Implications of delayed diagnosis of infantile spasm in a child with Down syndrome.

Trisomy 21, leading to Down syndrome (DS) is the most common genetic cause of intellectual disability. Approximately 1-13% of children with DS have co-morbid seizures, with infantile spasm being the most frequent type of seizure identified. Although the clinical and electroencephalography findings of infantile spasm are similar between children with DS and typically developing children, there is often a delay in the diagnosis of these seizures in children with DS. We present the case of a male infant with DS, where the diagnosis of infantile spasm was delayed by 5 mo. His case was associated with developmental regression and intractable seizure activity following diagnosis. The case highlights the implications of delayed diagnosis on treatment strategies and developmental outcomes. Keywords: Down syndrome, infantile spasm, delayed diagnosis.