Autonomic aspects of sudden unexpected death in epilepsy (SUDEP)

Abstract

Sudden unexpected death in epilepsy (SUDEP) is a major cause of epilepsy-related mortality. SUDEP is highly linked to seizures, with most deaths occurring after convulsive seizures in sleep. In most cases of SUDEP, convulsive seizures appear to directly trigger catastrophic cardiorespiratory dysfunction leading to death. In the last few decades, many pathophysiological mechanisms have been proposed to explain the sequence of events leading to death. Patients with epilepsy often have underlying autonomic dysfunction, as measured by heart rate variability and other testing modalities. Additionally, seizures often trigger acute cardiac and respiratory dysfunction. While sinus tachycardia is the most common cardiac finding during seizures, asystole and malignant tachyarrhythmias may also occur. Seizures can also lead to respiratory dysfunction, including central ictal and obstructive apnea related to laryngospasm. Available data suggest that there could be underlying autonomic dysfunction, potentially related to genetic, medication, and other factors that might predispose individuals to sudden catastrophic cardio-respiratory dysfunction in the setting of a seizure, resulting in SUDEP. Further exploration of this possible link is needed. Patients with medically refractory epilepsy are at the highest risk, and adequate management via medical therapy to control convulsive seizures, or surgical intervention may decrease the SUDEP risk. Recently, many automated seizure detection systems have been developed to detect convulsive seizures, which may enable caregivers to more closely monitor individuals with epilepsy. Improved identification of seizures may be important for patients with refractory epilepsy as close supervision and timely intervention after a seizure could potentially reduce the risk of SUDEP.