The 2015 NMOSD diagnostic criteria - are they an improvement?

Abstract

Revision to the widely accepted Wingerchuk 2006 criteria for diagnosis of neuromyelitis optica (NMO) was necessary for several reasons: 1. The spectrum of the disease was determined to be broader than previously recognized and to include certain brainstem, hypothalamic and cerebral syndromes; 2. The advent of a specific biomarker, aquaporin-4 IgG (AQP4-IgG), enabled a confident NMO diagnosis at first presentation; 3. Whether AQP4-IgG seronegative patients with symptoms compatible with NMO could be diagnosed with this condition needed to be clarified. The criteria proposed by the International Panel on NMO Diagnosis (IPND) subsumed all NMO-associated syndromes under the term “NMO spectrum disorders (NMOSD).” A diagnosis in AQP4-IgG seropositive patients requires only a single compatible syndrome and neither optic neuritis nor myelitis. For AQP4-IgG seronegative patients, dissemination in space is necessary in addition to certain MRI requirements to increase stringency and reliability. Retrospective studies from Korea and the U.K. have documented 75-85% increased sensitivity of the new IPND criteria, especially for seropositive cases. However, the specificity of the IPND criteria and ability to discriminate NMOSD from a growing number of mimic conditions remains to be established. It seems likely that a new form of NMOSD associated with myelin oligodendrocyte glycoprotein IgG antibodies will be considered a distinct form of NMOSD with an overlapping but somewhat distinct prognosis and possibly similar requirement for immunosuppression rather than MS-directed immunomodulatory treatment. Although the IPND criteria represent an incremental improvement, diagnostic criteria for NMOSD will likely evolve especially based on discovery of novel pathogenic autoantibody biomarkers.