Response to treatment and outcomes of infantile spasms in Down syndrome

AIM: To estimate the prevalence, and evaluate presentation, treatment response, treatment side effects, and long‐term seizure outcomes in all known cases of children with Down syndrome and infantile spasms on the island of Ireland. METHOD: This was a 10‐year retrospective multicentre review of clinical records and investigations, focusing on treatment response, side effects, and long‐term outcomes. RESULTS: The prevalence of infantile spasms in Down syndrome was 3.0% during the study period. Fifty‐four infants were identified with median age of spasm onset at 201 days (interquartile range [IQR] 156–242). Spasm cessation was achieved in 88% (n=46) at a median of 110 days (IQR 5–66). The most common first‐line medications were prednisolone (n=20, 37%), vigabatrin (n=18, 33.3%), and sodium valproate (n=9, 16.7%). At follow‐up (median age 23.7mo; IQR 13.4–40.6), 25% had ongoing seizures and 85% had developmental concerns. Treatment within 60 days did not correlate with spasm cessation. Seventeen children (31%) experienced medication side effects, with vigabatrin accounting for 52%. INTERPRETATION: Prednisolone is an effective and well‐tolerated medication for treating infantile spasms in Down syndrome. Despite the high percentage of spasm cessation, developmental concerns and ongoing seizures were common.