Postictal generalized EEG suppression: a potential biomarker for sudep Elizabeth Donner, MD, MSc, FRCPC The Hospital for Sick Children University of Toronto

Searching for a biomarker… Objectively measured characteristic that predicts a clinical state People with drug resistant epilepsy have hundreds of seizures and survive What distinguishes the SUDEP patient from the rest? What distinguishes the fatal event from past seizures?

SUDEP CHRONIC EPILEPSY Theoretical considerations for mechanism of SUDEP Intrinsic factors CHRONIC EPILEPSY Precipitating Seizure Respiratory arrest Cardiac arrest Electrocerebral shutdown SUDEP Extrinsic factors Altered brain function/structure Autonomic dysfunction Altered heart function/structure Genetic factors AED management changes Sleep environment Poor AED adherance Prolonged postictal state Lack of supervision

Mechanisms Witnessed, EMU-recorded events support a seizure, typically GTC, as the terminal event 3 main mechanism emerge from EMU cases: Primary respiratory causes: central or obstructive apnea Cardiac arrhythmias Cerebral shutdown: diffuse post-ictal suppression of EEG preceding EKG or respiratory changes Friedman et al. JCI 2013