To the Editor:
Neuromyelitis optica (NMO) is a demyelinating, organ-specific, autoimmune disorder that preferentially targets the optic nerve and spinal cord. Since the discovery and validation of NMO-IgG serum antibodies in patients with NMO, the disorder has been considered a separate disease entity from multiple sclerosis (MS). NMO-IgG antibodies target aquaporin-4 (AQP4), the predominant water-channel protein within the central nervous system. AQP4 antibodies have also been described in formes frustes of NMO, longitudinally extensive transverse myelitis (LETM), and recurrent optic neuritis (ON)1. The specificity of NMO-IgG antibodies for the disease led to the addition of NMO-IgG antibodies to the diagnostic criteria of NMO2. Incomplete forms of NMO have also been recognized, and in such patients the presence of NMO-IgG antibody positivity increases the risk of progression and has resulted in the designation of NMO spectrum disorders (NMOSD). The diagnostic criteria for NMOSD have also been recently defined3. Several case series have been described regarding the coexistence of connective tissue disease (CTD), and this has spurred interest in NMO/NMOSD in the field of rheumatology3. The 2 most commonly reported coexistent CTD are Sjögren’s …
Address correspondence to Dr. Chogle; E-mail: archogle{at}vsnl.net/arunchogle{at}yahoo.com
