Sudden unexpected death in epilepsy, periictal physiology, and the SUDEP-7 Inventory

Sudden unexpected death in epilepsy (SUDEP) is a significant public health burden. Epidemiological studies have identified clinical SUDEP risk factors across large populations, but the means to apply this information to individual patients are lacking. The SUDEP-7 Inventory was developed as a marker of clinical SUDEP risk and has been used in studies of potential SUDEP biomarkers. We retrospectively reviewed clinical data from 16 patients dying of SUDEP and 48 matched living epilepsy controls to determine whether individuals succumbing to SUDEP could be distinguished from living epilepsy controls using the revised SUDEP-7 Inventory, the absolute number of clinical risk factors as identified by an International League Against Epilepsy meta-analysis (ILAE score), and physiological characteristics previously associated with SUDEP risk. Mean revised SUDEP-7 Inventory score was 3.3 ± 2.0 in SUDEP cases and 3.8 ± 2.3 in controls (P = 0.39). Mean ILAE score was 2.4 ± 1.1 in SUDEP cases and 2.6 ± 1.4 in controls (P = 0.62). There were no significant differences in interictal heart rate variability (measured by the root mean square of differences of successive RR intervals), periictal cardiorespiratory dysfunction, and postictal generalized electroencephalographic suppression between the groups. This demonstrates that a reliable instrument for individual SUDEP risk stratification is lacking and highlights the need for improved understanding of SUDEP pathophysiology and individual risk determination.