Autoimmune encephalitis; a paraneoplasic syndrome of a mature ovarian teratoma

Abstract

Background: The anti-N-methyl-D-aspartate (NMDAr) encephalitis was first described in 2005 and in 2007 the antibodies against the NMDA were identified by Dalmau et al. It is estimated that it affects 1.5 per million individuals every year, but it is more frequent in young women ranging from 15 to 25 years, and 37% of them can manifest as a paraneoplasic syndrome in association with an ovarian teratoma. Case description: A 17-yearold female with personal history of left ovarian teratoma, one week after its surgical removal presents: auditory hallucinations, persecutory delusions, insomnia, anhedonia, agitation, speech impairment, orofacial dyskinesia, and gait alterations during one month. An electroencephalogram (ECG) reported severe corticalsubcortical. The cerebral Magnetic Resonance Imaging (MRI) and the Cerebrospinal Fluid (CSF) analysis, reported no findings. Given the clinical suspicion, immunosuppressive treatment with intravenous corticosteroids was initiated, along with symptomatic management antipsychotic, for agitation and anxiety; initially with midazolam infusion and then with olanzapine, risperidone, and clonazepam; obtaining satisfactory clinical improvement. Finally, the diagnosis was confirmed by a positive IgG against the N1 glutamate subunit (Glu N1) of the NMDAr. Conclusion: The anti NMDAr encephalitis is a rare and underdiagnosed condition, which can be mistaken as a primary psychiatric disease. Given a first psychotic episode, an extense interrogatory and evaluation must be done to exclude secondary causes, such as, autoimmune disorders with neurologic repercusions.