Clinical and radiological profile of neuromyelitis optica spectrum disorders in a Pakistani cohort

Abstract

Background: The clinical and radiological characteristics of neuromyelitis optica spectrum disorder (NMOSD) from Pakistan is unknown. Our study aimed to describe the clinical and radiological features of NMOSD patients presenting to a Pakistani tertiary care center.

Materials and methods: This retrospective, observational study was conducted at the Neurology Department, Pakistan Institute of Medical Sciences between January 2017 and September 2021 (56 months). The study included patients diagnosed with neuromyelitis optica spectrum disorder (NMOSD) according to the 2015 International Panel for NMO Diagnosis (IPND) criteria, with the exclusion of patients under 12 years of age and those who tested positive for Myelin oligodendrocyte glycoprotein (MOG) IgG antibody. The patients were divided into two groups based on clinical presentation and the presence of NMO-IgG antibodies: NMO-IgG positive NMO (Seropositive NMO) and NMO-IgG negative (Seronegative NMO). The clinical features of NMOSD were recorded, and data was analyzed using SPSS version 26.0.

Results: Among 204 patients with suspected demyelination, multiple sclerosis was diagnosed in 100 individuals (49.02%), while acute disseminated encephalomyelitis (ADEM), clinically isolated syndrome (CIS), and neuromyelitis optica (NMO) were found in 5 patients each (2.45%, 2.45%, and 17.65%, respectively). Out of 36 patients with NMO, 32 (88.89%) tested positive for NMO-Ab, while the remaining 4 (11.11%) were seronegative for both NMO and anti-MOG Abs. The mean age of NMO-positive patients who tested positive for NMO antibodies was 31.03±10.12 years, compared to 27.95±2.5 years for NMO-negative patients, though this difference was not statistically significant (p>0.05). Females were more commonly affected by NMO, accounting for 72.2% of the NMO-positive group, and there was a significant difference in clinical phenotypes between the two groups (p<0.05). The NMO-positive group predominantly had relapsing NMO presentation (75%), and 72.8% of these patients showed longitudinally extensive transverse myelitis on the MRI spine. Azathioprine was the most frequently administered treatment for positive NMO patients (69.44%), followed by rituximab and MMF. The follow-up period for the study participants lasted 24 months.

Conclusion: This is the first study on NMOSD cases in Pakistan. According to the present study, NMOSD is most prevalent among women in their forties. Relapsing NMO was the most common form of presentation. 89% of patients had antibodies against AQP4. 72.8% of patients suffered from LETM during the course of their disease. There are some features of our NMOSD cases that appear comparable with those around the world, despite some limitations in testing and access to care. It is clear that the clinical and radiological spectrums of patients with NMO and NMOSD in this cohort are similar. It is reasonable to suspect NMO if demyelinating episodes are not characteristic of MS.

Keywords: MOG antibody disease; Neuromyelitis optica; Neuromyelitis optica spectrum disorder; Optic neuritis; Serum antibody against aquaporin 4 (AQP4); Transverse myelitis.