EEG Findings and Releases From Hospital for Patients With Anti-NMDA Receptor Encephalitis

Quantitative Electroencephalography Biomarkers in Patients With Anti-N-methyl-D-aspartate Receptor Encephalitis: A Case-Control Study

PURPOSE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune reaction involving Immunoglobulin G antibodies against GluN1 subunit of NMDAR. Absence of biomarkers for early diagnosis and prognosis poses a challenge. Several small case-control studies have emphasized the prospect of quantitative EEG measurements. This study aimed to analyze and identify novel scalp quantitative EEG biomarkers and their implications on outcome of NMDRA encephalitis compared with a control group.

METHODS

Retrospective (2012-2021) case-control study of patients with NMDRA encephalitis and with acute/subacute encephalitis from other causes. Clinical variables and outcomes were assessed with modified Rankin Scale at admission, discharge, and follow-up. All patients underwent extensive diagnostic workup, including scalp EEG within 72 hours of admission. Quantitative EEG was calculated for Renyi, Tsalis entropy, Hjorth complexity, mean energy, and spectral power of the following frequency bands and ratios: delta (0.5-4 Hz), theta (5-8 Hz), alpha (9-14 Hz), beta (15-30 Hz), gamma (31-45 Hz), gamma-beta, beta/alpha, beta/theta, and beta/delta. Descriptive statistics, power frequency bands, complexity measures, and Wilcoxon rank sum test were used.

RESULTS

Patients with anti-NMDAR encephalitis had significantly higher delta frequency peak power, higher beta/alpha and gamma/beta frequency ratios, lower alpha and beta peak power, and lower beta/delta frequency ratio than the control group. In patients with anti-NMDAR encephalitis, higher delta and alpha peak power had the worst clinical outcome, at discharge and follow-up, and patients with higher gamma peak power had better outcomes.

CONCLUSIONS

Quantitative EEG is a valuable tool to differentiate anti-NMDAR encephalitis from other inflammatory encephalitis and predict outcomes in patients with anti-NMDAR encephalitis.

Autoimmune Encephalitis in Latin America: A Critical Review

Autoimmune encephalitis is an increasingly recognized cause of encephalitis. The majority of case series report patients residing in developed countries in the northern hemisphere. The epidemiologic features of autoimmune encephalitis in Latin America are still unclear. The aim of the study was to perform a review of the clinical presentation of autoimmune encephalitis in Latin America and compare to world literature. References were identified by an in-depth literature search and selected on the basis of relevance to the topic and authors' judgment. We selected clinical studies and case reports published from 2007 to July, 2020 including patients from Latin American countries. Of the 379 patients included, the majority were cases of anti-NMDA receptor encephalitis (93.14%), followed by anti-VGKC-complex encephalitis (N = 17; 4.48%), anti-GAD encephalitis (N = 9; 2.37%), anti-AMPA receptor encephalitis (N = 1; 0.26%), anti-GABA receptor encephalitis (N = 1; 0. 26%), anti-mGluR5 encephalitis (N = 1; 0. 26%), and anti-mGluR1 encephalitis (N = 1; 0. 26%). Reported cases of Anti-NMDA encephalitis in Latin-America had a very slight female predominance, lower prevalence of associated tumors and a lower incidence of extreme delta brush on electroencephalogram. Autoimmune encephalitis is possibly underdiagnosed in underdeveloped countries. Its outcome after treatment, however, appears to be similarly favorable in Latin American patients as has been reported in developed countries based on available case reports and case series. Regional specificities in the manifestation of autoimmune encephalitis could be related to epidemiologic factors, such as the presence of different triggers and different genetic and immunologic background, that need to be studied by future research.

Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

Ring chromosome 20 [r(20)] syndrome is a rare condition characterized by a non-supernumerary ring chromosome 20 replacing a normal chromosome 20. It is commonly seen in a mosaic state and is diagnosed by means of karyotyping. r(20) syndrome is characterized by a recognizable epileptic phenotype with typical EEG pattern, intellectual disability manifesting after seizure onset in otherwise normally developing children, and behavioral changes. Despite the distinctive phenotype, many patients still lack a diagnosis-especially in the genomic era-and the pathomechanisms of ring formation are poorly understood. In this review we address the genetic and clinical aspects of r(20) syndrome, and discuss differential diagnoses and overlapping phenotypes, providing the reader with useful tools for clinical and laboratory practice. We also discuss the current issues in understanding the mechanisms through which ring 20 chromosome causes the typical manifestations, and present unpublished data about methylation studies. Ultimately, we explore future perspectives of r(20) research. Our intended audience is clinical and laboratory geneticists, child and adult neurologists, and genetic counselors.