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VideoNystagmography (VNG) Report — Detailed Analysis & Diagnosis

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1. SACCADES

• Right eye horizontal saccade velocity (355°/s) is within normal limits, but left eye velocity (561°/s) is hypermetric — possibly a data artifact or asymmetric pursuit disengagement.
• Right eye horizontal latency (283 ms) is mildly prolonged (>260 ms); vertical latencies bilaterally (403–411 ms) are significantly prolonged.
• Vertical velocities for both eyes (241–271°/s) are below the 275°/s threshold, indicating bilateral slowed vertical saccades.
• Precision is normal bilaterally in all planes.

⚠️ Interpretation: Prolonged vertical saccade latencies and reduced vertical saccade velocities are a central nervous system (CNS) indicator. Isolated vertical saccade slowing can be seen in cerebellar, brainstem, or supranuclear pathologies.

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2. SMOOTH PURSUIT

• Horizontal smooth pursuit gain is reduced bilaterally (0.74–0.82 vs. normal ≥0.9) — consistent with bilateral symmetric smooth pursuit impairment.
• Downward vertical pursuit is markedly reduced (0.63–0.64) — significant.
• Upward vertical pursuit is normal (0.96–0.98).

⚠️ Interpretation: Bilateral horizontal smooth pursuit impairment with downward pursuit deficits suggests a central vestibular or cerebellar lesion (pursuit is mediated by the cerebellum and parieto-occipital cortex). Isolated downward pursuit deficits are classically associated with cerebellar or dorsal midbrain pathology.

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3. OPTOKINETIC NYSTAGMUS (OKN)

• Horizontal OKN is symmetric and normal in both directions.
• Vertical OKN (top-to-bottom) is severely reduced (0.17–0.27), and bottom-to-top OKN is absent/unmeasurable.

⚠️ Interpretation: A severe and asymmetric vertical OKN deficit with preserved horizontal OKN is highly suggestive of a central lesion (brainstem or cerebellar). Vertical OKN is particularly sensitive to dorsal midbrain and medullary pathology.

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4. SPONTANEOUS NYSTAGMUS

• No spontaneous nystagmus in light (normal).
• Mild spontaneous nystagmus in darkness in the right eye (SPV 1.53°/s) — borderline, as pathological threshold is typically ≥5°/s; however, even low-grade dark spontaneous nystagmus indicates possible peripheral or minor central asymmetry.

Interpretation: Mildly abnormal — suggests a subtle right-sided vestibular asymmetry or very early unilateral peripheral weakness.

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5. GAZE TESTS

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6. POSITIONAL TESTING — DIX-HALLPIKE

Right Side (Dix-Hallpike Right)

Positive Dix-Hallpike Right with combined horizontal and vertical nystagmus components. Fast phase at 221° (inferomedial direction) with frequency 1.80 Hz is consistent with right posterior semicircular canal (PSC) BPPV — though the torsional component confirmation requires visual trace review.

Left Side (Dix-Hallpike Left)

Positive Dix-Hallpike Left as well. Bilateral Dix-Hallpike positivity with upward/torsional components and persistence of nystagmus across positions raises the possibility of bilateral BPPV or cupulolithiasis variant.

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7. McCLURE-PAGNINI (HORIZONTAL CANAL) TESTING

The downbeat vertical nystagmus in supine neutral (SPV up to −13.68°/s) is particularly notable — downbeat nystagmus in supine is a key sign of anterior (superior) semicircular canal BPPV or central pathology (especially cerebellar, particularly floccular/parafloccular lesions).

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8. HEAD POSITION TESTS

• Yaw Left provokes positional nystagmus — asymmetric compared to Yaw Right (which is clean), suggesting left labyrinthine or canal sensitivity.
• Pitch Backward elicits downbeat nystagmus (SPV −5 to −6°/s) — this is a well-recognized sign of anterior canal BPPV or central downbeat nystagmus syndrome (cerebellar flocculus/paraflocculus pathology).
• Roll Left provokes mild horizontal nystagmus in the right eye, consistent with lateral canal BPPV asymmetry.

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SUMMARY & DIAGNOSIS

Primary Diagnosis

BPPV — Multiple Canal Involvement (Predominantly Right Posterior + Bilateral Horizontal Canal + Possible Anterior Canal Component)

Secondary/Concurrent Concern: Central Vestibular Features

⚠️ The combination of impaired smooth pursuit, vertical OKN deficits, prolonged vertical saccade latencies, and downbeat positional nystagmus in a 63-year-old woman warrants neuroimaging (MRI brain with posterior fossa/cerebellum protocol) to exclude central pathology — especially cerebellar degeneration, posterior fossa mass, or Arnold-Chiari malformation.

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CLINICAL RECOMMENDATIONS

1. Canalith Repositioning Maneuver (CRM):
   • Epley maneuver for right posterior canal BPPV
   • Modified Epley for left posterior canal BPPV
   • Barbeque roll (Lempert maneuver) for bilateral horizontal canal BPPV
   • Consider Semont liberatory maneuver if cupulolithiasis variant suspected
2. MRI Brain (Posterior Fossa Protocol):
   • To evaluate for cerebellar atrophy, space-occupying lesion, demyelination, Chiari malformation, or brainstem pathology given the central features
3. Neurology/Neuro-otology Referral:
   • Given the mixed central and peripheral findings and the patient's age (63)
4. Follow-up VNG:
   • Repeat VNG after Epley maneuver to assess clearance of positional nystagmus and document whether central features persist in isolation
5. Vestibular Rehabilitation Therapy (VRT):
   • Indicated regardless of central vs. peripheral final diagnosis to reduce fall risk and improve gaze stability

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