Fast track — ArticlesAnti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies
Introduction
NMDA receptors are ligand-gated cation channels with crucial roles in synaptic transmission and plasticity. The receptors are heteromers of NR1 subunits that bind glycine and NR2 (A, B, C, or D) subunits that bind glutamate.1 NR1 and NR2 combine to form receptor subtypes with distinct pharmacological properties, localisation, and ability to interact with intracellular messengers. Overactivity of NMDA receptors causing excitotoxicity is a proposed underlying mechanism for epilepsy, dementia, and stroke, whereas low activity produces symptoms of schizophrenia.2, 3, 4
We recently identified a disorder, designated anti-NMDA-receptor encephalitis, that associates with antibodies against NR1–NR2 heteromers and results in a characteristic neuropsychiatric syndrome.5 The first patients identified were young women with ovarian teratoma who presented with psychosis or memory problems, rapidly progressing to multiple neurological deficits requiring prolonged intensive care support. Despite the severity of the disorder, patients often recovered after tumour removal and immunotherapy, suggesting an immune-mediated pathogenesis. Preliminary studies suggested the target epitopes were located in extracellular regions of NR1–NR2B NMDA receptors.5 However, selective disruption of receptors containing NR2B, which are predominantly expressed in the forebrain and hippocampus, would not explain the extensive deficits of patients. We postulated that the crucial epitopes were present in the more widely expressed NR1 subunit. If the antibodies were pathogenic we reasoned that their effects on NMDA receptors would be reversible because most patients recover.
We report the clinical features of 100 patients, analysing the frequency and type of tumour association, antibody titres, and response to treatment. We also investigate the epitopic region of the NMDA receptor and how antibodies affect NMDA receptors in primary cultures of hippocampal neurons.
Section snippets
Patients and procedures
Clinical information was obtained by the authors or provided by referring physicians, and has been partly reported for 21 patients.5, 6, 7, 8, 9 The webappendix contains additional information and details of control individuals. Control samples were obtained from 20 healthy individuals and 230 patients with suspected autoimmune or paraneoplastic encephalitis, or patients with tumours without encephalitis examined during the period of this study. Samples were from patients seen at University of
Results
Table 1 summarises the clinical information. 86 patients who could be assessed had headache, low-grade fever, or a non-specific viral-like illness within 2 weeks before hospital admission. 77 patients presented with prominent psychiatric symptoms, including anxiety, agitation, bizarre behaviour, delusional or paranoid thoughts, and visual or auditory hallucinations. 23 presented with short-term memory loss or seizures alone or associated with psychiatric manifestations.
During the first 3 weeks
Discussion
Of 100 patients with anti-NMDA-receptor encephalitis, a disorder that associates with antibodies against the NR1 subunit of the receptor, many were initially seen by psychiatrists or admitted to psychiatric centres but subsequently developed seizures, decline of consciousness, and complex symptoms requiring multidisciplinary care. While poorly responsive or in a catatonic-like state, 93 patients developed hypoventilation, autonomic imbalance, or abnormal movements, all overlapping in 52
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These authors contributed equally to this paper