Anatomical variability of the relationship between the sympathetic trunk and the intercostal veins during thoracoscopic sympathectomy

•The article investigates the anatomical variations in venous blood flow on the right and left sides of the second, third, and fourth intercostal spaces in the chest.•The effects of TS were studied in 80 patients with palmar, axillary, plantar, and facial hyperhidrosis.•Surgical procedures involving the right-sided sympathetic trunk may have increased risks due to its anatomical complexity and a higher frequency of dilated and full-blooded anterior crossing intercostal veins.