CVT Assessment & Diagnosis of Vestibular Disorders 2 — Questions and Answers
Question 1: During the head impulse test (HIT), a corrective saccade after a rapid head thrust indicates:
- Intact VOR gain on the tested side
- Reduced VOR gain on the ipsilateral semicircular canal (Correct answer)
- Central vestibular pathology exclusively
- Otolith dysfunction
Correct answer: Reduced VOR gain on the ipsilateral semicircular canal
A corrective saccade following the head impulse indicates the VOR is insufficient to maintain gaze, reflecting ipsilateral canal hypofunction.
Question 2: The HINTS exam (Head Impulse, Nystagmus, Test of Skew) is primarily used to differentiate:
- BPPV from Meniere's disease
- Peripheral vestibular neuritis from central stroke (Correct answer)
- Otolith dysfunction from canal dysfunction
- Unilateral from bilateral vestibular loss
Correct answer: Peripheral vestibular neuritis from central stroke
HINTS distinguishes benign peripheral vestibular neuritis from dangerous posterior fossa stroke in acute vestibular syndrome.
Question 3: In caloric testing, a canal paresis (CP) is calculated using which formula?
- (RW + RC) − (LW + LC) / (RW + RC + LW + LC) × 100
- (RW + LC) − (RC + LW) / (RW + LC + RC + LW) × 100
- (RW + RC − LW − LC) / (RW + RC + LW + LC) × 100 (Correct answer)
- (RC − LW) / (RC + LW) × 100
Correct answer: (RW + RC − LW − LC) / (RW + RC + LW + LC) × 100
Canal paresis compares the sum of responses from one ear to the other, using Jongkees' formula with all four irrigations.
Question 4: A patient with Meniere's disease is MOST likely to show which pattern on electrocochleography (ECoG)?
- Reduced summating potential (SP)
- Elevated SP/AP ratio above 0.4 (Correct answer)
- Absent cochlear microphonic
- Normal SP/AP with elevated ABR wave V latency
Correct answer: Elevated SP/AP ratio above 0.4
Endolymphatic hydrops in Meniere's disease enlarges the summating potential, raising the SP/AP ratio above the normal threshold of approximately 0.4.
Question 5: Which finding on video head impulse testing (vHIT) is MOST consistent with superior semicircular canal dehiscence (SSCD)?
- Covert saccades on all three canals
- Normal or elevated VOR gain with overt saccades
- Normal VOR gain without corrective saccades (Correct answer)
- Severely reduced VOR gain bilaterally
Correct answer: Normal VOR gain without corrective saccades
SSCD typically shows normal or even elevated VOR gain on vHIT because the dehiscence creates a third mobile window rather than reducing canal sensitivity.
Question 6: The subjective visual vertical (SVV) test assesses which aspect of vestibular function?
- Semicircular canal function during head rotation
- Otolith (utricle) perception of gravitational vertical (Correct answer)
- Central cerebellar gaze-holding ability
- Saccular response to linear acceleration
Correct answer: Otolith (utricle) perception of gravitational vertical
SVV measures the utricular contribution to spatial orientation by asking the patient to align a luminous bar with perceived vertical in darkness.
Question 7: When interpreting rotary chair sinusoidal harmonic acceleration (SHA) testing, phase lead indicates:
- The eyes move after the head, suggesting high VOR gain
- The eyes lead the expected compensatory response, suggesting peripheral hypofunction (Correct answer)
- Normal VOR function at all frequencies
- A central lesion exclusively
Correct answer: The eyes lead the expected compensatory response, suggesting peripheral hypofunction
Phase lead means the VOR response occurs slightly earlier than expected, a compensatory pattern seen in peripheral vestibular hypofunction at low frequencies.
CVT Assessment & Diagnosis of Vestibular Disorders 2
During the head impulse test (HIT), a corrective saccade after a rapid head thrust indicates: