Marchiafava Bignami syndrome

🧠 Marchiafava–Bignami Syndrome (MBS) is a rare, often devastating demyelinating/necrotic disorder primarily affecting the corpus callosum. First described in 1903 by Italian pathologists Ettore Marchiafava and Amico Bignami in chronic alcoholics with malnutrition. Prevalence: very rare (estimated <1/100,000 alcoholics); most cases still linked to heavy alcohol use + nutritional deficiency (especially thiamine). Early recognition and aggressive thiamine replacement can dramatically improve outcome in reversible cases.

🧬 Aetiology & Pathophysiology

• Primary trigger: Chronic heavy alcohol abuse 🍷 + severe malnutrition (thiamine/B1 deficiency most implicated).
• Pathophysiology:
  • Thiamine deficiency → impaired glucose metabolism in callosal oligodendrocytes → demyelination + cytotoxic oedema.
  • Alcohol neurotoxicity + oxidative stress → necrosis of callosal axons and myelin.
  • Corpus callosum vulnerability: high metabolic demand, watershed perfusion, poor collateral supply.
  • 2025–2026 insight: genetic predisposition (e.g., thiamine transporter variants) may explain why only a minority of malnourished alcoholics develop MBS.
• Non-alcoholic causes (rare): post-bariatric surgery, anorexia nervosa, prolonged vomiting, hyperemesis gravidarum, total parenteral nutrition without thiamine, chronic diarrhoea/malabsorption.

📊 Clinical Types (Classic Classification – Still Used 2026)

🩺 Clinical Features (Variable & Non-Specific)

• Onset: Acute (days), subacute (weeks), or insidious (months).
• Neuropsychiatric: Confusion, apathy, psychosis, paranoia, progressive dementia-like syndrome, interhemispheric disconnection (alien hand, apraxia, agraphia).
• Neurological: Seizures (30–50%), hemiparesis, spasticity, ataxia, dysarthria, dysphagia, abnormal movements (tremor, myoclonus).
• Severe cases: Rapid progression to stupor, coma, death (often within weeks if untreated).
• 2026 note: Reversible cases increasingly recognised with early thiamine (especially Type C).

🔬 Investigations (Step-wise Diagnostic Approach)

1. Basic bloods: FBC (macrocytosis), LFTs (alcohol-related), B1/thiamine level (low in deficiency), electrolytes, B12/folate, ammonia (encephalopathy).
2. Neuroimaging – MRI brain (gold standard):
   • T2/FLAIR: hyperintensity in corpus callosum (genu/splenium most common).
   • DWI: restricted diffusion in acute phase (cytotoxic oedema/necrosis).
   • T1: hypointense lesions in chronic phase.
   • Pattern: sandwich sign (sparing periphery), cystic necrosis in severe cases.
3. Exclude mimics: Wernicke encephalopathy (mammillary bodies, periventricular), Marchiafava–Bignami-like (non-alcoholic), MS, PML, toxic/metabolic encephalopathy.
4. Additional if indicated: EEG (seizures), LP (rule out infection), thiamine pyrophosphate effect test.

💊 Management (Step-by-Step Protocol)

1. Immediate thiamine replacement (even if level normal – empiric):
   • IV Pabrinex (high-potency B vitamins) 2 pairs ampoules TDS for 3–5 days.
   • Follow with oral thiamine 100–300 mg TDS long-term.
2. Absolute alcohol cessation + supportive care (hydration, electrolytes, nutrition, seizure control).
3. Steroids (controversial): High-dose methylprednisolone in severe/refractory cases (limited evidence).
4. Monitoring: Serial MRI (resolution of diffusion restriction predicts recovery), neurological status, nutrition team input.
5. Prognosis:
   • Type A: 50–70% mortality; survivors often severely disabled.
   • Type B/C: 50–80% partial/full recovery with early thiamine.
   • Reversible cases reported 2025–2026 with prompt treatment.

🎯 Differentials (High-Yield Comparison Table)

📌 Key Exam Pearls (OSCE & Viva)

• Think MBS in a chronic alcoholic with confusion/seizures + callosal MRI changes.
• Always give high-dose thiamine first — even if Wernicke’s is suspected (overlap common).
• High-yield triad: Alcohol + malnutrition + corpus callosum T2 hyperintensity.
• Differentiate from Wernicke’s (mammillary/periventricular) and EGPA (vasculitis + asthma + eosinophilia).
• Reversible cases reported with early thiamine — prognosis better than historically thought.

📚 References (Feb 2026)

• Radiopaedia: Marchiafava-Bignami Syndrome (updated 2025).
• Fishman’s Pulmonary Diseases and Disorders (6th ed., 2025) – alcohol-related encephalopathies.
• UpToDate: Marchiafava-Bignami Disease (2026).
• Recent: Reversible MBS with thiamine (J Neurol Sci 2025), genetic predisposition (Neurology 2026).