Anti-N-Methyl-d-Aspartate Receptor Encephalitis in Adult Patients Requiring Intensive Care

Encephalitis caused by anti-N-methyl-d-aspartate receptor (NMDAR) antibodies is the leading cause of immune-mediated encephalitis. There are limited data on intensive care unit (ICU) management of these patients.

To identify prognostic factors of good neurologic outcome in patients admitted to an ICU with anti-NMDAR encephalitis.

This was an observational multicenter study of all consecutive adult patients diagnosed with anti-NMDAR encephalitis at the French National Reference Centre, admitted to an ICU between 2008 and 2014. The primary outcome was a good neurologic outcome at 6 months after ICU admission, defined by a modified Rankin Scale score of 0-2.

Seventy-seven patients were included from 52 ICUs. First-line immunotherapy consisted of steroids (n = 61/74; 82%), intravenous immunoglobulins (n = 71/74; 96%), and plasmapheresis (n = 17/74; 23%). Forty-five (61%) patients received second-line immunotherapy (cyclophosphamide, rituximab, or both). At 6 months, 57% of patients had a good neurologic outcome. Independent factors of good neurologic outcome were early (≤8 d after ICU admission) immunotherapy (odds ratio, 16.16; 95% confidence interval, 3.32-78.64; for combined first-line immunotherapy with steroids and intravenous immunoglobulins vs. late immunotherapy), and a low white blood cell count on the first cerebrospinal examination (odds ratio, 9.83 for <5 vs. >50 cells/mm³; 95% confidence interval, 1.07-90.65). Presence of nonneurologic organ failures at ICU admission and occurrence of status epilepticus during ICU stay were not associated with neurologic outcome.

The prognosis of adult patients with anti-NMDAR encephalitis requiring intensive care is good, especially when immunotherapy is initiated early, advocating for prompt diagnosis and early aggressive treatment.