Detailed VNG (Videonystagmography) Report - Clinical Interpretation

Patient Information

Summary of All VNG Test Findings

1. SACCADE TEST (Rapid Eye Movement)

• Right Eye Velocity: 489 / 459 °/s
• Left Eye Velocity: 779 / 782 °/s
• Right Eye Precision: 73.49 / 71.52 (notably reduced)
• Right Eye Latency: 211 / 273 ms

2. OPTOKINETIC TEST (OKN)

3. SPONTANEOUS NYSTAGMUS

In Light (With Fixation):

In Dark (Without Fixation):

• No nystagmus recorded in any plane in either eye.

• A low-amplitude vertical spontaneous nystagmus is present in the right eye in light, with a slow phase velocity of 5.35 °/s and amplitude of 1.93°. This is a subtle but real finding.
• The fact that it disappears in the dark (without fixation) suggests the nystagmus may be fixation-dependent or suppressed in darkness, a pattern sometimes seen in central/vertical nystagmus types.
• Alternatively, it may represent a very low-level peripheral tone imbalance. Vertical spontaneous nystagmus, however, is more characteristically associated with central vestibular pathology (e.g., cervicomedullary junction, cerebellum) rather than peripheral pathology, which typically produces horizontal nystagmus.
• SPV of 5.35 °/s is at the low end - anything >6 °/s is clearly abnormal, but values between 3 and 6 °/s warrant clinical correlation.

4. HIGH-FREQUENCY HEAD SHAKE TEST

• All values negative (no nystagmus) in horizontal or vertical planes.
• Interpretation: No head-shaking nystagmus. This is a normal finding and does not show the asymmetric vestibular loss pattern that produces post-shake nystagmus. This makes a significant unilateral peripheral vestibular hypofunction less likely as a sole cause.

5. GAZE TESTS

WITH FIXATION (all gaze positions - Center, Left, Up, Right, Down):

• All nystagmus values negative/absent in all positions.
• Interpretation: No gaze-evoked nystagmus with fixation. Normal.

WITHOUT FIXATION:

• Right gaze-evoked nystagmus without fixation (SPV 3.46 °/s, Amplitude 4.09°): A low-amplitude nystagmus appears in the right eye when gazing right without fixation. This is a right-beating gaze-evoked nystagmus which is typically seen in:
  • Peripheral vestibular uncompensated right-sided lesion (nystagmus beating toward the irritated side or away from the lesion depending on phase)
  • Early cerebellopontine angle or cerebellar involvement
  • It may also represent Alexander's Law - nystagmus intensity increases when gazing in the direction of the fast phase

6. DIX-HALLPIKE POSITIONAL TESTS (for posterior/anterior canal BPPV)

• The first Dix-Hallpike Right (sitting with head right) produced vertical nystagmus, SPV 15.24 °/s, amplitude 8.03°, frequency 0.88 Hz - this is a clearly positive and significant result.
• The finding was in the sitting phase (repositioning to upright), not in the supine position, suggesting the nystagmus may be triggered during the head movement into or out of the test position.
• The nystagmus disappeared on repeat testing (2nd DHP Right sit position = negative) - this fatigability is a hallmark of BPPV (canalolithiasis type).
• Right-sided provocation with vertical nystagmus and fatigability = Right Posterior Semicircular Canal BPPV is the primary diagnosis.

7. MCCLURE-PAGNINI (SUPINE ROLL) TEST (for horizontal canal BPPV)

• Left lateral roll position produces a horizontal nystagmus exclusively in the left eye with SPV 6.69 °/s and amplitude 11.27°. This is a clearly positive roll test result.
• In the supine roll (McClure-Pagnini) test:
  • Geotropic horizontal nystagmus (beats toward the ground/dependent ear) = Canalithiasis type horizontal canal BPPV
  • Apogeotropic horizontal nystagmus (beats away from the ground) = Cupulolithiasis type horizontal canal BPPV
• The nystagmus appeared in the left eye with left lateral position - the direction needs correlation with the physical eye-movement trace to determine geotropic vs. apogeotropic, but the presence of nystagmus strongly indicates LEFT Horizontal Semicircular Canal BPPV.

8. SUBJECTIVE VISUAL VERTICAL (SVV)

• All three trials show consistent left-sided tilt (the patient perceives vertical as tilted to the left).
• Deviations of -1° to -3° are borderline - the -3° value with blank background is approaching the abnormal range.
• SVV deviation to the left suggests possible dysfunction of the right otolith (utricular) system or the right descending vestibulospinal/otolithic pathways.
• Consistent left-tilt across all conditions supports a subtle right-sided vestibular imbalance affecting otolithic function.

Consolidated Abnormal Findings Table

PRIMARY DIAGNOSIS

Benign Paroxysmal Positional Vertigo (BPPV) - Multi-Canal Involvement

1. Right Posterior Semicircular Canal BPPV (Canalithiasis) - Positive Dix-Hallpike Right with fatigable vertical nystagmus (SPV 15.24 °/s) - Primary finding
2. Left Horizontal Semicircular Canal BPPV - Positive left lateral roll test (SPV 6.69 °/s) - Secondary finding

SECONDARY/INCIDENTAL FINDINGS

Possible Central Vestibular Component (requires further evaluation):

• Vertical spontaneous nystagmus (SPV 5.35 °/s in light, absent in dark): Vertical spontaneous nystagmus is atypical for purely peripheral BPPV. While mild, it warrants consideration of:
  • Cerebellar or brainstem microangiopathy (common in elderly, hypertensive patients)
  • Central positional nystagmus as a differential
• Right gaze-evoked nystagmus without fixation: May reflect incomplete vestibular compensation on the right side, but could also indicate cerebellar hemispheric dysfunction.

Borderline SVV left tilt:

• Consistent left tilt (-1° to -3°) suggests subtle right utricular dysfunction, consistent with a right-sided peripheral vestibular process.

INTERPRETATION SUMMARY

DIFFERENTIAL DIAGNOSES TO CONSIDER

1. BPPV (Multi-canal) - Most likely diagnosis, supported by positional tests
2. Age-related peripheral vestibular degeneration (Presbyvestibulopathy) - Common at age 75, may co-exist with BPPV
3. Central vestibular pathology (cerebellar/brainstem) - Must be excluded given the vertical spontaneous nystagmus; MRI brain with focus on posterior fossa is recommended
4. Vestibular neuritis (partially compensated) - Less likely given no head-shake nystagmus and intact OKN

CLINICAL RECOMMENDATIONS

Immediate Treatment (BPPV):

1. Epley Maneuver (Canalith Repositioning) - For the Right Posterior Canal BPPV - this is the first-line treatment with 80-90% success rate in a single session
2. BBQ Roll (Log Roll) / Lempert Maneuver - For the Left Horizontal Canal BPPV

Further Investigations:

1. MRI Brain with Posterior Fossa sequences (FLAIR, DWI) - To rule out cerebellar infarct or demyelinating lesion given the vertical spontaneous nystagmus and gaze-evoked nystagmus
2. Audiometry (Pure Tone and Speech) - To assess cochlear function and rule out Meniere's disease
3. Video Head Impulse Test (vHIT) if available - To quantify semicircular canal gain and detect any canal paresis not captured on this VNG
4. Blood pressure (orthostatic) - Rule out orthostatic hypotension contributing to dizziness while walking at age 75

Lifestyle Advice:

• Fall risk precautions - the patient is 75 years old with active BPPV; dizziness while walking significantly increases the risk of falls
• Vestibular rehabilitation exercises post-repositioning maneuver
• Avoid sudden head movements until BPPV is treated

CONCLUSION

Bilateral multi-canal BPPV with right posterior semicircular canal canalithiasis as the dominant lesion, and concurrent left horizontal semicircular canal BPPV. A borderline vertical spontaneous nystagmus and right gaze-evoked nystagmus (without fixation) raise the possibility of a mild central vestibular component that warrants MRI evaluation to exclude posterior fossa pathology.