Neuromyelitis optica-IgG testing in an Indian cohort with neuromyelitis optica and related demyelinating disorders: Our experience

Abstract

Background: Neuromyelitis optica (NMO) is an immune-mediated inflammatory demyelinating disorder of the central nervous system with a predilection for the optic nerves and the spinal cord. Immunopathological evidence suggests that the target antigen of the disease is aquaporin-4. An IgG antibody against this protein has been explored as a molecular marker for the disease and as a diagnostic tool due to its high sensitivity and specificity in various populations.

Objective: To assess the value of NMO-IgG testing in Indian patients with clinical and magnetic resonance imaging features consistent with NMO and longitudinally extensive transverse myelitis (LETM).

Materials and methods: Forty-five patients with clinical and magnetic resonance imaging features consistent with NMO, LETM, and MS were tested for serum NMO-IgG. Of these patients, 22 patients satisfied revised (2006) Wingerchuk criteria for NMO (excluding NMO-IgG status) and 11 patients had LETM. Twelve patients satisfied the revised (2010) McDonald criteria for multiple sclerosis (MS).

Results: Of the 21 patients, satisfying the criteria for NMO and for whom the test results were available, 17 were positive for NMO-IgG (80.9%), and of the 11 patients having LETM, 6 (54.5%) were positive for NMO-IgG. In one patient with NMO, the test result was not available. None of the 12 patients satisfying McDonald criteria for MS showed NMO-IgG seropositivity.

Conclusion: Our study suggests that it is worthwhile to pursue NMO-IgG testing as a diagnostic tool for patients with clinical and Magnetic Resonance Imaging (MRI) features consistent with NMO and LETM in the Indian population.

Keywords: Anti-aquaporin-4 seropositivity; neuromyelitis optica; neuromyelitis optica-Immunoglobulin G seropositivity; transverse myelitis.

Graph 1

NMO-IgG percentage seropositivity in the three study groups (NMO = Neuromyelitis Optica, LETM = Longitudinally Extensive Transverse Myelitis, MS = Multiple Sclerosis)

Graph 2

Comparison of sensitivity and specificity of NMO-IgG test in various studies (NMO = Neuromyelitis Optica, LETM = Longitudinally Extensive Transverse Myelitis, MS = Multiple Sclerosis)