Editors' note: Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP)

Abstract

In “Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP)”, Vilella et al. found that in a cohort of patients with intractable generalized or focal epilepsy, 22% of seizures were followed by postconvulsive central apnea (PCCA), defined as ≥1 missed breath without any other explanation; one of these patients died of probable SUDEP, suggesting that the incidence of SUDEP is 5.1 per 1,000 patient-years. They concluded that PCCA may be a clinical biomarker for SUDEP. Pursuant to these findings, Rose et al. report a case of SUDEP in a patient with PCCA; however, they comment that although PCCA may be associated with SUDEP, they suspect that it is not a requirement for SUDEP, given that there is a known relationship between SUDEP and prone positioning (which can lead to obstructive apnea). They also question the proposed incidence rate of SUDEP, as it was based on only 1 death. Dasheiff notes that (1) it is not possible to distinguish between PCCA and central sleep apnea without advanced instrumentation, and (2) a threshold higher than 1 missed breath should be used to define PCCA. Vilella et al. respond that (1) the true incidence of PCCA and SUDEP, both individually and separately, is, indeed, unknown; (2) there may be a multitude of risk factors for SUDEP, including both prone positioning and PCCA; and (3) using a higher bar to define PCCA would, actually, better illustrate the relationship between PCCA and SUDEP in this series. Further research on the risk factors and incidence of SUDEP is needed. In “Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP)”, Vilella et al. found that in a cohort of patients with intractable generalized or focal epilepsy, 22% of seizures were followed by postconvulsive central apnea (PCCA), defined as ≥1 missed breath without any other explanation; one of these patients died of probable SUDEP, suggesting that the incidence of SUDEP is 5.1 per 1,000 patient-years. They concluded that PCCA may be a clinical biomarker for SUDEP. Pursuant to these findings, Rose et al. report a case of SUDEP in a patient with PCCA; however, they comment that although PCCA may be associated with SUDEP, they suspect that it is not a requirement for SUDEP, given that there is a known relationship between SUDEP and prone positioning (which can lead to obstructive apnea). They also question the proposed incidence rate of SUDEP, as it was based on only 1 death. Dasheiff notes that (1) it is not possible to distinguish between PCCA and central sleep apnea without advanced instrumentation, and (2) a threshold higher than 1 missed breath should be used to define PCCA. Vilella et al. respond that (1) the true incidence of PCCA and SUDEP, both individually and separately, is, indeed, unknown; (2) there may be a multitude of risk factors for SUDEP, including both prone positioning and PCCA; and (3) using a higher bar to define PCCA would, actually, better illustrate the relationship between PCCA and SUDEP in this series. Further research on the risk factors and incidence of SUDEP is needed.