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Videonystagmography (VNG) Report - Detailed Analysis

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1. SACCADE TEST

Horizontal Saccades

Vertical Saccades

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2. SMOOTH PURSUIT TEST

Horizontal Smooth Pursuit

Vertical Smooth Pursuit

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3. OPTOKINETIC TEST (OKN)

• Horizontal OKN: Gains are normal and symmetric (0.74-0.84). No fast-phase direction noted for horizontal stimuli (indicating no spontaneous nystagmus driving a fast phase).
• Vertical OKN (Top to Bottom): Normal gains (0.90-0.96) with a fast phase direction of ~62-66°.
• Vertical OKN (Bottom to Top): Gains are elevated (1.26-1.22), which is abnormal. A gain >1.0 in OKN can indicate an enhanced vestibulo-ocular response or central pathology. Fast phase direction shows only left eye (235.21°) with absent right eye fast phase direction.

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4. NYSTAGMUS TESTS

Spontaneous Nystagmus (Light and Dark)

• In Light: All parameters (Slow Phase Velocity, Amplitude, Frequency) are absent (-) bilaterally. No spontaneous nystagmus in light.
• In Dark: All parameters absent (-) bilaterally. No spontaneous nystagmus in darkness.

High-Frequency Head Shake Test

• All nystagmus parameters absent (-). No post-head-shake nystagmus.

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5. GAZE TEST

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

Without Fixation (Monocularly Covered Eyes)

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6. POSITIONAL TESTS

Dix-Hallpike Right

Dix-Hallpike Left

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7. YACOVINO POSITIONAL TEST

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8. McCLURE-PAGNINI TEST (Horizontal/Lateral Roll Test)

1. Horizontal Canal BPPV (Geotropic type - Cupulolithiasis on the left), or
2. A central positional disorder given the magnitude, combination with other central signs, and persistent low-level nystagmus in neutral positions.

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9. SUBJECTIVE VISUAL VERTICAL (SVV)

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OVERALL SUMMARY AND CLINICAL INTERPRETATION

Key Abnormal Findings

Clinical Impression

1. Benign Paroxysmal Positional Vertigo (BPPV) - likely multi-canal involvement:
   • Right posterior canal BPPV (positive Dix-Hallpike Right)
   • Left posterior/anterior canal BPPV (strongly positive Dix-Hallpike Left)
   • Left horizontal canal BPPV (strongly positive left lateral roll on McClure-Pagnini, with SPV >37 °/s)
   • The positive Yacovino raises the possibility of anterior canal involvement
2. Central Oculomotor Dysfunction - several findings suggest concurrent central nervous system involvement (brainstem or cerebellar):
   • Reduced vertical saccade precision
   • Asymmetric left eye vertical smooth pursuit deficit
   • Abnormal vertical OKN (elevated gains Bottom-to-Top, absent fast phase in one eye)
   • The combined pattern warrants MRI/MRA of the posterior fossa to rule out cerebellar or brainstem pathology

Recommendations

• Canalith Repositioning Maneuvers: Epley maneuver for posterior canal BPPV (both sides); Barbecue roll (Lempert) for horizontal canal BPPV
• Neuroimaging: MRI of the posterior fossa (cerebellum and brainstem) given the multiple central oculomotor signs, especially in a 74-year-old
• Vestibular Rehabilitation: Given multi-canal BPPV and possible central involvement
• Follow-up VNG: After repositioning maneuvers to confirm resolution of positional nystagmus
• Neurology referral: Given the combination of central signs and age

Note: This analysis is based solely on the VNG report data. Clinical correlation with the patient's symptom history, neurological examination, and audiological findings is essential for final diagnosis and management.

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Nystagmus in Positional Tests - Description from the VNG Graphs

How to Read the VNG Graph Traces

• 'b' = beginning of each eye movement (slow drift away from center)
• 'e' = end of each eye movement (fast corrective snap back)

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Graph-by-Graph Nystagmus Description

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1. Dix-Hallpike Right - Supine Head Extension & Right (Page 13)

Right Eye:  bb b bb (slow drift) → e e e ee (fast phase)
Left Eye:   b b b b (slow drift) → e e e e (fast phase)

• The 'b' markers represent the slow phase - the eyes drift slowly in one direction (vestibulo-ocular reflex driven, measured at -16.34 °/s right eye, -7.09 °/s left eye)
• The 'e' markers represent the fast phase - sudden corrective saccade back
• The negative sign of Slow Phase Velocity (-16.34 °/s) indicates slow phase drifting downward/leftward with fast phase beating upward/rightward (toward the dependent/right ear = geotropic)
• Frequency: 1.21 Hz (right), 0.58 Hz (left) - rapid, episodic bursting pattern

Hallmark feature: The bursts of 'b→e' cycles appear clustered, representing the crescendo-decrescendo (paroxysmal) pattern typical of posterior canal BPPV. The nystagmus begins, builds in amplitude, then fatigues - all within the recording window.

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2. Dix-Hallpike Left - Supine Head Extension & Left (Page 15-16)

Right Eye Horizontal:  be be be be be   (rapid alternation, SPV 24.34 °/s)
Left Eye Horizontal:   be be be be be   (SPV 16.35 °/s)
Left Eye Vertical:     e e e (fast phase upward), b b b (slow drift down)
Fast Phase Direction:  322.34° (left eye) ≈ upward-torsional

• The combined horizontal + vertical components seen in both eyes indicates a mixed torsional nystagmus - the hallmark of posterior semicircular canal stimulation
• The high SPV of 24.34 °/s is notably intense, suggesting either a large otolith load or canal cupulolithiasis variant
• Fast phase direction of 322.34° (roughly upward-left) on the left eye confirms the upward-torsional fast phase toward the uppermost ear = consistent with posterior canal BPPV of the left ear
• In the "Sit Head Left" position (second recording), fast phase direction was 43.94° / 41.95° (both eyes, bilaterally symmetric) - this persistent bilateral nystagmus even after repositioning suggests cupulolithiasis (heavy debris adherent to cupula) rather than simple canalolithiasis (free-floating particles)

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3. McClure-Pagnini Left Lateral (Page 19-20) - Most Striking Finding

Right Eye:  eeeeebbbbbbbbbbbbbbbb  (long slow drift b's, then burst of e's)
            bbbbbeeeeeeeeeeeeeeee
Left Eye:   eeeeeeeeeeeeee
            bbbbbbbbbbbbbb
SPV Right: 37.20 °/s    SPV Left: 29.82 °/s
Fast Phase Dir: 30.41° (R) vs 318.25° (L)
Frequency: 2.88 Hz (R), 3.05 Hz (L)

• The trace shows long runs of 'b' (slow drift) followed by bursts of 'e' (fast phase) - this sawtooth-like pattern is the hallmark of geotropic nystagmus
• In the left lateral position, the right eye beats toward the ground (geotropic, fast phase ~30°) while the left eye beats in the opposite torsional direction (318° ≈ downward-right) - this near-opposite fast phase direction between the two eyes indicates a conjugate horizontal nystagmus with a torsional twist, consistent with horizontal semicircular canal stimulation
• The high frequency (2.88-3.05 Hz) and high velocity (37 °/s) represent a strong otolith/canal-cupula interaction
• Compare Right Lateral (SPV only 4.66 °/s) vs. Left Lateral (37.20 °/s) = ~8:1 asymmetry ratio - this directional preponderance strongly localizes the lesion to the left horizontal canal

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4. Yacovino Test - Supine Head Extension 90° (Page 17)

Right Eye Vertical:  e ee e (fast phase upward) / b b b b (slow drift down)
Left Eye Vertical:   e e e e / b b b b
Vert SPV: 5.53 °/s (R), 2.27 °/s (L)

Left Eye:  e b b (fast upward), b e e (slow down)
Left Eye Vertical SPV: -13.00 °/s (downbeat direction)

• Extension 90° produces upbeat nystagmus (fast phase upward, slow phase downward) - both eyes
• Head Flex 45° produces downbeat nystagmus in the left eye (fast phase downward, SPV -13.00 °/s)
• This direction reversal with head position change (upbeat → downbeat) is the defining feature of a positive Yacovino test

As noted in Bradley & Daroff's Neurology: "Nystagmus is classified as spontaneous, gaze-evoked, or positional... vertical or purely torsional [nystagmus] that does not decrease with fixation = central pattern." Direction-changing vertical positional nystagmus is a central sign.

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5. Gaze Tests Without Fixation - Center Position (Page 12)

Right Eye: eee e e e e (fast phase) / bbb b b b (slow drift)
SPV: 8.17 °/s, Amplitude: 7.05°, Frequency: 1.04 Hz

• The fact that nystagmus is absent with fixation but present without fixation (SPV 8.17 °/s, 7.05° amplitude) indicates fixation suppression is intact - a feature more consistent with peripheral vestibular nystagmus
• However, this is present only in the right eye at center, which makes it asymmetric and possibly of central origin

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Summary Table: Nystagmus Types by Test

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Overall Nystagmus Classification

1. Paroxysmal Jerk Nystagmus - seen in Dix-Hallpike tests; classic BPPV sawtooth waveform with slow drift and fast reset
2. Geotropic Horizontal Jerk Nystagmus - dominant pattern in McClure-Pagnini left lateral; beats toward the ground (left ear down = nystagmus toward left) - characteristic of left horizontal canal BPPV
3. Direction-Changing Positional Vertical Nystagmus - Yacovino test; upbeat in extension, downbeat in flexion - this pattern is the central red flag (anterior canal BPPV or cerebellar/brainstem origin)
4. Fixation-suppressible Residual Jerk Nystagmus - gaze test without fixation; mild horizontal jerk indicating residual vestibular imbalance

Supported by K J Lee's Essential Otolaryngology: "Peripheral nystagmus is usually horizontal ± torsional component and decreases with visual fixation. Central nystagmus is vertical or purely torsional, does not decrease with visual fixation, and may change directions in different gaze positions."