Predicting Sudden Death from Epilepsy

Wednesday, May 30, 2012

Drs. Poh and colleagues from the Harvard MIT Division of Health Sciences and Technology, and the Division of Epilepsy and Clinical Neurophysiology and Department of Neurosurgery from Children’s Hospital Boston and Department of Neurology of Epilepsy at Brigham and Women’s Hospital present an analysis of 34 seizures comprising of 22 complex partial and 12 tonic clonic seizures from 11 patients. The analysis was done using a custom built wrist worn sensor to continuously record sympathetically mediated electrodermal activity of patients (changes in nerve signals in the skin) with refractory epilepsy admitted to a video EEG monitoring unit. Heart rate changes were interpreted from the EKG used during monitoring. The purpose of the analysis was to examine what are the autonomic or automatic changes that occur with a seizure that can be detected by a wrist worn sensor and assess the relationship between those autonomic changes and EEG changes that occur once a seizure has stopped.

The investigators found that the period after seizure otherwise known as a postictal period was characterized by a surge in electrodermal activity and heightened heart rate coinciding with the seizures. This change relates to heart rate variability. An increase in this electrodermal activity correlated with the increase in the duration of this EEG suppression. A decrease in heart rate variability correlated with an increase in the duration of EEG suppression.

The investigators concluded that the magnitude of both sympathetic activation and parasympathetic suppression increases the duration of the EEG suppression after tonic clonic seizures. These results provide autonomic signals of postictal EEG suppression and highlight a critical window when the heart may malfunction during and after a seizure. This could be relevant in causing SUDEP. The investigators went on to state that these findings could be utilized as a predictor of individuals who are at risk of sudden death from autonomic changes. This study also opens up the door to new devices that may be predictive of serious changes in autonomic activity that might be used to signal patients and caregivers in the future that an abnormal heart rate change is occurring thus potentially preventing death.

Authored by: Joseph I Sirven, MD on 5/2012

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