Good morningʻ dear all. Want to discuss a tricky case for your inputs.

Good morningʻ dear all. Want to discuss a tricky case for your inputs. A young male, medico, is currently admitted with acute non positional constant vertigo for about 1 week now. At presentation, he had subtle left beat unidirectional nystagmus, HIT negative, Romberg positive ( mild), sense of instability on walking. Next day, nystagmus became right beating and remains so for 2 days now. Nystagmus is more on removing fixation and slightly increases on right McClure pagnini but no crescendo decrescendo or latency or increased symptom severity in that position ( negative positional test). HIT remains negative ( F-HIT twice done, normal and clinical HIT also negative) No aural symptoms. H/o episodic migrainous headaches is there in past. MRI brain contrast, CTAngio, PTA all normal. Patient not responding to flunarizine, iv solumedrol ( 40mg given one day and 250 mg on 2nd day). Betahistine is ineffective. Symptoms are rather escalating. Gave stemetil 5mg- again no significant effect. Looking for valuable suggestions

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direction changing nystagmus spontaneous central vertigo differential diagnosis

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vestibular neuritis treatment failure escalating symptoms management

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This is a rich, nuanced case. Let me synthesize a comprehensive analysis.

Clinical Analysis: Acute Sustained Vertigo with Direction-Changing Nystagmus

The Key Red Flags in This Case

Before anything else, the combination of findings here is highly concerning for a central cause, and the clinical picture needs urgent re-evaluation even with a "normal" MRI.

Feature	Peripheral Implication	This Patient
Nystagmus direction	Fixed, unidirectional	Changed direction (L → R beat)
HIT	Positive (canal paresis)	Negative x3 (clinical + F-HIT x2)
Fixation suppression	Suppresses nystagmus	Enhanced on removal of fixation
Duration	Improves within days	Worsening at 1 week
Response to treatment	Typically responds	No response to steroids, antiemetics, betahistine
Positional component	Classic BPPV pattern	Atypical — no latency/crescendo-decrescendo

As per Harrison's (p. 721): "Nystagmus that changes direction with gaze is due to a central lesion" and "Absence of a head impulse sign in a patient with acute prolonged vertigo should suggest a central cause."

The Direction-Changing Nystagmus — What It Means

The nystagmus changed from left-beating to right-beating over 24–48 hours. This is critical:

Peripheral nystagmus is fixed and unidirectional by Alexander's Law. Direction-reversal of spontaneous nystagmus is a central sign. The differential for this specific pattern includes:

Central Vestibular Migraine (Vestibular Migraine with central features)
Brainstem / cerebellar lesion — particularly affecting the:
- Nodulus/uvula of cerebellum (can produce direction-changing positional nystagmus)
- Nucleus prepositus hypoglossi / MVN (velocity storage mechanism)
MS plaque in brainstem or vestibular nuclei
Wernicke's encephalopathy (given he's a young medico — consider nutrition/stress)
Autoimmune encephalitis (anti-NMDAR, LGI1, CASPR2 — can present with isolated brainstem/vestibular symptoms)
Episodic ataxia type 2 (EA2) — CACNA1A mutation, can mimic this pattern

Why Vestibular Migraine Doesn't Fully Fit

Yes, he has a migrainous history — but several features argue against pure vestibular migraine:

Continuous (non-episodic) vertigo for 1 week
Direction reversal of nystagmus — unusual even for VM
No response to flunarizine (a calcium channel blocker commonly used in VM)
Escalating rather than plateauing symptoms

VM typically produces episodic vertigo. A sustained 1-week continuous course with worsening and direction-changing nystagmus pushes toward central structural or inflammatory pathology.

MRI Was "Normal" — But Is It Truly Negative?

This is the most important caveat. MRI can miss posterior fossa pathology, especially early:

Acute cerebellar/brainstem infarcts can be MRI-invisible in the first 24–72 hours on DWI (false-negative DWI rate for posterior fossa infarcts is 15–20%)
Small demyelinating plaques in the vestibular nuclei or fasciculus longitudinalis medialis (MLF) can be missed on standard sequences
Was the MRI done with dedicated posterior fossa sequences (thin-cut FLAIR, high-resolution T2 through brainstem)?

Recommendation: Repeat MRI at 7–10 days with dedicated brainstem/posterior fossa protocol (3T if possible) — this is standard practice for suspected posterior fossa stroke/demyelination with initial negative DWI.

Priority Investigations to Add

Investigation	Rationale
Repeat MRI brain (3T, posterior fossa protocol, DWI repeat)	Miss rate for early posterior fossa infarct/demyelination
CSF analysis (LP)	MS (oligoclonal bands, IgG index), viral/autoimmune encephalitis, Lyme
Autoimmune encephalitis panel (serum + CSF)	Anti-NMDAR, LGI1, CASPR2, GABA-B, AMPA — all can cause brainstem/vestibular symptoms
Anti-GAD65 antibodies	Cerebellar ataxia/vestibular syndrome
Serum B1 (thiamine)	Rule out Wernicke's — especially a stressed young medico with possible poor intake
VHIT with video-oculography	Formal VNG/VOG to characterize nystagmus waveform fully
ANA, ANCA, anti-dsDNA, complement	Vasculitic/CNS autoimmune etiology
Genetic testing (CACNA1A)	If EA2 suspected

Diagnostic Framework

Acute central vestibular syndrome (ACVS) with direction-changing nystagmus
                    ↓
        Structural vs. Inflammatory vs. Channelopathy
        ↙                    ↓                    ↘
Posterior fossa        MS/demyelination       EA2 / Autoimmune
infarct/mass           (repeat MRI + CSF)     encephalitis
(repeat DWI)                                  (autoimmune panel)

Management Thoughts

Stop betahistine — no role in central vestibular syndrome; may confound
Withhold further empirical steroids until LP/autoimmune workup is done — if autoimmune encephalitis is confirmed, higher-dose IVIG/plasmapheresis or rituximab will be needed
Thiamine 100mg IV empirically is low-risk and high-yield if Wernicke's hasn't been excluded
Neurology + Neuro-otology / Neuro-ophthalmology consultation urgently if not already done
If EA2 is suspected (episodic component + migraine history + calcium channelopathy), acetazolamide 250mg BD is dramatically effective and also serves as a diagnostic trial
Avoid vestibular suppressants (stemetil, cinnarizine) long-term in central lesions — they impair CNS compensation

Bottom Line

This patient has a central vestibular syndrome until proven otherwise. The direction reversal of nystagmus, negative HIT, lack of treatment response, and worsening trajectory are incompatible with a peripheral diagnosis. The normal MRI does not exclude early posterior fossa infarct, small demyelinating plaque, or autoimmune/paraneoplastic brainstem encephalitis.

Immediate next steps:

Repeat MRI (posterior fossa protocol, 3T if available)
LP (cell count, protein, glucose, oligoclonal bands, autoimmune encephalitis panel in CSF)
Serum autoimmune encephalitis panel + anti-GAD65
IV thiamine empirically
Consider acetazolamide trial if EA2 remains in differential

This young medico deserves a systematic central workup before any further empirical treatment.

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