Seizure characteristics, treatment, and outcome in autoimmune synaptic encephalitis: A long-term study

The objective of this study was to report seizure characteristics, long-term outcome, and potential factors associated with persistent seizures in patients with autoimmune synaptic encephalitis (ASE).

Clinical data and courses of 52 patients with ASE who presented with seizures at the Department of Neurology of the First Hospital of Jilin University from January 2015 to August 2017 were reviewed. Seizure outcomes were assessed with a median follow-up duration of 30 months (8-40 months).

Most patients (71.2%) presented with seizure at initial consultation; focal to bilateral tonic-clonic seizures (50.0%) were the most common type. The temporal lobe (73.5%) was the prominent region of seizure origin, which was incident with hippocampal lesions on magnetic resonance imaging (MRI) in 62.1% of the patients. Status epilepticus, subclinical seizures, and nonepileptic events were observed in 28.9%, 36.8%, and 28.9% of the patients, respectively. Twenty-seven out of the 43 followed-up patients (62.8%) exhibited seizure remission after initial immunotherapy. Others (37.2%) developed persistent seizures to different extents. Six out of 9 patients experienced additional seizure freedom because of antiepileptic drugs (AEDs); however, the seizures of the other three patients, with serious conditions, showed poor response. Patients with anti-N-methyl-d-aspartate receptor antibodies had a lower risk of developing persistent seizures than those with anti-leucine-rich glioma-inactivated 1 (LGI1) or anti-γ-aminobutyric acid receptor type B receptor (GABA_BR) antibodies (P = 0.001).

A complex of clinical and subclinical seizures, and nonepileptic events characterize ASE. Patients with anti-LGI1 or anti-GABA_BR antibodies have a higher risk of developing persistent seizures; AEDs are suitable for achieving additional seizure freedom, but not for patients with serious conditions. A few patients present with super-refractory epilepsy despite multiple treatments.