Patients with hemispheric epilepsy: Electroclinical characteristics and factors associated with intractability

Hemispheric epilepsy has diagnostic and therapeutic challenges and is frequently complicated by drug-resistant epilepsy (DRE). This study aimed to characterize the electroclinical and radiological profile of hemispheric epilepsy and evaluate factors associated with intractability to support individualized management.

A retrospective observational study at the Cairo University Epilepsy Unit included 83 patients with a strictly unilateral hemispheric structural lesion on MRI epilepsy protocol, with disease duration ≥ 1 year. All patients had a comprehensive clinical assessment (including QuickDASH), video-EEG evaluation (background, interictal/ictal findings, and concordance), neuroimaging review, and treatment outcome. Logistic regression was used to determine factors associated with DRE.

In this cohort, the median age was 22 years (IQR= 14-31) with a near-equal sex distribution. About half had abnormal development, 36% had intellectual disability, and most had mild functional disability. Seizures started at a median age of 9 years (IQR= 4-16). DRE was identified in 54.2%. EEG showed hemispheric slowing in 32.5%. Interictal discharges were ipsilateral in ~75%, and ictal onset (when captured) was ipsilateral in 84.4%. MRI showed mostly left-sided lesions (95%). Etiologies were split between malformations of cortical development (MCDs) -mainly heterotopia/FCD- and acquired (notably post-injury and Rasmussen). Single-domain developmental delay, MCDs, and progressive acquired etiology are associated with DRE (OR ≈7.6, 31.8, and 193.8, respectively).

The outcome of hemispheric epilepsy is largely determined by the type of brain lesion, with MCDs and Rasmussen encephalitis conferring the highest risk for intractability. In contrast, static acquired lesions were more often associated with better seizure control.