What is known about the mechanisms underlying SUDEP?
So EL (2008) What is known about the mechanisms underlying SUDEP? Epilepsia 49 Suppl 9: 93–8.
Abstract: This article highlights studies in three major domains of potential mechanisms of sudden unexplained death in epilepsy (SUDEP): cardiac, respiratory, and autonomic. Ictal cardiac arrest is a clinically rare but well-recognized potential mechanism of SUDEP. Studies have failed to identify preexisting cardiac electrophysiologic or structural abnormalities that distinguish SUDEP persons. Some degree of pulmonary congestion is a common autopsy finding, but severe pulmonary edema occurs very rarely with seizures. In contrast, periictal apnea and hypoxia occur commonly with generalized tonic-clonic seizures and, to a lesser degree, with complex partial seizures. There are several animal models of postictal respiratory arrest. Postictal respiratory arrest in audiogenic seizure mice can be induced by serotonin receptor inhibition or prevented by selective serotonin reuptake inhibitor (SSRI) drugs. Reduced heart rate variability occurs in patients with refractory epilepsy and can be induced in animal seizure models, but its precise role in predisposing persons to sudden death requires further investigation.
Keywords: Cardiac arrest, Epilepsy, Heartrate, Respiratory arrest, Seizures, Sudden death.
- Review of mechanistic hypotheses about SUDEP and discussion of animal models. Takes the view that severe pulmonary edema occurs only rarely with seizures, but ictal apnea is more common. Highlights the possible contribution of insufficient activation of serotonin receptors in triggering respiratory arrest, as demonstrated by Tupal and Faingold. Helpful discussion of the strengths and weakness of evidence linking reduced heart rate variability to sudden death. On the whole takes the view most SUDEP events likely result from ictal apnea that leads to asystole (cardiorespiratory reflex; Nashef et al.). Discusses the importance link of GTCS and complex partial seizures with apnea and hypoxia. Also discusses heart rate variability.