Seizures and status epilepticus in anti-NMDA receptor encephalitis

Seizures, including status epilepticus (SE), are common in anti-NMDA receptor encephalitis (NMDARE). We aimed to describe clinical and electrographic features of patients with seizures with NMDARE, determine factors associated with SE, and describe long-term seizure outcomes.

We retrospectively identified patients with seizures in the setting of NMDARE treated at inpatient Mayo Clinic sites during the acute phase of encephalitis between October 2008 and March 2023. Seizure semiology, clinical symptoms, electrographic features, neuroimaging, treatment course, complications, and outcome were abstracted. We compared clinical features between patients with and without SE.

We identified 29 patients with seizures during acute NMDARE. Temporal onset was the most common EEG localization (n = 14, 48.3%). Subclinical seizures were recorded in 15 (51.7%). Twelve (41.4%) patients had SE, which was associated with temporal T2-signal hyperintensity, seizures with unilateral clonic and/or tonic movements, multiple seizure foci on EEG, temporal and midline/central onset seizures, higher acute CASE scores, intensive care unit (ICU) admission, longer length of hospitalization, and need for post-hospitalization rehabilitation. One patient (3.4%) died during the acute encephalitis. One patient (3.4%) developed chronic epilepsy. The remaining patients were seizure-free at the last follow-up (median 23 months, range 2-163 months). SE was not associated with differences in outcome at last follow-up.

Seizures in NMDARE are frequently temporal onset. SE is common and associated with higher likelihood of ICU level care, longer hospitalization, and higher need for post-hospital rehabilitation. Despite the significant short-term impact of SE, long-term outcome was not affected, and seizure prognosis was favorable.