Relationship between initial electroencephalographic characteristics and seizure outcomes in children with non-lesional West syndrome

Background: To characterize the initial interictal electroencephalography (EEG) activities associated with seizure outcomes in children with non-lesional West syndrome (WS), and their worth in the prediction of seizure-free (SF) vs no seizure-free (No-SF) outcomes. Methods: We retrospectively reviewed the initial scalp EEGs for at least a 40-min duration, and the medical records of 66 children who were diagnosed as WS with normal MRI, and who were followed-up with for 4.5 +/- 2.1 years. We assessed the following clinical and EEG findings: onset of seizures, development, underlying etiologies, initial interictal EEGs, and seizure evolution. These variables were compared between two groups: SF vs No-SF groups. Results: In total, 36 (54.5%) children had SF outcomes and 30(45.5%) had No-SF outcomes during long-term follow-up (4.4 +/- 2.3 vs 4.6 +/- 2.0 years, p = 0.7644). The mean age at seizure onset was similar in the SF and No-SF groups (6.0 +/- 3.0 vs 6.9 +/- 3.2 months, p = 0.2443). Delayed development before the onset of spasms was similarly observed in both groups (13.9% vs 13.3%). Initial EEG findings significantly differed with typical hypsarrhythmia (41.7% vs 73.3%, p = 0.0098), multiple independent spike foci (MISF) (55.6% vs 83.3%, p = 0.0158), frontal-dominant MISF (0.0% vs 40.0%, p <0.0001), and frontal-dominant generalized epileptiform discharges (EDs) (0.0% vs 16.7%, p = 0.0108) being involved more infrequently in the SF group than in the No-SF group, respectively. Patients in the SF group showed no frontal-dominant MISF or frontal-dominant generalized EDs, and a more often normal to borderline sleep-spindle (83.3% vs 40.0%, p = 0.0002) than the No-SF group. Conclusion: Patients with SF outcomes more frequently showed the posterior-dominant generalized EDs and normal to borderline sleep-spindle, and the No-SF group more often had typical hypsarrhythmia, frontal-dominant MISF, frontal-dominant generalized EDs, and no normal sleep-spindle. Initial interictal EEG findings may predict seizure outcomes in patients with non-lesional WS. (C) 2014 Elsevier B.V. All rights reserved.