Verringerte Herzfrequenzvariabilität und Repolarisationsstörungen bei bilateral tonisch-klonischen Anfällen

Introduction Bilateral tonic-clonic seizures are, according to current knowledge, the most important risk factor for the occurrence of a SUDEP. Chronic and acute changes in the autonomic nervous system as well as in the formation and conduction of excitation in the heart are well documented in people with epilepsy. We investigated periictal changes in heart action in bilateral tonic-clonic seizures compared to complex-focal seizures. Methods At the epilepsy centre in Marburg all patients from the epilepsy monitoring unit who had bilateral tonic-clonic as well as complex-focal seizures between 2007 and 2015 were retrospectively evaluated. Further selection criteria were the diagnosis of focal epilepsy and the complete presence of continuous 2-channel ECG. The seizures were examined in the EEG 10 minutes before the onset of the seizure until 30 minutes after the end of EEG seizure. In addition, heart rate variability (HRV) was determined at two interictal times (in the morning during sleep and during wakefulness). Results In total, 50 patients (mean age 35.3 years, 50% female) with focal epilepsy (64% temporal epilepsy, 36% extratemporal epilepsy) could be included who met the above criteria. In bilateral tonic-clonic seizures, the ictal heart rate was comparatively higher and the tachycardia persisted for 30 minutes. After the bilateral tonic-clonic seizures a significantly reduced heart rate variability (HRV) was observed. In addition, we found a significant reduction in QTc time in the immediate postictal measurements, i.e. one minute after a bilateral tonic-clonic seizure. Discussion Reduced heart rate variability and, in particular, a shortened QTc time each represent independent risk factors for sudden cardiac death. Previous reported cases of patients with a SUDEP were observed to have an immediate postictal central-vegetative mediated cardiorespiratory dysfunction, resulting in sudden death. The available data show a postictally present disorder of parasympathetic innervation and cardiac repolarization and once again illustrate the crucial importance of bilateral tonic-clonic seizures for the occurrence of SUDEP.