion
signs of vestibular neuritis
nystagmus
abnormal VOR
medical treatment of vestibular neuritis
anti-emetics, histamines, cholinergics
steroids
prognosis of vestibular neuritis
over 6 wks to 3 months
may have persistent symptoms
what is an acoustic neuroma
benign tumor within schwann cells of vestibular nerve sheath
s/s of acoustic neuroma? which is different?
dizziness and dysequilibrium
– hearing loss is a differentiator
how to diagnose acoustic neuroma? what about treatment?
MRI
surgery
what causes meniere’s disease
malabsorption of endolymph fluid
– increased fluid volume
s/s of meniere’s disease
- any differentiators
fullness feeling in ear
TINNITUS
fluctuating vertigo
HEARING LOSS
imbalance
caps are differentiators
diagnosis / treatment of meniere’s
MD confirmation via s/s and audiogram
medical treatment - diuretics, diet (NA restriction)
could have surgery to prevent fluid buildup / ablation of vestibular nerve
when is PT appropriate in meniere’s disease progression
acute = not appropriate
vestib rehab after
when considering s/s of peripheral vestibular disorders, explain timing of symptoms
meniere and bppv = episodic
neuroma = come upon slowly
neuritis = very fast onset
ototoxicity targets the
cochlea and/or hair cells
what is the differentiator of ototoxicity
bilateral permanent damage
strokes involving the ____ and/or ____ via these arteries will cause _____ vestibular hypofunction
brainstem and or cerebellum
Basilar - AICA
Vertebral - PICA
central
for central disorders, when is PT appropriate? what is indicated?
once medically stable
VR, postural control and gait interventions
what is VNG and ENG? what is the point
video or electro nystagmography
capture nystagmus associated with vestibular dysfunction to determine CNS or PNS cause
what is CDP? what is the point?
computerized dynamic posturgraphy
– assess ability to remain posture under various environmental conditions
– evaluate somatosensory and visual influences on posture and equilibrium
what in a general sense does CDP assess vs ENG/VNG
CDP - one’s ability to integrate various sensory inputs to maintain postural control
V/ENG - CNS or PNS cause of vestibular disorders
differential in testing the central vestibular system vs peripheral vestibular system
both include:
oculomotor exam / postural control
CNS includes = red flags
PNS includes = VOR
how is vestibular rehabilitation designed
must produce an error signal in order for brain to adapt / compensate
explain acute vestibular rehabilitation and symptom reproduction
must exacerbate symptoms then allow for system to return to baseline
progressively challenges the vestibular system to improve its ability
canalithiasis vs cupulolithiasis
canal = otoconia displacement from macula into SCC
cupulo = otoconia adhere to cupula
– more intense and for >60 seconds
