Abstracts

Rationale: The EPISTOP project is a multi-center prospective European study tracking epileptogenesis and epilepsy in infants with TSC. Here we report the observations of serial EEG studies in the first 14 months of life. Methods: Between 2013 and 2016, 81 TSC children younger than 5 months were included. At enrollment, all of them were seizure free and on no anti-epileptic drugs. Serial video-EEGs of at least 1 hour were performed every 4-6 weeks and analyzed with a uniform scoring system in the referring centers. Scoring categories were as follows: focal epileptiform abnormalities (score A), multifocal epilepsy (score B or C), hypsarrhythmia (score D); I: < 1%, II: 1-10%, III: 10-50%, IV more than 50% of the time. In addition we scored electrographic seizures and background patterns both in sleep and during wakefulness. Results: 48 children were included in this first analysis (follow up range 31-753 days, median 300 days). We here report the EEG data until the age of 14 months. During follow up epileptiform activity was already reported before the age of 3 months in 45%, of which 85% showed multifocal epileptiform abnormalities (score B or C). Only 22% of the EEGs in the age group 12-14 months were normal; 58% showed multifocal epileptiform abnormalities. However less than 10% showed hypsarrhythmia during follow up. In only 6/48 children the EEG remained normal and none of them developed seizures (follow up range 75-116 days, median 97 days). In the remaining 42, 27/42 (64%) developed electrographic or clinical seizures. In 22/27 (81%) the onset of seizures was below 6 months. In 16/27 (59%), the first seizure was a clinical seizure (median age 100 days). In the other 11/27 (41%), the first seizure was an electrographic seizure (median age 28 days). Of these 11 children, 6 eventually did develop clinical seizures. The duration from the first electrographic seizure to the first clinical seizure was 22-130 days (median 58 days) Conclusions: 87% of the TSC patients have interictal epileptiform discharges before the age of 14 months; 64% of these patients developed electrographic or clinical seizures. None of the infants with a normal EEG developed seizures so far. Our results emphasize the necessity of frequent routine EEG recordings as abnormalities, including electrographic seizures, were found in a large number of patients, already within the first 6 months of life. Epileptiform EEG abnormalities are related to a high risk of seizures in TSC patients as compared to those without EEG abnormalities. Funding: We are grateful to all the partners of the EPISTOP consortium who participate in this multi-center European project. The research was funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n°602391 – EPISTOP.