Previous studies have examined the platelet-to-lymphocyte (PLR) and neutrophil-to-lymphocyte (NLR) ratios as biomarkers of inflammation and disease activity in autoimmune diseases. Researchers assessed the ability of these ratios to discern between MS and seropositive neuromyelitis optica spectrum disorder (NMOSD) at disease onset among 50 patients with MS and 33 with NMOSD. The study team retrospectively enrolled and revised the medical records of patients, obtaining demographic data, clinical information (manifestation and disability), and neuroradiological features (contrast-enhancing lesions), and compared MS with NMOSD. PLR was increased among patients with NMOSD compared with MS (229.4±86.74 vs 186.6±70.17; P = .01), but no significant differences were seen with NLR (3.516±1.293 vs 3.301±1.174; P = 0.43). Patients with NMOSD had a higher median Expanded Disability Status Scale score (3) compared with patients with MS (2; P < .0001). Brainstem and cerebral manifestations significantly correlated with MS compared with NMOSD, though no significant differences were seen regarding contrast-enhancing lesions between the two groups. The researchers noted that PLR could provide additional information for discerning between MS and NMOSD.