Utility of Magnetic Resonance Imaging to differentiate optic neuritis due to inflammatory demyelinating diseases among patients presented to the Institute of Neurology at the National Hospital of Sri Lanka

Optic neuritis (ON) is an inflammatory condition of the optic nerve, commonly linked to demyelinating diseases such as Multiple Sclerosis (MS), Neuromyelitis Optica Spectrum Disorder (NMO/NMOSD), and Myelin Oligodendrocyte Glycoprotein antibody-associated disease (MOGAD). Early differentiation is crucial for appropriate treatment. Magnetic Resonance Imaging (MRI) plays a key role in distinguishing disease-specific patterns. A retrospective cross-sectional study analyzed MRI data of ON patients at the Institute of Neurology, National Hospital of Sri Lanka (NHSL, from April 2018 to December 2021. Diagnoses were confirmed through clinical evaluation, Visual Evoked Potential (VEP), Optical Coherence Tomography (OCT), AQP4/MOG antibody testing, and cerebrospinal fluid (CSF) oligoclonal band analysis. MRI findings were independently reviewed by two radiologists. A total of 111 patients (76.6% female, mean age 40.6 ± 13.2 years) were included. The most common diagnosis was MS (45.05%), followed by AQP4-NMO/NMOSD (19.82%), MOGAD (18.92%), and Chronic Relapsing Inflammatory Optic Neuropathy (CRION) (16.22%). MRI findings showed cerebral white matter lesions in 55.9% of cases. Optic chiasma involvement was prominent in AQP4-ON (76.9%), while MOG-ON showed optic nerve swelling (72.2%) and perineural inflammation (76.9%). CRION was significantly associated with age >50 years. Different MRI characteristics of the optic nerves aid in distinguishing ON subtypes. These findings enable early diagnosis and targeted immunotherapy, particularly in settings where antibody testing is not readily available.