Seizures occur frequent in autoimmune encephalitis (AIE). Seizures often seem unresponsive to AEDs, while responses to immunotherapy are good. Nevertheless, seizure freedom is not always achieved while using immunotherapy and AEDs are sometimes needed as well. However, it is unclear whether AEDs are safe in these patients, if they are effective, and what AEDs should be preferred.

To evaluate responses of seizures to immunotherapy and antiepileptic drugs (AEDs) in patients with anti-leucine-rich glioma-inactivated 1 (LGI1), anti-N-Methyl-D-Aspartate Receptor (NMDAR), and anti-Gamma-Aminobutyric-Acid-B Receptor (GABA_BR) encephalitis, and to describe the risk for chronic epilepsy.

Patients with new-onset seizures and anti-LGI1, anti- GABA_BR or anti-NMDAR encephalitis were included in this nationwide cohort study. Medical information about disease course, types of AEDs and immunotherapies used, effects and side-effects were collected. Outcome measures were: 1) seizure freedom achieved while using AEDs, and while using immunotherapy, 2) days to seizure freedom from start of AEDs and from start of immunotherapy, 3) development of chronic epilepsy, and 4) reported side effects.

Of 153 AIE patients (53 LGI1; 75 NMDAR; 25 GABA_BR), 72% (n=110) had epilepsy, and 89% reached seizure freedom. At least 53% reached seizure freedom shortly after immunotherapy, and 14% achieved seizure freedom while using only AEDs (p<0.0001). Median time to seizure freedom from AEDs start was 59 days (IQR 27-160), and 28 days from start of immunotherapy (IQR 9-71, p<0.0001). Carbamazepine was more effective than levetiracetam in reducing seizures in anti-LGI1 encephalitis (p=0.031). Only one patient, of 86 surviving patients, developed chronic epilepsy.