PurposeTo observe the evolution of heart rate variability (HRV) in patients with palmar hyperhidrosis before and after endoscopic thoracic sympathotomy and to evaluate the effects of the surgery on the autonomic nervous system.Materials and MethodsEndoscopic thoracic sympathotomy was performed on 20 patients with palmar hyperhidrosis. The thoracic sympathetic chain at the level of the third to fourth rib (R3-R4) was transected, but the ganglia were left in position without removal. A slightly larger ramus, in comparison to the other rami, that arose laterally from the sympathetic chain was interrupted to achieve adequate sympathetic denervation of the upper extremity. Before and on the day after the surgery, 24-hour Holter Electrocardiograph was performed, obtaining time domain and frequency domain parameters.ResultsCompared with preoperative variables, there was a significant increase in the number of adjacent normal R wave to R wave (R-R) intervals that differed by more than 50 ms, as percent of the total number of normal RR intervals (pNN50); root mean square difference, the square root of the mean of the sum of squared differences between adjacent normal RR intervals over the entire 24-hour recording; standard deviation of the average normal RR interval for all 5-minute segments of a 24-hour recording (SDANN) after thoracic sympathotomy. Low frequencies (LF, 0.04 to 0.15 Hz) decreased significantly. There was no statistical difference in high frequencies (HF, 0.15 to 0.40 Hz), LF/HF ratio (LF/HF), or standard deviation for all normal RR intervals for the entire 24-h recording (SDNN) before and after thoracic sympathotomy.ConclusionThere was a significant improvement in HRV in patients with palmar hyperhidrosis after thoracic sympathotomy. This may be attributable to an improvement autonomic nervous system balance and parasympathetic predominance in the early postoperative stage.