One Size Does Not Fit All: Novel Individualized Use of Dexamethasone in Infantile Epileptic Spasms Syndrome

Dexamethasone is an effective emerging agent for the treatment of infantile epileptic spasms syndrome (IESS), which, unlike with adrenocorticotropic hormone (ACTH) and prednisolone, does not yet have a universally accepted dosing protocol. We present a novel, highly individualizable pulsed dexamethasone dosing scheme for IESS therapy.

We retrospectively analyzed data of infants with IESS treated in our center with pulsed dexamethasone: 20 mg/m²/day was given intravenously for 3 days every 1-4 weeks. Five pulses were aimed for; the final amount and interval between them were determined individually depending on the patient's seizure burden, EEG findings, and IESS etiology. Demographic, clinical, and EEG data were extracted from clinical records. Response to therapy was defined on the basis of seizure freedom and EEG findings 4 weeks after dexamethasone administration.

Sixty-six infants with 57.6% male predominance were included in analysis. Mean age was 6.2 months at first seizure and 7.3 months at diagnosis. IESS etiology was unknown in 37.9%, structural in 33.3%, and genetic in 13.6% of patients, the rest being mixed. Median delay between diagnosis and treatment start was 1 day. Patients received up to 11 pulses, with the majority (47%) given 5. Seizure freedom was achieved in 81.8% of patients, 11.4 days after first pulse on average. Unknown IESS was associated with best response to therapy. Compared to poor responders, where more administered pulses mirrored IESS pharmacoresistance, fewer pulses were sufficient to achieve remission with no relapses in the 6 months following therapy end in good responders. No major side effects were observed.

Dexamethasone is an effective alternative to ACTH and prednisolone in IESS therapy. Our therapy regimen is effective, well tolerated, and flexible. Reflecting its potential as an individualized, patient-tailored approach, we demonstrate that fewer pulses may suffice to achieve a relapse-free remission in carefully selected patient cohorts.