Exhaustive clinical examination of etiology and initial response to first‐line treatment in 577 children with infantile epileptic spasm syndrome children: A 5‐year retrospective observational study

Abstract Objective Employing whole‐exome sequencing (WES) technology to investigate the etiology of infantile epileptic spasm syndrome (IESS), and determining whether different etiologies exhibit phenotypic variations, while elucidating the potential associated factors, might improve short‐term responses to first‐line treatment. Methods We retrospectively evaluated patients with IESS admitted for treatment between January 2018 and June 2023. Clinical phenotypic differences among etiological classifications and clinical manifestations were analyzed. Variable selection using the best subset method was performed, followed by logistic regression analysis to identify the factors influencing treatment response. Results A total of 577 patients were included; 412 completed trio‐WES. Magnetic resonance imaging abnormalities were detected in 387 patients (67.1%). Patients with etiology as structural abnormalities were likelier to have non‐spasms at the initial seizure onset. A total of 532 patients completed the first‐line treatment; 273 patients received it for the first time at our hospital (initial response rates: 30.1% and 42.1%, respectively). The response group had a lower proportion of early‐onset seizures (≤3 months) than the no‐response group (11.3% vs. 23.7%, p < 0.01 and 11.3% vs. 21.5%, p = 0.03, respectively). Logistic regression analysis indicated that earlier initiation of first‐line treatment was associated with a higher likelihood of an initial response. However, the etiological classification did not have a significant impact on the initial response. Interpretation IESS patients with structural abnormalities are more likely to present with non‐spasm seizures at initial onset. Early initiation of first‐line treatment is crucial; however, initial responses may be less favorable when seizures occur in early infancy.