Vestibular Testing Flashcards
A nerve stimulator is placed at the stylomastoid foramen and used to measure the electrical threshold which will elicit gross facial movement. What test does this describe?
Nerve excitability test.
(A difference >3.5 mA suggests weakness of one side compared to the other, and that the patient may be a good candidates for surgical decompression)
ECOG (electrocochleography) with an elevated SP/AP ratio is typically above ___.
0.4
55F w/ L-sided pulsatile tinnitus and says she hears her footsteps loudly when she walks. Her audiogram reveals a mild conductive hearing loss w/air-bone gaps greatest in the lower frequencies. Acoustic reflexes are normal. ECOG reveals an SP/AP ration of 0.6. Based on history and testing alone, what is the most likely diagnosis?
SSCD (a portion of acoustic energy through the dehiscence is shunted away from the cochlea, resulting in a CHL).
(Pt has autophony, pulsatile tinnitus, normal symmetric hearing w/conductive hearing loss w/larger low-frequency air-bone gaps, and supra-normal bone conduction thresholds).
Patients with SSCD typically have a ___ cVEMP due to a “third mobile window” which increases the sensitivity of the vestibular receptors to sound and pressure stimuli. Amplitudes will be ___.
Patients with SSCD typically have a lower threshold cVEMP due to a “third mobile window” which increases the sensitivity of the vestibular receptors to sound and pressure stimuli. Amplitudes will be higher.
Cervical vestibular evoked myogenic potential (cVEMP) are used to assess the function of the ___.
Saccule and/or Inferior vestibular nerve.
In a cVEMP test, the ___ of responses and threshold asymmetries between the R and L ___ are assessed.
In a cVEMP test, the Amplitude of responses and threshold asymmetries btwn. the R and L SCM muscles are assessed.
[Figure: cVEMP obtained in an individual with a modest left sided conductive hearing loss. The VEMP on the R was normal, and the VEMP on the L, entirely absent. (P1 designates the potential that occurs at 13msec)]
How are cVEMPs generated?
Sound stimulates the saccule, traverses the vestibular n. (mainly inferior, but a bit also in the superior) and vestibular ganglion to reach the vestibular nucleus in the brainstem. From there, impulses are sent to the SCM via the medial vestibulospinal tract (MVST), then the spinal accessory nucleus, and the accessory nerve.
The pathology of SSCD involves:
Bony dehiscence overlying the semicircular canal
Which vestibular test is capable of testing each side of the vestibular system independently?
Caloric testing.
During caloric testing, each ear is tested independently w/both cold and warm water to illicit increasing or decreasing amounts of ___.
During caloric testing, each ear is tested independently w/both cold and warm water to illicit increasing or decreasing amounts of Nystagmus.
Which SCC is stimulated w/caloric testing?
B/c the horizontal SCC is most lateral, this is what is being stimulated w/caloric testing.
Ménière’s disease diagnosis is based on ___, a definitive diagnosis can only be made via __.
Ménière’s disease diagnosis is based on clinical symptoms, a definitive diagnosis can only be made via autopsy.
Vertigo experienced by patients w/Ménière’s disease is characterized by recurrent well-defined episodes of spinning that last ___ . It may be associated with nystagmus and nausea.
Vertigo experienced by patients w/Ménière’s disease is characterized by recurrent well-defined episodes of spinning that last 20mins to 12hrs. It may be associated with nystagmus and nausea.
Tinnitus experienced by patients w/Ménière’s disease is ___ during attacks, ___, ___, and subjective.
Tinnitus experienced by patients w/Ménière’s disease is louder during attacks, low-pitched, unilateral, and subjective.
What is the relative size of the semicircular duct of the membranous labyrinth compared w/the semicircular canal of the osseous labyrinth w/in which it lies?
The semicircular ducts occupy a small portion of the semicircular canals of the bony labyrinth.
A Valsalva maneuver increases intracranial pressure and causes an increased pressure within the ___ semicircular canal.
This elicits ___ in the direction of the canal.
A Valsalva maneuver increases intracranial pressure and causes an increased pressure within the Unilateral semicircular canal.
This elicits Nystagmus in the direction of the canal.
SSCD creates another portal (‘third window’) of ___ within the labyrinthine system.
Pressure release
Which vestibular test is capable of testing each side of the vestibular system independently?
Caloric testing.
(The horizontal SCC is tested w/both cold and warm water to illicit increasing or decreasing amounts of nystagmus).
Headshake nystagmus test:
If at least ___ consecutive beats of horizontal nystagmus are present directly following the headshake (30 times), this is considered a unilateral vestibulopathy.
3-5 beats of nystagmus.
Smooth pursuit tracking is the most sensitive oculomotor test to detect ___ vestibular dysfunction.
Central vestibular dyfunction.
(the eye may fall behind the target and has to make an abrupt more rapid mvmnt to “catch up.” People with central dysfxn will have several “catch up” saccades and asymmetrical pursuit (worse in one direction than the other).
Auditory brainstem implants are FDA approved for patients ___ years of age.
12 years old.
Directional preponderance is a measure of the difference in total eye speeds between ___ phases of nystagmus on each side.
Slow phases.
List the diagnoses in the image.
(Right -> Left: 1, 2, 3)
- Ménière’s disease
- Labyrinthitis
- Vestibular neuritis
Vestibular neuritis is treated with:
IV Hydration and Anti-emetics, + Trial of steroids can be employed for symptom control
