Long‐term seizure outcomes in patients with autoimmune encephalitis: A prospective observational registry study update

Abstract

Objective: This study was undertaken to update and evaluate long-term seizure outcomes in patients with autoimmune encephalitis (AE) based on a large cohort study with long follow-up. Methods: In this prospective observational registry study, we analyzed data from patients with AE mediated by common types of neuronal surface antibodies (anti-N-methyl-d-aspartate receptor [NMDAR], anti-leucine-rich glioma-inactivated 1 [LGI1]/contactin-associated protein-like 2 [Caspr2], anti-γaminobutyric acid type B receptor [GABA B R]). All patients were recruited from the Department of Neurology at West China Hospital between October 2011 and June 2019, and data were collected prospectively on their demographic and clinical characteristics, treatment strategy, and seizure outcomes, with a median follow-up of 42 months (range = 6-93 months). Potential risk factors associated with seizure recurrence were also assessed.Results: Of 320 AE patients, 75.9% had acute seizures, among whom >90% of patients had their last seizure within 12 months of disease onset. During our follow-up, 21 (9.3%) patients experienced seizure recurrence. Patients with anti-GABA B R encephalitis had a higher cumulative incidence of seizure recurrence than those with anti-NMDAR (log-rank p = .03) or anti-LGI1/Caspr2 encephalitis (log-rank p = .04). Among patients with anti-NMDAR encephalitis, women had a significantly higher cumulative incidence of seizure recurrence than men (log-rank p = .01). Interictal epileptiform discharges (IEDs) or seizures captured on continuous electroencephalogram (EEG) in the acute phase were identified as potential risk factors for seizure recurrence (p = .04, p = .007). Among 163 patients with ≥24 months of follow-up, five (3.1%) showed persistent seizures and required ongoing antiseizure medications despite aggressive immunotherapy.

When Encephalitis Burns Out, Are You Left With a Spark?

“…These findings are similar to that reported by a Dutch cohort 2 which had reported very low (1%) rates of persistent seizures at last follow-up in a group of 110 patients with NMDA-R, LGI1, and GABA-B antibody-mediated encephalitis. It should be noted that a recent long-term follow-up study of 49 patients with LGI1 encephalitis reported that about one-fifth of the patients continued to have seizures at the 2 year mark and beyond, 7 a significantly higher proportion than that suggested by this recent Chinese cohort 6 and prior Dutch cohort. 2 These discrepancies in outcomes may be due to genetic contributions to outcomes, differences in treatment practices across various centers, but also differences in outcome ascertainment.…”

“…Recently, the ILAE Autoimmunity Taskforce recommended a conceptual distinction between seizures occurring acutely in the setting of AE (acute symptomatic seizures) versus chronically in a recurrent unprovoked manner (autoimmune-associated epilepsy). 5 The latest publication by Liu et al 6 makes an explicit attempt at identifying which patients with NMDA-R, LGI1, CASPR2, and GABA-B antibody-mediated encephalitis go on to develop autoimmune-associated epilepsy.…”

Early predictors of new-onset immune-related seizures: a preliminary study

“…However, the detection rate of IEDs in patients with immuneassociated epileptic seizures was not high, of which about 43.4% (10/23) showed focal slow wave activity or rhythm. However, some studies showed that IEDs might be a risk factor for the recurrence of epilepsy in patients with all types of AE [23]. Also, multivariate analysis showed that both NSAbs and APE2 were independent factors for the early prediction of immune-related seizures (P<0.05).…”

Seizure outcome-related factors in autoimmune encephalitis: A systematic review and meta-analysis

“…The risk of experiencing persistent seizures or developing chronic epilepsy after resolved AE has been uncertain. A recent prospective cohort study reported that 9.3% of patients experienced seizure recurrence and 3.1% developed chronic epilepsy after the acute phase of AE ( 10 ). However, Zhang and his colleagues reported that 37.2% of AE patients developed persistent seizures after discharge ( 11 ).…”

“…Thus, identifying the predictors for seizure outcome and investigating how to prevent persistent seizures effectively would have major clinical benefits. Previous literature investigating such predictors has examined sex, status epilepticus, EEG abnormalities, time from clinical onset to immunotherapy, and antibody titer ( 6 , 7 , 10 , 12 ). We recently reported that abnormal EEG findings and delayed immunotherapy increased the risk of persistent seizures ( 6 ).…”