Vestibular Disorders Flashcards
The 3 primary functions of the peripheral vestibular system?
- stabilizing visual images during head movements (for clear vision)
- maintaining postural stability (especially with head movements)
- providing information for spatial orientation
Each semicircular canal has a contralateral coplanar mate, so one side is being depolarized/excited while the opposite is being hyperpolarized/inhibited. Which pairs are working together if a person is turning their head to the left?
- left lateral (horizontal) canal is being depolarized/excited
- right lateral (horizontal) canal is being polarized/inhibited.
Name the semicircular canal coplanar pair’s that work together.
- left and right lateral (horizontal) canal’s
- left anterior (superior) and right posterior canal’s
- right anterior (superior) and left posterior canal’s
What are the 2 otolith organs?
- saccule
- utricle
How does the brain detect the direction head movement?
- by comparing input from coplanar pairs
- motion of endolymph results in opening or closing of transduction channels of hair cells
What is the ampulla?
- located at the enlarged end of each canal
- within the ampulla lies the cupola (gelatinous barrier that contains the sensory hair cells)
Which otolith organ is excited during horizontal linear acceleration and/or static head tilt?
- utricle (vertical hair cells)
Which otolith organ is excited during vertical acceleration?
- saccule (hair cells are lateral)
What part of the central vestibular system provides primary control of many vestibular reflexes?
- brainstem
Where does vestibular pathways terminate (cortical area)?
- junction of parietal and insular lobes
When sitting still what does the cerebellum pay more attention to?
- info from somatosensory system (touch, pressure, joint position)
When you move what does the cerebellum pay more attention to?
- vision and vestibular inputs
What is VOR gain and phrase?
- gain is equal and opposite velocity of head and eye’s
- phase is equal and opposite head and eye relationship
What is VOR responsible for?
- maintaining stability of an image on the fovea of the retina during rapid head movements (rapid compensatory eye movements in opposite direction of the head when moving/rotating)
Peripheral vestibular pathology can be one of two types?
- mechanical (BPPV, most common)
- decreased receptor input (UVH or BVH)
What most commonly causes unilateral vestibular hypofunction?
- virus, trauma, vascular events
What most commonly causes bilateral vestibular hypofunction?
- most common is ototoxicity
- others include meningitis, autoimmune disorders, head trauma
Define otoconia?
- the “crystals”
- located in the gelatinous matrix
- calcium carbonate
What is cupulolithiasis?
- otoconia adhere to the cupula of one of the SCC’s
What is canalithiasis?
- otoconia are floating freely in one of the SCC’s
BPPV symptoms?
- NYSTAGMUS and VERTIGO with HEAD POSITIONING
- occasionally nausea, vomiting, disequilibrium
UVH symptoms?
- SPONTANEOUS NYSTAGMUS (at rest)
- vertigo
- visual blurring
- oscillopsia during head movements
- postural instability
- dysequalibrium
BVH symptoms?
- DYSEQUILIBRIUM (unsteadiness)
- oscilliopsia
- gait ataxia
Red Flags that require referral to neurologist?
- horizontal or vertical diplopia (double vision) lasting longer than 2 weeks
- pure vertical nystagmus
- spontaneous up-beating nystagmus
- positive test for skew deviation
Contraindications to vestibular rehab (8)?
- acute episode of Meniere’s disease
- uncontrolled migraine
- PLF
- unrepaired superior semicircular canal dehiscence
- sudden loss of hearing
- increase feeling of pressure or fullness in one of both ears that is uncomfortable
- post surgical, observe for fluid in ears
- acute neck injuries may not tolerate
What % of patients sustaining mild head injury (TBI) complain of vertigo?
- 78%
- 20-37% still after 6 mo - 5 yrs later
Central nervous system pathology that could cause vestibular symptoms that needs to be filtered out during the exam(6)?
- CVA
- Vertebrobasilar insufficiency (VBI)
- TBI
- MS
- Nystagmus
- Other indicators (lateropulsion, visual perceptual difficulties, oculomotor signs, skew deviation of the eyes)
Compare common symptoms of Central vs Peripheral vestibular pathology (7).
- Central - ataxia, severe (Peripheral - mild)
- Central - abnormal smooth pursuit and saccades (Peripheral - both normal)
- Central - usually no hearing loss but if so is sudden/permanent (Peripheral - may be hearing loss, fullness in ears, tinnitus)
- Central - Sx diplopia, altered consciousness, lateropulsion (Peripheral - none of those)
- Central - acute vertigo not usually suppressed by fixation (Peripheral - acute vertigo suppressed by visual fixation) (Peripheral vertigo usually intense)
- Central - pendular nystagmus (Peripheral - slow and fast phases of nystagmus)
- Central - pure persistent vertical nystagmus regardless of positions (Peripheral - spontaneous horizontal nystagmus)
What symptoms would be common in Meniere’s disease (4)?
- low frequency hearing loss and episodic vertigo
- sense of fullness in ears and tinnitus
- episodes can last several hours
- PT indicated for chronic meniere’s
How can a PT help motion sickness?
- habituation training can be effective if debilitating
Why is it important to know if your vestibular patient has MS?
- can cause symptoms just like UVH (CN VIII)
What % of patients with migraine-related dizziness had abnormal nystagmus during episode?
100%
What is cervicogenic dizziness?
- pathology affecting c-spine and related soft tissue
- upper c-spine sends proprioceptive input to contralateral vestibular nucleus
- soft tissue injury or joint dysfunction might alter afferent input
