This is the first study to examine the blood perfusion using LDF during ELS in patients with plantar hyperhidrosis. ELS is not only a complicated technique, especially with respect to difficulties in the localization at the retroperitoneal space with associated potential risks, such as sexual dysfunction, problematic bleeding, or invalid ablation, but there is also limited research on the monitoring techniques during ELS when compared with endoscopic thoracic sympathectomy in patients with palmar hyperhidrosis13,14. In this regard, we evaluated a real-time monitoring technique that would determine the exact target levels of the sympathetic trunks using LDF.
Based on our findings, intraoperative monitoring of skin blood flow via LDF revealed an increased mean percent change of PUs by 173.27 (195.48) and 392.98 (597.27) in the left and right sole during ELS, respectively. During the procedure, percutaneous blood flow decreased instantaneously after cauterization of the lumbar sympathetic chain, and increased abruptly right after the complete sympathectomy. As LDF represents a relative quantification of the microvascular circulation, as proportional to the flux of moving blood cells, our finding indicated that reflex vasoconstriction may occur with an increase in plantar blood flow by sympathetic ablation and subsequent vasodilator effect15–17.
Several studies found that sympathetic nervous system plays a key role in the management of vasomotor and sudotmotor activities of the skin, which is related to hyperhidrosis10,18,19. In the glabrous skin regions, such as plantar region, blockage of sympathetic outflow can lead the activation of arteriovenous anastomoses, where the sympathetic vasoconstrictor nerves innervate10. According to Eisenach JH et al., this substantial change in the sympathetic activity can explain the immediate change in blood perfusion of the palmar region during sympathetic denervation8. Our recent study showed a similar change in the perfusion of plantar region during ELS, suggesting that ELS may be considered as the surgical treatment for improving perfusion on the sole of feet in patients with plantar hyperhidrosis. Moreover, increased perfusion units measured by LDF can reflect a digital vasodilatory response as the therapeutic effects of systemic sclerosis with Raynaud’s phenomenon after nitroglycerin patch treatment20, and LDF can be used for objectively categorizing both the extent of microvascular circulatory impairment and treatment outcome in patients with thromboangiitis obliterans, known as Buerger’s disease21. This suggests that we can consider the increased perfusion of the plantar region observed by LDF during ELS as potential evidence that ELS may be effective in treating peripheral vascular diseases, such as SSc and TAO20–22.
There are several limitations to our study. First, due to the relatively small-sized sample from a single center, there can be unadjusted confounders or biases in our study. Second, we used values of percent change to estimate the percutaneous blood flow during ELS; however, we found considerable variation in the absolute values of perfusion units before and after ELS. This might lead to a detection bias; therefore, further studies are needed to adjust for any possible biases. Third, our study did not include therapeutic outcomes or compensatory hyperhidrosis as a complication of sympathectomy surgery. As the first investigation to evaluate LDF in plantar hyperhidrosis, we believe this study would lay the foundation for subsequent studies evaluating the efficacy of LDF in plantar hyperhidrosis.
In spite of these limitations, our observations also have several strengths. To the best of our knowledge, this is the first study to investigate the blood perfusion of anatomical distribution of sympathetic chain quantitatively and qualitatively during sympathectomy so that verify the potential efficacy of ELS for microvascular circulation in patients with plantar hyperhidrosis. Unlike endoscopic thoracic sympathectomy for palmar hyperhidrosis, which has been studied and proven through many studies, the efficacy of ELS for plantar hyperhidrosis remains unclear. Further randomized controlled trial investigations and larger-sized sample studies are needed to better understand the mechanism and prove the efficacy of ELS in plantar hyperhidrosis. Moreover, ELS is a very challenging surgery due to the retroperitoneal approach used in the procedure, and it is difficult for the surgeons to find the accurate anatomical site, which may cause plantar hyperhidrosis. In this aspect, our study shows that LDF can be considered as a useful intraoperative guiding tool for identification of the target nerve.
In conclusion, our study found that the perfusion units evaluated by LDF significantly increased during ELS in patients with plantar hyperhidrosis. This study demonstrates the efficacy of monitoring skin blood flow via LDF during ELS and suggests that appropriate monitoring of blood flow using LDF is useful for improving the accuracy of ELS by checking the perfusion site on the sole. Nonetheless, subsequent studies are needed to better understand the mechanism and further evaluate the efficacy of ELS in plantar hyperhidrosis.