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VNG Report Analysis: Mrs. Akanccha Parveen

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SECTION-BY-SECTION TEST ANALYSIS

1. SACCADE TESTS (Eye Movement Accuracy & Speed)

Horizontal Saccades

• Peak velocities are within broadly acceptable ranges for a 55-year-old female
• Asymmetry noted: Right eye saccade velocity is consistently higher than left eye (especially at 0.3 Hz: right 1203°/s vs left 868°/s - a difference of ~28%). This asymmetry is clinically significant and suggests a potential left-sided oculomotor or peripheral vestibular dysfunction
• Precision (accuracy) is generally acceptable (>70%), suggesting no major cerebellar dysmetria
• Latencies are mildly prolonged (normal typically <220-250 ms), suggesting mild slowing of saccade initiation

Vertical Saccades

• Vertical saccade precision drops dramatically with increasing frequency: precision at 0.45 Hz is ~43-47% and at 0.6 Hz falls to 28-34%, which is well below the normal threshold of ~70%
• This pattern of poor accuracy on faster vertical saccades raises concern for central vestibular pathology (cerebellar or brainstem involvement), particularly affecting the vertical ocular motor system

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2. SMOOTH PURSUIT TESTS

Horizontal Pursuit

• At 0.6 Hz, horizontal smooth pursuit gain is severely reduced: rightward gain ~0.30, leftward gain ~0.47 (normal ≥0.80). This is a prominent abnormality
• At 0.2 Hz: gains are normal (~0.86-0.90), confirming good low-frequency tracking
• At 0.4 Hz: gains fall to ~0.60, and at 0.6 Hz they crash to ~0.30
• This frequency-dependent deterioration of smooth pursuit is characteristic of central pathway dysfunction (particularly cerebellar or cortical-parietal), not peripheral vestibular disease

Vertical Pursuit

• Vertical smooth pursuit at 0.6 Hz is critically low: upward gain 0.12-0.19 and downward gain 0.18-0.19, which is severely below normal (≥0.80)
• At 0.2 Hz vertical: gains recover to 0.68-0.79 (approaching normal)
• At 0.4 Hz vertical: gains are reduced (0.34-0.40)
• The severe reduction of vertical smooth pursuit across frequencies, combined with poor vertical saccade precision at higher frequencies, strongly points to central vestibular/cerebellar pathology

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3. OPTOKINETIC TESTS (OKN)

• Horizontal OKN gains are all normal (0.76-0.97) - this is reassuring and indicates preserved horizontal OKN pathways
• Vertical OKN at higher speeds (20°, 40°) shows absent/unrecorded data ("-") suggesting inability to elicit or track adequately at higher velocities, consistent with the vertical pursuit deficit
• Fast Phase Direction recorded at Right→Left 40°: 172°/161° - these directions suggest the fast phase (corrective saccades) are being generated, but the vertical OKN responses at higher speeds remain abnormal

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4. NYSTAGMUS TESTS

Spontaneous Nystagmus in Light

• Horizontal: Slow Phase Velocity "-", Amplitude "-" → No spontaneous nystagmus in light (normal - fixation suppression intact)
• Vertical: No nystagmus detected

Spontaneous Nystagmus in Dark

• All parameters "-" → No spontaneous nystagmus in darkness either (normal)

High Frequency Head Shake

• All parameters "-" → No post-head-shake nystagmus (negative head shake test - no evidence of vestibular asymmetry from this test)

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5. GAZE TESTS

With Fixation (Center, Left, Right, Up, Down)

• All gaze positions: SPV "-", Amplitude "-", Frequency "-"
• No gaze-evoked nystagmus with fixation (all positions normal) - suggests no obvious cerebellar gaze-holding failure under fixation conditions

Without Fixation

• Center gaze WITHOUT fixation reveals: Vertical slow phase velocity -2.98°/s, Amplitude -4.05°, Frequency 0.37 Hz
• This indicates low-amplitude vertical nystagmus that is only visible when fixation is removed - a finding that is classically associated with central vestibular pathology
• The nystagmus is only in the vertical plane and only apparent without fixation, pointing to a subtle otolithic or central vertical pathway lesion

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6. DIX-HALLPIKE POSITIONAL TESTS (BPPV Testing)

Dix-Hallpike Right

• Sit Head Right → No nystagmus (SPV "-", Amplitude "-")
• Supine Head Ext. + Right → No nystagmus
• Return to Sit → No nystagmus

Dix-Hallpike Left

• Sit Head Left → No nystagmus
• Supine Head Ext. + Left → No nystagmus
• Return to Sit → No nystagmus

• All Dix-Hallpike positions NEGATIVE - this effectively rules out Benign Paroxysmal Positional Vertigo (BPPV) as the cause of her symptoms

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7. McCLURE-PAGNINI ROLL TEST (Horizontal Canal BPPV)

• Negative for horizontal canal BPPV - no geotropic or apogeotropic nystagmus elicited in any lateral position

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8. SUBJECTIVE VISUAL VERTICAL (SVV)

• Normal SVV is within ±2° of true vertical
• A deviation of -3° (Left) on anti-clockwise testing exceeds the normal threshold slightly
• The blank background deviation of -1° is borderline normal
• A left-tilted SVV (patient perceives vertical as tilted to the left) is associated with left otolith (utricular) dysfunction or central tilt
• This is consistent with a subtle left peripheral or central vestibular lesion

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CONSOLIDATED FINDINGS SUMMARY

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CLINICAL DIAGNOSIS & INTERPRETATION

Primary Impression: Central Vestibular Dysfunction

1. Severely impaired smooth pursuit - especially vertical (gain as low as 0.12), which is a hallmark of central (cerebellar/brainstem) dysfunction, as peripheral lesions do not typically impair smooth pursuit this severely
2. Poor vertical saccade precision at higher frequencies, pointing to a central oculomotor system deficit
3. Vertical nystagmus unmasked only without fixation - this pattern (nystagmus suppressed by fixation but present in darkness) can occur in both central and some peripheral lesions, but combined with other findings here, favors central origin
4. Abnormal SVV with left tilt - indicating left-sided utricular or vertical canal pathway involvement
5. Intact horizontal OKN with preserved horizontal pursuit at low frequencies - suggests the lesion is not diffuse and spares some horizontal pathways
6. Complete absence of positional nystagmus (Dix-Hallpike and Roll test all negative) - definitively excludes BPPV, which is the most common cause of episodic vertigo

Differential Diagnosis (in order of probability)

What is RULED OUT

• BPPV (all positional tests negative) - most common cause, definitively excluded
• Active unilateral peripheral vestibular lesion - no spontaneous nystagmus, negative head-shake test
• Pure labyrinthine lesion - cannot explain the smooth pursuit and saccade abnormalities

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URGENT RECOMMENDATIONS

⚠ Important Notice: This analysis is based solely on the VNG report. Clinical judgment by a qualified otolaryngologist/neurologist is essential for final diagnosis and management.

1. Urgent MRI Brain with contrast (including posterior fossa sequences) to exclude cerebellar infarction, demyelinating lesion, or posterior fossa mass - this is the most important next step given the central pattern
2. Neurology/Neuro-otology referral - the VNG pattern here requires neurological evaluation, not just ENT
3. Full vestibular assessment: Consider caloric testing (not included in this report) to quantify peripheral canal paresis if not already done
4. Video Head Impulse Test (vHIT) - to assess semicircular canal function specifically
5. Audiometry - to check for associated hearing loss (not included in this report)
6. Cardiovascular evaluation - at age 55, vascular risk factors for posterior circulation stroke must be assessed (blood pressure, lipids, HbA1c, ECG)
7. Medication history - several drugs cause central vestibular effects (anticonvulsants, sedatives, aminoglycosides)

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What I Am Confident About

✅ CONFIRMED findings from this VNG:

1. BPPV is excluded - Dix-Hallpike and Roll tests were completely negative bilaterally. This is reliable.
2. No active peripheral vestibular lesion currently generating spontaneous nystagmus - both light and dark conditions showed no spontaneous nystagmus.
3. Smooth pursuit is impaired - especially vertical, and especially at higher frequencies. This is an objective numerical finding.
4. Vertical smooth pursuit is more impaired than horizontal - this pattern is a real and significant asymmetry.
5. Vertical nystagmus appears only without fixation (center gaze, dark) - a real finding.
6. SVV shows mild left tilt (-3°) - marginally outside normal range.

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What I Am NOT Confirmed About

⚠ Critical gaps in this report:

• We don't know if she has associated hearing loss, tinnitus, or ear fullness
• No HINTS exam (Head Impulse, Nystagmus, Test of Skew) results
• No blood pressure or neurological exam findings

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Honest Summary

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What Needs to Happen Before a Confirmed Diagnosis

1. MRI Brain + posterior fossa with contrast - highest priority
2. Caloric test - still the most important missing vestibular test
3. vHIT - modern high-frequency canal assessment
4. Full clinical history - headache, hearing loss, tinnitus, medications, vascular risk factors
5. Neurological examination - including HINTS exam, coordination testing, cranial nerves
6. Audiogram - associated hearing changes would shift the differential significantly

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