Literature Review

Epilepsy Patients Who Die of SUDEP Largely Live Alone and Die Unwitnessed at Home

The data also suggest that over half of SUDEP cases occur at night.


 

Patients whose fatality is attributed to sudden unexpected death in epilepsy (SUDEP) largely live alone; die unwitnessed at home at night, usually in the prone position; and have an indication of a preceding seizure, according to research published in the May issue of Epilepsia.

“Our results … highlight the difficulties in implementing preventive efforts that require immediate availability of another person to identify a seizure, to interact and correct body position, or to give pharmacological emergency treatment,” said Olafur Sveinsson, a graduate student at the Karolinska Institute in Stockholm, and colleagues. “These obstacles need to be considered when strategies for SUDEP prevention are being developed.”

Investigating Circumstances of SUDEP

Previous case-control studies have identified a high frequency of tonic-clonic seizures, nocturnal seizures, and lack of nighttime supervision as risk factors for SUDEP, but mechanisms of SUDEP remain unclear. To analyze the circumstances of SUDEP and its incidence in relation to time of year, week, and day, Mr. Sveinsson and colleagues conducted a nationwide population-based case series.

For their study, the investigators used the Swedish National Patient Registry to identify all persons that, at some point between 1998 and 2005 had an ICD-10 code for epilepsy and were alive on June 30, 2006. Eligible SUDEP cases were all deaths with epilepsy mentioned on the death certificate together with all individuals who died during 2008, irrespective of whether epilepsy was mentioned on the death certificate. Obvious non-SUDEP deaths such as cancer, terminal illness, postmortem confirmed pneumonia, stroke, or myocardial infarction were excluded from further analysis.

SUDEP cases were divided into three subgroups based on the certainty of the diagnosis: definite SUDEP (when all clinical criteria were met and an autopsy revealed no alternate cause of death), probable SUDEP (when all clinical criteria were met but no autopsy was performed), and possible SUDEP (when SUDEP could not be ruled out but insufficient evidence was available regarding the circumstances of death and no autopsy was performed). To identify SUDEP cases and related circumstances, investigators reviewed death certificates, medical charts, autopsy, and police records. Autopsied non-SUDEP deaths from the study population served as a reference.

Circumstances of Death Characterized

Researchers reviewed 3,166 deaths and identified 329 cases of SUDEP (37% were female). Of these, 167 were definite, 89 were probable, and 73 were possible. SUDEP cases were younger at death (50.8 years) than non-SUDEP deaths (73.3 years). Most SUDEP cases occurred at night (58%), at home (91%), and 65% were found dead in bed. When documented, 70% were found in prone position, which may “facilitate SUDEP by compromising postictal ventilation,” said the authors.

Death was witnessed in 17% of SUDEP cases and in 88% of these, a seizure was observed. In all, 71% of patients were living alone and 14% shared a bedroom. Among the witnessed definite SUDEP patients, a tonic-clonic seizure was present in 95% or cases compared with 21% in the autopsied non-SUDEP reference group, strengthening the notion that SUDEP in most cases is a seizure-related event, the researchers said.

Although sudden infant death syndrome (SIDS) and cardiac death have a higher incidence in the winter, the researchers did not find the same to be true in their SUDEP cohort. Furthermore, they did not find a preponderance for Mondays or morning hours, as reported for sudden cardiac death. The researchers did, however, find a clear diurnal variation, with the majority of cases dying during the night hours. Taken together, these findings prompted the researchers to conclude that the underlying mechanisms in SUDEP are different from those of SIDS and sudden cardiac death.

Strengths of the study include the size of the case series, the population-based, nationwide study design, and the standardized validation of SUDEP cases with a comparatively high proportion of definite cases, the authors noted. Despite these strengths, these results “should not be considered as evidence that these circumstances constitute risk factors for SUDEP,” said the researchers. “We cannot exclude that the described living conditions reflect the general situation for people with refractory epilepsy, an established SUDEP risk factor.” The researchers are in the process of conducting a case-control study that will compare seizure control and living conditions between SUDEP cases and living epilepsy controls.

Erica Tricarico

Suggested Reading

Sveinnson O, Andersson T, Carlsson S, Tomson T. Circumstances of SUDEP: a nationwide population-based case series. Epilepsia. 2018;59(5):1074-1082.

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