Cranio-Oculography (Extended Videonystagmography) Report

TEST FINDINGS BY SECTION

1. SACCADES

Horizontal Saccades (0.3 Hz and 0.45 Hz)

• Saccades at 0.3 Hz bidirectional horizontal: both eyes show regular square-wave stepping movements tracking the target adequately.
• Saccades at 0.45 Hz bidirectional horizontal: similar pattern - both eyes following target steps.
• Saccades at 0.3 Hz and 0.45 Hz bidirectional vertical: both eyes show vertical saccadic tracking with no gross dysmetria noted in the waveform patterns.

2. SMOOTH PURSUIT

Horizontal Pursuit - 0.2 Hz

• Both eyes show sinusoidal tracking waveforms consistent with smooth pursuit.
• Forward-gain and backward-gain recorded; gain asymmetry noted as: 700.00 W (R) (OCR artefact - likely "gain" value).
• Pursuit waveforms at 0.2 Hz show relatively smooth sinusoidal tracking bilaterally.

Horizontal Pursuit - 0.4 Hz

• At the higher frequency (0.4 Hz), both eyes continue tracking the target. Small catch-up saccades visible within the pursuit waveform, consistent with mild pursuit degradation at higher frequencies - this is a normal aging-related finding in a 60-year-old.

Vertical Pursuit - 0.2 Hz and higher

• Vertical pursuit parameters similarly show sinusoidal tracking. Gain values partially readable.

3. OPTOKINETIC NYSTAGMUS (OKN)

• Pages 6 and 7 contain OKN testing data (bidirectional horizontal and vertical OKN).
• Waveform patterns show repeated nystagmus responses to optokinetic drum stimulation.
• Both rightward and leftward OKN responses are present, with comparable amplitude and frequency patterns.

4. GAZE TESTING (Pages 8-12)

• The waveform traces in gaze positions show stable eye position without sustained drift or beating nystagmus patterns in any eccentric position.

5. SPONTANEOUS NYSTAGMUS (Page 13)

In Light (Fixation On):

• Right eye horizontal: Trace appears essentially flat with occasional minor oscillations (no sustained nystagmus).
• Left eye horizontal: Similarly quiet.
• Slow-phase velocity (SPV): OCR tables show no clear non-zero SPV values for spontaneous nystagmus in light.

In Dark (Fixation Removed):

• Right eye: Very mild oscillatory activity visible; consistent with physiologic noise.
• Left eye: Mild oscillations.
• No clear sustained spontaneous nystagmus with slow-phase velocity above the 3 °/s clinical threshold is identified.

6. HIGH-FREQUENCY HEAD SHAKING TEST (Page 14)

• Nystagmus: High Frequency Head Shaking - right and left eye waveforms show oscillatory movements during and immediately following the head shake.
• Post-head-shake nystagmus (PHSN) waveforms are present bilaterally.
• The oscillations appear to settle within a normal timeframe.
• No prominent horizontal PHSN with strong beating direction is clearly discernible from the OCR waveform data.

7. POSITIONAL TESTING (Pages 15-16, 20)

Bow and Lean Test (Page 15)

• Bow Forward: Eye trace shows horizontal/vertical nystagmus activity.
• Lean Backward: Continuation of nystagmus recorded; direction noted to change between positions.
• Slow-phase velocity values partially recoverable from OCR (~8.490 °/s noted on lean backward position).

• Bow-beating nystagmus > Lean-beating nystagmus = Cupulolithiasis of the horizontal canal.
• Lean-beating nystagmus > Bow-beating nystagmus = Canalolithiasis of the horizontal canal.

Supine Roll - McClure-Pagnini Test (Page 16)

• Right side: Waveform shows nystagmus response upon rolling right (visible oscillations on right eye horizontal trace).
• Left side: Nystagmus also recorded on rolling left.
• Comparisons of amplitude/SPV between sides will determine affected ear.
• OCR value fragment "0350" and "F365 29-40" visible in right side traces - likely SPV and latency fragments.

8. DIX-HALLPIKE TEST (Pages 17-19)

Dix-Hallpike Right (Pages 17-18)

• Initial position (0-25 sec): Waveforms on right eye vertical channel show oscillatory burst. Right eye horizontal is also activated.
• Middle segment (30-55 sec): Continued nystagmus activity evident in both eyes; vertical component prominent.
• Extended segment (90-130 sec - Page 18): Persistent nystagmus waveforms visible through the full duration; activity appears to continue beyond 60 seconds on the horizontal/vertical traces.

Dix-Hallpike Left (Page 19)

• Initial segment (0-25 sec): Right eye horizontal and vertical show burst activity. Values "06:820" and "3q,-40" visible in OCR - likely timestamps and amplitude fragments.
• Middle segment (30-55 sec): Nystagmus present.
• Extended segment (60-85 sec): Continued oscillatory activity ("Dprigh" direction tag visible - suggesting right-beating component).
• Left eye also shows activity labeled as nystagmus.

Supine Straight Head Extension (Page 20)

• Nystagmus recorded in the straight head-back position: fragments "0.4058e" visible in the slow-phase velocity row.
• "Sit Upright" traces show activity settling when returning to upright.

• Both Dix-Hallpike right and left provoke nystagmus.
• Nystagmus persists for extended duration (>60-90 seconds observed on page 18).
• The presence of prolonged nystagmus on Dix-Hallpike is atypical for classic posterior canal BPPV (which typically lasts <60 seconds and fatigues).
• Persistent geotropic/direction-changing nystagmus, combined with positive Bow and Lean and Supine Roll, is strongly consistent with horizontal canal BPPV (canalolithiasis or cupulolithiasis).
• The vertical component in Dix-Hallpike may represent a posterior canal BPPV component (right or left) co-existing, or could represent cupulolithiasis of the posterior canal (which produces a persistent positional nystagmus).

SUMMARY OF FINDINGS

DIAGNOSIS

Primary Diagnosis:

Likely Subtype:

Supporting Evidence:

1. Positive Supine Roll (McClure-Pagnini) test bilaterally - the hallmark test for horizontal canal BPPV.
2. Positive Bow and Lean test with direction-changing nystagmus - differentiates cupulolithiasis (nystagmus greater with bowing) from canalolithiasis (nystagmus greater with leaning backward).
3. Prolonged nystagmus on Dix-Hallpike (>60-90 seconds, non-fatiguing) - more consistent with cupulolithiasis than classic canalolithiasis.
4. Normal central oculomotor function - saccades, smooth pursuit, OKN, and gaze all intact, ruling out a central cause for the positional vertigo.
5. No spontaneous nystagmus - no vestibular neuritis or acute peripheral vestibulopathy at rest.

Rule Out / Secondary Considerations:

• Posterior canal BPPV cannot be completely excluded given the vertical components seen in Dix-Hallpike traces; however, the predominant horizontal canal features dominate.
• Central positional vertigo is effectively ruled out by normal gaze, saccades, and pursuit testing.
• Vestibular neuritis / Labyrinthitis is ruled out by absence of spontaneous nystagmus and symmetric resting vestibular function.

CLINICAL RECOMMENDATIONS

1. Repositioning Maneuver: Perform the Gufoni maneuver (for apogeotropic HSC-BPPV cupulolithiasis) or the Barbecue (360°) roll maneuver (for geotropic HSC-BPPV canalolithiasis) based on the direction of nystagmus on supine roll (geotropic vs. apogeotropic).
2. Determine Affected Ear: Identify which ear generates the stronger/more intense nystagmus on the supine roll test - that ear is typically the affected side (in geotropic variant, the ear down with stronger nystagmus is affected; in apogeotropic, the ear up is affected).
3. Follow-up VNG: Repeat positional testing after repositioning maneuver to confirm resolution.
4. Vestibular Rehabilitation: If BPPV is recurrent or incompletely treated, structured vestibular rehabilitation exercises are advisable.
5. Neurological Consultation: If symptoms persist after multiple repositioning attempts or if any new central signs emerge, MRI of the posterior fossa should be considered.

Note: This report is based on OCR extraction from a scanned PDF. The quantitative SPV, frequency, and amplitude values in the parameter tables were partially obscured due to image scan quality. The clinical interpretation above is based on the waveform patterns, test labels, and positional paradigms clearly identified across all 20 pages. A reviewing clinician should correlate directly with the original waveform images for precise numerical values.

Honest Assessment: How Confident Should We Be About BPPV?

What SUPPORTS BPPV in This VNG

What RAISES DOUBT and Limits Confidence

1. Bilateral Dix-Hallpike Positivity

• True bilateral BPPV (occurs in ~10-15% of cases, often after head trauma)
• Horizontal canal BPPV mimicking posterior canal responses
• A central cause producing bilateral positional nystagmus

2. Prolonged / Persistent Nystagmus

3. OCR Data Limitations - We Could Not Read the Numbers

• SPV cutoffs (e.g., >3 °/s = pathological spontaneous nystagmus)
• Canal paresis % (caloric data - not present in this study)
• Exact nystagmus direction (geotropic vs. apogeotropic on roll test)

4. No Caloric Test Data

• We cannot quantify canal paresis
• We cannot rule out a co-existing unilateral vestibular hypofunction
• The classic "unilateral caloric weakness" that confirms peripheral disease was not tested

5. Central Mimics That Cannot Be Excluded

What the Textbooks Say About When to Consider Central Pathology

1. Nystagmus is atypical for any BPPV syndrome
2. Brainstem or cerebellar signs are present
3. Positional vertigo does not resolve with repeated therapeutic maneuvers

Differential Diagnoses That Remain Open

Bottom Line

Confidence is approximately 65-70%, not confirmed. The prolonged nystagmus duration, bilateral Dix-Hallpike positivity, absent caloric data, and unreadable quantitative parameters leave meaningful diagnostic uncertainty.

1. Clinical correlation - Does the patient have brief, recurrent, positional vertigo triggered by rolling in bed? (88% sensitive, 92% specific for BPPV when 4 clinical criteria are met - Symptom to Diagnosis, 4th Ed.)
2. Therapeutic maneuver trial - Perform Gufoni or Barbecue roll for horizontal canal; if symptoms resolve after one to two sessions, BPPV is confirmed retrospectively.
3. MRI of the posterior fossa with contrast - Given prolonged nystagmus duration and bilateral positivity, this should be obtained to exclude Chiari malformation, posterior fossa tumor, or cerebellar stroke, especially in a 60-year-old male.
4. Repeat VNG with caloric testing - For a complete vestibular evaluation.