Early mortality in SCN8A-related epilepsies.

SCN8A-related epilepsies are often severe developmental and epileptic encephalopathies. Seizures can be treatment resistant, and patients suffer from severe intellectual disability. Reports have suggested that SCN8A-related epilepsies have a high mortality with SUDEP as the major underlying cause. SUDEP is a catastrophic event, and the risk of occurrence should be correctly and carefully discussed with patients and families. We tested the hypothesis of SUDEP as the main cause of death in SCN8A-related epilepsies by reviewing all the currently reported patients with SCN8A. In addition, we collected unpublished patients through an international network. In total, we reviewed the data of 190 patients. In our cohort, 10 patients were deceased, and the overall mortality was 5.3%. Within the ten deceased patients, age at death ranged from 16 months to 17 years; the majority (7/10) of them died in early childhood. Three patients died of probable or definite SUDEP. Thus, our data do not indicate an increased risk when compared to other DEEs. Indeed, death in SCN8A-related epilepsies seems to occur most often in children experiencing a relentless worsening of their epilepsy and neurological condition, rendering them susceptible to pulmonary infections and respiratory distress that ultimately can be fatal.