Vestibular Disorders Flashcards
What are the goals of otologic evaluation?
- In the acute state: r/o stroke
-
Primary Goal: Is this otologic?
- If otologic then which ear?
- If can identify an ear, then which canal?
- Develop a differential diagnosis
What are the types of dizziness?
-
Vertigo
- Sensation of inappropriate movement
- Spinning
- lateral pulsion?
-
Disequilibrium / Imbalance
- Unsteadiness
-
Lightheadedness / Giddiness
- “wooziness”, disorientation, feeling “off”, faint
- Vertigo is typically ________.
- __________ is usually “ear” generated and causes a sensation of spinning
- otologic
- Nystagmus
Ewald’s First Law:
Stimulation of a semicircular canal generates eye movements in the plane of that canal
How are eye movements evoked by the stimulation of individual semicircular canals?
Nystagmus:
- Opposite the direction evoked by canal excitation
-
Corrective mechanism
- Rapidly bring eyes back to where they belong
- Named for the fast direction of motion
- Left / right; up / down
- Rotary: clockwise / counterclockwise
What are ways to provoke a nystagmus?
- Head Thrust Test
- Gaze Evoked Nystagmus
- Head Shake Test
Vestibular Ocular Reflex (VOR):
- Most important vestibular reflex
- Maintains eye position during motion
- Extremely fast responses
- Disturbances are demonstrated by eye examination
- Eye movements that are inappropriate:
- cause sensation of dizziness and nausea
Alexander’s Law:
- Gaze in the direction of the fast phase of nystagmus increases amplitude and frequency
- i.e. look to the stronger side
Ewald’s Second Law:
Excitatory responses for the angular VOR > inhibitory responses
- Turning toward a side, activates that side greater than turning away from a side, inhibits that side
- Activation/Inhibition close together add up
Head Shake Exam:
Which law is being exercised here?
-
Shake the patient’s head back and forth vigorously for 10-15 seconds
- Make sure no neck problems
- If one side is weak, the excitation on the stronger side will predominate
- Eye movements will mimic unilateral canal excitation (fast beat to better side)
♦This demonstrates Ewald’s 2nd Law♦
Another way to generate eye movements to see which _____ and side are affected
canal
Superior Canal Dehiscence:
- Loss of bone covering over the superior canal
- Excitation by various stimuli:
- Tones
- Exercise
- Pressure
Benign Paroxysmal Positional Vertigo (BPPV):
- Posterior canal canalithiasis
- Posterior canal activated by movement
- Otoconia move in canal simulating movement
-
Nystagmus is toward affected ear and rotary in nature
- Geotropic beating (toward the ground)
Name some vestibular disorders:
- Labyrinthitis / Vestibular Neuronitis
- Meniere’s Disease
- Migraine
Labyrinthitis:
- 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
Vestibular Neuronitis:
-
Superior Vestibular Nerve:
- Horizontal and superior canals
- Posterior canal spared (BPPV)
-
Acute Phase:
- Nystagmus beating away from affected ear
-
Chronic Phase:
- Loss of unilateral VOR
- Head thrust; head shake; calorics
Vestibular Neuronitis:
Acute Phase
- 1st week
- Sudden and intense vertigo and imbalance
- Need to stay still
- Nausea and vomiting
- Typically seen in ER
Vestibular Neuronitis:
Sub-acute Phase
- 1-6 months
- Episodic vertigo
- Short, less intense episodes
- Motion sensitivity
- Gradual improvement in balance
Vestibular Neuronitis:
Chronic Phase
- > 6 months after initial attack
- Weakness in balance function on one side
- Sensitive to rapid head movements
- Rare to have recurrence of initial attack
- May develop BPPV
- 30% develop anxiety/”fear of dizziness”
Meniere’s Disease:
- Inner ear fluid imbalance
- Episodic vertigo
- Fluctuating hearing loss
- Entire labyrinth affected
- Usually unilateral so should be able to elicit unilateral signs
- Head shake
- Head thrust
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
Meniere’s Disease:
Fluctuating Hearing
- Low frequency
- One ear
- Lasts minutes to weeks to months
- Can become permanent
- May respond to steroids
Meniere’s Disease:
Associated Symptoms
-
Tinnitus:
- Low-frequency, rumble, hummmm
- Worsens before attacks; better after
-
Aural fullness:
- One sided pressure
- Worsens before attacks; better after
- Which disease has a long vertgio and hearing loss?
- Which disease has a short vertgio and hearing loss?
- Which disease has a long vertgio and no hearing loss?
- Which disease has a short vertgio and no hearing loss?
- Labyrinthitis
- Meniere’s Disease
- Vestibular Neuronitis
- Benign Paroxysmal Positional Vertigo (BPPV)
Vestibular symptoms are more common in patients suffering from migraine with _____.
aura
Vestibular Migraine:
Veritgo
-
Spontaneous vertigo including:
- **Internal vertigo: **a false sensation of self-motion
- External vertigo: a false sensation that the visual surround is spinning or flowing
- **Positional vertigo: **
- occurring after a change in head position (but not specific like BPPV)
-
Visually induced vertigo:
- triggered by complex or large moving visual stimulus
-
Head motion induced vertigo:
- occurring during head motion
Vestibular Migraine:
Duration
-
Episode length
- 30% lasting minutes
- 30% lasting hours
- 30% several days
- 10% seconds (mostly related to head movement or visual stimuli)
- Note: some patients may take weeks to fully recover from an episode
Question: If I stimulate the right horizontal canal (ex: warm caloric on the right), I will see nystagmus that beats:
- Horizontal to the left
- Horizontal to the right
- Rotary to the left
- Rotary to the right
Answer:
- Horizontal to the right
- Beats in the plane of the stimulated canal
- Beats toward the more active side
- Ewald’s 1st Law
Question: My 3 days post-op left acoustic neuroma patient (left nerve was cut) no longer has visible nystagmus. I can bring out the nystagmus by having them look to the:
- Left
- Right
- Up
- I can’t bring out nystagmus
Answer:
- Right
- Has left hypofunction due to cutting nerve at surgery
- Nystagmus beats to stronger side (i.e., the right)
- Alexander says look to stronger side and increase nystagmus
Question: My left acoustic neuroma patient is seen 1 month post-op. If I do a head shake exam I will see nystagmus beating to the:
- Left
- Right
- Up
- There will be no nystagmus
Answer:
- Right
- Left is permanently weak
- Will beat toward stronger side (forever)
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:
- Head thrust test
- Head shake exam
- Both A and B
Answer:
- 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)
