Long-term seizure outcomes in patients with anti-Leucine-rich glioma-inactivated 1 encephalitis

Abstract

Background: This study aimed to investigate the semiology of seizure disorders, including electroencephalographic characteristics, and seizure outcomes in participants with anti-leucine-rich glioma-inactivated 1 (LGI-1) encephalitis.

Methods: Seventy participants who presented with seizures during the acute phase of anti-LGI-1 encephalitis at Peking Union Medical College Hospital from May 2013 to July 2020 were reviewed. All participants underwent follow-up for longer than 2 years.

Results: At the time of presentation, 48 (68.6%) participants had generalized seizures and 57 (81.4%) had focal seizures. The most common focal motor seizures were faciobrachial dystonic seizures (FDS). The main manifestations of focal nonmotor seizures were dyscognitive features, goosebumps, and disorders of sensation. All participants received immunomodulatory therapy. Thirty-five (50%) participants were seizure free after 1 year of follow-up, and 48 (68.6%) participants were seizure free over a follow-up of 2 years. Participants with seizures continued longer than 1 year were older than participants whose seizure duration was shorter than 1 year (P = 0.021). However, after an extended follow-up period, the difference between the incidences of seizures based on age was not significant. The frequency of focal motor seizures was higher in participants who became seizure free within 1 year, compared to participants who had seizures for longer than 1 year (75% vs 54.3%, respectively; P = 0.015). Participants with seizures continued over 2 years tended to have focal nonmotor seizures, and tended to show an elevated incidence of abnormal EEG results. Participants receiving early corticosteroid and longer duration immunosuppressant treatments, tended to have a lower risk of persistent seizures and better seizure outcomes, with no statistical significance.

Conclusions: Most participants obtained remission from seizures after immunomodulatory therapy. The seizure manifestation of anti-LGI1 encephalitis is diverse and variable. The type of focal seizures may affect the outcome of participants with seizures. Older age could lead to longer duration of the seizure disorder, but did not affect the rate of seizures over the long term. Early and prolonged administration of immunomodulatory therapy may be useful for shortening the time to becoming seizure free.

Keywords: Anti-LGI1 encephalitis; EEG; Outcome; Seizure; Treatment.