The effect of epilepsy on function of autonomic nervous system in human

• Main Authors: Tomor Harnod, 哈鐵木爾
• Other Authors: Kun-Ruey Shieh
• Format: Others
• Language: en_US
• Online Access: http://ndltd.ncl.edu.tw/handle/yc7563

博士 === 慈濟大學 === 醫學研究所 === 96 === Impairment of cardiovascular regulation in the autonomic nervous system has been reported in humans and animal models of epilepsy. This dysregulation has been positively correlated with long-term morbidity and mortality in epileptic patients. In epileptic patients, the risk of sudden unexpected death (SUDEP) is about 40 times higher than healthy people. Previous studies of heart rate variability (HRV) in epilepsy patients provided evidences that the risk of SUDEP probably comes from a higher interictal sympathetic activity coupled with an ictal surge in sympathetic activity. Most studies of HRV in epilepsy patients are limited in standard temporal lobe epilepsy (TLE). We designed these studies in pediatric and adult patients with epilepsy other than TLE to understand their respective changes of sympathetic and parasympathetic regulations. Patients diagnosed as non-TLE using electroencephalography were enrolled. By their seizure frequency, refractory or non-refractory epilepsy was defined. Their seizure types were variable but generalized seizures were recorded in most subjects. The patients having arrhythmia, diabetic neuropathy and adverse effects with their medications were excluded from this study. Lead I electrocardiograms, for 300 seconds in each recording, were carried out at the times of enrollment and follow-up. These were taken during the interictal period of awaken patients in daytime while they lied in head up 30-45 degree posture quietly. Frequency-domain analysis of HRV was performed using fast Fourier transformation of the heart beat contour. Each power spectrum was subsequently converted to R-R interval (RR) and standard frequency-domain measures, including high frequency power (HF; 0.15-0.45 Hz), low frequency power (LF; 0.04-0.15 Hz), and LF/(HF + LF) expressed in normalized units (LF%). The HF component is considered to represent cardiac vagal (parasympathetic) regulation. The fraction LF% is considered to mirror sympathetic regulation. Frequency-domain analysis of HRV showed that seizure control in patients with generalized seizures was accompanied by significant increase in parasympathetic regulation and significant decrease in sympathetic regulation. Our study confirmed that seizure control might modulate the autonomic function. In further analysis, the indicator of parasympathetic regulation, HF, showed to be a better prognostic tool than the sympathetic indicator, LF%, when assessing seizure control among patients with generalized seizures. In epileptic adults with generalized seizures, they had shorter interictal heart rate intervals and faster heart rates, which might be due to higher sympathetic and lower parasympathetic regulation of autonomic cardiac activity. This results are similar to that have been reported in patients with TLE. Epileptic children with refractory generalized epilepsy had lower HRV during the interictal period, which we postulated resulting from parasympathetic or vagal reduction. Patients with frontal lobe epilepsy had shorter interictal heart rate intervals and faster heart rates, which we postulated might be due to lower parasympathetic or vagal regulation of autonomic cardiac activity. These results suggest 1) that the mechanism of decreased HRV in children with epilepsy is probably different than in adults with epilepsy and 2) the mechanism of decreased HRV in patients with FLE is probably different from that in patients with TLE.