ETS is an established surgical treatment for focal hyperhidrosis, the condition in which the palms, armpits, or face sweat excessively, and it is also offered for refractory facial blushing. During the procedure, a surgeon inserts a thoracoscope through small incisions and interrupts the thoracic sympathetic chain, typically at spinal levels T2 to T4, using cauterization, resection, or titanium clips. The interruption abolishes the overactive sweating signals traveling to the target region, and most patients enjoy immediate and durable dryness where it matters most to them. But the sympathetic trunk is not a set of isolated wires serving single destinations. It is a longitudinally interconnected conduit carrying afferent and efferent signals between the brain, spinal cord, and virtually every organ below the neck, and the new study argues that cutting it inevitably perturbs far more than sweat glands in the hands.

The research team, led by surgeons at Linkou Chang Gung Memorial Hospital in Taiwan, developed a dedicated instrument called the Chang Gung Sympathetic Function Questionnaire to capture this broader picture. The 60-item survey rates each symptom on a 0 to 10 numeric scale, allowing respondents to classify complaints as none, mild, moderate, or severe, with scores of 8 or above counted as severe. Before deploying it, the team validated the questionnaire psychometrically: internal consistency was excellent across all domains, with Cronbach’s alpha values between 0.89 and 0.96, sampling adequacy was high, and exploratory factor analysis confirmed that the items clustered into the four theoretical domains the researchers had predicted, explaining 65 to 81 percent of total variance. The survey was distributed anonymously in English and Mandarin through closed online communities dedicated to hyperhidrosis support between April and August 2025.

The most striking finding concerned compensatory sweating, the phenomenon in which the body, deprived of its ability to sweat in the denervated upper regions, redirects sweat output to areas below the neck. More than 80 percent of ETS patients reported compensatory sweating in the chest, back, abdomen, buttocks, thighs, calves, or feet, and in multiple regions the severity reached the severe threshold in more than 40 percent of patients. The data also revealed that this burden grows with time: chest sweating severity correlated moderately with postoperative duration, and receiver operating characteristic analysis identified a cutoff of roughly 16.75 years after surgery as the point at which severe chest sweating became most predictable. In other words, the longer patients live with the operation, the more likely their compensatory sweating is to become disabling.

Beyond sweating, the survey documented a constellation of vascular and sensory disturbances that few patients are warned about. Facial, hand, and foot blushing were reported by 43 to 53 percent of ETS patients, compared with 15 to 29 percent of controls, suggesting persistent vasomotor dysregulation. Erythromelalgia, a condition marked by burning redness in the extremities, was present in 40 percent of patients versus 11.3 percent of controls. Hand and foot paresthesia, abnormal tingling sensations, were both more frequent and more severe after surgery, and skin complaints including itchiness, dermatitis, and discoloration were consistently worse. The researchers attribute these changes to the loss of sympathetic vasoconstrictor tone in cutaneous arterioles, which destabilizes blood flow regulation and microcirculation rather than merely drying the skin.

Perhaps the most provocative results concern the brain. After compensatory sweating, the central nervous system was the most frequently affected system in the survey. ETS patients reported markedly higher severity of cognitive complaints, including inattention, memory loss, brain fog, and a disturbing sense of loss of reality, along with affective symptoms such as anxiety, depression, loss of motivation, loss of interest, tiredness, and insomnia. For several of these items, severe ratings of 8 or above occurred in more than 30 percent of patients. Notably, some symptoms, such as sound sensitivity and tiredness, showed similar prevalence in both groups but significantly greater severity among ETS patients, suggesting that the surgery intensifies underlying central dysregulation rather than creating new symptoms from nothing.

The study offers a physiologically coherent explanation for these neuropsychological effects. The sympathetic nervous system governs arousal, vigilance, and emotional modulation, and surgical interruption of the thoracic chain alters the afferent feedback reaching the central autonomic network, a distributed set of cortical and subcortical structures including the insula, anterior cingulate cortex, amygdala, hypothalamus, and brainstem nuclei that integrates visceral signals and balances sympathetic and parasympathetic output. Physiological studies have documented parasympathetic predominance and reduced sympathetic drive after ETS, visible in heart rate variability and baroreflex sensitivity, supporting the idea of a systemic autonomic shift rather than an isolated peripheral denervation. In this framework, brain fog and mood disturbance after ETS are not imagined side effects but plausible consequences of rewiring the body’s stress and arousal circuitry.

The systemic reach of the surgery extended to the viscera as well. Cardiorespiratory complaints, including palpitations, shortness of breath, chest tightness, and chest tingling, were significantly more frequent and severe among ETS patients, each affecting more than half of respondents. Gastrointestinal symptoms such as heartburn, diarrhea, nausea, and indigestion were also elevated, consistent with the disruption of splanchnic sympathetic pathways that connect thoracic ganglia to the abdominal organs. Urogenital disturbances, particularly difficulty urinating and incomplete bladder emptying, increased markedly. Interestingly, a few symptoms moved in the opposite direction: dysmenorrhea and irregular menstrual cycles were less common in the ETS group, and shoulder and neck pain was less prevalent, though the authors caution that the ETS cohort was 70.4 percent male versus 10.1 percent of controls, so some of these apparent reductions likely reflect demographic imbalance rather than genuine protection.

The clinical implications are significant. The authors argue that the breadth of these findings supports more selective surgical techniques, such as limited ganglion resection or rami-only procedures, even though these carry a higher risk of hyperhidrosis recurrence. For patients already suffering severe complications, sympathetic trunk reconstruction, in which sural nerve or intercostal nerve grafts are used to restore continuity across the surgical gap, has emerged as the most definitive reversal option, and the Chang Gung team has pioneered robot-assisted microsurgical versions of this procedure with preliminary improvements in compensatory sweating and systemic symptoms. But reconstruction is complex surgery in its own right, and no pharmacologic or minimally invasive treatment currently exists that reliably reverses the systemic complications of ETS.

The study has limitations that temper but do not erase its message. Its cross-sectional design cannot prove causation, surgical details such as the exact level and extent of sympathectomy were self-reported and often incomplete, and recruitment through online hyperhidrosis communities may have overrepresented dissatisfied patients, potentially inflating symptom prevalence. The questionnaire has not yet been externally validated in independent cohorts, and no objective autonomic testing was performed. Even so, the sheer consistency of the signal across four symptom domains, measured against a validated instrument and a control group, makes a compelling case that ETS is not the localized procedure it is often portrayed to be. As the authors conclude, the operation produces global dysregulation of sympathetic control, and patients deserve preoperative counseling that reflects the true, multisystemic scope of what they are signing up for.

Subject of Research: Systemic adverse effects of endoscopic thoracic sympathectomy for hyperhidrosis

Article Title: The systemic adverse effects of endoscopic thoracic sympathectomy are underrecognized: a questionnaire-based study

Article References: Sung, C. W.-H., Chen, L. W.-Y., Lee, C.-H., Lu, J. C.-Y., Huang, J.-J., Chao, Y.-K., Chuang, D. C.-C., & Chang, T. N.-J. (2025). The systemic adverse effects of endoscopic thoracic sympathectomy are underrecognized: a questionnaire-based study. BMC Plastic and Reconstructive Surgery, 1(1), Article 7. https://doi.org/10.1186/s44452-025-00007-3

Image Credits: AI Generated

DOI: 10.1186/s44452-025-00007-3

Keywords: endoscopic thoracic sympathectomy, hyperhidrosis, compensatory sweating, autonomic nervous system, sympathetic chain, brain fog, vasomotor dysregulation, questionnaire study, sympathetic trunk reconstruction, patient counseling, central autonomic network, surgical complications