Neuromyelitis optica spectrum disorder (NMOSD) associated with anti-AQP4 antibodies targets aquaporin-4 water channels on astrocyte end-feet at the blood-brain barrier. The characteristic lesion pattern that distinguishes NMOSD from MS is:

• A Dawson's fingers periventricular lesions
• B Cortical/juxtacortical lesions in U-fibres
• C Infratentorial lesions at the cervicomedullary junction
• D Longitudinally extensive transverse myelitis (LETM) spanning ≥3 vertebral segments ✓

Explanation

NMOSD classically presents with longitudinally extensive transverse myelitis (LETM) spanning ≥3 vertebral segments on MRI — in contrast to MS where cord lesions are typically short (<2 segments). NMOSD also characteristically causes bilateral or severe optic neuritis (often with chiasmal involvement), area postrema lesions (causing intractable hiccups/vomiting), and hypothalamic lesions. Dawson's fingers (periventricular finger-like lesions) are characteristic of MS. AQP4-Ab NMOSD is treated with immunosuppressants (azathioprine, mycophenolate, rituximab) — not MS DMTs.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.