How to avoid missing a diagnosis of neuromyelitis optica spectrum disorder

Recognizing neuromyelitis optica spectrum disorder (NMOSD) and differentiating NMOSD from multiple sclerosis (MS) and other disorders can be challenging yet it is extremely important to prevent misdiagnosis, defined in this review as the incorrect diagnosis of patients who truly have NMOSD, particularly in aquaporin-4-IgG (AQP4-IgG)-seronegative cases. The heterogeneity of clinical presentations and wide range of differential diagnoses often lead to missed diagnoses of NMOSD. Misapplication of the 2015 NMOSD criteria and misinterpretation of clinical and neuroradiological findings are relevant factors associated with misdiagnosis in clinical practice. Despite the presence of a specific biomarker for NMOSD (AQP4-IgG), misdiagnosis rates have been reported as high as 35%. Studies indicate that misdiagnosed patients often undergo unnecessary prolonged immunotherapy, leading to health risks and increased morbidity. Accurate definitive diagnosis is crucial as long-term outcomes and treatment approaches differ based on the correct diagnosis, and inappropriate immunotherapy can lead to disability in NMOSD patients. This review outlines factors linked to NMOSD misdiagnosis and briefly discusses strategies to reduce misdiagnosis.