Autoimmune Encephalitis: NMDA Receptor Encephalitis as an Example of Translational Neuroscience

Anti-N-Methyl-D Receptor Encephalitis During Long-Term Adalimumab Therapy for Crohn's Disease

A 46-year-old woman with fistulizing Crohn's disease in clinical remission in the setting of long-term adalimumab therapy presented to hospital and was ultimately diagnosed with anti-N-methyl-D (NMDA) receptor antibody-mediated autoimmune encephalitis (NMDAr-AE). Inflammatory central nervous system and antibody-mediated adverse effects have been found to be associated with anti-tumor necrosis factor agents, with 5 previous case reports noting cases of NMDAr-AE in patients on these medications. The current article reports this case, which is unique for the length of adalimumab therapy before this presentation, as well as a summary of literature regarding anti-tumor necrosis factors and NMDAr-AE.

Therapeutic plasma exchange in anti-N-methyl-D-aspartate receptor encephalitis

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is the most commonly identified cause of autoimmune encephalitis. Therapeutic plasma exchange has been increasingly employed to treat this disease. This expansion is a consequence of improved techniques and apheresis instruments, as well as the recognition of its applicability in neurological diseases. However, several aspects of treatment remain incompletely clarified, and treatment strategies are still heterogeneous, especially with regard to therapeutic plasma exchange in anti-NMDAR encephalitis. This review provides an overview of the use of therapeutic plasma exchange including the principle and mechanisms, the evidence, initial time, efficiency and complications in anti-NMDAR encephalitis.

Intrathecal methotrexate - Another tool for the treatment of refractory autoimmune encephalitis - Single institution cohort and literature review

BACKGROUND

Autoimmune encephalitis (AIE) encompasses a range of inflammatory disorders manifesting with some combination of encephalopathy, seizures, behavioral changes, movement disorders, dysautonomia or other neurologic symptoms. Anti-N-methyl-d-aspartate receptor encephalitis (NMDARE) is the most common AIE and is an autoantibody mediated disorder, often paraneoplastic. Untreated or undertreated AIE has a high degree of morbidity and mortality. Immunosuppressive treatment regimens including glucocorticoids, plasma exchange (PLEX), intravenous immunoglobulin (IVIG) and rituximab used alone or in combination for such patients. Patients' refractory to such treatments requires more aggressive and potentially toxic therapies. We report favorable outcomes in patients with refractory AIE who received intrathecal methotrexate (IT-MTX) as part of treatment.

METHODS

Cases at our institution seen between 2010 and 2020 were reviewed. We identified 5 patients in our clinical practice whose clinical presentation was compatible with NMDARE. Three patients met criteria for definite NMDARE. An additional two patients met criteria for probable NMDARE in the acute setting but were ultimately seronegative autoimmune encephalitis. All patients received at least one dose of IT-MTX after failing conventional therapies. At the time of IT-MTX administration patients were catatonic, comatose, or severely encephalopathic despite initial treatments.

RESULTS

All patients were treated with methylprednisolone; 3 received a course of IVIG, 4 underwent PLEX, and 4 received rituximab. At the time IT-MTX was given, three patients required mechanical ventilation and 1 had a pacemaker placed for autonomic failure. Two patients were under consideration for transition to palliative care. All patients improved and were at or near their premorbid baseline at last follow-up. All patients tolerated IT-MTX well.

CONCLUSIONS

This retrospective review demonstrates the efficacy of intrathecal methotrexate in the treatment of severe AIE who had failed other immunosuppressive regimens.

Understanding Seizures and Prognosis of the Extreme Delta Brush Pattern in Anti-N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis: A Systematic Review

Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis (ANMDARE) is an autoimmune disorder with neurological and psychiatric features. The disease presents with a viral prodrome, followed by psychiatric manifestations. In the next phase, movement disorders or/and seizures occur. Finally, in the last phase, there is a decrease in the level of consciousness. Central hypoventilation and autonomic dysfunction can occur. Recently a unique EEG (electroencephalogram) pattern has been associated with anti-NMDA receptor encephalitis, the extreme delta brush (EDB). Although the association of the EDB with ANMDARE is known by the medical community, its significance is mainly unknown. A systematic review on NMDARE is also scarce. We decided to conduct a systematic review on this topic to consolidate the knowledge and establish the importance of the EDB as a prognostic factor. To conduct this systematic review, we used only studies conducted in humans, written in English, and published in the last 20 years. We used PubMed as a database and searched the following search terms: ("NMDA encephalitis"[Title/Abstract] AND "Epilepsy"[Title/Abstract]) OR (NMDA encephalitis"[Title/Abstract] AND "seizures" [Title/Abstract]) OR ("NMDA encephalitis"[Title/Abstract] AND "extreme delta brush"[Title/Abstract]). The protocol used for this systematic review was the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) protocol, and to analyze the bias of the studies, we used the ROBINS-1 tool. Eight studies were collected from our search strategy. Our data pulling showed that seizures were present in 178/249 (71.48%) patients. Status Epilepticus was reported in 29/96 (30.20%), and the EBD was seen in 30.89% (55/178) patients with seizures. The range of EDB was 5.9%-33% among the studies. Because the sample size was small, the statistical power was decreased. We had a low overall risk of bias. The wide range in the results could be related to the timing of the EEG recording. EDB was associated overall with increased length of hospital stay, increased ICU admission, and incidence of status epilepticus. The etiology of the EDB remains mainly unknown. However, it has been postulated that in NMDAR encephalitis, there is a disruption of the rhythmic neuronal activity. When antibodies block/target the NMDAR, the rhythmic neuronal activity is disrupted, leading to the unique EDB pattern. Another theory suggests that delta activity is caused because of focal abnormalities in the brain, and the superimposition of the beta waves is related to the alterations of the NMDA receptors.

Monoclonal Antibodies From Anti-NMDA Receptor Encephalitis Patient as a Tool to Study Autoimmune Seizures

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis manifests with precipitous cognitive decline, abnormal movements, and severe seizures that can be challenging to control with conventional anti-seizure medications. We previously demonstrated that intracerebroventricular (i.c.v.) administration of cerebrospinal fluid from affected patients, or purified NMDA receptor antibodies from encephalitis patients to mice precipitated seizures, thereby confirming that antibodies are directly pathogenic for seizures. Although different repertoires of anti-NMDA receptor antibodies could contribute to the distinct clinical manifestations in encephalitis patients, the role of specific antibodies in the expression of seizure, motor, and cognitive phenotypes remains unclear. Using three different patient-derived monoclonal antibodies with distinct epitopes within the N-terminal domain (NTD) of the NMDA receptor, we characterized the seizure burden, motor activity and anxiety-related behavior in mice. We found that continuous administration of 5F5, 2G6 or 3C11 antibodies for 2 weeks precipitated seizures, as measured with continuous EEG using cortical screw electrodes. The seizure burden was comparable in all three antibody-treated groups. The seizures were accompanied by increased hippocampal C-C chemokine ligand 2 (CCL2) mRNA expression 3 days after antibody infusion had stopped. Antibodies did not affect the motor performance or anxiety scores in mice. These findings suggest that neuronal antibodies targeting different epitopes within the NMDA receptor may result in a similar seizure phenotype.

Gastrointestinal dysfunction in neuroinflammatory diseases: Multiple sclerosis, neuromyelitis optica, acute autonomic ganglionopathy and related conditions

Disorders of the nervous system can produce a variety of gastrointestinal (GI) dysfunctions. Among these, lesions in various brain structures can cause appetite loss (hypothalamus), decreased peristalsis (presumably the basal ganglia, pontine defecation center/Barrington's nucleus), decreased abdominal strain (presumably parabrachial nucleus/Kolliker-Fuse nucleus) and hiccupping and vomiting (area postrema/dorsal vagal complex). In addition, decreased peristalsis with/without loss of bowel sensation can be caused by lesions of the spinal long tracts and the intermediolateral nucleus or of the peripheral nerves and myenteric plexus. Recently, neural diseases of inflammatory etiology, particularly those affecting the PNS, are being recognized to contribute to GI dysfunction. Here, we review neuroinflammatory diseases that potentially cause GI dysfunction. Among such CNS diseases are multiple sclerosis, neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein associated disorder, and autoimmune encephalitis. Peripheral nervous system diseases impacting the gut include Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, acute sensory-autonomic neuropathy/acute motor-sensory-autonomic neuropathy, acute autonomic ganglionopathy, myasthenia gravis and acute autonomic neuropathy with paraneoplastic syndrome. Finally, collagen diseases, such as Sjogren syndrome and systemic sclerosis, and celiac disease affect both CNS and PNS. These neuro-associated GI dysfunctions may predate or present concurrently with brain, spinal cord or peripheral nerve dysfunction. Such patients may visit gastroenterologists or physicians first, before the neurological diagnosis is made. Therefore, awareness of these phenomena among general practitioners and collaboration between gastroenterologists and neurologists are highly recommended in order for their early diagnosis and optimal management, as well as for systematic documentation of their presentations and treatment.

Influential factors and predictors of anti-N-methyl-D-aspartate receptor encephalitis associated with severity at admission

OBJECTIVE

We aimed to study the clinical characteristics and biological indicators of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis with different severity levels to explore factors predicting disease severity at admission.

METHODS

Using the modified Rankin scale (mRS), patients were divided into mild-to-moderate group (mRS ≤ 3) and severe group (mRS > 3) on admission based on severity of illness. General information, previous history, premonitory symptoms, clinical manifestations before admission, imaging findings and biochemical tests were compared to explore the clinical manifestations and biological indicators related to the severity of illness at admission.

RESULTS

In the severe group, the incidences of fever, anti-infective therapy, generalized seizures, consciousness disorder, blood white blood cell, neutrophils, and neutrophil-lymphocyte ratio (NLR) were higher than those in mild-to-moderate group (P < 0.001, P = 0.001, P = 0.020, P < 0.001, P = 0.002, P < 0.001, P < 0.001, respectively); blood lymphocyte counts was lower than those in mild-to-moderate group (P < 0.001). There was the strongest significant positive correlation between the NLR and disease severity at admission (rs = 0.684, P < 0.001). In multivariate logistic regression, fever, generalized seizures, consciousness disorder, and elevated NLR were independent risk factors for disease severity; the area under the receiver operating characteristic curve was 0.896 (95%CI: 0.840-0.952, P < 0.001).

CONCLUSION

Fever, generalized seizures, consciousness disorder, and elevated NLR were independent risk factors for disease severity. NLR is a good predictor of the severity of illness at admission.

Case Report: Severe Adolescent Major Depressive Syndrome Turns Out to Be an Unusual Case of Anti-NMDA Receptor Encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a neuroinflammatory condition mediated by autoantibodies against the GluN1 subunit of the receptor. Clinically, it is characterized by a complex neuropsychiatric presentation with rapidly progressive psychiatric symptoms, cognitive deficits, seizures, and abnormal movements. Isolated psychiatric manifestations of anti-NMDAR encephalitis are rare and usually dominated by psychotic symptoms. We present a case of an 18-year-old female high school student-without a previous history of psychiatric disorders-with a rapid onset severe depressive syndrome. Surprisingly, we found pleocytosis and anti-NMDAR autoantibodies in the cerebrospinal fluid (CSF), despite an otherwise unremarkable diagnostic workup, including blood test, clinical examination, and cranial magnetic resonance imaging (MRI). After intravenous immunoglobulins treatment, a complete remission of the initial symptoms was observed. In a follow-up 5 years later, the young woman did not experience any relapse or sequelae. Anti-NMDAR encephalitis can present in rare cases as an organic disorder with major depressive symptoms without distinct concomitant psychotic or neurological symptoms. A clinical presentation such as a rapid onset of symptoms, distinct disturbance in the thought process, restlessness, and cognitive deficits should prompt screening for NMDAR- and other neural autoantibodies to rule out this rare but debilitating pathology.