Lateralized interictal epileptiform discharges during rapid eye movement sleep correlate with epileptogenic hemisphere in children with intractable epilepsy secondary to tuberous sclerosis complex

Abstract

We assessed lateralization of interictal epileptiform discharges (IEDs) in children with intractable epilepsy secondary to tuberous sclerosis complexes (TSCs) during rapid eye movement sleep (R), compared with non-rapid eye movement sleep (NR) and wakefulness (W), to determine epileptogenicity of R-IEDs. We retrospectively studied 23 children with TSC, who underwent prolonged scalp video-electroencephalography (EEG) and magnetic resonance imaging (MRI). We determined the lateralization of ictal EEG, clinical semiology, and the largest tuber on MRI. We analyzed a minimum of 100 IEDs during R, NR, and W to classify right/left/generalized spikes to compare the lateralization with ictal EEG, clinical semiology, and MRI. R-IEDs were lateralized in 22 patients (96%), W-IEDs in 19 (83%), and NR-IEDs in 16 (70%). Ictal EEGs were lateralized in 15 patients (65%) and clinical semiology in 5 (22%). Ictal EEG lateralization was concordant to R-IEDs in 14 patients (93%), W-IEDs in 11 (73%), and NR-IEDs in 10 (67%). The lateralization of clinical semiology was concordant with R-IEDs in 4 (80%), W-IEDs in 3 (60%), and NR-IEDs in 2 (40%). MRI lateralization of the largest tuber was concordant with R-IEDs in 16 (70%), W-IEDs in 12 (52%), and NR-IEDs in 11 (48%). Thirteen patients (57%) underwent resective surgery, the hemisphere of which was concordant with R-IEDs in 13 (100%), W-IEDs in 8 (62%), and NR-IEDs in 8 (62%). Nine (69%) of them achieved good seizure control after surgery. R provoked the most lateralized IEDs compared to NR and W in children with TSC. Lateralization of R-IEDs corresponded with the hemisphere of ictal EEG and largest tuber, and can be used to identify surgical candidacy in TSC children with intractable epilepsy.