Clinical features and outcomes of late-onset epilepsy of unknown etiology: A retrospective study in West China

Abstract

Purpose

Late-onset epilepsy (LOE) usually refers to the development of epilepsy at the age of 50 years or older. Approximately 20 % of LOE cases are diagnosed as late-onset epilepsy of unknown etiology (LOUE) due to a lack of an identifiable cause. The aim of this study was to investigate the clinical features, seizure and cognitive outcomes of patients with LOUE in West China.

Methods

Patients diagnosed with LOUE at West China Hospital between January 2015 and December 2022 were retrospectively recruited. The seizure and cognitive outcome were followed up for at least 1 year after discharge. Logistic regression models were applied to investigate the risk factors of recurrent seizure and cognitive impairment in patients with LOUE.

Results

We included 286 LOUE patients with a median seizure onset age of 59 years. The most common seizure types were focal to bilateral tonic-clonic seizure (61.9 %) and focal non-motor seizure (37.0 %). Two-hundred and seventy-seven (96.9 %) patients underwent video electroencephalography (VEEG), with seizures recorded in 11.9 % of patients and interictal epileptiform discharges in 58.2 % cases. Majority of the patients (73.4 %) received monotherapy, with levetiracetam, oxcarbazepine and valproate being the most commonly prescribed anti-seizure medications. During the follow-up, 69.1 % of patients achieved seizure-free. Multivariate analysis identified ictal event recorded during VEEG monitoring (OR:0.205, 95 % CI: 0.045–0.932, p = 0.040) and memory impairment (OR:2. 470, 95 % CI: 1.181–5.167, p = 0.016) as significant factors associated with recurrent seizure. Twenty-two patients were classified as cognitive impairment. The onset age (OR:1.095, 95 % CI:1.032–1.162, p = 0.003) and total Fazekas score (OR = 6.770, 95 % CI:1.972–23.241, p = 0.002) were significant risk factors associated with cognitive dysfunction.

Conclusion

LOUE is generally a benign form of epilepsy with a high percentage of patients achieving seizure-free status. However, these patients are at a higher risk of memory decline and cognitive dysfunction.