Spectrum of Anti-NMDA Receptor Antibody Encephalitis: Clinical Profile, Management and Outcomes

Autoimmune encephalitis in a resource-limited public health setting: a case series analysis

BACKGROUND

 Autoimmune encephalitis (AE) consists of a group of acquired diseases that affect the central nervous system. A myriad of phenotypes may be present at the onset. Due to the heterogeneity of clinical presentations, it is difficult to achieve uniformity for the diagnostic and therapeutic processes and follow-up strategies.

OBJECTIVE

 To describe a series of patients diagnosed with AE in a resource-limited public hospital in southern Brazil and to analyze therapeutics and outcomes.

METHODS

 We retrospectively reviewed the electronic medical records of patients diagnosed with AE at the Hospital de Clínicas de Porto Alegre from 2014 to 2022. Data collected included clinical presentation, neuroimaging, cerebrospinal fluid testings, electroencephalogram, autoantibodies, treatments, outcomes, follow-up time, degree of neurological impairment, and mortality.

RESULTS

 Data from 17 patients were retrieved. Eleven cases were classified as definite AE and 6 as possible AE. Autoantibodies were identified in 9 patients. Timing for diagnosis was impacted by the high costs associated with autoantibody testing. Most patients became functionally dependent (82.4%) and most survivors remained with autoimmune-associated epilepsy (75%). Five patients died during hospitalization, and one after a 26-month of follow-up.

CONCLUSION

 In this resource-limited hospital, patients with AE had a worse clinical outcome than that previously described in the literature. Development of epilepsy during follow-up and mortality were greater, whilst functional outcome was inferior. Autoantibody testing was initially denied in most patients, which impacted the definitive diagnosis and the use of second-line therapies.

VH2+ Antigen-Experienced B Cells in the Cerebrospinal Fluid Are Expanded and Enriched in Pediatric Anti-NMDA Receptor Encephalitis

Pediatric and adult autoimmune encephalitis (AE) are often associated with Abs to the NR1 subunit of the N-methyl-d-aspartate (NMDA) receptor (NMDAR). Very little is known regarding the cerebrospinal fluid humoral immune profile and Ab genetics associated with pediatric anti-NMDAR-AE. Using a combination of cellular, molecular, and immunogenetics tools, we collected cerebrospinal fluid from pediatric subjects and generated 1) flow cytometry data to calculate the frequency of B cell subtypes in the cerebrospinal fluid of pediatric subjects with anti-NMDAR-AE and controls, 2) a panel of recombinant human Abs from a pediatric case of anti-NMDAR-AE that was refractory to treatment, and 3) a detailed analysis of the Ab genes that bound the NR1 subunit of the NMDAR. Ag-experienced B cells including memory cells, plasmablasts, and Ab-secreting cells were expanded in the pediatric anti-NMDAR-AE cohort, but not in the controls. These Ag-experienced B cells in the cerebrospinal fluid of a pediatric case of NMDAR-AE that was refractory to treatment had expanded use of variable H chain family 2 (VH2) genes with high somatic hypermutation that all bound to the NR1 subunit of the NMDAR. A CDR3 motif was identified in this refractory case that likely drove early stage activation and expansion of naive B cells to Ab-secreting cells, facilitating autoimmunity associated with pediatric anti-NMDAR-AE through the production of Abs that bind NR1. These features of humoral immune responses in the cerebrospinal fluid of pediatric anti-NMDAR-AE patients may be relevant for clinical diagnosis and treatment.

Clinical Reasoning: A Young Adult With New Seizures and Chapeau de Gendarme

The evaluation of new seizures is a common clinical query for neurologists. It can be challenging to delineate between the numerous etiologies of new focal or generalized seizures and, if focal, to localize their onset. In this case report, we present a 26-year-old patient with a new onset of stereotyped events concerning for seizures featuring facial grimacing, dystonic left-hand posturing, and convulsions with immediate return to baseline. Throughout the case, we highlight a stepwise diagnostic approach to the evaluation of new-onset seizures, discuss clues that seizure semiology can provide for localization of ictal onset, and review a novel and atypical presentation of a disease entity frequently encountered by neurologists.

Autoimmune encephalitis: an observational study from South India

Background

Ever since AE was acknowledged as a potentially treatable cause of encephalitis, it has been increasingly recognised worldwide. Data suggests that these disorders are under-recognized, which calls for an increased awareness of the varying clinical, laboratory, electrophysiological and radiological presentations of the different types of autoimmune encephalitis. This cross-sectional observational study included all patients diagnosed with AE, who presented to a tertiary care centre from June 2016 to January 2021. Data were collected including patient’s demography, clinical, laboratory, radiological and electrophysiology studies, management and outcomes.

Results

31 study participants were included, of which 13 patients were anti-NMDA antibody positive, 12 patients were anti-LGI1 antibody positive, 2 patients were anti-CASPR2 antibody positive, 2 were positive for dual positive status (anti-LGi1 and anti-CASPR2), and one each for anti-GABA-B and anti-GAD 65. There was a marginal male predilection with overall seizures being the most common symptom (68%) followed by behavioural disturbance (64.5%), and impairment of consciousness (32.3%). Patients with Anti-NMDA encephalitis were likely to be young females, with CSF pleocytosis, a more protracted hospital course with more chances of relapse and residual disease, while the patients with anti-Lgi1 encephalitis were likely to be older males with a shorter, less severe hospital course.

Conclusion

The present study detailed the demographic, clinical, imaging, laboratory and EEG characteristics of 31 AE patients from a tertiary centre. The findings concurred with the literature and demonstrate the diverse spectrum of clinical manifestations of patients with AE, present with.

Anti-N-methyl D-aspartate Receptor Encephalitis in India: A Literature Review

Anti N-methyl D-aspartate receptor encephalitis (NMDAR-E) though rare, is currently considered as the commonest antibody mediated encephalitis in the world. No review on perspectives of NMDAR-E from India is available. The aim of the study was to review all the cases of NMDAR-E reported from India until June 2021 in terms of clinical features, diagnosis, and treatment, and perform a comparison of adult and paediatric cases. A literature review of NMDAR-E case reports/case series published from India till June 2021 was done. Demography, clinical profile, triggers, electroencephalography (EEG), neuroimaging, treatment details and outcomes were analysed. Sixteen case series and 35 case reports with a total of 249 cases were analysed. 82% of cases were from paediatric age group. The female to male ratio was 3:1. Psychiatric deficits, movement disorders, seizures, and language abnormalities were the most common clinical features. MRI brain abnormalities were seen in 45% patients. Electroencephalographic abnormalities were seen in 85% of patients. Infective triggers (herpes simplex virus and various other agents) were reported in 11% of the cases. Pediatric patients as compared with adults had more encephalopathy, autonomic dysfunctions, and normal imaging whereas the latter had more cognitive dysfunctions and delta brush pattern in electroencephalography (p<0.005). Therefore, to conclude, this literature review suggests that overall, the clinical spectrum of Indian cases is like cases described from other parts of the world. However, most reported cases from India belonged to paediatric age group who had more encephalopathy, autonomic dysfunctions, and normal brain imaging compared to adults. A few novel infectious agents as triggers were described from India.

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.

Mild Cognitive Impairment in Chronic Brain Injury Associated with Serum Anti-AP3B2 Autoantibodies: Report and Literature Review

BACKGROUND

Chronic traumatic brain injury is a condition that predisposes the brain to activate B-cells and produce neural autoantibodies. Anti-adaptor protein 3, subunit B2 (AP3B2) autoantibodies have thus far been associated with diseases affecting the cerebellum or vestibulocerebellum. Through this case report, we aim to broaden the spectrum of anti-AP3B2-associated disease.

CASE DESCRIPTION

We report on a 51-year-old woman with a brain injury approximately 28 years ago who recently underwent neuropsychological testing, magnetic resonance imaging of the brain (cMRI), and cerebrospinal fluid (CSF) analysis. Neural autoantibodies were determined in serum and CSF. Our patient suffered from mild cognitive impairment (amnestic MCI, multiple domains) with stable memory deficits and a decline in verbal fluency and processing speed within a two-year interval after the first presentation in our memory clinic. Brain MRI showed brain damage in the right temporoparietal, frontolateral region and thalamus, as well as in the left posterior border of the capsula interna and white matter in the frontal region. Since the brain damage, she suffered paresis of the upper extremities on the left side and lower extremities on the right side as well as gait disturbance. Our search for autoantibodies revealed anti-AP3B2 autoantibodies in serum.

CONCLUSIONS

Our report expands the spectrum of symptoms to mild cognitive impairment in addition to a gait disturbance associated with anti-AP3B2 autoantibodies. Furthermore, it is conceivable that a prior traumatic brain injury could initiate the development of anti-AP3B2-antibody-associated brain autoimmunity, reported here for the first time.