Abstracts

Rationale: To characterize the initial interictal electroencephalography (EEG) activities associated with seizure outcomes in children of infantile spasms (IS) with normal MRI finding and their worth in predicting the outcomes of seizure-free (SF) vs no seizure-free (NoSF). Methods: We retrospectively reviewed the initial scalp EEGs of at least 30 minutes duration and medical records of 58 children who were diagnosed as IS without MRI lesion in our hospital and were followed-up for 4.2±2.1 years. We assessed the following clinical and EEG findings; seizures onset, development, underlying etiologies, initial interictal EEGs, and seizure evolution. These variables were compared between two groups of SF vs NoSF. Results: Thirty (51.7%) children had SF outcomes and 28 (48.3%) had NoSF outcomes during long-term follow-up (4.1±2.3 vs 4.2±2.0 years). Age at seizure onset was similar in SF and NoSF groups (5.0±3.0 vs 6.4±3.2 months). Delayed development before spasms was similarly observed in two groups (33.3% vs 53.6%). Preceding other seizures were more frequently seen in NoSF than SF group (25.0% vs 6.7%, p=0.054). Initial EEG findings significantly differed with posterior-dominant generalized epileptiform discharges (ED) (50.0% vs 3.6%, p=0.0001) and normal or borderline sleep spindle (SS) (60.0% vs 28.6%, p=0.016) being involved more often in SF group, and typical hypsarrhythmia (78.6% vs 50.0%, p=0.024), multiple independent spike foci (75.0% vs 46.7%, p=0.028), frontal-dominant generalized ED (17.9% vs 0.0%, p=0.008) or frontal-dominant focal ED (7.1% vs 0.0%, p=0.023), and no normal SS (71.4% vs 40.0%, p=0.016) involved more often in NoSF group. Conclusions: Initial interictal EEG findings may predict seizure outcomes in patients of IS without MRI lesion. Patients with SF outcomes showed the posterior-dominant generalized ED and normal or borderline SS, and NoSF group had more often typical hypsarrhythmia, frontal-dominant generalized or focal ED and no normal SS.