Cohort study of infantile epileptic spasms syndrome: etiological analysis and treatment of corticosteroids

Infantile epileptic spasms syndrome (IESS) is the most common type of severe epilepsy in infants. However, etiological frequency and optimized therapy, particularly corticosteroid regimen and dose, remain unknown.An ambispective study of an IESS-diagnosed cohort was conducted. Etiologies were evaluated based on the 2017 International League Against Epilepsy classification system. Patients received intravenous dexamethasone or methylprednisolone for 3-5 consecutive days, followed by usual-dose (2 mg/kg/d) oral prednisone for 60-90 days with tapering doses for 1-2 months or high-dose (4 mg/kg/d) oral prednisone for 9-11 days with tapering doses for 2-4 weeks. Treatment responses were compared between the usual and high-dose prednisone groups after propensity score matching. Correlation analysis between treatment responses and underlying etiology was performed.Of the 441 included participants, 218 (49.4%) cases had proven etiologies. The most common etiology of IESS was acquired-structural (23.6%), followed by genetic (15.4%) and congenital-structural (7.0%). Hypoxic-ischemic encephalopathy (55, 52.8%) was the most common acquired-structural etiology. Among the 242 patients administered corticosteroids, 95 received usual-dose oral prednisone and 147 received high-dose oral prednisone. After propensity score matching, 54 patients were included in the usual-dose and high-dose groups, respectively, and treatment effectiveness was compared. There were no significant differences in seizure freedom at days 13-14 (55.6% vs. 51.9%, p = 0.700) and continued seizure freedom between days 14-42 (29.6% vs. 38.9%, p = 0.311) post corticosteroid administration between the usual- and high-dose prednisone groups. The proportion of children achieving seizure cessation at days 13-14 (χ2 = 1.470, p = 0.698) and days 14-42 (χ2 = 0.928, p = 0.836) was similar in the different etiological subgroups. Unknown etiological group showed significantly higher resolution of hypsarrhythmia than other etiological groups (χ2 = 10.761, p = 0.009). Both usual-dose and high-dose group showed tolerance to full-dose corticosteroids and similar adverse events over the observation period.IESS etiology was primarily related to structural causes. Clinical response in short-term follow-up was independent of prednisone dosage and underlying etiology. Better EEG responses may occur in patients with unknown etiology.