J Thorac Cardiovasc Surg 2008;135:635-641
© 2008 The American Association for Thoracic Surgery
An objective assessment of the sudomotor response after thoracoscopic sympathectomy
Pramod Bonde, MD, MS, FRCSa,*,
Nnamdi Nwaejike, MD, MRCS(Irel)a,
Colin Fullerton, PhDb,
Judith Allen, PhDb,
James Mcguigan, MD, FRCSa
a Department of Cardiothoracic Surgery, Royal Victoria Hospital, Belfast, UK
b Department of Physiology, Queens University of Belfast, Belfast, UK
Received for publication October 13, 2006; revisions received November 16, 2007; accepted for publication November 26, 2007.
* Address for reprints: Pramod Bonde, MD, MS, FRCS, Royal Victoria Hospital, Grosvenor Rd, Belfast, BT12 6BA UK. (Email: prambond{at}hotmail.com).
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Abstract
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Objective: Thoracoscopic sympathectomy has become an accepted therapeutic option for palmar hyperhidrosis. Objective assessment of sweat output after sympathectomy, however, has not been reported to date. We report for the first time sweat output measurements after sympathectomy during a 3-year postoperative period.
Methods: Thoracoscopic sympathectomy was performed by division of T2 and T3 sympathetic ganglia in 17 healthy adult patients with no comorbidities. Preoperative and postoperative sweat measurements were done at 29°C (below sweat threshold, at baseline, after conversation, and after a mental arithmetic challenge) and at 40°C (baseline and after exercise) with the ventilated capsule technique in left palm, sole, and chest wall. Serial postoperative measurements were conducted at 1 and 6 months and 1, 2, and 3 years.
Results: Sweat output fell significantly after sympathectomy relative to preoperative levels under all experimental conditions (P < .001, analysis of variance) in the left palm. Differences in sweat outputs in the left palm were statistically significant between groups at baseline and postoperatively after mental arithmetic challenge and exercise at 40°C (P < .05, analysis of variance). Compensatory increases in the sweat outputs from the left sole and chest were observed after sympathectomy. No patients had recurrence of preoperative sweat output values at follow-up.
Conclusion: According to objective sweat output measurements, thoracoscopic sympathectomy results in long-term control of palmar hyperhidrosis. This evaluation method is valuable in investigating recurrence of symptoms or compensatory hyperhidrosis after sympathectomy, providing a robust and objective criterion for planning intervention.
Abbreviations and Acronyms MA = mental arithmetic
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Introduction
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Thermoregulatory mechanisms in human beings involve heat loss through sweat production by the eccrine gland, which is mediated through the sympathetic system. Primary palmar hyperhidrosis is excessive sweating, above that necessary for normal thermoregulatory mechanisms. Palmar hyperhidrosis, although of minimal medical significance, can be restrictive socially and in the workplace. Thoracoscopic sympathectomy has been proved to be of benefit, with immediate amelioration of symptoms; however, this benefit is frequently offset by troublesome compensatory hyperhidrosis from the trunk and lower extremities.
Several investigators have reported excellent long-term results, with improved subjective satisfaction reported by patients.1,2
An objective assessment of sweat output after sympathectomy could assist in investigating the mechanisms of compensatory sweating as well as provide a research tool to determine the level of sympatholysis potentially needed to prevent complications associated with thoracoscopic sympathectomy. In this investigation, our aim was objective assessment of sweat outputs after sympathectomy.
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Materials and Methods
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Institutional review board approval was granted for this study. Consecutive patients admitted for planned thoracoscopic sympathectomy with no comorbidities were counseled, and written consent was obtained from those who elected to participate. Only patients with primary palmar hyperhidrosis were included in this study. We excluded any patients who had peripheral vascular disease, were older than 40 years, were undergoing reoperative sympathectomy, were unable to complete the study as a result of noncompliance, or had any surgical complications needing additional treatment.
Thoracoscopic Sympathectomy
The preoperative, perioperative, and postoperative care regimens were identical for all patients. Patients were intubated with a double-lumen endotracheal tube. Thoracoscopic sympathectomy was performed through two 5-mm ports, and carbon dioxide insufflation was used to achieve partial lung collapse. Thoracic sympathetic ganglia over the second and third ribs were divided, with an extension laterally over the second rib to include division of accessory pathways by means of diathermy. The procedure was repeated on the other side after reinflation of the contralateral lung under visual guidance.
Pretesting Preparation
All patients wore cotton surgical gowns in a heat chamber at 29°C (just below thermal sweating threshold). Patients rested for 30 minutes in a supine position for equilibration to environmental temperature. During this time, sweat capsules were attached to both palms, anterior chest wall, and left sole of the foot.
Sweat output was measured by a ventilated capsule technique3 (
Figure 1). The gas content that perfuses over the skin under the capsule is measured. This technique calculates sweat output in micrograms per square centimeter of skin per minute. The protocol was similar for preoperative and all postoperative visits. The total duration of each study was approximately 3 hours. Vascular measurements were estimated from finger blood flow measured at rest (finger at temperature of 32°C), responses to sympathetic vasoconstrictor stimuli, and finger systolic pressure before and after provocative cold testing for vasospasm. Vascular measurements were performed to rule out any vascular phenomena. Any patients who showed positive signs of vasospasm were excluded, and the protocol was terminated.
Sweat Measurements
Three readings for each minute were noted. In addition, readings of sweat output were measured at peak stimulation during various experimental conditions. The peak values were subsequently analyzed.
Stimuli and Measurements
Baseline (29°C)
The baseline measurement was obtained after equilibrium, with a chamber temperature of 29°C. This was done after the subject had been left undisturbed for 5 minutes. Then sweat measurements were done for 5 minutes, with three recordings for each minute for 15 minutes. The mean value was chosen to represent the baseline sweat output.
Verbal stimulus (29°C)
A conversation was initiated about the subject's condition and continued for 2 minutes, with three measurements obtained during each minute. The mean value was chosen as the best response to verbal stimulus.
Mental arithmetic challenge (29°C)
After verbal stimulus measurements, 5 minutes of resting recordings were made. Values for the last minute acted as controls for mental arithmetic (MA) mean. The subject was given simple arithmetic problems to solve; complexity of the problems was altered through time. Increasing pressure was put on the subject to obtain a solution within the specified, time with constant reminders of the time elapsed and a gentle but constant reprimand for the time taken to perform the calculations. Five minutes was given for the challenge, with three readings each minute; and means for fourth and fifth minutes and the overall peak were considered to represent the MA value. After this, 5 minutes was allowed for recovery. Although values during the recovery time were continuously recorded, they were not analyzed.
Thermal stimulus (40°C)
The temperature in the chamber was then raised to 40°C gradually during 10 minutes. Sweat measurements (three per minute for the last minute of every 5-minute interval) were undertaken for as long as 35 minutes at 40°C. Measurements were then made at a rate of three per minute for the remaining time to 40 minutes at 40°C, and an overall peak for the entire 40-minute period minutes was taken as the thermal stimulus mean value.
Exercise (40°C)
Step exercise was explained to the subject. Briefly, the subject stood up with the sole and right palm disconnected and exercised for 2 minutes in time to a metronome. Three values and a mean for each minute plus the overall peak were recorded.
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Results
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Reproducibility tests were conducted on 13 healthy subjects (controls). There were 7 female and 6 male control subjects (mean age 27 ± 8 years, range 18–46 years). The control subjects had no history of hyperhidrosis, and their mean sweat outputs were plotted to show the variation with time for the stimulus conditions (
Figure 2).
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Figure 2. Control subjects. Under similar experimental conditions, 13 healthy volunteers were subjected to various stimuli with mean sweat outputs from left palm measured at intervals under various conditions. Baseline, No extraneous stimuli at temperature of 29°C; Peak Chat, verbal stimulus at 29°C; Thermal, temperature increase to 40°C; peak exercise, exercise challenge at 40°C.
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Seventeen subjects underwent thoracoscopic sympathectomy in this study. All subjects completed the preoperative, 1-week, and 1-month postoperative measurements, with additional follow-up to 6 months (n = 13), 1 year (n = 10), 2 years (n = 9), and 3 years or more (n = 6). Subjects were all healthy adults between the ages of 20 and 30 years. None of the patients had any postoperative complications, and all were discharged on the day after the procedure. All reported subjective improvement after the procedure, with clinical examination confirming dry, warm hands.
The sweat outputs from both palmar surfaces were equal. For simplicity and clarity, the left palmar sweat output is presented here for all observations.
Preoperative Sweat Output
Preoperative sweat outputs from the left palmar surface were as follows: at baseline, 215 µg/(cm2 · min) (range 37–1070 µg/[cm2 · min]); under verbal stimulus, 555.7 µg/(cm2 · min) (range 59–1708 µg/[cm2 · min]); after MA, 877 µg/(cm2 · min) (range 207–1899 µg/[cm2 · min]); after thermal stimulus, 1017 µg/(cm2 · min) (range 390–1870 µg/[cm2 · min]); and after exercise, 1289 µg/(cm2 · min) (range 425–2098 µg/[cm2 · min];
Figure 3).
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Figure 3. Preoperative sweat outputs from left palm in response to various stimuli. Baseline, No extraneous stimuli at temperature of 29°C; Verbal, verbal stimulus at 29°C; MA, mental arithmetic challenge at 29°C; Temp, temperature increase to 40°C; Exercise, exercise challenge at 40°C.
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Postoperative Sweat Output
Sweat outputs from the palmar surfaces fell sharply relative to preoperative levels (analysis of variance, P < .01) under all experimental conditions. The baseline values were as follows: 1 month, 66.2 ± 27.8 µg/(cm2 · min); 6 months, 71.3 ± 31 µg/(cm2 · min); 1 year, 62.9 ± 27.1 µg/(cm2 · min); 2 years, 76.3 ± 26.2 µg/(cm2 · min); and 3 years, 86.1 ± 26.2 µg/(cm2 · min). The postoperative response to stimuli was characterized by sweat production less than 200 µg/(cm2 · min) under all experimental conditions, irrespective of the nature of stimuli. The effect of the thoracoscopic sympathectomy was evident even at 3 years when serially measured (
Figure 4).
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Figure 4. Sweat outputs from left palm in response to different stimuli. Reduction in sweat outputs after sympathectomy in response to different stimuli. Baseline, No extraneous stimuli at temperature of 29°C; Peak Chat, verbal stimulus at 29°C; Thermal, temperature increase to 40°C; peak exercise, exercise challenge at 40°C.
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Compensatory Sweat Output from Chest and Feet
There were compensatory rises in sweat outputs from the anterior chest noted with MA, with temperature rise, and after exercise (
Figure 5). There was no difference noted between preoperative and postoperative values under baseline conditions and after verbal stimulus. The compensatory sweat outputs returned to preoperative levels by 6 months for MA and temperature rise and stayed such for 2 years. After 2 years, there were significant rises in compensatory sweating under these experimental conditions relative to preoperative values. Compensatory sweat output from the anterior chest wall after exercise was considerably higher and took a year to reach the baseline; after reaching the preoperative level, however, it also showed a rise from 2 years after the procedure and was significantly higher than the preoperative level.
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Figure 5. Compensatory outputs from chest. Changes in sweat outputs from chest (as indicator of axillary sweating) with time after sympathectomy. Baseline, No extraneous stimuli at temperature of 29°C; Peak Chat, verbal stimulus at 29°C; MA, mental arithmetic challenge at 29°C; 40°C, temperature increase to 40°C; Exercise, exercise challenge at 40°C.
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There was no compensatory sweat output from the feet except under thermal stimulation in the early postoperative period (
Figure 6). Sweat production showed a decreasing trend in the 2-year postoperative period, during which the actual values under experimental conditions fell below the preoperative levels. After 2 years, however, this sympatholytic effect was lost, with increasing sweat outputs noted under all the experimental conditions.
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Figure 6. Compensatory output from left sole. Changes in sweat outputs from left sole with time after sympathectomy. Baseline, No extraneous stimuli at temperature of 29°C; Chat, verbal stimulus at 29°C; MA, mental arithmetic challenge at 29°C; Temp, temperature increase to 40°C.
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Discussion
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This study shows that the efficacy of thoracoscopic sympathectomy for primary palmar hyperhidrosis can be assessed objectively. We have also demonstrated objective measurements of compensatory hyperhidrosis and how this varies with mental stress (MA), temperature, and exercise. Another aspect, one that is seldom mentioned by patients or reported in literature, is the reduced sweating from the feet after thoracoscopic sympathectomy for palmar hyperhidrosis that was noted in this study.
Several recent reports and a detailed review have claimed excellent results after thoracoscopic sympathectomy.1,2,4 Only one report, however, has examined actual sweat output measurements at 3-month intervals to study the effect of thoracoscopic sympathectomy.5 One consistently reported drawback of this procedure is compensatory hyperhidrosis.4,6
Published reports have tended to use patient satisfaction surveys or quality of life indicators to assess the postoperative outcome after sympathectomy for various indications. On the basis of these reports, several attempts have been made to modify the extent of resection of the sympathetic ganglia to abolish or diminish compensatory hyperhidrosis.7 Patient satisfaction can be based on various factors, however—including the duration of symptoms, severity of symptoms, extent and distribution of sweating patterns, previous interventions, and postoperative outcome—and may be variable vary from patient to patient. Compensatory hyperhidrosis also depends on geography, climate, seasonal variations, occupational factors, psychologic state of the patient, and the specific stimuli that may lead to symptoms.
This study showed significant reductions after thoracic sympathectomy in sweat production on the palmar surface under all experimental conditions. The experimental conditions were designed to simulate stressful situations and encourage excess sweating. Postprocedure, baseline, and verbal stimulation measurements did not show alteration in the severity of compensatory hyperhidrosis. There was, however, increasing compensatory hyperhidrosis noted with mental stress (MA), with thermal stimulation, and after exercise; this may be due to the body's initial attempt to maintain adequate thermoregulatory balance in the absence of the reduced or abolished palmar hidrosis by surgery. The initial compensatory hyperhidrosis pattern returned to baseline 6 months after the procedure, as was reported in many earlier studies.1 This effect eventually disappeared, however, and there was increasing compensatory hyperhidrosis observed after 2 years. This effect may be unrelated to the original division of the ganglia and may reflect either regrowth or activation of other compensatory sympathetic pathways that affect the thermoregulatory mechanisms in the upper part of the body. Such increases were not noticed when the actual sweat productions from the palms were measured during this period.
Sweat production from the lower limbs was noted to be significantly lower than preoperative values, and this decrease continued for 2 years. Interestingly, observed values eventually returned to preoperative levels under all experimental conditions. Although the lower limbs are supplied by T10 to L2 sympathetic ganglia, there appear to be preganglionic fibers in the T2 and T3 (divided sympathetic ganglia) that may contribute to the synapses in the lower (T10–L2) sympathetic ganglia, although this study is unable to prove this assumption conclusively.
In conclusion, these findings demonstrate that thoracoscopic sympathectomy results in long-term control of primary palmar hyperhidrosis. The actual measurement of sweat output is valuable in quantifying preoperative severity and in investigating recurrence of symptoms or onset of compensatory hyperhidrosis following sympathectomy. Such evaluation provides robust and objective criteria for planning intervention and postoperative lifestyle modifications that may reduce the severity of compensatory hyperhidrosis.
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Footnotes
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Read at the Eighty-seventh Annual Meeting of The American Association for Thoracic Surgery, Washington, DC, May 5–9, 2007.
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References
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- Dumont P, Denoyer A, Robin P. Long-term results of thoracoscopic sympathectomy for hyperhydrosis. Ann Thorac Surg 2004;78:1801-1807.[Abstract/Free Full Text]
- Kwong KF, Cooper LB, Bennet LA, Burrows W, Gamliel Z, Krasna MJ. Clinical experience in 397 consecutive thoracoscopic sympathectomies. Ann Thorac Surg 2005;80:1063-1066.[Abstract/Free Full Text]
- Brengelmann G, McKeag M, Rowell L. Use of dewpoint detection for quantitative measurement of sweating rate. J Appl Physiol 1975;39498-50.
- Ojimba TA, Cameron AE. Drawbacks of endoscopic thoracic sympathectomy. Br J Surg 2004;91:264-269.[Medline]
- Schick CH, Fronek K, Birklein F, Hohenberger W, Schmelz M. Differential effects of surgical sympathetic block on sudomotor and vasoconstrictor function. Neurology 2003;60:1770-1776.[Abstract/Free Full Text]
- Hashmonai M, Kopelman D. The pathophysiology of cervical and upper thoracic sympathetic surgery. Clin Auton Res 2003;13(Suppl. 1):140-144.
- Hashmonai M, Assalia A, Kopelman D. Thoracoscopic sympathectomy for palmar hyperhidrosis. Ablate or resect?. Surg Endosc 2001;15:435-441.[Medline]
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J. Thorac. Cardiovasc. Surg. 2008 135: 640-641.
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Abstract
Introduction
