Case Report: Anti-N-methyl-D-aspartate receptor encephalitis associated with bilateral mature ovarian teratomas in early pregnancy

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis that may present with acute psychiatric symptoms, seizures, movement disorders, impaired consciousness and autonomic dysfunction. A 30-year-old previously healthy woman at 10-11 weeks of gestation was admitted to the intensive care unit after an approximately 2-3-week history, reported by relatives, of insomnia, behavioral change, auditory and visual hallucinations, psychomotor agitation, aggressive behavior, and a generalized tonic-clonic seizure before admission. On admission, the patient had severe encephalopathy and subsequently required mechanical ventilation because of hypoventilation. Cerebrospinal fluid testing detected IgG antibodies against NMDAR at a titer of 1:160. Brain magnetic resonance imaging showed a right hippocampal lesion consistent with limbic encephalitis, and pelvic ultrasonography identified adnexal masses suspicious for teratoma. Prolonged EEG demonstrated diffuse delta-theta slowing with a delta-brush pattern, without findings consistent with focal or myoclonic seizures. The patient received high-dose methylprednisolone, intravenous immunoglobulin, plasma exchange, rituximab, pregnancy-conscious antiseizure therapy, individualized pregnancy management, and laparoscopic removal of bilateral mature ovarian teratomas. Following combined immunotherapy, ventilatory and supportive ICU care, antiseizure therapy, individualized maternal-fetal management, and tumor removal, the recurrent motor events ceased by the end of the first postoperative week. The patient's consciousness, speech, and motor function gradually improved. This case highlights that anti-NMDAR encephalitis in pregnancy requires early cerebrospinal fluid antibody testing, exclusion of infectious mimics, supportive neurocritical care, prompt immunotherapy, timely teratoma removal and individualized reasoning regarding pregnancy management.