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NMOSD — RACP Adult Medicine MCQ

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ModerateNeurologyNMOSDRACP Adult Medicine

A 30-year-old woman presents with a 3-day history of progressive bilateral leg weakness and urinary retention. MRI shows a longitudinally extensive transverse myelitis (LETM) spanning T3–T9 (>3 vertebral segments). Serum AQP4-IgG (anti-aquaporin-4) antibodies are positive. What is the diagnosis?

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Correct answer: B — Spinal cord infarction

LETM (≥3 vertebral segments) with positive AQP4-IgG antibodies is diagnostic of NMOSD (formerly Devic's disease). This is a critical distinction from MS because the treatments differ – some MS therapies (fingolimod, natalizumab) can WORSEN NMOSD. Acute treatment is high-dose IV methylprednisolone; plasma exchange for steroid-refractory attacks. Long-term prevention uses rituximab, eculizumab, inebilizumab, or satralizumab (all with evidence from RCTs – PREVENT, N-MOmentum, SAkuraSky trials).

Reference: eTG – 2025 – Neurology; Wingerchuk et al – 2015 – NMOSD Diagnostic Criteria