Sweat Dysfunction Research Articles

Interest of Sudoscan in the detection of diabetic peripheral neuropathy

Introduction: Disturbance of pain sensation is considered one of the major initial risk factors for diabetic foot ulcers. Sweat dysfunction leading to abnormal skin conditions, including dryness and fissures, may increase the risk of foot ulcer. The objective of this study was to evaluate the Sudoscan, a new rapid, non-invasive, quantitative method for early detection of diabetic peripheral neuropathy by measuring sweat electrical conduction (SEC). Patients and methods: We conducted this study on 85 type 2 diabetic patients. The data of the study were collected through a questionnaire, clinical examination (DN4, monofilament) and sudoscan for SEC. Results: We recruited 85 patients, the average age of the subjects was 58.32 ± 10.89 years. 77.6% were women and 22.4% were men. A significant proportion (67%) of our study population had a duration of diabetes of less than 10 years, Among 85 patients 40% had a positive DN4 and only 17.2% of the participants had a positive monofilamant test. 52.9% of the patients had a moderate dysfunction of the electrical conduction of sweat (SEC) and only 29.4% had a severe dysfunction, and 17.6% of the patients had a normal conduction we did not objectify a significant correlation between the sudoscan and the other tests notably the DN4 and the monofilament. Conclusion: The Sudoscan is a reproducible technique, with a high specificity, it is a simple test for the detection of neuropathy diabetic peripheral allowing an early prevention of foot lesions.

Sudomotor dysfunction in patients recovered from COVID-19

Dysautonomia has been reported in COVID-19. Sweat function testing has been proposed to assess autonomic neuropathy. Fifty Indian patients consulting for neurological symptoms participated in this observational study. The NHS questionnaire for neurological symptoms was completed and electrochemical skin conductance was measured using Sudoscan. The 26% of patients with sweat dysfunction i) were older (p = 0.001), ii) were more frequently treated at home (p = 0.008), iii) were more likely to have received antiviral treatment (p = 0.0006), and iv) more frequently reported at least one motor, sensory or autonomic symptom (p = 0.04). This preliminary study suggests that patients with COVID-19 should be screened for dysautonomia.

Assessment of Small C-Fiber Status for Screening of Oxidative Stress in Patients at Risk of Diabetes

Oxidized LDL (oxLDL), anti-oxLDL antibody (anti-oxLDL) and paraoxonase (PON1) are increasingly being reported to be associated with diabetic atherosclerosis. Oxidative stress could affect also small C-fibers innervating the sweat glands even in prediabetes. Hence it could be hypothesized that sweat dysfunction may be a predictor of oxidative stress status for early detection of diabetes. Ezscan, a new device, has recently been developed to measure the sweat function. Therefore, this study was aimed to determine the relevance of this Ezscan method to identify impairment in oxidative stress parameters. Plasma levels of oxLDL and anti-oxLDL were measured by enzyme immunoassay and ELISA respectively. Small C-fiber status was assessed by measurement of hand and foot sweat function with the help of Ezscan device and subsequent calculation of a risk score. Out of 82 subjects recruited in this study, 38 had impaired glucose tolerance and 6 had newly diagnosed diabetes mellitus. Ezscan risk score was significantly (p=0.004) correlated with oxLDL/anti-oxLDL ratio (0.32). Area under the curve (AUC) of receiver operating characteristics (ROC) analysis for detection of oxLDL/anti-oxLDL ratio (>0.12) was 0.76. For an Ezscan risk score of 50%, the sensitivity and specificity were 68% and 71% respectively. After adjustment for age and BMI, PON1 activity showed significant difference among the 3 risk groups defined by Ezscan risk score. Based on these results it may be concluded that Ezscan could be a useful screening tool in daily practice to assess alterations in oxidative stress parameters in individuals at risk of developing diabetes.

Small fiber neuropathy diagnosis by a non-invasive electrochemical method: mimicking the in-vivo responses by optimization of electrolytic cell parameters

Prevalence of type II diabetes and cardiometabolic diseases is increasing worldwide and early identification of their complications could reduce healthcare costs. An early complication of diabetes is small fiber neuropathy that can be diagnosed through assessment of sweat dysfunction. In this context, the Sudoscan™ technology developed by Impeto Medical provides early diagnosis, rapid and non-invasive analysis of sudomotor functions. This technology is based on measurements of skin current density via the imposition of low amplitude voltages (4 to 1.5V) between electrodes applied to the skin and measuring the low current generated. These electrodes are sensitive to the composition of the sweat produced by the eccrine glands when stimulated. To optimize the electrode materials and the diagnosis, a better insight into the origin of the electrochemical signals is needed by mimicking the in vivo results through the use of a model electrochemical cell reproducing physiological sweat conditions. In this paper, the electrode surface was modified with polymeric membranes to mimic the role of the filter of the skin and to get similar results to those obtained by Sudoscan™. Then, the composition of the electrolyte was changed by optimizing its viscosity to reduce the flow of Cl − ions to the electrode surface. The electrochemical behavior of the electrodes, measured in terms of current-voltage studied in artificial sweat, were compared to those of the Sudoscan™ technology.

Screening of Cardiovascular Autonomic Neuropathy in Patients with Diabetes by Quick and Simple Assessment of Sudomotor Function

Aims: Cardiovascular Autonomic Neuropathy (CAN) is a common but overlooked complication of diabetes. Sympathetic C-fibers innervating sweat glands can be impaired early in patients with diabetes. SUDOSCAN, a new and non-invasive device that assesses sudomotor function, was compared to Heart Rate Variability (HRV) and to Ewing tests, known to be reliable methods for the investigation of CAN. Methods: 232 patients with diabetes were measured for HRV at rest and during moderate activity (stair climbing). Time and frequency domain analysis techniques, including measurement of Standard Deviation of the average NN intervals over 5 minutes (SDNN), High Frequency domain component (HF) and Low Frequency domain component (LF), were assessed during HRV testing. Heart rate variations during deep breathing and heart rate and blood pressure responses while standing, as described by Ewing were also assessed. Electrochemical Sweat Conductance (ESC) was measured on the hands and feet, and a risk score was calculated. Patients were classified according to their risk score. The classifications were as follow: no sweat dysfunction, moderate sweat dysfunction and high sweat dysfunction. All results are means ± SD. Results: The highest correlation was observed between the risk score based on sudomotor function and the LF component during moderate activity (r = 0.47, p 405 ms 2 (3 rd quartile) (46 ± 13 vs 30 ± 13, p < 0.001). When taking the LF power component during moderate activity < 90 ms 2 as a reference value, the AUC of the ROC curve for the SUDOSCAN risk score was 0.77. Conclusions: SUDOSCAN allowing quick and quantitative assessment of sudomotor function can be used for the early screening of cardiovascular autonomic neuropathy in daily clinical practice before more sophisticated, specific, and time-consuming tests.

Non-invasive and quantitative assessment of sudomotor function for peripheral diabetic neuropathy evaluation

Aims Perturbation of pain sensation is considered one of the major initiating risk factors for diabetic foot ulcer. Sweat dysfunction leading to abnormal skin conditions, including dryness and fissures, can increase foot ulcer risk. The aim of this study was to evaluate Sudoscan™, a new, quick, non-invasive and quantitative method of measuring sudomotor dysfunction as a co-indicator of the severity of diabetic polyneuropathy (DPN). Methods A total of 142 diabetic patients (age 62 ± 18 years, diabetes duration 13 ± 14 years, HbA 1c 8.9 ± 2.5%) were measured for vibration perception threshold (VPT), using a biothesiometer, and for sudomotor dysfunction, using electrochemical sweat conductance (ESC) based on the electrochemical reaction between sweat chloride and electrodes in contact with the hands and feet. Retinopathy status was also assessed, as well as reproducibility between two ESC measurements and the effect of glycaemia levels. Results ESC measurements in the feet of patients showed a descending trend from 66 ± 17 μS to 43 ± 39 μS, corresponding to an ascending trend in VPT threshold from < 15 V to > 25 V ( P = 0.001). Correlation between VPT and ESC was −0.45 ( P < 0.0001). Foot ESC was lower in patients with fissures, while VPT was comparable. Both VPT and foot ESC correlated with retinopathy status. Bland–Altman plots indicated good reproducibility between two measurements, and between low and high glycaemia levels. Conclusion Sudoscan™ is a reproducible technique with results that are not influenced by blood glucose levels. Sweating status may be a quantitative indicator of the severity of polyneuropathy that may be useful for the early prevention of foot skin lesions.

Asymptomatic Autonomic and Sweat Dysfunction in Patients With Adie??s Syndrome

A study was conducted to determine by using noninvasive tests whether autonomic dysfunction occurs in patients with Adie's syndrome. Eighteen consecutive patients with Aide's syndrome prospectively underwent a standardized battery of five noninvasive tests of autonomic function, including three that predominantly reflected parasympathetic function and two that predominantly reflected sympathetic function. Eight of these patients additionally underwent thermoregulatory sweat testing. Of the 18 patients 10 (56%) had no abnormal autonomic test results, 5 (28%) had one abnormal result, 2 (11%) had two abnormal results, and 1 (6%) had three abnormal results. None of the patients had more than three abnormal results. Tests that predominantly reflected parasympathetic function produced abnormal results more frequently than those that predominantly reflected sympathetic function. Three of eight (38%) patients who underwent thermoregulatory sweat testing showed abnormal patterns of sweating. Although abnormal autonomic and sweat functions are not uncommon in patients with Aide's syndrome, the abnormalities are mild and are generally unassociated with symptoms of dysautonomia. Such abnormalities have little clinical significance but may be important from a nosologic point of view.

Naevus sudoriferus (local eccrine hyperhidrosis)

Naevus sudoriferus (local hyperhidrosis) or ephidrosis, in an 8-year-old girl is presented. The symptoms consisted of sweating in an area on the dorsal aspect of the right forearm and had been present for approximately 1 year. Episodes of hyperhidrosis occurred 2–4 times daily. The diagnosis was supported using the starch-iodine sweat test, which delineated the area of sweat dysfunction. The patient was treated topically with aluminium chloride solution.

Naevus sudoriferus (local eccrine hyperhidrosis)

AbstractNaevus sudoriferus (local hyperhidrosis) or ephidrosis, in an 8‐year‐old girl is presented. The symptoms consisted of sweating in an area on the dorsal aspect of the right forearm and had been present for approximately 1 year. Episodes of hyperhidrosis occurred 2–4 times daily. The diagnosis was supported using the starch‐iodine sweat test, which delineated the area of sweat dysfunction, The patient was treated topically with aluminium chloride solution.

Sudomotor functional dissection of neurodegenerative diseases

We performed a quantitative sudomotor function test using thermal stimulation (40°C) and thyrotropin-releasing hormone (TRH) in 14 patients with multiple system atrophy (MSA), 10 patients with Parkinson's disease (PD), 11 patients with amyotrophic lateral sclerosis (ALS) and in 11 age-matched control subjects. There was thermal sudomotor dysfunction in the lower extremities of the MSA patients. The PD patients failed to increase their local sweating and frequency of sweat expulsions with TRH infusion, in spite of the fact that they still had normal thermal sweating. ALS patients had mild thermoregulatory sweat dysfunction in their lower extremities. These results suggest that in MSA the lesion most responsible for sudomotor dysfunction is the intermediolateral column cells of the spinal cord and postganglionic sympathetic neurons. There may be an impairment of TRH-induced sympathetic responses in PD, and there is a mild postganglionic sympathetic lesion in the lower extremities of ALS patients.