Anti-N-methyl-D-aspartate Receptor Encephalitis as a Paraneoplastic Presentation of Mature Ovarian Teratoma.

BACKGROUND Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a potentially fatal form of autoimmune encephalitis that involves autoantibodies directed against the NR1 subunit of the receptor. This leads to dysregulation of neurotransmission and resultant psychotic and neuroanatomical symptoms. Anti-NMDAR encephalitis classically presents in women who have ovarian teratomas, but it also has been associated with a preceding herpes infection, testicular germ cell tumor, small cell lung cancer, and neuroblastoma. CASE REPORT The present case report illustrates the course of severe anti-NMDAR encephalitis in a patient who had poor prognostic factors, including a high anti-NMDAR titer in cerebrospinal fluid and extreme delta brush electroencephalography pattern. In addition, it underscores the importance of a multidisciplinary approach when treating these patients. CONCLUSIONS Despite being the most common form of autoimmune encephalitis, anti-NMDAR encephalitis remains underrecognized in clinical settings because of discrepancies in patient presentations and their resulting hospital courses. These variations make it difficult to devise an appropriate immunotherapy regimen and plan for intensive care management. It has been estimated that 25% of patients with anti-NMDAR encephalitis experience permanent neuropsychiatric debilitation or death even when they receive mainstay treatment. Relapse is estimated to occur in 15% to 24% of patients and is more common in individuals who do not have underlying tumors. Nonetheless, approximately 75% of patients with anti-NMDAR encephalitis recover or have only mild sequelae.