Epilepsy and Activity of the Autonomic Nervous System

Decrease of Sympathetic Cardiovascular Modulation after Temporal Lobe Epilepsy Surgery Hilz MJ, Devinsky O, Doyle W, Mauerer A, Dutsch M. Brain 2002;125(Pt 5):985–995 In temporal lobe epilepsy (TLE), there is evidence of ictal and interictal autonomic dysregulation, predominantly with sympathetic overactivity. The effects of TLE surgery on autonomic cardiovascular control and on baroreflex sensitivity (BRS) have not been studied. To evaluate such effects, we monitored heart rate (HR), systolic blood pressure [BP(sys)], and respiration in 18 TLE patients 3–4 months before and after TLE surgery. We used Blackman-Tukey spectral analysis to assess sympathetic and parasympathetic modulation as powers of HR and BP(sys) oscillations in the low-frequency (LF, 0.04–0.15 Hz) and high-frequency (HF, 0.15–0.5 Hz) bands. BRS was determined as the LF transfer function gain between BP and HR. After surgery, HR, BP(sys), respiration, and HF powers remained unchanged, whereas LF powers of HR [1.57 ± 1.54 beats/min( 2 )] and BP(sys) [2.19 ± 1.34 mm Hg( 2 )] and BRS (0.68 ± 0.31 beats/min/mm Hg) were smaller than presurgical LF powers of HR [3.87 ± 3.26 beats/min( 2 )] and BP(sys) [4.80 ± 3.84 mm Hg( 2 )] and BRS (1.12 ± 0.39 beasts/min/mm Hg; P < 0.05). After TLE surgery, there is a reduction of sympathetic cardiovascular modulation and BRS that might result from decreased influences of interictal epileptogenic discharges on brain areas involved in cardiovascular autonomic control. TLE surgery seems to stabilize the cardiovascular control in epilepsy patients by reducing the risk of sympathetically mediated tachyarrhythmias and excessive brady-cardiac counterregulation, both of which might be relevant for the pathophysiology of sudden unexpected death in epilepsy patients (SUDEP). Thus TLE surgery might contribute to reducing the risk of SUDEP.