NMO-IgG in the diagnosis of neuromyelitis optica

Recently, a newly detected serum autoantibody (called NMO-IgG) has been reported to distinguish between neuromyelitis optica (NMO) and multiple sclerosis (MS),1 and revised diagnostic criteria for NMO giving a crucial role to this antibody have been suggested.2 This proposal has important clinical implications and therefore demands independent confirmation. We studied 36 unselected patients with NMO (33 relapsing, three monophasic). All patients met the 1999 criteria of Wingerchuk et al.3 Spinal cord lesions in three or more segments were present in 35 of 36. Median follow-up from onset was 38 months. In addition, we tested 80 patients with MS according to the revised McDonald criteria4 (71% relapsing-remitting, 20% secondary progressive, 9% primary progressive), five patients with longitudinally extensive transverse myelitis (LETM),1,5 11 patients with non-LETM myelitis, 21 with miscellaneous neurologic disorders, and 25 healthy controls. NMO-IgG was detected by indirect immunofluorescence.1 Briefly, adult mouse cerebellum cryosections (10 μm) were incubated with 10% phosphate-buffered formalin for 4 minutes. After three washes in phosphate-buffered saline (PBS), detergent (1% CHAPS in PBS) was applied for 4 minutes. After …