Comparison of clinico-radiological profile, optical coherence tomography parameters, and outcome in MOGAD and Neuromyelitis optica spectrum disorder subtypes: A prospective observational study

Abstract

Objectives: The objectives of the study were to compare the clinico-radiological profile, optical coherence tomography (OCT) parameters and outcome in Myelin Oligodendrocyte Glycoprotein-IgG-associated disorders (MOGAD) and Neuromyelitis Optica Spectrum disorder subtypes. Materials and Methods: This prospective study involved collection of data regarding neurological assessment, neuroimaging, cerebrospinal fluid analysis, OCT parameters, treatment and outcome. Disease severity and disability were assessed using Expanded Disability Status Scale and modified Rankin scale. Patients were categorized into aquaporin-4 (AQP4+), MOGAD, and double negative (DN; both AQP4 and MOG negative). Results: Among 31 patients included, 42% were AQP4+, 32.2% were MOGAD, and 25.7% were DN. The median age at onset was comparable (AQP4+ vs. MOGAD vs. DN = 28 years vs. 24.4 years vs. 31.5years; P = 0.31). Females predominated in AQP4+ compared to MOGAD group (76.9% vs. 30%; P = 0.02). Majority of patients (73.5%) had a relapsing course with a median of two (range = 1–9) relapses. Ninety-nine demyelinating events occurred: Transverse myelitis (TM) in 60/99 (60.6%), optic neuritis (ON) in 43/99 (43.4%), area postrema (AP) syndrome in 20/99 (20.1%), and optico-spinal syndrome in 10/99 (10.1%). ON was common in MOGAD than AQP4+ patients (58.6% vs. 32.1%; P = 0.03). Spinal cord and brain lesions on magnetic resonance imaging (MRI) were seen in 90.3% and 54.8% patients, respectively. A significantly higher proportion of AQP4+ patients showed longitudinally extensive transverse myelitis as compared to MOGAD group (69.2 % vs. 20 %; P = 0.04), specifically involving dorsal cord (92.3% vs. 50%; P = 0.02). MRI brain lesions, especially involving AP, was frequent in DN than MOGAD (47.1% vs. 6.9%; P = 0.003) and AQP4+ (47.1% vs. 18.9%; P = 0.03) patients. AQP4+ group showed significant nasal RNFL thinning on OCT (P = 0.04). Although 6-month good functional outcome was better in MOGAD than DN and AQP4+ (80% vs. 71.4% vs. 41.7%) groups, they were comparable (P = 0.13). Conclusion: Nearly three-fourth of our patients showed a relapsing course, with TM being the most common clinical presentation. AQP4+ group showed female preponderance, frequent dorsal cord longitudinally extensive transverse myelitis, less frequent ON, and greater nasal RNFL thinning compared to MOGAD group. MRI brain lesions were more common in DN patients. All three groups exhibited good response to pulse corticosteroids and showed a comparable functional outcome at 6-month follow-up.