SUDEP and other causes of mortality in childhood-onset epilepsy

There are few prospective studies on the causes of mortality in well-characterized cohorts with epilepsy and even fewer that have autopsy data that allow for reliable determination of SUDEP. We report causes of mortality and mortality rates in the Finnish cohort with childhood-onset epilepsy.

A population-based cohort of 245 children with epilepsy in 1964 has been prospectively followed for almost 40 years. Seizure outcomes and mortality were assessed. Autopsy data were available in 70% of the cases. Sudden unexpected death in epilepsy (SUDEP) rates were assessed, and SUDEP was confirmed by autopsy.

During the follow-up, 60 subjects died. The major risk factor for mortality was lack of terminal remission (p < 0.0001). Remote symptomatic etiology also increased the risk for death (p < 0.0001) but did not remain significant on multivariate analysis after adjusting for effect of remission. Of the deaths, 33/60 (55%) were epilepsy-related including SUDEP in 23/60 (38%) using the Nashef criteria, status epilepticus in 4/60 (7%), and accidental drowning in 6/60 (10%). The nonepilepsy-related deaths occurred primarily in the remote symptomatic group and were often related to the underlying disorder or to medical comorbidities that developed after the onset of the epilepsy. Risk factors for SUDEP on multivariable analysis included lack of 5-year terminal remission and not having a localization-related epilepsy. In cryptogenic/idiopathic cases, SUDEP did not occur in childhood but begins only in adolescence.

Childhood-onset epilepsy is associated with a substantial risk of epilepsy-related mortality, primarily SUDEP. In otherwise neurologically normal individuals, the increased SUDEP risk begins in adolescence. The higher mortality rates reported in this cohort are related to duration of follow-up as most of the mortality occurs many years after the onset of the epilepsy.