Immunotherapy for anti-NMDAR encephalitis: A review of paraneoplastic, autoimmune encephalopathy

Prevention of oral and maxillofacial trauma secondary to orofacial dyskinesias associated with anti-N-methyl-D-aspartate receptor encephalitis: a case series

Background

Anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) is a multi-stage autoimmune-mediated disease associated with a multitude of neuropsychiatric and dysautonomic features. Orofacial dyskinesias are frequently associated with this condition and manifest as abnormal movements of the orofacial musculature. These involuntary movements may result in significant trauma to the oral and maxillofacial complex including the avulsion of the dentition and orofacial lacerations.

Case presentation

We describe the course of two female patients with anti-NMDARE in whom significant involuntary self-inflicted maxillofacial trauma was suffered despite the use of complex parenteral sedation regimens. The application of traditional maxillomandibular wiring techniques and pharmacologic strategies, including botulinum toxin, to immobilize the mandible were initially unsuccessful. These difficulties led to the fabrication and wire-based fixation of a patient-specific acrylic oral appliance that maintained the mandible in a depressed position and mitigated all lateral and protrusive movements.

Discussion and conclusions

These cases illustrate the first known successful use of an appliance-based therapy for managing orofacial dyskinesias in the anti-NMDARE patient population through an adaptation of traditional maxillomandibular fixation techniques. This approach eliminated further orofacial trauma and afforded physicians with safer means to manage and assess patients afflicted with this condition during their protracted intensive care unit admissions.

Neurocritical care for Anti-NMDA receptor encephalitis

In this review, we summarize the clinical presentations of the acute stage of anti-N-methyl-d-aspartate (NMDA) receptor encephalitis and the neurocritical care strategy in intensive care units. Anti-NMDA receptor encephalitis has characteristic clinical features and is predominantly seen in young adults and children. Most patients have five stages of clinical presentation, including a prodromal phase, psychotic and/or seizure phase, unresponsive and/or catatonic phase, hyperkinetic phase, and gradual recovery phase. The clinical course usually begins with viral infection-like symptoms that last for up to 2 weeks (prodromal phase), followed by the rapid development of schizophrenia-like psychiatric symptoms and seizures (psychotic and seizure phase). Patients may have a decreased level of consciousness with central hypoventilation, frequently requiring mechanical ventilation. In the subsequent hyperkinetic phase, patients present with orofacial-limb dyskinesia and autonomic instability. Children with significant neurological symptoms of anti-NMDA receptor encephalitis should initially be managed in a pediatric intensive care unit. The acute critical presentations are, refractory seizures, autonomic dysfunction, hypoventilation, cardiac arrhythmia, and hyperkinetic crisis. Symptom-guided therapies and critical care are necessary in the acute stage to improve the prognosis.

Immunotherapy for anti-NMDA receptor encephalitis: Experience from a single center in Taiwan

BACKGROUND

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an anti-neuronal antibody-mediated inflammatory brain disease that causes severe psychiatric and neurological deficits in previously healthy patients. The aims of this study were to demonstrate the clinical characteristics of patients diagnosed with anti-NMDA receptor encephalitis and to compare the different treatment strategies among these patients.

METHODS

Patients presenting with newly acquired psychiatric and/or neurological deficits were studied retrospectively from 2009 to 2017. Patients with evidence of anti-NMDA receptor antibodies in serum and/or cerebrospinal fluid were enrolled. The modified Rankin scale was used to assess the initial status and outcomes of the enrolled patients. Details of the clinical presentations and results of investigations were analyzed.

RESULTS

All (n = 24) of the patients received first-line immunotherapy (steroids, and/or intravenous immunoglobulin, and/or plasma exchange), and 14 patients received second-line immunotherapy (rituximab and/or cyclophosphamide). The mean time between the first- and second-line treatment was 13 days. During the first 6 months, 20 patients (20/24, 83%) achieved a good outcome (modified Rankin Scale score ≤2) and 15 patients (15/24, 62.5%) completely recovered. Four patients (17.7%) relapsed, and three patients (12.5%) had associated tumors.

CONCLUSION

Immunotherapy is an effective treatment for anti-NMDA receptor encephalitis. Rituximab and/or cyclophosphamide are treatment options for those who cannot tolerate or do not respond to first-line immunotherapy. Prospective studies are necessary to investigate the role of rituximab and cyclophosphamide in anti-NMDA receptor encephalitis.

Optimization of an Anti-NMDA Receptor Autoantibody Diagnostic Bioassay

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is one of the most frequently encountered autoimmune encephalitis. The pathogenesis of both anti-NMDAR encephalitis and schizophrenia involve down-regulation of NMDA receptors. Whether autoantibody-mediated destruction of neuronal NMDA receptors is associated with schizophrenia or first-episode psychosis (FEP) remains unclear, as the current findings from different groups are inconsistent. The main culprits are likely due to heterogeneity of autoantibodies (autoAbs) in a patient's blood or cerebrospinal fluid (CSF), as well as due to limitation of the current detection methods for anti-NMDAR autoAbs. Here, we optimized the current diagnostic method based on the only commercially-available anti-NMDAR test kit. We first increased detection sensitivity by replacing reporter fluorophore fluorescein isothiocyanate (FITC) in the kit with Alexa Fluor 488, which is superior in resisting photobleaching. We also found that using an advanced imaging system could increase the detection limit, compared to using a simple fluorescence microscope. To improve test accuracy, we implemented secondary labeling with a well-characterized mouse anti-NR1 monoclonal antibody (mAb) after immunostaining with a patient's sample. The degree of colocalization between mouse and human antisera in NMDAR-expressing cells served to validate test results to be truly anti-NMDAR positive or false-positive. We also incorporated DNA-specific DAPI to simultaneously differentiate autoAbs targeting the plasma membrane from those targeting cell nuclei or perinuclear compartments. All the technical implementation could be integrated in a general hospital laboratory setting, without the need of specialized expertise or equipment. By sharing our experience, we hope this may help improve sensitivity and accuracy of the mainstream method for anti-NMDAR detection.