The Etiology of Primary Hyperhidrosis: A Systematic Review

Implications of the non-neuronal cholinergic system for therapeutic interventions of inflammatory skin diseases

The pivotal roles of acetylcholine (ACh) in physiological processes encompass both the nervous and non-neuronal cholinergic systems (NNCS). This review delineates the synthesis, release, receptor interactions, and degradation of ACh within the nervous system, and explores the NNCS in depth within skin cells including keratinocytes, endothelial cells, fibroblasts, macrophages, and other immune cells. We highlight the NNCS's essential functions in maintaining epidermal barrier integrity, promoting wound healing, regulating microcirculation, and modulating inflammatory responses. The potential of the NNCS as a therapeutic target for localized ACh regulation in the skin is discussed, though the translation of these findings into clinical practice remains uncertain due to the complexity of cholinergic signalling and the lack of comprehensive human studies. The review progresses to therapeutic modulation strategies of the NNCS, including AChE inhibitors, nicotinic and muscarinic receptor agonists and antagonists, choline uptake enhancers, and botulinum toxin, highlighting their relevance in dermatology. We highlight the impact of the NNCS on prevalent skin diseases such as psoriasis, atopic dermatitis, rosacea, acne, bullous diseases, hyperhidrosis and hypohidrosis, illustrating its significance in disease pathogenesis and therapy. This comprehensive overview aims to enhance understanding of the NNCS's role in skin health and disease, offering a foundation for future research and therapeutic innovation.

Infrared thermography in the diagnosis of palmar hyperhidrosis: A diagnostic study

Background

Primary hyperhidrosis is a common condition affecting 1-3% of the general population. Excessive sweating leads to reduced surface temperature due to evaporation that can be captured using a thermal camera. We performed this study to find the utility of thermography in the diagnosis of palmar hyperhidrosis.

Methods

This was a cross-sectional diagnostic study conducted in a tertiary care dermatology center during the study period Apr 20-Mar 21. Adult patients with palmar hyperhidrosis diagnosed by expert dermatologists were recruited. The severity was assessed using the hyperhidrosis disease severity scale (HDSS). The measurements were done using a FLIR™ thermal camera. A pilot study, including 30 patients and 30 controls were performed. The results of the pilot study were used for the calculation of sample size.

Result

The study included 55 patients and 110 controls. The mean age of the patients and controls was 22.4 (±3) years and 21.7 (±2.5) years, respectively. The mean temperature difference in the patient and control group was found to be 19.6 (±3.3)0 F and 5.8 (±2.9)0 F, respectively (p < 0.001). A receiver operating characteristics curve (ROC) to assess the discriminatory ability of mean temperature difference in diagnosis of hyperhidrosis found the area under the curve (AUC) to be 0.995 and a temperature difference of 11.5 °F provides sensitivity and specificity of 98.2% and 97.3% for the diagnosis of hyperhidrosis.

Conclusions

Thermal imaging is a simple, noninvasive, and objective tool for the diagnosis of hyperhidrosis. It has potential utility in monitoring the effect of the treatment.

Hyperhidrosis: A Central Nervous Dysfunction of Sweat Secretion

Hyperhidrosis (HH) is a central nervous dysfunction characterized by abnormally increased sweating due to a central dysregulation of sweat secretion. HH significantly affects the quality of life of patients in their private, social and professional environments. Physiologically, sweating is a mechanism that regulates body temperature, but it may also be triggered by emotional or gustatory stimuli. There are two main types of sweat glands: eccrine and apocrine glands. The central nervous system controls sweat secretion through the release of neurotransmitters into the autonomous nervous system (ANS) that activate the sweat glands. The hypothalamus has two separate neuronal pathways, one for thermoregulation and one for emotions. HH may thus be due to either a neuronal dysfunction of ANS regulation leading to a hyperactivity of the sympathetic nervous system, or to abnormal central processing of emotions. Crucially, there is no dysfunction of the sweat glands themselves. Various pathogenic mechanisms have been proposed to be involved in pathological sweat secretion in HH, ranging from structural changes within the ANS to increased expression of aquaporin 5 and upregulation of activin A receptor type 1 in eccrine sweat glands. Although a genetic predisposition has been demonstrated, it remains unclear exactly which genes are involved. To identify new, potential therapeutic targets and to improve treatment options, a good understanding of the signaling pathways involved, the underlying mechanisms, and the genetic components is essential. In this review we discuss the various aspects of sweat physiology and function that are necessary to explain pathological sweating. Our aim is to raise awareness of the complexity of HH to promote a better understanding of the disorder.

Antagonist of Chrna1 prevents the pathogenesis of primary focal hyperhidrosis

Background

Primary focal hyperhidrosis (PFH) is an autonomic neurological disease in which exocrine glands are oversecreted due to autonomic dysfunction of the sympathetic nervous system. Chrna1 promotes the pathogenesis of PFH. We aimed to check if downregulating of Chrna1 by cisatracurium could alleviate the symptoms of PFH.

Methods

The effect of cisatracurium in a hyperhidrosis mice model induced by pilocarpine hydrochloride was monitored for sweat gland secretion, and ultrastructural sweat secretory granules in sweat glands were analyzed. Meanwhile, markers of hyperhidrosis were checked, and release of Bdnf and Nrg1 from sympathetic ganglia axon was tested. Furthermore, the mechanism of cisatracurium function was evaluated in vitro using HEK293 expressing Chrna1. Finally, the effect of cisatracurium was determined in the hyperhidrosis mice model with overexpression or downregulation of Chrna1.

Results

In hyperhidrosis mice, pretreatment with cisatracurium effectively inhibited sweat secretion, along with fewer particle secretion in sweat glands. The molecular markers of hyperhidrosis (Aqp5 and Cacna1c) were inhibited by cisatracurium, acetylcholine (Ach) level in serum was found decreased. Neurotrophic factors (Bdnf and Nrg1) secreted by sympathetic axon activation were also inhibited. At last, it was confirmed that cisatracurium could not alter the gene or protein expression level of Chrna1, but could block the ion channel. Overexpression of Chrna1 abolished the effect of cisatracurium on hyperhidrosis, while cisatracurium could not function more in siChrna1‐treated mice.

Conclusion

Our results suggested that pretreatment of cisatracurium could alleviate hyperhidrosis in mice, probably through blocking the ion channel function of Chrna1.

Paeoniflorin inhibits proliferation and promotes autophagy and apoptosis of sweat gland cells

Axillary bromhidrosis is sweat excreted by apocrine glands in the armpits, mouth corners and other parts. The clinical manifestation includes excessive sweating and heavy odor, leading to the growth of bacteria and skin disease. The present study investigated the mechanism underlying the effect of paeoniflorin (PF) in the treatment of bromhidrosis. PF was injected into the feet of rats, and the foot skin was dissected for histological analysis. Primary human sweat gland cells (hSGCs) were isolated from patients with bromhidrosis. After 24 h treatment with PF or 3-methyladenine, the production of reactive oxygen species (ROS), autophagy, apoptosis, proliferation and cell cycle distribution were determined. PF induced nuclear pyknosis in rat SGCs. In vitro PF treatment inhibited cell proliferation with a 25% inhibitory concentration of 9.530 µM. Treatment with 9.530 µM PF for 24 h significantly increased apoptosis, ROS production and autophagy in hSGCs. PF promoted LC3B and Beclin 1 expression, but inhibited p62, phosphorylated (p)-PI3K and p-Akt expression. 3-methyladenine treatment reversed PF-induced changes in hSGCs. PF-induced inhibition of hSGC proliferation was associated with ROS production, apoptosis, and autophagy. These findings provide a basis for treating bromhidrosis.

Potential factors affecting chronic chemical intolerance associated with constitutional predisposition or lifestyle and environment during childhood: From a six-year follow-up study

OBJECTIVE

The Japanese chemical intolerance (JCI) study was conducted in January 2012 with a cohort of 7245 adults from population-based sampling. This study aimed to investigate the childhood constitutional and environmental factors involved in the development of chronic CI from the prospective cohort study.

METHODS

In the cohort, 4683 persons were identified after six years. Self-reported questionnaires were administered to the subjects to obtain information on CI status; medical history; constitution, lifestyle, and housing environment during childhood; and recent psychosomatic states. We assessed the differences between individuals with persisting CI status during the follow-up (defined as chronic CI) and controls not having CI status during the follow-up.

RESULTS

A total of 2500 individuals responded. Multiple logistic regression analyses revealed significant associations between chronic CI and motion sickness to car or bus and allergic conjunctivitis during childhood. Significant associations between a possible increased risk of CI and the existence of high-voltage power lines close to housing, the use of vinyl covering in wall material, the use of strong perfume by a family member, and the experience of stinky odor of paint or wax at elementary school were observed. However, the use of carpet in floor material and plaster coating in wall material was associated with a possible decreased risk of CI.

CONCLUSIONS

Some potential constitutional predisposition from childhood, including inherent susceptibility in the autonomic nervous system may be involved in the development of CI.

Retroperitoneoscopic lumbar sympathectomy for the treatment of primary plantar hyperhidrosis

Background

Primary plantar hyperhidrosis (PPH) is an idiopathic disease, characterized by excessive sweating of the feet. It leads to significant disturbance in private and professional daily lifestyle, due to excessive sweating. The aim of this study is to present the safety, efficacy and procedures of retroperitoneoscopic lumbar sympathectomy (RLS) for treatment of PPH.

Methods

RLS was performed 60 times in 30 patients (18 men, 12 women) with PPH in our institution from May 2019 to October 2020. All procedures were carried out by laparoscopy with retroperitoneal approach. Clinical data including patient demographics and perioperative, postoperative outcomes were evaluated. Recurrence of symptoms, and any adverse effects of surgery were evaluated after 7 to 30 days in outpatient clinic, and thereafter every 6 months.

Results

Mean age of patients was 33.6 (± standard deviation 10.8) years. Fourteen and fifteen patients were previously treated with medical therapy or endoscopic thoracic sympathectomy (ETS) respectively. Mean preoperative quality of life (QoL) score of patients was 91.8 (VERY BAD), but postoperative 12 months (QoL) score decreased to 29.1 (MUCH BETTER). There was no serious postoperative complication. During the mean 22 months of follow-up period, no compensatory sweating was observed.

Conclusions

RLS can be a safe and effective surgical treatment for severe PPH, especially for the patients with persistent plantar sweating even after conservative management and ETS. RLS also could be offered to surgeons who are familiar with retroperitoneal space anatomy as feasible surgical treatment for PPH.

Can thiol-disulfide balance be an indicator of oxidative stress for hyperhidrosis?

BACKGROUND

Hyperhidrosis is responsible for various causes. The increased reactive oxygen radical production with insufficient antioxidant mechanism capacity may play a role in the etiopathogenesis of hyperhidrosis. It is probable to gather data about oxidative stress by detecting plasma thiol/disulfide ratio. The aim of this study was to determine whether thiol-disulfide balance changes in patients with hyperhidrosis.

METHODS

The files of patients who were diagnosed with hyperhidrosis in the dermatology outpatient clinic between 2015 and 2018 and whose native thiol, total thiol, and disulfide values were examined for any reason were examined.

RESULTS

Seventy-three patients were included in the study. 33 of the patients with hyperhidrosis were primary. Mean age; for primary hyperhidrosis patients (PHH) = 26.36 ± 7.61, primary hyperhidrosis (PHH) control group = 27.16 ± 7.94; secondary hyperhidrosis (SHH) patients = 47.88 ± 12.29, SHH control (45.40 ± 12.02). The native thiol values of PHH (469.93 ± 56.82 μmol/L) were higher than SHH (440.64 ± 62.72) (p = 0.024). However, as a result of thiol-disulfide comparison between hyperhidrosis patients (PHH and SHH) and control groups, disulfide levels increased (p = 0.04). In the PHH group, total thiol was measured as 512 ± 54.84 μmol/L, and SHH was measured as 484.11 ± 58.9 μmol/L, (p = 0.074).

CONCLUSION

Serum thiol levels in SHH increased more than PHH. As a result of thiol-disulfide comparison between hyperhidrosis patients and control groups, the balance shifted in favor of disulfide and oxidative side.

Paroxysmal localized Hyperhidrosis, a case-report: When excessive sweating occurs in combination with severe headaches

BACKGROUND

Paroxysmal localized hyperhidrosis is a rare disorder of the central autonomic nervous system. No association between paroxysmal hyperhidrosis and severe headache has been previously described in literature.Case description: A 65-year-old woman with idiopathic paroxysmal localized hyperhidrosis combined with severe holocranial headache attacks is described in this case report. Extensive diagnostic testing by means of laboratory examinations, 24-hour urinalyses, chest X-ray, abdominal ultrasound and computed tomography scans, and brain and spinal cord magnetic resonance imaging could not identify an underlying disorder. A diagnosis of idiopathic paroxysmal localized hyperhidrosis was made, and the patient was successfully treated with clonidine 0.075 mg three times a day, without any side effects.

CONCLUSION

Paroxysmal localized hyperhidrosis is a rare central autonomic nervous system disorder that can occur in combination with severe headache. Both the headache and paroxysmal hyperhidrosis complaints were treated effectively with clonidine in the patient described in this case-report.

Moisture Response Films Versus the Starch Iodine Test for the Detection of Palmar Hyperhidrosis

BACKGROUND

The starch iodine test (SIT) is the gold-standard diagnostic tool for primary palmar hyperhidrosis (PPH).

OBJECTIVE

This study aimed to evaluate the clinical effectiveness and safety profile of a novel approach for the detection of PPH by moisture response films (MRF) in comparison to the SIT.

METHODS

This prospective comparative study of the 2 tests was conducted on 17 patients with PPH. Disease severity was evaluated by the SIT and the MRF methods during 4 sessions (twice before and twice after botulinum toxin [BTX] injections) on different days and by different investigators. The physician's global assessment (PGA) scoring of the comparable visual results was evaluated by 2 blinded independent dermatologists. The Hyperhidrosis Disease Severity Scale (HDSS) scores of the patients at baseline and after the BTX injections were correlated with the SIT and MRF results.

RESULTS

The objective PGA scoring of the SIT results demonstrated poor correlation, whereas the objective PGA scoring of the MRF results correlated highly with the patients' HDSS scores both at baseline and after the BTX injections.

CONCLUSION

Analysis of palmar hyperhidrosis by means of MRF was superior to SIT and was demonstrated to be more efficient, convenient, and accurate.

How to diagnose and measure primary hyperhidrosis: a systematic review of the literature

PURPOSE

Hyperhidrosis (i.e. excessive sweating) is diagnosed from patient medical history and physical examination. In addition, focal sweat measurements can substantiate the hyperhidrosis diagnosis. Likewise, the impact of living with hyperhidrosis can be assessed with patient-reported outcome measures. However, no consensus exists on how to diagnose hyperhidrosis, how to quantify the disease, or how to measure the impact hyperhidrosis has on patients. Therefore, the objective of this review was to summarize the literature on diagnostic criteria, focal sweat measurement methods, and patient-reported outcome measures of hyperhidrosis.

METHODS

A literature search of Cochrane Library, Embase, and PubMed was conducted. Studies that included and aimed at developing or validating hyperhidrosis diagnostic criteria, focal sweat measurement methods, or patient-reported outcome measures for individuals with hyperhidrosis were eligible for inclusion. The methodological quality of diagnostic accuracy studies about focal sweat measurement methods was determined using the Quality Assessment of Diagnostic Accuracy Studies-2.

RESULTS

Overall, 33 studies were included. We identified two sets of hyperhidrosis diagnostic criteria, one scale for assessment of severity of hyperhidrosis sweating, four focal sweat measurement methods, and 15 patient-reported outcome measures.

CONCLUSION

The algorithm for diagnosing hyperhidrosis and focal sweat measurement methods needs validation in large cohorts. Most patient-reported outcome measures for hyperhidrosis are not adequately validated. A potential solution is to develop a core outcome set that can standardize outcomes reported in clinical trials.

CHRNA1 promotes the pathogenesis of primary focal hyperhidrosis

The aim of the study was to elucidate the involvement of cholinergic receptor nicotinic alpha 1 subunit (CHRNA1) in the pathogenesis of primary focal hyperhidrosis (PFH). The hyperhidrosis mouse model was constructed using pilocarpine injection. The expression levels of CHRNA1 in sweat gland tissues of PFH patients and hyperhidrosis mice were compared using Western blots and quantitative real-time PCR (qRT-PCR) analyses. Sweat secretion in hyperhidrosis mice treated with small-interfering RNA (siRNA) targeting CHRNA1 (si-CHRNA1) or non-specific siRNA were compared. Sweat secretory granules in the sweat gland cells of hyperhidrosis mice were examined using transmission electron microscopy. The serum level of acetylcholine was measured using enzyme-linked immunosorbent assay, while markers associated with PFH, including Aquaporin 5 (AQP5) and Calcium Voltage-Gated Channel Subunit Alpha1 C (CACNA1C), were assessed using immunohistochemical assay and Western blots. Brain-derived neurotrophic factor (BDNF) and Neuregulin 1 (NRG-1) in sympathetic ganglia axons of hyperhidrosis mice were quantified using Western blots. CHRNA1 up-regulation is a characteristic of the sweat glands of PFH patients and Hyperhidrosis mice. Silencing CHRNA1 decreased sweat secretion and the number of sweat secretory granules of hyperhidrosis mice. Serum acetylcholine, as well as AQP5 and CACNA1C expression in the sweat glands, was reduced by siCHRNA1. BDNF1 and NRG-1 levels in the sympathetic ganglia axons were also attenuated by siCHRNA1 treatment. CHRNA1 up-regulation is a potential biomarker of PFH and downregulating CHRNA1 could alleviate the symptoms of PFH through inactivating the sympathetic system.

Symptoms of anxiety and depression in patients with primary hyperhidrosis and its association with the result of clinical treatment with oxybutynin

OBJECTIVES

Studies have identified correlations between the psychological characteristics of individuals with primary hyperhidrosis (HH), the degree of sweating, and the quality of life (QoL). This study aimed to evaluate the prevalence of anxiety and depression symptoms in patients with HH before and after oxybutynin treatment.

METHODS

Data were collected from 81 patients. Palmar or axillary HH was the most frequent complaint (84.0%). All patients were evaluated before the medication was prescribed and after five weeks of treatment. The Beck Depression Inventory and Beck Anxiety Inventory were used to evaluate depression and anxiety.

RESULTS

Improvement in HH occurred in 58 patients (71.6%), but there was no improvement in 23 patients (28.4%). The QoL before treatment in all patients was either "poor" or "very poor." Patients who experienced improvement in sweating rates also experienced a greater improvement in QoL than patients who did not experience improvement in sweating at the main site (87.9% vs. 34.7%) (p<0.001). A total of 19.7% of patients showed an improvement in their level of depression, and a total of 46.9% of patients exhibited improvements in their level of anxiety. A significant correlation was observed between sweating and anxiety (p=0.015).

CONCLUSION

Patients with HH who experienced improvements in sweating immediately after treatment with oxybutynin exhibited small improvements in their levels of depression and significant improvements in their levels of anxiety and QoL.

Primary hyperhidrosis prevalence and characteristics among medical students in Rio de Janeiro

Background

Hyperhidrosis is a pathological condition defined by excessive sweating beyond thermoregulatory physiological needs, which can cause substantial psychological impact and impairment of daily activities. Studies regarding its prevalence, however, are scarce and vary widely in their findings. The population of medical students is a particularly interesting subset for its recurring demand of physical contact during patient examination or procedures, and the potential for professional adversity. We aimed at furthering the comprehension of this disease prevalence and characteristics among medical students.

Methods

Questionnaires inquiring about the presence and characteristics of Primary Hyperhidrosis (PH) were applied through either written or digital means to all eligible medical students enrolled in three Medical Schools in the State of Rio de Janeiro who agreed to take part in the study. Demographic data regarding gender, ethnicity, current age, weight and height was collected in addition to clinical data (sweat site, age of onset, familial history, severity and previous treatments). Severity was evaluated through the Hyperhidrosis Disease Severity Scale (HDSS) and a symptoms survey.

Findings

Our response rate was roughly 1/3 of all eligible students (900/2700). PH prevalence was 20.56% (185/900). It was similar between men and women (23.08% and 19.41%, respectively) and strongly associated with family history of the disease (Prevalence Ratio of 4.27). Regarding ethnicity, of the total sample 73.78% (664/900) self-declared white, among which 19.28% (128/664) had PH. Mixed-race and other ethnicities encompassed 26.22% (236/900) of the sample, among which 24.15% (57/236) had PH. Most positive subjects (64.32%) presented associated forms of PH. Overall involvement of each site (both associated and isolated) was: 63.78% axillary, 50.81% palmar, 43.24% plantar, 20.54% craniofacial, 18.38% facial flushing and 2.16% gustatory sweating. Mean current age was 23.11(±4.04) years for PH patients, and age of onset was ≤18 years in 93.94% of cases. Regarding body mass index (BMI), 71.09% of PH patients had BMI<25kg/m² and only 4.69% presented BMI≥30kg/m², none ≥35kg/m². Some degree of life quality impairment was reported by 89.20% of PH patients, and 23.89% had HDSS 3 or 4 (moderate to severe).

Conclusions

PH prevalence among Rio de Janeiro medical students was 20.56%, similar between men and women, predominating associated presentations, axillary, palmar and plantar sites, strong familial history, age of onset before 18 years, and some degree of life impairment.

Investigation on aetiological factors in patients with hyperhidrosis

BACKGROUND

Hyperhidrosis is a condition where the amount of sweat released to skin surface increases due to the over-active eccrine sweat glands. Hyperhidrosis causes considerable psychosocial distress in affected people. It affects the quality of life and leads to social anxiety disorders.

AIMS

No study has been conducted in our country to investigate the epidemiological, clinical, and laboratory data of patients with hyperhidrosis. In this study, we aimed to retrospectively investigate the clinical and demographic characteristics, causes of sweating and laboratory findings in patients treated for hyperhidrosis at our outpatient clinic and to compare these data with the literature data.

MATERIALS AND METHODS

A retrospective review was conducted on medical records of patients diagnosed with and treated for hyperhidrosis at outpatient clinic between 2014 and 2017. Adults aged over 18 years were included in study. Age and gender of patients, type and localization of sweating, duration of disease, age of onset of sweating, presence of stress, fever, joint pain and comorbidity, family history, medication use, and examination results were recorded.

RESULTS

Records of a total of 70 patients consisting of 30 men and 40 women with hyperhidrosis were examined. Overall mean age was 37.1 years. Mean age was 41 years in women and 32 years in men. Most frequent forms were palmoplantar and axillary hyperhidrosis for primary hyperhidrosis (primary HH), and head-neck and generalized hyperhidrosis for secondary hyperhidrosis (secondary HH). Most common comorbidities were diabetes mellitus, thyroid disease, non-specific joint and bone pain, cardiovascular disease, and neuropsychiatric disease. Cases with secondary HH had a history of drug use (antithyroid drugs, nonsteroidal anti-inflammatory drugs, antidiabetic agents, antidepressants, and antihypertensives).

CONCLUSION

This is the first study that investigated the characteristics of patients with primary and secondary HH in our country. These characteristics can help determine the cause and apply treatment for hyperhidrosis by an appropriate examination and approach.