Thoracoscopic sympathetic surgery is currently accepted to be the most effective and endurable therapeutic method for treating palmar hyperhidrosis. However, postoperative compensatory sweating (CS) after thoracoscopic sympathetic surgery remains a major issue.
The common hypothesis regarding CS suggests that this phenomenon involves a thermoregulatory mechanism in which the sweat glands compensate for decreased amounts of secretory tissues after sympathectomy . It has been reported that the total amount of body perspiration is not altered after sympathetic surgery, despite a reduction in hand sweat . Therefore, it is suggested that CS involves a redistribution of sweat from areas denervated by surgery to uninjured areas under sympathetic control. This hypothesis is simple; however, it does not explain the wide variation of CS. Another hypothesis is that CS is caused by a feedback mechanism in the hypothalamus. Afferent thermal information from different body parts is transmitted to the hypothalamus, which releases efferent signals to the sweat glands. Interruption of the sympathetic ganglia blocks negative feedback signals and amplifies efferent signals. These signals induce excessive sweat on the body except in sympathetically denervated areas . No theory can fully explain CS. However, based on these theories and the results of anatomical studies, various surgical methods have been attempted to manage CS.
One method is selective interruption of rami communicantes with preservation of the main trunk, first proposed and practiced by Wittmoser . This method by far causes the least interference with the sympathetic system. It does lower the incidence of compensatory sweating; however, it is associated with a higher incidence of recurrence than conventional resection. Approximately 5.0–23.5 % of patients who undergo this procedure experience persistent sweating on one or both hands, which prevents it from being widely accepted. However, Gossot et al.  compared a group of patients who underwent T2–T4 sympathectomy with a group of patients who underwent T2–T4 ramicotomy. No differences in the incidence of CS were noted, although the incidence of severe CS was higher in the sympathectomy group (27 vs. 13 %). The authors concluded that preservation of the sympathetic trunk is important to decrease the incidence of CS.
In patients with facial hyperhidrosis, T2 ramicotomy has been compared with T2 clipping,  and as expected, the incidence of CS is lower in patients who undergo T2 ramicotomy and the rate of operation failure is higher compared to T2 clipping. Other studies have compared two-level ramicotomy (T2–T3) and single level ramicotomy (T3) with sympathectomy . In those studies, CS occurred less frequently in the patients who underwent ramicotomy; however, the incidence of persistent postoperative sweating was relatively high.
Based on those results and the fact that T3,4 preganglionic fibers are considered to be the main lesions of hand sweating , we had adopted T3,4 ramicotomy to reduce the incidence and recurrence of CS. This method reduced the recurrence rate and increased the satisfaction rate compared to previous ramicotomy data (Table 4) [3–5, 12, 14].
Limited sympathicotomy is another method of reducing CS with a high success rate. During the last two decades, we also changed our strategy of treating palmar hyperhidrosis from sympathectomy (resection of sympathetic ganglion) to sympathicotomy to reduce CS and to preserve the T2 ganglion. It is known that preserving the T2 ganglion and performing resection more caudal to the T2 ganglion reduces CS [9, 15]. In our study, we adopted T3 sympathicotomy. T3 sympathicotomy requires shorter operation times and induces less injury to the pleura. Therefore, the incidence of complications is lower than that observed with ramicotomy. In this study, the patients who underwent sympathicotomy had better outcomes than those who underwent ramicotomy(Table 5) [6, 16, 17]. Recently, T4 sympathicotomy has been reported to be superior to T3 sympathicotomy, because it results in reduced CS and only slight hand moisture. The results are felt to be more natural by patients. In this study, we compared only T3 sympathicotomy patients to ramicotomy patients because we had recently adopted T4 sympathicotomy. Therefore, the number of cases available for comparison was small.
More than 80 % of the patients with palmar hyperhidrosis had associated plantar hyperhidrosis. Hsu et al. . reported that 64 % of patients with plantar hyperhidrosis are cured after undergoing T2 sympathectomy. Wolosker et al.  reported that 62.5 % of patients improve after 1 year. As time progresses, the satisfaction rates decrease. It is supposed that the worsening of plantar hyperhidrosis over time may be related to a return of the emotional stress that was initially lessened through the high degree of satisfaction obtained from the postoperative palmar anhidrosis. In these cases, no actual worsening of plantar sweating occurred. However, in our cases, compared with the T3 sympathicotomy group, the main reason for CS in the ramicotomy group was aggravated sweat on the lower legs. Increased sweat on the lower extremities after ramicotomy directly affected dissatisfaction in four patients (9.3 %) in our data.
Cho et al.  reported that lower extremity sweating occurs in 28 % of ramicotomy cases on the presumption that ramicotomy leaves the main trunk intact without disrupting sympathetic chains, while sympathicotomy interrupt sympathetic chains. Ironically, ramicotomy affects sweating on the soles more sensitively than the palms because feedback pathways are not interrupted. This might explain why more aggravated plantar sweating was observed in the ramicotomy group than in sympathicotomy group.
In conclusion, despite the potential advantages of treating hyperhidrosis with anatomic resection to provide natural postoperative conditions of adequately humid hands, ramicotomy shows two clear limitations: first, the two-level ramicotomy method results in a higher recurrence rate than T3 sympathicotomy and second, unexpected excessive sweating occurs on the lower extremities. Although the exact mechanisms have not been established, we suppose that this phenomenon is related to the preservation of the main sympathetic trunk. The unexpected lower extremity sweating that occurs following ramicotomy leads to lower levels of satisfaction compared with sympathicotomy.