The Role of Autonomic Factors in Sudden Unexpected Death in Epilepsy - Abstract
Sudden unexpected death in epilepsy (SUDEP) is the most important direct
epilepsy-related cause of death. Despite its growing recognition amongst clinicians
caring for patients with epilepsy, the exact pathophysiologic mechanisms behind
SUDEP have not yet been fully elucidated. However, autonomic effects of seizures are thought to most likely to contribute to sudden unexpected death. Such autonomic effects may affect the heart. These include peri-ictal tachycardia, bradycardia, asystole, repolarization abnormalities, and/or reduced heart rate variability. Respiration may also be affected by seizures, with resulting hypoventilation, apnea, and hypoxemia. More recently, postictal generalized EEG suppression (PGES) has been hypothesized to be an electrophysiologic marker of increased SUDEP risk. If the cortical neuronal inhibition suggested by PGES affects deeper subcortical and brainstem structures, it may interfere with respiratory drive and result in apnea, putting patients at risk for sudden death. Given that SUDEP occurs less frequently than any peri-ictal autonomic disturbance in isolation, it is possible that death only occurs when several precipitating factors come together in a “perfect storm.” Increasing our understanding of SUDEP will require further exploration of ictal and interictal autonomic dysfunction in patients with seizures. It is only through such research that we may one day understand SUDEP enough to fully prevent it.