Vestibular Anatomy and Function Flashcards
What are the 3 Roles of the Vestibular System?
- Stabilize visual image during head movement
- Provide sensory info for spatial orientation
- Maintain postural stability when stationary and during movement
Controls the body position in space for stability and orientation between body segments and the environment, appropriate for a task
Postural control
Maintenance of the COM within the BOS
Postural Stability
Ability to maintain a relationship between body segments and between body and environment for a task
postural orientation
_____ System
-recognizes motion
Visual
Children <7.5 rely on what system for balance?
Vision
What 3 things make up the vestibular system?
- Gaze stabilization
- Spatial orientation
- Postural stability
____ System
-recognizes relative body movements and position
base of support, joint proprioception, pressure, cervical proprioception and kinesthesia
Somatosensory
Explain central processing
adaptive strategies that change with the demands of a task
anticipatory strategies “pretune” sensory and motor systems based on prior learning
Ex: Cognitive override due to consideration of motivation intent and attention
Give an example of central processing
a volley baller going to dive for the ball the central portion of the brain overrides the body going outside of its BOS.
What arteries supply blood to the vesibular peripheral organ?
Posterior blood supply
1. Basilar Artery
2. Anterior Inferior Cerebellar Artery
Labyrinethine artery
-anterio-vestibular artery
-common cochlear
What are the two otoliths?
utricle and saccule
What motion is recognized by the utricle
horizontal plane motion
What motion is recognized by the saccule
vertical plane motion
Explain what otoconia do?
provide shear forces for hair cell deflection
Are otoconia gravity dependent and what does that mean?
Yes Otoconia are gravity dependent
if you tip your head Otoconia shift deflecting hair cells sending signals to the brain.
these otoconia should not fall off the otolithic membrane but if they do thats what causes vertigo
What motion do the otoliths regonize
forward/backward
up/down
tilting
What does tonic discharge mean?
both ears have discharge even at rest
Explain the push pull relationship between the otolith organs
if you tilt head left discharge increases while the right discharge decreases
What motion is recognized by the semicircular canals?
angular motion-rotation
What do the hair cells do?
tell your brain that you have moved
How many semicircular canals are there?
3
anterior
posterior
horizontal
Describe what happens if you move down and to the right what canal stimulates and what decreases?
stimulates right anterior and decrease left posterior
Where does Cranial nerve VIII have its cell bodies?
scarpas ganglion
has bipolar ends
Describe cranial never VII and VIII course of action?
travel together through the internal auditory meatus
enter the pontomedullary junction of the brain
Explain where the CN VII VIII enter the brainstem in terms of nuclei
- superior vestibular nuclei
- inferior vestibular nuclei
- lateral vestibular nuclei
- medial vestibular nuclei
Do the vestibulospinal mechanisms for postural control continue to develop beyond 15 years of age?
true
The vestibulo cerebellum is
Flocculonodular lobe
What do the vestibular nuclei do to the cerebellum
can fine tune communicate info from the nuclei to the cerebellum for input and output
What is responsible for the discrimination between self movement and environment movement?
thalamus
Explain what the reticular formation does?
interprets info from all vestibular nuclei
can determine if motion from a rollercoaster causes vomiting
can determine that rocking a baby is safe and soothing
Why is our vestibular cortex so small?
we aren’t that conscious of the motion that occurs around us
What is the blood supply for the inferior vestibular nucleus
posterior inferior cerebellar nucleus
What blood supplies the pons and more superior vestibular nuclei
basilar artery
Explain the Vestibular ocular reflex
Stabilizes gaze during head movements
ex: if you turn your head your extra ocular eye muscles will go the other way
When is the VOR intact and mature
by one year
Describe the flow of input for VOR
inner ear–vestibular nuclei— MLF— extra ocular eye muscles
Describe the vestibulo-spinal reflex
coordinates head and body movements to maintain head in upright position
Explain the path of VSR
info from inner ear–> vestibular nuclei–> descends to the cervical spinal cord–> to extension response to catch our balance
What tracts does the VSR utilize?
LVST- Lateral vestibulo-spinal tract
MVST- Medial vesibulospinal tract
Describe what the Vestibulo-colic reflex does?
head righting
stabilizes head/neck
produces coordinated movements to track a moving target
think of the chicken video
Describe ATNR (asymmetric tonic neck reflex)
neck rotation excites ipsilateral extensors and contralateral flexors
Describe STNR (symmetric tonic neck reflex)
neck extension excites ipsilateral UE extension LE flexion
Cervico- occular reflex
eye movements are driven by neck proprioception
supplements the VOR when needed
facilitated when vestibular organ is injured
Cervicospinal reflex
can supplement the VSR by alerting tone in the body
cervicocolic reflex
stabilizes the head on the body
may be facilitated after vestibular loss
What are some Central Pathologies of vestibular disfunction
Traumatic Brain injury
Multiple Sclerosis
Stroke
Brain tumor
Vestibular migrane
What is the most common cause of true vertigo?
Benign Paroxysmal Positional Vertigo
What is the 2nd most common cause of true vertigo?
neuritis- CN VII becomes inflammed
A floor warping, ceiling spinning, brain churning, think you’re gonna die and afraid you might not- hangover
Endolymphatic Hydrops Meniere’s Disease
Describe some of the presentation of Meniere’s disease
acute episodes of 30 min to 24 hours
usually recovery in 72 hours
What is the treatment of meniere’s disease? PT involvement
Surgery or ablation- managed medically
PT can help with education
What is the presentation of Perilymph Fistula?
vertigo after very loud sounds
Congenital, prior ear surgery, barotrauma
What is the treatment for Perilymph Fistula? PT involvement
PT will refer!
What is the presentation of Superior Canal Dehiscence?
Creates a window through the bone
vertigo and oscilopsia induced by loud noises
What is the treatment for Superior Canal Dehiscense?
Primarily medical management
PTs Refer!!
What is the common presentation of Mal de Debarquement Syndrome?
perception of motion when stationary and eyes are open
Usually occurs after exposure to motion, such as a cruise
Difficulty adapting back to stable environment
What is the treatment for Mal de Debarquement Syndrome? PT involvement?
Possible treatment with medication
focus on somatosensory referencing to vestibular sense
Know how to examine- as a pt
Very common but very hard to treat
What is the presentation of Peripheral Neoplasm Acoustic Neuroma?
Tumor affecting CN VII
What is the treatment for Peripheral neoplasm acoustic neuroma? PT involvement
surgical removal or radio-surgery
Commonly and appropriately referred to PT for treatment
What is persistent Postural Perceptual Dizziness?
Persistent dizziness
Non-spinning Vertigo
Perceived unsteadiness
A result of long term maladaption
What is the treatment of persistent postural perceptual dizziness?
Commonly and appropriately referred to PT for treatment
___%. of those with whiplash dizziness can take longer than 20 weeks to return to work
20%
What is the primary symptom of wiplash?
Neck pain
What are common subjective findings with patients who have cervicogenic dizziness?
occipital or bitemporal HA
Neck Pain
People tell me my head is not straight
What are some common subjective findings of someone who is just having dizziness non specific?
Dizziness
Sensation of falling
Difficulty reading
Feeling tired
What are some medical and audiologic tests commonly used to diagnose vestibular disorders?
Electronystagmography
Videonystagmography
Medical diagnostic testing- rotary chair testing
Autiogram
Medications such as Cisplatin and gentamycin, streptomycin can cause what?
ototoxic
When should you use the vertebral artery test?
neck trauma
cervical surgery and/or arthritis
Is there a high specificity or sensitivity with the vertebral artery test
Specificity if it is positive likey they have insufficient blood flow
What are the 5 Ds and 3 Ns
Dizziness
Diplopia
Dsyphagia
Dysarthria
Drop attack
Numbness
Nystagmus
Nausea
What are test can be used to diagnosis an issue with VOR?
Head impulse test
Head thrust test
How do you test gaze stability?
Dynamic Visual acuity
SNELLN chart
What are 3 positional testing for BPPV
Dix- hallpike
Sidelying Test
Roll Test
What are some test for postural control?
Berg Balance
Mini Best Test
Four Square step
CTSIB
ROmberg
FUnctional reach
How to test for head righting response?
sitting on rocker board
Standing on rocker board
Tandem standing
What is a normal loss of line during the VOR head motion visual acuity testing
loss of 2 lines is normal
Nystagmus is named for what
the fast phase direction
Your patient has dizziness/vertigo what is the treatment
Habituation: Exercises designed to perform several repetitions of body movements or watch visual motion that cause mild to moderate symptoms
Your patient has Visual blurring with head movements what is the treatment
Gaze stability
adaptation exercise to maximize remaining vestibular function
Your patient has imbalance and/or falls what is your treatment
Balance and gait
may involve changes in base of support to increase balance challenge and weight shifting to improve center of gravity control
produce an error signal and recalibrate vestibular input
up-train or force use particular senses
central selection, prioritization, integration
remediation=adaptation/uptraining
Repetition of provoking movement with cautious symptom provocation and settling
sensory habituation=desensitization
If sensory information is missing
inherent limitaitons- may need additional compensations under certain circumstances
sensory substitution= Compensation
What should be considered with central pathologies
Consider burden and location of damage
uptrain vestibular function when able
compensate with vision and somatosensory when maximum adaptation has occured
If patient has dizziness when the head is moved where is a strong hypothesis this is coming from?
cervical
If patient moves body and the head doesnt move and the patient has dizziness then what is your hypothesis?
vestibular
During a smooth pursuit neck torsion test the neck is placed at ____ degrees of rotation
45 degrees
What is a negative test for the smooth pursuit neck torsion test?
saccades, increase dizziness
