🔄 Acute Ataxia
• Acute cerebellar ataxia (postinfectious cerebellitis): most common (40%). Preceding illness 5-21 days, normal mental status, preserved reflexes
• Drug ingestion: anticonvulsants, benzodiazepines, alcohol, antihistamines → mental status changes common
• Miller Fisher syndrome (GBS variant): ataxia + ophthalmoplegia + areflexia, anti-GQ1b antibodies
• Opsoclonus-myoclonus: opsoclonus (chaotic eye movements), myoclonus, ataxia → neuroblastoma until proven otherwise
⚠️ Red Flags – Posterior Fossa Tumor
• Headache on awakening, morning vomiting
• Papilledema, cranial nerve palsies (CN VI)
• Progressive ataxia (days to weeks)
• Dysmetria, intention tremor
• MRI brain with contrast
🩺 Episodic/Recurrent Ataxia
• Migraine variants: benign paroxysmal vertigo (toddlers, collapse, nystagmus, no LOC)
• Episodic ataxia type 1 & 2 (ion channel mutations), acetazolamide-responsive
• Metabolic disorders: Hartnup disease, maple syrup urine disease (intermittent form), pyruvate dehydrogenase deficiency
📋 Chronic Progressive Ataxia
• Friedreich ataxia: GAA trinucleotide repeat, progressive ataxia, areflexia, extensor plantar responses, cardiomyopathy, diabetes
• Ataxia-telangiectasia: cerebellar ataxia (onset ~2y), oculocutaneous telangiectasias, IgA deficiency, sinopulmonary infections, increased AFP, malignancy risk
• ADEM, MS, spinocerebellar degenerations
📌 Decision strategy: Acute ataxia + normal mental status + preserved reflexes → acute cerebellar ataxia (most common). Ataxia + mental status change → drug ingestion or toxic/metabolic cause. Opsoclonus-myoclonus → urgent neuroblastoma workup.