Anti-N-methyl-D-aspartate receptor encephalitis: characteristics and rapid diagnostic approach in the emergency department

Abstract

Background: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a common type of autoimmune encephalitis. Patients with this condition are frequently very ill but are often misdiagnosed in the Emergency Department (ED). The objective of this study was to analyze the clinical characteristics of anti-NMDAR patients in the ED and to identify any associations with a diagnosis of anti-NMDAR encephalitis.

Methods: We performed a retrospective analysis of a prospectively obtained cohort of ED patients from May 2011 to December 2017. We identified patients diagnosed with anti-NMDAR encephalitis in this cohort and extracted key patient characteristics and clinical data, including patient gender, age, presentation, modified Rank Score (m-RS), laboratory test results, significant treatments, and mortality.

Results: Eighty-seven patients with anti-NMDAR encephalitis were identified. 54 (62.1%) were female, 23 (26.4%) were < 18 years old, 14 (16.1%) had teratoma, and 45 (51.7%) had an m-RS ≥ 4. Fever, altered mental status, and seizures were the most common symptoms, with a > 50% incidence of each symptom in the cohort. The sensitivity of CSF oligoclonal band (OB) testing was 78.9%. 22 (25.3%) were admitted to the ICU, 20 (23.0%) patients were intubated, but only one patient died (1.1%). 47 (54.0%) were misdiagnosed prior to ED arrival. All patients underwent immunotherapy as first-line treatment for anti-NMDAR encephalitis.

Conclusions: A majority of anti-NMDAR encephalitis patients presenting to the ED were female and were likely to be misdiagnosed prior to arrival. Patients with symptoms of fever, altered mental status, and seizures need a lumbar puncture, including CSF OB testing, for definitive diagnosis.

Keywords: Anti-N-Methyl-D-Aspartate Receptor Encephalitis; Diagnostic Errors; Emergency Department; Oligoclonal Bands; Teratoma.

Fig. 1

In patients with m-RS ≥ 4, 24.4% patients with teratoma, most of them needed monitoring, but with good outcome. * Teratoma: 11 patients positive (blue) and 34 patients negative (red). Outcome after treatment: 37 patients went into remission (blue), 3 patients had no response (red), and 5 patients’ data were lost (green). Monitored: 20 patients were monitored and intubated (blue), 16 patients were monitored only (red), and 9 patients had no monitoring (green)

Fig. 2

Patients with teratomas, 78.6% had m-RS >  = 4, almost all of them went into remission except one after operation and first line treatment