The frequency and significance of antibodies to NMDAR were determined in 19 adolescents and young women, aged 15 to 45 years, with unexplained new-onset epilepsies, seen between Jan 2005 and June 2007 at the University of Bonn, Germany; Univ of Pennsylvania, Philadelphia; and John Radcliffe Hospital, Oxford, UK. Five (25%) patients had anti-NMDAR antibodies, and all 5 had a history of psychiatric symptoms, pleocytosis, seizures, and relapsing-remitting course. All recovered, either spontaneously or following corticosteroid or intravenous immunoglobulin treatment. Only 1 patient had a neoplasm (multiple neuroendocrine tumors including the ovaries). In a control series of 61 patients with other cryptogenic epilepsies and 11 surgically treated patients with epilepsy, one, a 22-year-old man, was NMDAR antibody positive and he had recovered from a severe encephalopathy. 
COMMENT. A significant proportion of unexplained new-onset epilepsies in adolescents and young women may be caused by anti-NMDAR encephalitis. Seizures are a common symptom in patients with anti-NMDAR encephalitis, reported in 76 of 100 cases.