Vestibular Disorders Flashcards
Vestibular system is a key _____ receptor
sensory
VS is sensitive to:
- head movement
- head position
- effect of gravity
Function of VS
- detect movement
- maintain gaze stability during motion
- maintain balance
When not functioning properly, what other systems compensate and what is the main impairment
Visual and SS compensate (body must learn this)
balance is an issue
What are the peripheral parts of VS?
Labyrinth! = 3 SC canals and otolith (saccule + utricle)
What type of movement/position does the otolith (saccule and utricle) respond to?
static positions
linear acceleration
What type of movement/position do the semicircular canals respond to?
Angular head movements
Anterior = head nod (tilt in sagital plane)
Posterior = head tilt (tilt in frontal plane)
Horizontal = head turns (tilt in transverse plane)
What is the pathway of information transmission from SC canals –> brain?
endolymph in SC canal moves –> hair cells moved in opposite direction –> sends info to cortex –> stabilizes eyes to target
Push-Pull Phenomenon
Activation of SC canal on one side inhibits SC canal on other side
*i.e. head turn to right = activation R horizontal SC canal (don’t move eyes here) + inhibition of L horizontal SC canal (turn eyes that way)
Central structures of VS
- cochlea nerve and vestibular nerve (inflammation/injury to one can cause issues with the other)
- Facial nerve (issues here can cause issues in chochlea or vestibular nerve)
- Cerebellum (inhibition or facillitation of VOR)
Lesion in central v peripheral structures (recovery time)
longer recovery time for central lesions- pt must learn compensation strategies
Corrective saccade
eyes correct themselves to reorient to center (occurs in healthy system)
Saccade
voluntary corrective movement
Smooth pursuit
slow saccades - voluntary
Nystagmus
involuntary; quick corrective movement of the eyes back to the center
Retinal Slip
image slips from person’s eyes; they are unable to process changes to a moving image (see it as more than 1 object in front of you)
Vestibulo-Occular Reflex (VOR), purpose, types/what senses it
purpose: hold images steady on retina with head movement
Angular VOR: sensed by SCC
Linear VOR: sensed by otolith
Ocular Tilt Reflex: sensed by utricle
Nystagmus- what side is the lesion on
typically the side with a quicker nystagmus is the side of the lesion (direction of the fast phase)
*evaluate during tonic and dynamic system- central lesions have nystagmus in both
Tonic System deficit
nystagmus present without movement (at rest)
Dynamic system deficit
nystagmus with movement
What is considered a “Central lesion” v “Peripheral lesion”
central = everything past internal auditory canal (disorders of the CNS) Peripheral = everything before internal auditory canal (SCC and otolith)
Peripheral lesion symptoms
- Dizziness with positional changes
- hearing loss, tinnitus
- balance problems
- symptoms with head movement during gait
- acute nystagmus
- nystagmus only present chronically if they have NOT learned to compensate
- oscillopsia- jumping of objects in visual field (can’t focus, feel like its moving up and down)
Central Lesion Symptoms
- constant dizziness
- Downbeating nystagmus (but present with anterior SCC deficit- differentiate whether it is present at rest)
- Cerebellar signs/sx (ataxia/imbalance)
- Associated head injuries/cervical injuries
- Horner’s Dyndrome
- swallowing difficulty
- Sensory changes
- babinski, clonus, changes in DTRs
- Impaired balance and gait
Symptoms common in peripheral and central lesions
- Spinning/vertigo (worsened with 3D shapes)
- Vomitting
- Nausea
- Headache
- dizziness
- impaired balance