Infantile Spasms in Inborn Errors of Metabolism: Diagnostic and Therapeutic Considerations

Infantile epileptic spasms syndrome is an early-onset epileptic encephalopathy. Its association with inborn errors of metabolism is underrecognized, and the treatment can be complicated by the biochemical vulnerability. This report showed individualized treatment in 2 patients with inborn errors of metabolism. The first patient was found to have propionic acidemia in the setting of encephalopathy by third day of life. Infantile epileptic spasms syndrome was diagnosed at 10 months. Levetiracetam was started, and vigabatrin was introduced following liver transplant, which resulted in seizure freedom. The second patient presented at 6 months with hyperammonemia and elevated orotic acid consistent with ornithine transcarbamylase deficiency. Infantile epileptic spasms syndrome was diagnosed 3 weeks later. Treatment with vigabatrin, adjunctive to levetiracetam, led to a brief period of seizure cessation. The patient was later treated with two 4-week courses of enteral prednisolone, leading to the cessation of spasm. These cases emphasize the complexity in managing infantile epileptic spasms syndrome in patients at high risk for metabolic decompensation.