Sudden unexpected death in epilepsy (SUDEP): a clinical perspective and a search for risk factors

Objectives-To examine the risk factors and their relative importance and possible role in sudden unexpected death in epilepsy (SUDEP). Methods-The study was conducted as a retrospective analysis of deaths in an outpatient population of a tertiary referral centre, based on clinical and pathological data. Results-Of a total of 140 deaths, 61 (44%) had not been to postmortem and were excluded, 37 (26%) had a verified cause of death and formed the non-SUDEP group, and 42 (30%) were classified as SUDEP. In the SUDEP group there was pulmonary oedema in 62%, signs of preceding seizures in 67%, no visible seizures in three of six observed deaths. A high seizure frequency prevailed in SUDEP as well as non-SUDEP. Sixty per cent of deaths were sleep related. Various other circumstances were temporally associated with death. The prone position at death was seen in 71% of the SUDEP patients; possible interpretations are discussed. Supposedly subtherapeutic serum concentrations of one or more antiepileptic drugs were found in 57% of those with reported serum concentrations. Alcohol was not a factor in the material, whereas hyponatraemia was seen in two cases. Conclusions-Most cases of SUDEP are preceded by seizures; their presence, frequency, type, aetiology, tractability, and the use of antiepileptic drugs are factors in the demise. No common risk factor, present in all cases of SUDEP, could be found, suggesting the probability of multiple mechanisms behind SUDEP.