Development of extensive brain lesions following interferon beta therapy in relapsing neuromyelitis optica and longitudinally extensive myelitis

Abstract

Sirs: Relapsing neuromyelitis optica (RNMO) is characterised by recurrent longitudinally extensive myelitis (RLEM) and severe optic neuritis [5, 7, 10, 14]. The effects of disease-modifying therapies, including interferon beta (IFNβ), have not been fully established in RNMO or RLEM [15]. The neuromyelitis optica immunoglobulin G (NMO-IgG) auto-antibody (Ab) is a marker for NMO [3], which binds to the aquaporin 4 (AQP4) water channel protein [2]. AntiAQP4 antibody titres may have implications in diagnosing NMO [13]. We report two cases of RNMO or RLEM with anti-AQP4 Ab, in which extensive (tumefactive) brain lesions developed within 2 months after initiation of IFNβ-1b.