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

Purpose: 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. Methods: 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. Key Findings: 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. Significance: 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.