T2 sympathectomy leads to long-lasting inhibition of palmar sweating, which does not correlate to loss of vasoconstriction. Recurrent and enhanced vasoconstrictor function 3 months following endoscopic sympathetic block has major implications for its use to treat enhanced vasoconstriction.

Endoscopic sympathetic block (ESB) is used as a treatment of excessive palmar sweating. In a prospective study we compared the effect of ESB at the level of the second (T2) and fourth thoracic ganglion (T4) on vasoconstriction and sweating of the hands. Sympathetic vasoconstriction was measured by computerassisted infrared thermography following ice water immersion of the hands in 22 hyperhidrosis patients before, two days and 3 months post op. In addition, palmar sweating before and 3 months post op was assessed by sudometry. After ESB the rewarming was accelerated in both T2 and T4 patients, but was significantly slower in the T4 group. Three months postoperatively rewarming had returned to the preoperative pattern in T4 patients but was still significantly faster in the T2 group. These effects were more pronounced in the fingertips than the hand dorsum. Sudomotor function was blocked in all T2 patients but had relapsed in 2 patients in the T4 group. Two T4 patients had not shown an effect on sudomotor function postoperatively. The normalization of rewarming kinetics may be explained by remaining fibers, denervation hypersensitivity or stimulation of catecholamine receptors, or neuronal reorganization. The effect of ESB T4 on sudomotor function has to be proven.

Interruption of sympathetic outflow by surgical sympathetic block has been used to treat hyperhidrosis for decades. In this study the effect of gender and the level of sympathetic block (T2 vs. T3) on the rewarming kinetics following ice water immersion were assessed in a prospective study on 60 hyperhidrosis patients before, 2 days, and 3 months postoperatively. Rewarming kinetics following endoscopic sympathetic block (ESB) was massively enhanced 2 days post-operatively, but had returned to pre-operative conditions at the 3 month follow-up for ESB at level T3. ESB at level T2 provoked significantly faster rewarming as compared to T3 at the 2 day and 3 month follow-up. Independent of the level of ESB, there was a slower rewarming in women already pre-operatively. This gender difference was clearly reduced at the 2 day follow-up, but had increased again at the 3 month follow-up. There was no correlation between the rewarming kinetics of the fingertips and palmar sweating. We conclude that for the sympathetic vasoconstriction of the fingertips the sympathetic ganglion T2 is crucial. Gender differences have to be taken into account when assessing effect of ESB by cold induced vasoconstriction. It remains to be established whether the quantification of vasoconstriction has some predictive value for the long-term prognosis of sudomotor blockade.