Does First-Line Treatment Impact Outcomes in Trisomy 21-Associated Infantile Epileptic Spasms Syndrome? A Multi-Center North American Analysis

Objective This study aimed to evaluate electroclinical remission and long-term outcomes in children with infantile epileptic spasms syndrome (IESS) associated with trisomy 21 (T21). We hypothesized that initial treatment with hormone therapy would result in higher remission rates compared to treatment with vigabatrin. Methods A retrospective study of T21 and IESS patients was conducted across six North American tertiary pediatric centers. Results A total of 114 children with IESS were identified. Electroclinical remission without relapse occurred in 31.5% (17/54) of patients receiving hormone therapy as first-line treatment compared with 16.7% (6/36) treated with vigabatrin monotherapy (p = 0.114). Median time to remission was shorter with hormone therapy (41 days) than with vigabatrin (142 days; p < 0.001). Median age at last follow-up was 33 months (IQR 18–83) with a median follow-up duration of 25 months (IQR 11–74). At last follow-up, ongoing epilepsy was present in 30.7% (35/114) and autism spectrum disorder (ASD) in 25.4% (29/114), with similar rates across first-line treatment groups (ongoing epilepsy: hormonal 28.6% vs vigabatrin 30.6%; ASD: 21.4% vs 33.3%; all p > 0.05). Conclusions Children with T21-associated IESS were approximately two times more likely to achieve electroclinical remission with hormone therapy as first treatment compared to vigabatrin, although this difference did not reach statistical significance. The median time to remission was significantly shorter in children who received hormone therapy as their first treatment compared to those treated with vigabatrin. The initial treatment did not impact long-term clinical outcomes, such as ongoing epilepsy or ASD.