European experience of steroid therapy in children with developmental and epileptic encephalopathy with spike wave activation in sleep ((D)EE-SWAS).

Background: Developmental and epileptic encephalopathy with spike wave activation in sleep (DEE-SWAS) and epileptic encephalopathy with spike wave activation in sleep (EE-SWAS) are rare but well-known childhood epileptic disorders. Steroids are one of the first line treatment options, but a variety of steroid regimens exists. The aim of this survey was to evaluate the practices of steroid therapy in the treatment of (D)EE-SWAS across European centers.

Methods: An online survey was conducted (via 'SurveyMonkey' Europe) among European epilepsy centers. Questions asked included: characteristics of replying center, applied definition of DEE-SWAS, existence of regional/national guidelines regarding diagnostic and therapeutic management. Particular attention was paid to the indication/contraindication of steroids and treatment regimens used.

Results: Responses were obtained from 60 centers across 18 countries. Only 15% of centers reported the availability of national guidelines for the management of (D)EE-SWAS. There were variations in definition of (D)EE-SWAS, with Spike-Wave- Index (SWI) > 85 (irrespective of cognitive status) and SWI > 50% with concurrent neurodevelopmental regression being the most prevalent, reported in 36% and 50%, respectively. Steroids and clobazam were considered the predominant treatment options, with the primary indication for steroids being neurodevelopmental arrest (52%) and failure of clobazam treatment (51%). Treatment goals of steroid treatment primarily focused on neurodevelopmental improvement (95%), and reduction of SWI (66%). Methylprednisolone and prednisone were the most frequently used steroids, although other steroid types were also reported. Pulse therapy was utilized exclusively in 47% of centers. The most commonly used steroid regimen was intravenous/oral methylprednisolone pulse therapy (20 mg/kg/day for 3 days, either monthly or weekly), although a broad variety of different regimens were reported. Criteria influencing decisions about steroid treatment were largely based on personal experience, with scientific publications playing a role in decision-making in only 14% of centers.

Conclusion: Steroids are part of the first line therapy of (D)EE-SWAS across Europe, but heterogeneity in formulations, dosages, and regimens persists due to limited guideline availability. The absence of comparative studies and the discordant definitions of (D)EE-SWAS further hinder comparisons of treatment efficacy. We recommend that harmonizing steroid treatment strategies is imperative for optimizing (D)EE-SWAS management.