[Psychiatric symptoms of a paraneoplastic anti-N-methyl-D-aspartate receptor encephalitis: A case report]

We describe the case of a young woman affected by a benign ovarian teratoma with paraneoplastic encephalitis. Several cases have already been reported, but it is the first article that focuses on details of the psychiatric symptoms of this disorder.

Paraneoplastic encephalitis usually begins with a prodromal phase, followed first by prominent psychiatric symptoms or, less frequently, short-term memory loss, seizure, catatonia-like symptoms, dyskynesias and, secondly, by autonomic instability and central hypoventilation requiring intensive care. In our case and to our knowledge, for the first time in the literature, the patient was hospitalized in a psychiatric unit for a suspected manic episode with psychotic features, in association with short-term memory impairment and anxiety. It has been shown that patients suffering from paraneoplastic encephalitis associated with ovarian teratoma display antibodies for anti-N-methyl-D-aspartate (NMDA) receptors in CSF or plasma (more specifically for the NR1 subunit of the NRl/NR2 heteromers required to form a functional NMDA receptor). The NR1/NR2B heteromers are preferentially expressed in the adult hippocampus/forebrain, which are brain regions involved in the pathogenesis of various psychiatric, psychotic in particular, symptoms. Furthermore, the glutamatergic NMDA receptors are the major mediator of excitotoxicity and their dysfunction had been associated with neurologic disorders, but also with schizophrenia and, more recently, with mood disorders.

This case supports the idea that the dysfunction of NMDA receptors may play a major role in psychiatric disorders, especially in psychosis and affective disorders. This article will briefly summarize the different evidences and hypotheses reported in the literature on NMDA receptors implication and will report how these receptors may serve as therapeutic targets.