Etiology-specific subgroup analysis of initial pharmacotherapy in infantile epileptic spasm syndrome: A single-center cohort study.

Aim: To evaluate the efficacy of initial pharmacotherapy for infantile epileptic spasm syndrome (IESS) with electro-clinical outcome characteristics.

Method: A retrospective comparative cohort study with 280 IESS patients was designed; I. vigabatrin monotherapy (n = 129, 46 %); II. hormonotherapy (ACTH/oral prednisolone) (n = 73, 26 %); and III. vigabatrin plus early initiation of hormonotherapy in the first 14 days (n = 78, 28 %). Two types of outcomes were defined: (1) short-term outcome with spasm cessation time ≤42 days and resolution of hypsarrhythmia on the EEG on ≤3 months and (2) long-term outcome with spasm relapse rate or evolution to a new epileptic syndrome.

Results: The etiology-specific diagnoses of the IESS cohort were defined according to the ILAE classification: structural (n = 131, 46.8 %), genetic (n = 28, 10 %), metabolic (n = 13, 4.6 %), immune-infectious (n = 10, 3.6 %), and unknown (n = 98, 35 %). Each treatment modalities had similar short- and long-term outcome characteristics. However, hormonotherapy with steroids (ACTH/oral prednisolone) provided "early IESS resolution" with spasm cessation and resolution of hypsarrhythmia (p = 0.042). The relapse rates of IESS were significantly higher in the etiology well-defined group compared to the unknown group (p = 0.005). The genetic-etiology specific group was more likely to have evolved to a new electro-clinical syndrome with a rate of 83.3 % than the others (p = 0.039).

Conclusion: We observed that the early initiation of hormonotherapy with VGB (sequential therapy) should be investigated in etiology well-defined subgroup with short- and long-term outcome characteristics.