The clinical research organization went out of business.

This is a multinational, multicentre, non-interventional, retrospective data collection (manual Medical Chart Review).

This is a multinational, multicentre, non-interventional, retrospective data collection (manual Medical Chart Review). The identified local site staff (or trained independent data abstractors, if requested by the site) will review the medical records of all participants meeting the eligibility criteria, who have provided a signed inform consent form (ICF) for data collection and analysis. For participants who are less than 18 years of age, in addition to the assent form being signed by the participant, an informed consent would be obtained from parental or legally authorized representative.

In line with the retrospective nature of the study: there is no assignment of a participant to a particular therapeutic strategy; no additional diagnostic or monitoring procedures shall be applied to the participants; epidemiological methods shall be used for the analysis of collected data; the prescription of any medication for the treatment of the epileptic syndrome occur before the collection of the data in this study and is clearly separated from the decision to include the participant in the study.

Inclusion Criteria:

• Age ≥2 years
• Disease history of at least 24 months from date of first seizure
• Medical history of epilepsy associated with moderate to severe intellectual disability, cognitive developmental delay or cognitive regression
• Medical history of onset of seizures in early childhood (≤ 8 years)
• Failure of adequate trials of two tolerated and appropriately chosen and used Anti-Epileptic Drug (AED) schedules (whether as monotherapies or in combination) to achieve sustained seizure freedom
• Ongoing refractory epilepsy
• MRI and EEG data are available for the participant
• Participants (or their parents/ legal representative as appropriate) have provided written informed consent / assent form to collect the data specified.

Exclusion Criteria:

• Normal cognitive development.
• Any acute symptomatic seizures in participants with underlying developmental delay.
• Any progressive intellectual and neurological deterioration conditions.

Participants with rare epilepsy syndromes up to the date of the most recent visit at the study site.