Mortality in epilepsy.

Both community-based studies and reports from more selected epilepsy populations consistently reveal persons with epilepsy to have a mortality rate two to three times that of the general population. This increased rate is most pronounced in patients with remote symptomatic epilepsy, although many studies also report a significant excess mortality also among those with idiopathic epilepsy. The highest standardized mortality ratios (SMR) are seen in young age groups, mainly due to the low expected mortality in children, and during the first 5-10 years after diagnosis. Many of these observations suggest that the higher mortality is partly related to the underlying disorder causing epilepsy rather than a direct consequence of the seizures. For example, mortality in cerebrovascular diseases is increased, with SMRs ranging from 1.8 to 5.3 in the various studies. Deaths due to neoplasms, and in particular brain tumors, is also increased among patients with epilepsy. Accidents, status epilepticus, and sudden unexpected death (SUD) are more directly seizure-related causes of death. The incidence of such deaths vary considerably depending on the population being studied. While rare among patients with new-onset epilepsy, seizure-related deaths may account for up to 40% of all deaths in patients with chronic epilepsy. SUD is probably the most frequent seizure-related cause of death among young adults with epilepsy, with an SMR more than 20 compared with the general population. Seizure-induced autonomic cardiorespiratory effects have been suggested, but the mechanisms behind SUD are far from fully understood. It appears, however, that the risk of SUD is closely related to seizure frequency, being 40 times higher in patients who continue to have seizures than in those who are seizure-free.