Vestibular Dysfunction Flashcards
Function of the Vestibular System
Gaze stability (VOR)
Postural stability
Orientation in space
How does the Vestibular System play a role in Balance
- Processes multimodal sensory information
- Drives appropriate motor output
- Provides sense of position in space
- Feedback in relation to gravity
- Slowest but “final decision maker” (side: fastest is somatosensory)
Components of Vestibular System
- Peripheral Sensory apparatus (PVS)
- Central Processor (CVS): brainstem/cerebellum
- Mechanism for motor output
Motor output of the Vestibular system includes
VOR
VSR
COR
VOR
vestibular ocular reflex: generates eye movements consist with head movements
If you turn your head, the eye will go the opposite way to stay in the middle. When you look toward where your head is turning you are overwriting the VOR
VSR
Vestibular spinal reflex: generates compensatory body movements to keep head upright
Train with high level balance
COR
Cervical occular reflex:generates eye movements opposite to head movements (similar to VOR but not as active)
Anatomy of Peripheral Vestibular System (PVS)
- Housed int he inner ear
- Size of a dime
- petrous portion of temporal bone
- labyrinths & oroliths
- CN 8
- Labyrinthine artery
Anatomy of the Labyrinths
Semicircular canals taht consist of Anterior, posterior, horizontal canals
has a bony outer portion (perilymph) & membranous portion (endolymph)
Both peri/endolympth should not communicate with each other
Perilymph and Endolymph has high _____ : _____ ratio
Perilymph: high Na:K ratio
Endolymph: high K:Na ratio
Function of perilymph vs. endolymph
perilymph: protection
endolymph: fluid movement allow for the body to sense which way the head is moving secondary to movement of hair cells
Anatomy of the Bony labyrinths
5 sensory organs:
- 3 membranous labyrinths
- 2 otolith organ (utricle/saccule)
- ampullae
- hair cells
Role of Labyrinth
- Register head velocity
- VOR
- Rate sensors
- 3 coplanar pairs (aligned with plane of extraocular mm)
- push-pull relationship
Vestibular system is most effect at _____ degree/sec
~30 degrees/sec
Explain the push pull relationship of the vestibular system
As the head rotates to one side, the ipsilateral side is being excited while the contralateral side becomes inhibited.
sensory redundancy
ignore changes that affect both sides
assists in compensation for sensor overload
Role of the otoliths
Consist of utricle and saccule
respond to linear movement
accelereation in relation to gravity
register tilt (plane assent/descent, take off/landing)… eventually you get to constant speed and can’t feel accel/decel.
How long of a blockage is needed to lead to hearing lost?
15seconds
Central vestibular system (CVS)
Vestibular Nerve
Vestibular Nuclei
Cerebellum
vestibular nuclei location
4 primary on each side in the pons and medulla
input to Vestibular Nuclei
- CN8
- visual system
- auditory system
- somatosensory system
- Inhibition from the cerebellum
- ocular motor nuclei
- brainstem
Output from Vestibular nuclei
VOR/VSR control
Extraocular/neck mm (MVST)
postural ms (LVST)
Cerebellum (“repair shop” for PVS)
Symptoms of vestibular dysfunction
(what they feel)
Vertigo
dizziness
oscillopsia
dysequilibrium
tinnitus
Oscillopsia
they are not able to keep their eye fix, so the world is moving.
it occurs in standing/moving
if feel when sitting “red flag” not a true sign
Tinnitus
Ringing of the ear.
ear damage due to loud noise.
PT cannot treat
Signs of Vestibular Dysfunction
(what we observe)
Decrease gaze stability (VOR)
ataxia gait (central sign)
imbalance
motion sensitivity (fear of movement, slowness in movement, rigid movement)
Nystagmus
Nystagmus
Nonvoluntary rhythmic oscillation of the eyes
Defined by fast/slow component
named by the fast
Direction of slow component indicates side of unilateral hypofunction with horizontal nystagmus
Explain: Right beat nystagmus…. which way is fast? which way is side of deficit?
Right beat: Right is fast
left hypofunction
Peripheral causes of Vestibular system dysfunction
Labyrinthitis
neuronitis
BPPV
Acoustic Neuroma Resection
Meniere’s Disease
Chronic Subjective Dizziness
Central cause of Vestibular System Dysfunction
Mild TBI/PCS
TBI
CVA of brainstem, MO, cerebellum
Brainstem CVA
Cerebellar Dysfunction
Vertebral artery insufficiency
MS
If you suspect of vestibular dysfunction what should you rule out?
acute or progressive CNS pathology
cardiac or vascular pathology
Medication AR
Migraines
Cervical spine
thryoid disease/lyme disease (via blood test)
Consider sinus or inner ear infection/pathology
refer to ENT or neurologist
Diagnostic tests
MRI/CT scan
ENG: electronystagmography: emg measures of spontaneous and induced eye movement
caloric testing (PVH vs CVH and % loss): stimulus of endolymph movement by water in IAC
rotary chair: recorded eye movements with sinusoidal chair movement: this can ID % lost better than caloric testing
Labyrinthitis/Neuronitis
inflammation/infection to canals or CN8
- Acute symptoms very intense / sick (not appropriate for PT)
- spontaneous nystagmus for few days
- use of medication to reduce vertigo/nausea
PT indicated ipt does not appear to be independently compensating, but usually ppl go straight to the ED
Meniere’s Disease (aka endolymphatic hydrops)
disorder of inner ear function (malabsorption of endolymph)
age 30-60
chronic hearing loss/imbalance
residual imbalance
TIME LIMITED: few years and it will completely go away by itself
signs and symptoms of Meniere’s Disease
aural fullness, hearing loss, tinnitus, rotational vertigo, n/v
lasting 30 min-24 hour
PT for Meniere’s Disease
after an attack:
VOR, standing exercises, habituation exercises
Benign Paroxysmal Postional Vertigo (BPPV)
Short episodes of vertigo (<60 sec)
Quick head movements (head up/rotated toward affected side)
Associated with nausea and rotary nystagmus
Due to displaced otoconia in canal
Questions to ask if suspecting BPPV or to r/o?
When the sx comes on, how long does it last and what do you feel? If it last for hours (not BPPV)
typically: roll out of bed causes sx. Sit and focus goes away, head up and down causes onset of sx
Hallmark assessment of BPPV
Dix-Hallpike Test
What is a positive Dix-Hallpike?
Torsional nystagmus
upbeat/downbeat
duration (<1min, crescendo, decresendo)
once nystagmus goes away, sx goes away
Most common site for crystal to be located in
posterior canal
Canalithiasis vs. cupulolithiasis
canalithiasis: crystal in the canal
cupulolithiasis: crystal in ampula (harder to remove)
How to treat BPPV?
Use of Dix Hallpike followed by Canalithiasis Repositioning maneuver (Epley)
Chronic Subjective Dizziness (CSD)
Signs and symptoms
Perisistent dizziness or subjective imbalance
- Ligh-headness, head “swimming/heavy”
- Ground moving
- hypersensitive motion (self and world)
- Sx aggravated with demanding visual tasks (like computer), and lost of horizon (crowd, bridges)
- Clinical impression of anxiety
Testing does not pick up PVS hypofunction or gross balance dysfunction
CSD with anxiety
3 types
Neuro-otologic illness => anxiety
anxiety => dizziness
Hx of anxiety and transient episode of true vertigo or other dx resulting in dizziness
Anxiety questionnaires
Hospital Anxiety and Depression scale
Patient health questionnaire
Dizziness handicap inventory: F scale = anxiety, E subscale = depression
Management of CSD
- Focus on desensitization and reduction of “Threat System” with:
- Habituation vs. retraining VOR
- Pts vestibular system is working => they’re just not using it
- Dec. “perception” of imbalance
- Go Slowly
- PT Education
- cognitive Therapy with Vestibular rehabilitation & balance therapy (VBRT)
Compare peripheral vs Central injuries in term of:
- Duration of symptoms
- intensity
- time to adapt
- others
Peripheral injuries
- shorter duration of sx
- inc. intensity
- less time to adapt
Central injuries
- longer duration of sx
- greater imbalance with basic task
- cognitive deficits
- greater time to adapt
- more motion sensitive
- Vertical and/or spontaneous nystagmus beyond acute
Vestibular Systems Evaluation should include
General Systems screening
Strong hx
vertibular ocular assessment (head thrust)
visual screening
postural and balance assessment
impairment based assessment/screen
motion sensitivity (MSQ)
Assessment of BBPV
History for vestibular evaluation should include:
How long do sx last?
What provokes them?
When did it start?
Meds? (side effects)
sinus/allergies
new glasses
what makes u better?
Fall d/t this?
did you drive here?
Motion Sensitivity Quotient (MSQ)
16 different positional changes
sx in response to change in position
uses ordinal scale to capture intensity and duration of sx
NORMAL: 0%
Vestibular dysfunction Interventions should focus on
Symptom mmgt
patient education/early HEP
Endurance/conditioning program
improve VOR gain/gaze stability
Dec. sensitivity to position change
balance retraining
Address functional impairments
Examples of Vestibular Exercises
VOR x2, 2-3 times/day
habituation exercises
balance exercises (near couch, counter, corner for safety)
walking program (avoid TM b/c of mismatch between somatosensory [walking] vs visual [not walking] senses)
Frequency/Duration of care for
- Central injuries
- Peripheral
- BPPV
Central: 1-2x week/10-12 weeks OP
Peripheral: 1x week/6-8 weeks OP
BPPV: a few visits then HEP
