Abstract
Neuromyelitis optica (NMO), now referred to as NMO spectrum disorders (NMOSD), presents with painful visual loss and spinal cord damage, resulting in paresthesia, paralysis, and bladder or bowel dysfunction, and can further be associated with muscle spasms, uncontrollable vomiting, and hiccups. Once considered a variant of MS, it has now been identified as a distinct condition, with the discovery of specific serum aquaporin-4 (AQP4) immunoglobulin G (IgG) antibodies. The current diagnostic criteria include the serology status of these AQP4-IgG (also known as NMO-IgG) antibodies, along with six core clinical characteristics; this gives rise to two defined categories: NMOSD with AQP4-IgG (requires one core clinical characteristic) and NMOSD without AQP4-IgG or Unknown AQP4-IgG status (requires two core clinical characteristics and typical MRI features). Given the pronounced similarities in their clinical and radiological presentations, NMOSD has often been misdiagnosed as MS, leading to a delay in diagnosis and ineffective and potentially harmful treatment regimens. This chapter summarizes the pathophysiology, diagnostic criteria, and management of NMOSD, including a brief update on emerging drug developments targeted at alleviating neurological damage from acute attacks.