3 episodes followed by vomiting २ times, moderate SNHL IN LEFT EAR NOW CORRELATE AND PROVIDE THE ANALYSIS.
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downbeat nystagmus cerebellar central vestibular sensorineural hearing loss
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VNG Analysis + Clinical Correlation Report
Patient: Sanjay Garg | Age: 55 | Male | ID: CCDA00362 | Date: 12-May-2026
Facility: Priority Hearing Care Pvt. Ltd.
Clinical Triad Presented for Correlation
| Feature | Detail |
|---|---|
| Episodic events | 3 episodes of presumed vertigo/dizziness |
| Vomiting | 2 episodes post-event |
| Left ear SNHL | Moderate sensorineural hearing loss (left side) |
VNG Findings — Structured Summary
1. Saccades
| Test | Finding | Significance |
|---|---|---|
| Horizontal saccades | Velocity preserved (>800°/s), latency 300–384 ms (normal 150–250 ms), precision mildly reduced | Central latency prolongation — brainstem circuit slowing |
| Vertical saccades | ⚠ Velocity 113–238°/s (normal >400°/s), precision 18–33%, latency >500 ms | Hallmark central/cerebellar sign — fastigial nucleus or posterior vermis dysfunction |
The severe selective impairment of vertical saccades is a critically important localizing sign. The fastigial nucleus in the cerebellum coordinates burst neurons driving vertical saccades; damage here produces exactly this pattern of slow, hypometric, delayed vertical movements — Bradley and Daroff's Neurology in Clinical Practice (Box 18.14).
2. Smooth Pursuit
| Direction | Gain at 0.2 Hz | Gain at 0.4 Hz | Normal |
|---|---|---|---|
| Horizontal | 0.30–0.39 | 0.12–0.18 | ≥0.8 / ~0.6–0.7 |
| Vertical | 0.20–0.26 | 0.09–0.13 | Similar |
Interpretation: Severely reduced, bilaterally symmetric, all-direction pursuit impairment. This pattern is the textbook signature of cerebellar flocculus/paraflocculus pathology — the flocculus acts as the gain controller for smooth pursuit. Bilateral symmetry rules out a unilateral hemispheric lesion and points to midline or diffuse cerebellar disease. (Bradley and Daroff's; Goldman-Cecil Medicine)
3. OKN (Optokinetic Nystagmus)
- Horizontal OKN: Normal (gain ≈ 1.0) — cortical/subcortical pathways intact
- Vertical OKN: Elevated (1.3–2.0) — abnormal velocity storage or vertical canal/otolith pathway dysfunction, indicating central vestibular pathway involvement
4. Spontaneous Nystagmus
- Absent in both light and dark — this effectively rules out acute peripheral vestibulopathy (vestibular neuritis, Menière's active attack), which would typically show spontaneous horizontal nystagmus suppressed by fixation.
5. Post-Head-Shake Nystagmus (HSN)
- Vertical component present (upward, right eye) — this is "perverted nystagmus." Horizontal head-shaking producing vertical nystagmus is a definitive CNS sign, attributed to enhanced activity in central anterior semicircular canal pathways. (Bradley and Daroff's, line 1438: "Development of downbeat nystagmus after horizontal head shaking, called perverted nystagmus, is a definite sign of CNS disease.")
6. Gaze-Evoked Nystagmus (Without Fixation)
Multiple gaze positions (Center, Left, Up, Right, Down) revealed predominantly vertical/mixed direction nystagmus without fixation, with bidirectional components in some positions. The pattern of direction-changing positional nystagmus seen across multiple positions, largely suppressed by fixation, represents a central/mixed pattern — it does not conform to the unidirectional, fixation-suppressed horizontal nystagmus of peripheral disease.
7. Dix-Hallpike & Positional Testing
- Both Dix-Hallpike positions (R and L): ABNORMAL — bilateral vertical (downbeat) nystagmus
- This is atypical BPPV. Classical posterior canal BPPV produces transient, geotropic, torsional-upbeat nystagmus on the affected side only. Bilateral downbeat positional nystagmus is instead characteristic of anterior canal BPPV or central positional nystagmus.
- McClure-Pagnini (Supine Roll Test): Negative — horizontal canal BPPV excluded.
8. Yacovino Test — THE KEY FINDING ⚠
| Position | Right Eye SPV | Left Eye SPV |
|---|---|---|
| Supine, head neutral | −10.32°/s | −10.39°/s |
| Supine, head extended 90° | −19.74°/s | −19.54°/s |
| Supine, head flexed 45° | Normal | Normal |
Strong, persistent, bilateral downbeat nystagmus reaching −19.74°/s on maximum head extension is the most diagnostically critical finding in this report.
The Yacovino sign — downbeat nystagmus elicited by head extension in the supine position — is classically associated with pathology of the cerebellar nodulus and uvula (vestibulocerebellum). The nystagmus is:
- Bilateral (not unilateral as in BPPV)
- Persistent (does not fatigue, unlike BPPV)
- High amplitude (SPV ~20°/s is significant)
This mechanistically reflects the loss of nodulo-uvular inhibition on the vestibulo-ocular reflex (VOR) in pitch, causing disinhibited upward eye drift corrected by downbeat saccades — as described in Bradley and Daroff's Neurology (lines 1436–1440):
"Downbeat nystagmus results from...bilateral damage to the vestibulocerebellum (flocculus, paraflocculus, nodulus, and uvula) that disinhibits the VOR in pitch."
Correlation with Clinical Symptoms
Episodic Vertigo (3 Episodes) + Vomiting (2×)
The episodic nature is important. The differential includes:
| Diagnosis | Supporting VNG Features | Conflicting Features |
|---|---|---|
| Cerebellar episodic ataxia type 2 (EA2) | Downbeat nystagmus, cerebellar pursuit/saccade deficits, interictal cerebellar signs | Requires CACNA1A mutation testing |
| Vertebrobasilar TIA/insufficiency | Age 55, episodic course, central VNG pattern | No acute caloric asymmetry reported |
| Cerebellar degeneration (MSA-C, SCA) | Symmetric bilateral pursuit loss, vertical saccade failure, downbeat positional nystagmus | Progressive, not typically episodic |
| Arnold-Chiari malformation type I | Downbeat positional nystagmus (Yacovino+), cerebellar findings | Requires MRI to confirm tonsillar herniation |
| Posterior fossa mass | All central VNG features | No caloric data; mass effect on flocculus/nodulus |
| Menière's disease | Episodic vertigo, unilateral SNHL | No spontaneous nystagmus, central VNG pattern is incompatible |
Menière's disease is effectively excluded by this VNG. Menière's would show spontaneous peripheral nystagmus during an attack, caloric asymmetry, and peripheral-pattern positional nystagmus — none of which are present. The left-sided SNHL in Menière's is fluctuating and low-frequency; without audiogram data to confirm this, and given the central VNG, an alternative explanation must be sought.
Left-Sided Moderate SNHL — Key Question
In a patient with a central VNG pattern, the left-sided moderate SNHL is not necessarily peripheral cochlear in origin. As noted in Harrison's Principles of Internal Medicine 22E:
"Sensorineural hearing loss may also result from any neoplastic, vascular, demyelinating, infectious, degenerative disease, or trauma affecting the central auditory pathways. In hearing loss due to CNS pathology, there is a reduction in clarity of hearing and speech comprehension disproportionate to the pure-tone audiometric loss."
The SNHL therefore raises the following:
- Cerebellopontine angle (CPA) lesion — a vestibular schwannoma on the left CPA compresses CN VIII → SNHL + vestibular disruption, but would classically show caloric asymmetry (absent here in the reported data).
- Anterior Inferior Cerebellar Artery (AICA) territory ischemia — AICA supplies the cochlea via the internal auditory artery + the flocculus/lateral cerebellum. AICA infarction/TIA classically presents with ipsilateral SNHL + ipsilateral peripheral vestibular loss + central cerebellar signs — a clinically recognized syndrome.
- Demyelinating plaque (MS) at the level of the pons/lateral medulla affecting the cochlear nucleus or the VIIIth nerve entry zone simultaneously with cerebellar tracts.
- Coincidental peripheral SNHL (noise-induced, age-related) with independent central vestibular pathology.
Integrated Clinical Impression
The VNG pattern is unequivocally central vestibular/cerebellar. Combined with:
- 3 episodic events (suggesting paroxysmal CNS dysfunction, not benign BPPV)
- Emesis (brainstem/vagal activation from vestibular nucleus input to the dorsal motor vagus)
- Left-sided moderate SNHL (possible ipsilateral cochlear territory ischemia or CPA lesion)
The most urgent working diagnosis to exclude is:
AICA territory TIA or infarction — particularly in a 55-year-old male, given the episodic onset, left SNHL, central cerebellar VNG, and age-appropriate vascular risk.
The most clinically plausible structural diagnosis requiring imaging exclusion:
Arnold-Chiari type I malformation — causes downbeat positional nystagmus with Yacovino sign, bilateral cerebellar signs, can present episodically.
Episodic Ataxia Type 2 (EA2) should also be strongly considered — it is characterized by interictal downbeat nystagmus, impaired smooth pursuit, and cerebellar oculomotor signs, with episodic attacks of vertigo and ataxia lasting hours, responsive to acetazolamide.
Recommended Workup (Priority Order)
| Priority | Investigation | Rationale |
|---|---|---|
| 🔴 Urgent | MRI Brain + posterior fossa with contrast (FIESTA/CISS sequence) | Rule out Chiari I, cerebellar infarct, CPA mass, demyelination |
| 🔴 Urgent | MRI Internal Auditory Canals (IAC) | Rule out vestibular schwannoma / CPA tumor → left SNHL |
| 🟠 High | MRA posterior circulation | Rule out vertebrobasilar stenosis / AICA involvement |
| 🟠 High | Neurological referral | Examine for cerebellar signs: dysmetria, dysdiadochokinesia, gait ataxia, Romberg |
| 🟡 Moderate | Caloric testing / vHIT | Quantify peripheral canal function bilaterally (absent from this VNG report) |
| 🟡 Moderate | Complete audiogram | Characterize SNHL (frequency pattern, speech discrimination, word recognition scores) |
| 🟡 Moderate | CACNA1A mutation analysis | If EA2 suspected after imaging |
| 🟢 Baseline | Vascular risk factors | BP, lipid panel, HbA1c, ECG, Holter — vascular etiology in 55M |
| 🟢 Baseline | B12, thiamine, magnesium | Nutritional causes of cerebellar downbeat nystagmus |
| 🟢 Baseline | Drug history | Lithium, phenytoin, carbamazepine, aminoglycosides — all cause downbeat nystagmus |
Summary Statement
This 55-year-old male (Sanjay Garg) presents with 3 episodic vestibulo-cerebellar attacks with emesis and moderate left-sided SNHL. The VNG demonstrates a central vestibular/cerebellar pattern — severe vertical saccade failure, bilaterally symmetric global smooth pursuit impairment, positive Yacovino test with high-amplitude persistent downbeat nystagmus (SPV ~20°/s), perverted post-head-shake nystagmus, and multi-directional gaze nystagmus without fixation. These findings are incompatible with Menière's disease, BPPV, or peripheral vestibular neuritis. The left-sided SNHL combined with the central cerebellar VNG pattern raises the possibility of a CPA/posterior fossa lesion, Chiari I malformation, AICA territory vascular event, or Episodic Ataxia Type 2. Urgent MRI posterior fossa with IAC protocol and neurological consultation are mandatory.
Sources: Bradley and Daroff's Neurology in Clinical Practice (pp. 316–320, Box 18.14 — Causes of Downbeat Nystagmus); Harrison's Principles of Internal Medicine 22E (Sensorineural Hearing Loss); Goldman-Cecil Medicine (Vestibulo-ocular reflex pathways); Cummings Otolaryngology Head and Neck Surgery.
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