Objectives Anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) is a severe, but treatable disease. This study aims to give a detailed description of electroencephalogram (EEG) results in paediatric and adult patients to improve disease recognition, and analyses the predictive value of the first EEG for the final clinical outcome.
Methods This nationwide cohort study includes patients with N-methyl-D-aspartate receptor antibodies confirmed with cell-based assay and immunohistochemistry in serum and cerebrospinal fluid. EEG recordings were re-evaluated by two experienced neurophysiologists, mixed with control EEGs for blinding. Initial EEG as well as follow-up registrations were analysed.
Results 35 adults and 18 children were included. Only two patients (4%) had a normal EEG. During the first recording, the majority of the patients had normal posterior rhythm (71%), which was associated with better modified Rankin Scale at final outcome (OR 4.74; 95% CI 1.56 to 14.47; p=0.006). In addition, EEGs showed focal (73%) or diffuse (67%) slowing. The first EEG was severely abnormal in 26%. However, 8 of 14 patients with a severely abnormal first EEG still had a favourable outcome. During the course of the disease, extreme delta brushes (EDBs) were present in 6 of 53(11%)patients.
Conclusions The first EEG commonly shows normal posterior rhythm with focal or diffuse slowing. Although the sensitivity of an abnormal EEG is high (96%), normal EEG does not exclude anti-NMDARE. EDBs are only present in severely affected patients. The first EEG recording is predictive of the final clinical outcome.
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Contributors AvS: study design, acquisition of data, statistical analysis, interpretation of data, draft of the manuscript. SA: study design, acquisition of data, interpretation of data, revision of manuscript for content. DLJT: study design, acquisition of data, interpretation of data, revision of manuscript for content. AEMB: acquisition of data, revision of manuscript for content. MAAMdB: acquisition of data, revision of manuscript for content. MWJS: acquisition of data, revision of manuscript for content. PAESS: study design, revision of manuscript for content. MJT: study design, statistical analysis, interpretation of data, revision of manuscript for content.
Funding MJT was supported by an Erasmus MC Fellowship, and has received funding from the Netherlands Organization for Scientific Research (NWO, Veni incentive), from the Dutch Epilepsy Foundation (NEF, project 14-19) and from ZonMw (Memorabel programme).
Competing interests PAESS holds a patent for the detection of anti-DNER and received research support from Euroimmun. MJT received research funds for serving on a scientific advisory board of MedImmune, for consultation at Guidepoint Global, an unrestricted research grant from Euroimmun AG and a travel grant for lecturing in India from Sun Pharma, India. Erasmus University Medical Center has filed a patent for methods for typing neurological disorders and cancer, and devices for use therein.
Patient consent Not required.
Ethics approval The study was approved by the Institutional Review Board of the Erasmus University Medical Center, Rotterdam.
Provenance and peer review Not commissioned; externally peer reviewed.