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

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: Classification; Corticosteroids; Etiology; Infantile epileptic spasms syndrome; Prednisone.