N-Methyl-d-aspartate Receptor Antibody Encephalitis: A Concise Review of the Disorder, Diagnosis, and Management.

Anti-NMDA ( N-methyl-d-aspartate) receptor (anti-NMDAR) encephalitis is one of the most common paraneoplastic encephalitides. It occurs in both sexes, across all age ranges, and may occur in the presence or absence of an associated tumor. Its pathogenesis and clinical presentation relate to the presence of IgG1 or IgG3 antibodies targeting the NR1 subunit of the NMDA receptor, leading to a disinhibition of neuronal excitatory pathways. Initial clinical manifestations may be nonspecific, resembling a viral-like illness; however, with disease progression, symptoms can become quite severe, including prominent psychiatric features, cognitive problems, motor dysfunction, and autonomic instability. Anti-NMDAR encephalitis may even result in death in severe untreated cases. Diagnosis can be challenging, given that initial laboratory and radiographic results are typically nonspecific. The majority of patients respond to first or second-line treatments, although therapeutic options remain limited, usually consisting of tumor removal (if there is confirmation of an underlying malignancy) in conjunction with prompt initiation of immunosuppressive medications along with intravenous immunoglobulins and/or plasma exchange. Although the clinical presentation of anti-NMDAR encephalitis overlaps with several other more common neurological and psychiatric disorders, early diagnosis and treatment is essential for a positive prognosis. Here, we concisely review the pathogenesis, diagnosis, and clinical management of this disease.