Vestibular disorders Flashcards
Sensation of inappropriate movement – Spinning
Vertigo
_______ is usually “ear” generated and causes a sensation of spinning
Nystagmus
main role of ear is to
keep eye fixed on target
Ear is constantly sending info to brain on baseline activty… if both ears are in same state means
you’re not moving
When you turn right, your right ear will send signals, the response is:
eyes accomidate to movement
loss of function of left ear: you don’t get normal tonic input so more input comes from right… brain intereprets this as..
you turning your head right = Unilateral hypofunction
Stimulation of a semicircular canal generates eye movements in the plane of that canal
Ewalds first law
Ewalds first law
Stimulation of a semicircular canal generates eye movements in the plane of that canal
Horizontal canal cauases eye movements to go
left and right
ampullopetal flow
Superior canal causes eyes
to go obqlique and off to the side
ampullofugal flow
Posterior canal causes eyes to
go oblique and to the back
ampullofugal flow
semicircular canals are at
right angle
stimulate the right horizontal canal, eyes move
left
stimulate the right superior canal, eyes move
eyes move UP, then rotate left
stim the right posterior canal, eyes move
eyes move down, then rotate left
Nystagmus occurs
Opposite the direction evoked by canal excitation
Nystagmus is a Corrective mechanism
– Rapidly bring eyes back to where they belong
if right horizontal canal is more active, nystagmus causes eyes
to the left
right superior canal is more active, nystagmus causes
eyes to go down and left
With nystagmus the eyes drift to the
weak side… then jerk back to more active side
if i stim right horizontal canal, i will see nystagmus that
beats to right… beats in plane of stimulated canal or towards more active side
if someone comes in and complains of dizziness but no nystagmus…
CANNOT be ear related
Three tests to uncover nystagmus
Head thrust
Gaze evoked nystagmus
head shake test
Most important vestibular reflex
• Maintains eye position during motion
• Extremely fast responses
• Disturbances are demonstrated by eye examination
Vestibulo ocular reflex
Loss of VOR on left side when you do a head shake:
eyes will pulse to the right
Gaze in the direction of the fast phase of nystagmus increases amplitude and frequency
alexanders law
Clinical situation:
patient looks left and see a slow, solid nystagmus
patient looks right and see it’s more active
diagnosis?
something is going on with the left eye
3 days post op left acoustic neuroma pt no longer has visible nystagmus but i can bring out a stronger nystagmus by having:
having patient look right
left is still hypofunctioning
Excitatory response for angular VOR are greater than inhibitory responses
Ewalds 2nd law
turing towards a side activates that side more then turning away from a side’s inhibtion
What happens to a normal patient during head shake exam?
nothing.. not nystagumus because summed up equally on both sides
during a head shake exam with a patient that has left side weakness… what happens when you’re done
see right beating nystagmus
loss of bone covering over superior canal is
superior canal dehiscence
you can mimic superior canal dehiscence by:
tones, exercise, pressure
• Posterior canal canalithiasis
• Posterior canal activated by movement
– Otoconia move in canal simulating movement (crystals)
• Nystagmus is toward affected ear and rotary in nature
– Geotropic beating (toward the ground)
Benign Paroxysmal Positional Vertigo BPPV
To diagnose BPPV
Dix-Hallpike Testing
chaning a lightbulb or getting the bed spins
• Head thrust and head shake can uncover a
weakness
Gaze can point to the
more active canal
Sound can stimulate a
dehiscent superior canal
Loss of vestibular function in all canals
• Can elicit signs of unilateral weakness
• Hearing loss
• Viral or bacterial in origin – Assess history of URI or otitis media
Labyrinthisis
Vestibular Neuronitis affects:
• Superior Vestibular Nerve – Horizontal and superior canals – Posterior canal spared (BPPV)
During Acute Phase of vestibular neuronitis
– Nystagmus beating away from affected ear
During Chronic Phase of vestibular neuronitis
> 6monthsafterinitialattack
• Weakness in balance function on one side
• Sensitive to rapid head movements
• Rare to have recurrence of initial attack
• May develop BPPV
• 30%developanxiety/”fearofdizziness”
1st week • Sudden and intense vertigo and imbalance • Need to stay still • Nausea and vomiting • Typically seen in ER
Vestibulo neuronitis
Question: I suspect vestibular neuritis in a patient with a single long vertigo attack 1 year ago. To identify a unilateral vestibular weakness and which ear was affected, my exam should include:
A. Head thrust test
B. Head shake exam
Both A and B
– Head thrust may show refixation saccades with thrust to the weak ear
– Head shake should uncover asymmetry with nystagmus beating to the good ear (away from the affected ear)
Inner ear fluid imbalance
Episodic vertigo
Fluctuating hearing loss
Menieres disease
Meniere’s Disease
Episodic Vertigo
Recurrent and episodic • Vertigo • Last 30 minutes to ~4 hours • Minimal imbalance between attacks • Unilateral balance weakness – fast turns or head rotations
