Seizure and electroencephalographic characteristics in anti-LGI1 encephalitis

To delineate seizure and electroencephalographic (EEG) characteristics in a cohort of patients with anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis.

Sixty-six newly diagnosed anti-LGI1 encephalitis patients with seizures were consecutively recruited. EEG data was obtainable for 63 patients, including 24-hour video EEG (VEEG) for 35 participants. Demographics, seizure characteristics, EEG findings, and general clinical data were reviewed.

Among 66 patients, facial brachial dystonic seizures (FBDS), focal non-FBDS seizures, and secondarily generalized tonic-clonic seizures (sGTCS) occurred in 27.3 %, 59.1 %, and 57.6 %, respectively. Piloerection was observed in 27.3 %, and daily focal seizures were reported in 74.2 %. Sex-related analysis indicated females exhibited younger onset age with higher prevalence of focal non-FBDS seizures, piloerection, and daily seizures, whereas males had more sGTCS and cerebrospinal fluid abnormalities (p < 0.05). Interictal EEG revealed excessive beta activity (EBA) in 40.0 %, interictal epileptiform discharges in 22.2 %, and rhythmic delta activity in 12.7 %. Quantitative analysis provided confirmation of EBA. VEEG captured clinical events in 48.6 % and subclinical seizures (SCS) in 20.0 %.

We highlight seizure characteristics in anti-LGI1 encephalitis, particularly piloerection, daily focal seizures, and sex-related differences. Beyond previously reported SCS, EBA appears to be a frequent EEG pattern.

These findings may facilitate the recognition of anti-LGI1 encephalitis.