Entropy of EKG Time Series Distinguishes Epileptic from Nonepileptic Patients

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Cleveland Clinic Journal of Medicine


Introduction: Autonomic cardiac dysfunction has been reported in small studies of patients with temporal lobe epilepsy (TLE), with a wide range of irregularities being described, varying from arrhythmias to decreased heart rate (HR) variability. We hypothesize that patients with TLE display cardiac dysautonomia in either a subclinical or a clinical manner. There are conflicting reports with regard to the degree of dysautonomia and the outcome of epilepsy surgery, which eliminates the epileptogenic focus. It has been suggested that patients with greater cardiac dysautonomia have a poorer postoperative outcome, although others report the opposite. Many independent studies show that biologic systems are controlled by nonlinear mechanisms that can be quantified by entropies calculated from physiologic time series. We measure the entropy of HR providing an objective, mathematically defined measurement of a system’s “complexity,” which in turn represents the “healthiness” of the system. We hypothesize that by measuring and comparing the entropy of HR, we will be able to distinguish TLE patients from patients with non-epileptic pseudo-seizures. In further studies, we extend the application of this method in a prognostic manner.