Impaired baroreflex function in temporal lobe epilepsy
Dütsch M, Hilz MJ, and Devinsky O (2006) Impaired baroreflex function in temporal lobe epilepsy. J Neurol 253:10 1300–8.
Abstract: Changes of cardiovascular function are frequent in temporal lobe epilepsy (TLE). The baroreflex - the most important reflex for cardiovascular stability - has not been studied systematically in TLE. We evaluated cardiovascular variability and baroreflex function in TLE. In 22 TLE patients and 20 controls, we continuously monitored heart rate (HR) and blood pressure (BP). Time-domain parameters were derived from recordings at rest and from standard cardiovascular reflex tests. Spectral analysis determined sympathetic and parasympathetic modulation of HR and BP in the low (LF-power) and high frequency range (HF-power). We calculated the relative LF- and HF-powers of HR in relation to the sum of LF- and HF-powers. LF/HF-ratio of HR was assessed as a parameter of sympatheticovagal balance. LF-transfer function gain between BP and HR determined baroreflex function.Time-domain parameters did not differ between TLE patients and controls. Spectral analysis showed decreased absolute LF- and HF-powers but increased relative LF-power and LF/HF-ratio of HR in TLE. LF-transfer function gain between BP and HR was reduced in TLE (p<0.05). The reduction of absolute LF- and HF-powers indicates decreased total autonomic variability in TLE. However, increased relative LF-power and LF/HF-ratio of HR in TLE show a relative increase of sympathetic tone. Most importantly, we demonstrate an impaired baroreflex function in TLE. These cardiovascular autonomic abnormalities may contribute to cardiac arrhythmia in TLE.
Keywords: temporal lobe epilepsy, autonomic nervous system, baroreflex function, cardiac arrhythmia, spectral analysis
Context
- Study of 22 patients and 20 controls with continuous monitoring of HR and BP, with spectral analysis to separate low-frequency and high-frequency components and thus isolate parasympathetic and sympathetic contributions (Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology). TLE patients had decreased autonomic control overall, but a relative increase in low-frequency power indicating increased sympathetic tone. The gain of the low-frequency transfer function between BP and HR was used as a metric of baroreceptor function, and this was impaired in TLE.