CVT Assessment & Diagnosis of Vestibular Disorders 3 — Questions and Answers
Question 1: During the Dix-Hallpike test for posterior canal BPPV, the characteristic nystagmus has which direction?
- Purely horizontal, direction-changing
- Upbeat-torsional toward the affected (down) ear (Correct answer)
- Downbeat with contraversive torsion
- Purely vertical, downbeat
Correct answer: Upbeat-torsional toward the affected (down) ear
Posterior canal BPPV produces upbeat-torsional nystagmus with the torsional component beating toward the undermost (affected) ear during Dix-Hallpike.
Question 2: A patient complains of vertigo that is provoked by rolling from supine to left lateral decubitus but NOT by Dix-Hallpike. The MOST likely diagnosis is:
- Posterior canal BPPV on the left
- Horizontal canal BPPV (Correct answer)
- Superior canal BPPV
- Vestibular neuritis
Correct answer: Horizontal canal BPPV
The roll test (Pagnini-McClure) provokes horizontal canal BPPV, which is not consistently elicited by the Dix-Hallpike maneuver.
Question 3: Skew deviation on the HINTS exam suggests pathology in which structure?
- Labyrinth or eighth nerve (peripheral)
- Brainstem otolithic pathways (central) (Correct answer)
- Semicircular canals exclusively
- Cochlea or auditory nerve
Correct answer: Brainstem otolithic pathways (central)
Skew deviation (vertical misalignment of the eyes) reflects disruption of central otolithic pathways in the brainstem or cerebellum, indicating central pathology.
Question 4: On dynamic posturography, a patient who falls only on Condition 6 (sway-referenced surface AND eyes closed) has difficulty with:
- Visual-vestibular conflict resolution
- Isolated vestibular system use for balance (Correct answer)
- Somatosensory reweighting only
- Cerebellar coordination
Correct answer: Isolated vestibular system use for balance
Condition 6 removes reliable visual and somatosensory input, forcing exclusive reliance on vestibular cues; failure indicates vestibular system deficit.
Question 5: The 'ice water caloric' test performed at bedside uses 0–4°C water to assess:
- Otolith function in obtunded patients
- Brainstem integrity and vestibulo-ocular pathways in comatose patients (Correct answer)
- High-frequency VOR gain
- Endolymphatic hydrops
Correct answer: Brainstem integrity and vestibulo-ocular pathways in comatose patients
Ice water caloric irrigation in comatose patients assesses the integrity of brainstem VOR pathways when standard testing is not possible.
Question 6: Which outcome measure is MOST appropriate for quantifying dizziness handicap in a patient with chronic vestibular dysfunction?
- Berg Balance Scale (BBS)
- Dizziness Handicap Inventory (DHI) (Correct answer)
- Activities-Specific Balance Confidence (ABC) scale
- Visual Analog Scale for pain
Correct answer: Dizziness Handicap Inventory (DHI)
The DHI is a validated 25-item self-report questionnaire specifically designed to measure the perceived handicap from dizziness across emotional, functional, and physical domains.
Question 7: A patient with unilateral vestibular loss shows spontaneous nystagmus that INCREASES when fixation is removed. This is MOST consistent with:
- Central nystagmus with fixation suppression failure
- Peripheral vestibular nystagmus normally suppressed by fixation (Correct answer)
- Congenital nystagmus
- Gaze-evoked nystagmus from cerebellar pathology
Correct answer: Peripheral vestibular nystagmus normally suppressed by fixation
Peripheral vestibular nystagmus is typically suppressed by visual fixation; removing fixation (e.g., with Frenzel lenses) unmasks or increases it.
CVT Assessment & Diagnosis of Vestibular Disorders 3
During the Dix-Hallpike test for posterior canal BPPV, the characteristic nystagmus has which direction?