Atypical anti-NMDAR encephalitis in a 28-year-old female patient with bilateral ovarian teratoma: A case report

Introduction

Most frequently recognized causes of encephalitis are infectious ; however, an increasing number of autoimmune encephalitis have been identified that can develop with core symptoms resembling infectious encephalitis, and with neurological and psychiatric manifestations without fever or cerebrospinal fluid (CSF) pleocytosis. To improve the recognition of these disorders, we present the atypical case of a 28-year-old female patient suffering from anti-NMDAR encephalitis associated with bilateral ovarian teratoma.

Case presentation

This is the case of a 28-year-old Mexican Mestizo patient with no significant medical or surgical history, brought in early April 2020 to the emergency room (ER) by her parents for behavioral disorders associating episodes of anxious agitation with phases of decrease of verbal output. Routine lab, CSF studies, and head CT were normal, so she was sent home with sertraline. She was brought back to the ER 2 years later, with a history of episodes of anxiety and disorganized thinking with phases of mutism. Within 9 h, low grade fever, weakness on the right side of the body followed by decreased level of consciousness by stupor appeared. Infectious encephalitis was suspected, and she received empirical antibiotics and acyclovir until the exclusion of infectious causes: CFS, brain IRM, antinuclear antibodies, bacterial and viral PCR panels were negative. In the absence of favorable progress after 3 days of treatment, autoimmune encephalitis was suspected, and she stopped receiving antimicrobials and acyclovir and was empirically started on a 3-day course of methylprednisolone 1 g/day, followed by oral glucocorticoid therapy at 1.0 mg/kg/day of prednisone with a 3-week taper of oral prednisone. After 2 days of the treatment, the patient showed a full recovery of level of consciousness, strength on the right side of the body and no fever but decreased verbal output and memory deficit persisted with no correlation in the electroencephalogram (EEG) patterns. In the presence of prominent psychiatric manifestations and response to immunotherapy, NMDAR encephalitis was suspected. An abdominal-pelvic CT scan and transvaginal ultrasound revealed a probable bilateral ovarian teratoma. A probable diagnosis of anti-NMDAR encephalitis was set. NMDAR antibodies against the GluN1 subunit in the CSF and serum were positive ( Figs. 1 and 2 ), the definite diagnosis of anti-NMDAR encephalitis with bilateral ovarian teratoma was set. In the presence of an ovarian tumor, its surgical excision is essential since it may be the origin of the autoimmune reaction, so the patient underwent a bilateral oophorectomy, the pathological examination confirmed the diagnosis of a mature teratoma. After 1 day, the evolution was rapidly favorable with gradual return to a normal state of cognitive and neurological functions and the behavioral problems were resolving, with full recovery at 2 months.