SUDOSCAN, an Innovative, Simple and Non-Invasive Medical Device for Assessing Sudomotor Function

Children and Young Adults with Epilepsy Exhibit an Interictal Autonomic Dysfunction: A Prospective Exploratory Study

Dysautonomic disorders are an increasingly studied group of conditions, either as isolated diseases or associated with other neurological disorders. There is growing interest in understanding how dysautonomia affects people with epilepsy, who may report autonomic symptoms before, during and after seizures. Furthermore, autonomic abnormalities appear to play a role in sudden unexpected death in epilepsy, likely contributing to the increased mortality rate described in epilepsy. To better understand the association between epilepsy and dysautonomia, we explored electrochemical skin conductance in a group of 18 children and young adults with epilepsy compared to 15 age- and sex-matched healthy controls by the SudoscanTM test. We found a significant difference in terms of electrochemical skin conductance, suggesting that people with epilepsy suffer significantly reduced conductance in small nerve fibers. Within patients, values were significantly different according to the type of epilepsy and to neuroimaging results, with lower conductance values in epilepsies of unknown origin and in patients with morphological abnormalities of the brain. Using a non-invasive test, we identified altered conductance of small sympathetic nerve fibers in children and young adults with epilepsy, suggesting underlying dysautonomia. Further studies are needed to investigate this association and to clarify its neurobiological substrates.

Validating the usefulness of Sudoscan in ATTRv: a single centre experience

BACKGROUND

Variant transthyretin amyloidosis (ATTRv) can cause sensorimotor and autonomic neuropathy. Objective quantification of sudomotor function may be essential for early diagnosis and early initiation of treatment. The aim of this study is to evaluate the diagnostic value of the Sudoscan® in ATTRv.

METHODS

Electrochemical skin conductance (ESC) was measured in V30M ATTRv patients, asymtomatic V30M carriers and healthy controls. Comparisons between the three groups were made using the Kruskal-Wallis test, and ROC curves were used to estimate the discriminatory power of ESC values between groups.

RESULTS

ESC was measured in 52 ATTRv patients, 107 asymptomatic carriers and 40 healthy controls. ESC was significantly lower in ATTRv patients compared to asymptomatic carriers and healthy controls in both feet and hands; median values are as follows: 40 µS, 78 µS and 81 µS, respectively (p < 0.001), and 53 µS, 69 µS and 74 µS, respectively (p < 0.001). ESC in feet < 70.5 µS had a sensitivity of 89.7% and specificity of 84.6% to discriminate asymptomatic carriers from patients with ATTRv.

CONCLUSION

The determination of ESC by Sudoscan® is a rapid, noninvasive and easily reproducible technique capable of discriminating patients with ATTRv from asymptomatic carriers and healthy controls with adequate sensitivity and specificity.

Association of sudomotor dysfunction with risk of diabetic retinopathy in patients with type 2 diabetes

PURPOSE

Sudomotor dysfunction is considered as one of the earliest manifestations of diabetic peripheral neuropathy. We aimed to investigate the association between sudomotor dysfunction non-invasively detected by the SUDOSCAN device and diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

A total of 2010 patients admitted to a tertiary hospital located in Shanghai were included from March 2020 to September 2023. Sudomotor function was assessed by the SUDOSCAN device, and sudomotor dysfunction was defined as feet electrochemical skin conductance (FESC) <60 μs. Fundus radiography was used for DR assessment, which was graded according to the severity, specifically: (1) non-DR; (2) mild nonproliferative DR (NPDR); (3) moderate NPDR/vision-threatening DR (VTDR).

RESULTS

Among the enrolled 2010 patients, 525 patients had sudomotor dysfunction; 648 were diagnosed with DR, which was equivalent to 32.2% of all patients. Patients with sudomotor dysfunction had a significantly higher prevalence of DR, compared to those with normal sudomotor function (40.8% vs. 29.2%, P < 0.05). After controlling for confounding factors including HbA1c, sudomotor dysfunction was significantly associated with any DR (odd ratio [OR] = 1.57, 95% CI 1.26-1.96). When FESC was considered as a continuous variable, the multivariable-adjusted OR of DR was 1.29 (95% CI 1.17-1.42) for per 1-SD decrease in FESC. Furthermore, multinomial logistic regression revealed significant associations between sudomotor dysfunction and all stages of DR (mild NPDR: OR = 1.40, 95% CI 1.11-1.78; moderate NPDR/VTDR: OR = 2.35, 95% CI 1.60-3.46).

CONCLUSIONS

Sudomotor dysfunction was significantly associated with DR in patients with type 2 diabetes.

The Relationship between the Ewing Test, Sudoscan Cardiovascular Autonomic Neuropathy Score and Cardiovascular Risk Score Calculated with SCORE2-Diabetes

Background and Objectives: Cardiac autonomic neuropathy (CAN) is a severe complication of diabetes mellitus (DM) strongly linked to a nearly five-fold higher risk of cardiovascular mortality. Patients with Type 2 Diabetes Mellitus (T2DM) are a significant cohort in which these assessments have particular relevance to the increased cardiovascular risk inherent in the condition. Materials and Methods: This study aimed to explore the subtle correlation between the Ewing test, Sudoscan-cardiovascular autonomic neuropathy score, and cardiovascular risk calculated using SCORE 2 Diabetes in individuals with T2DM. The methodology involved detailed assessments including Sudoscan tests to evaluate sudomotor function and various cardiovascular reflex tests (CART). The cohort consisted of 211 patients diagnosed with T2DM with overweight or obesity without established ASCVD, aged between 40 to 69 years. Results: The prevalence of CAN in our group was 67.2%. In the study group, according SCORE2-Diabetes, four patients (1.9%) were classified with moderate cardiovascular risk, thirty-five (16.6%) with high risk, and one hundred seventy-two (81.5%) with very high cardiovascular risk. Conclusions: On multiple linear regression, the SCORE2-Diabetes algorithm remained significantly associated with Sudoscan CAN-score and Sudoscan Nephro-score and Ewing test score. Testing for the diagnosis of CAN in very high-risk patients should be performed because approximately 70% of them associate CAN. Increased cardiovascular risk is associated with sudomotor damage and that Sudoscan is an effective and non-invasive measure of identifying such risk.

Normal values of sudomotor function assessed by electrochemical skin conductance in African population

BACKGROUND

Dysfunction of small nerve fibers remains a major public health concern. Subjects suspected of having small nerve fiber damage need to undergo reliable tests to confirm the diagnosis. Sudomotor function test is a reliable noninvasive exploration for detecting peripheral neuropathies. Nevertheless, the normal reference values derived from the sudomotor function test are not known in the African population. The objective of this study was therefore to describe the normal values of Electrochemical Skin Conductance (ESC) measured by the sudomotor function test in healthy African subjects.

MATERIALS AND METHODS

Between December 1st, 2021 and May 31st, 2022, ESC was measured in 475 healthy subjects (median age: 42 [31-53] years, 46% men) using a sudomotor function test, in the hands and feet. Investigators proposed the examination and received participants' consent; demographic, anthropometric, biological, and clinical data were obtained before the test. Data on 475 healthy study participants who underwent sudomotor function testing was collected and analyzed. The sociodemographic (age, sex), anthropometric (weight, height, waist circumference, body mass index), diastolic blood pressure, systolic blood pressure, heart rate, and electrochemical skin conductances of the hands and feet were assessed.

RESULTS

ESC values were statistically higher in men compared to women (right hand ESC: 70 [60-78] versus 63 [53-72], left hand ESC: 72 [61-80] versus 68 [57-75], right foot ESC: 77 [82-99] versus 72 [64-79], ESC left foot: 76 [68-82] versus 72 [62-78] respectively). ESC values were significantly inversely correlated with age (right hand ESC: r=-0.12, P=0.006; left hand ESC: r=-0.11, P=0.01; right foot ESC: r=-0.37, P<0.0001; ESC left foot: r=-0.38, P<0.0001). ESC values measured in feet were significantly inversely correlated with body mass index (right foot r=-0.22, P<0.0001; left foot r=-0.21, P<0.0001).

CONCLUSION

This study reports normal reference values for ESCs according to age and gender in the healthy African population. Progressive decrease in ESC with aging is confirmed by our data. The value of ESC seems lower in the African population than in other reported ethnicities. This finding needs to be further explored in additional studies.

The Importance of Evaluating Sudomotor Function in the Diagnosis of Cardiac Autonomic Neuropathy

INTRODUCTION

 Cardiac autonomic neuropathy (CAN) is a disorder affecting the autonomic nerves that regulate the cardiovascular system, leading to irregular heart rate and blood pressure control. It is commonly associated with diabetes mellitus but can also result from other conditions such as autoimmune disorders, chronic kidney disease, alcohol abuse, and certain medications. Screening for CAN is essential, particularly in individuals with poor glycemic control, cardiovascular risk factors, or complications. Early identification of CAN is vital for timely intervention to prevent or manage cardiovascular complications effectively. Regular screening helps detect CAN before symptoms emerge, enabling early intervention to slow or halt its progression. This study examined the relationship between sudomotor function and cardiovascular reflex tests.

MATERIAL AND METHODS

 This was a cross-sectional study conducted between June 2019 and June 2020. The study included 271 subjects aged 18 years and above who provided informed consent, were diagnosed with type 2 diabetes mellitus (T2DM), and were overweight or obese. Exclusion criteria encompassed patients with other types of diabetes, pregnant women, those with recent neoplasm diagnoses, stroke sequelae, history of myocardial infarction, or pelvic limb amputations. The assessment of cardiac autonomic neuropathy involved conducting an electrocardiogram and evaluating the QTc interval in the morning before taking medication. Additionally, cardiovascular reflex tests (CART) were conducted, including assessments of heart rate variability during deep breathing, the Valsalva maneuver, and changes in orthostatic position. Simultaneously, the diagnosis of CAN was assessed by performing a sweat test using a Sudoscan assessment (Impeto Medical, Moulineaux, France).  Results: More than half of the participants (52%, n=143) were female. Significant differences in statistical measures were noted between females and males regarding age, systolic blood pressure, fasting blood glucose, A1c level, total cholesterol, triglycerides, gamma-glutamyl transferase, and bilirubin levels. Within the CAN-diagnosed group (CAN+), 40.92% were classified as mild cases (n=90), 47.27% as moderate cases (n=104), and 11.81% as severe cases (n=26). Among the CAN+ group, 54% (n=119) were women. Electrochemical skin conductance was lower in the CAN+ group than the CAN- group in hands (67.34±15.51 μS versus 72.38±12.12 μS, p=0.008) and feet (73.37±13.38 μS versus 82.84 ±10.29 μS, p<0.001). The Sudoscan-CAN score significantly correlated with Ewing scores (r= 0.522, p<0.001). In multiple linear regression analysis, the Sudoscan-CAN score remained significantly associated with age, high BMI, long-standing diabetes, and Ewing score.

CONCLUSIONS

 Sudoscan demonstrates potential in identifying patients with an increased risk of CAN. Its integration into clinical practice can improve patient outcomes through early detection, risk stratification, and personalized treatment approaches. Its non-invasive, portable, and user-friendly features render it suitable for utilization in outreach programs or resource-constrained settings as part of screening efforts designed to pinpoint high-risk individuals for additional assessment.

Validation of the Body Scan®, a new device to detect small fiber neuropathy by assessment of the sudomotor function: agreement with the Sudoscan®

Background

Sudomotor dysfunction is one of the earliest manifestations of small fiber neuropathy (SFN), reflecting the alteration of sympathetic C fiber innervation of the sweat glands. Among other techniques, such innervation can be assessed by measuring electrochemical skin conductance (ESC) in microsiemens (μS). In this study, ESC was measured at the feet to detect distal SFN. For this objective, the performance of a new device, the Body Scan® (Withings, France), intended for home use, was compared with that of a reference device, the Sudoscan® (Impeto Medical, France), which requires a hospital setting.

Methods

In patients with diabetes with or without neuropathy or non-diabetic patients with lower-limb neuropathy, the diagnostic performance of the Body Scan® measurement was assessed by calculating its sensitivity (Se) and specificity (Sp) to detect at least moderate SFN (Se70 and Sp70), defined by a value of feet ESC ≤ 70 μS and > 50 μS on the Sudoscan® measure, or severe SFN (Se50 and Sp50), defined by a value of feet ESC ≤ 50 μS on the Sudoscan® measure. The agreement between the two devices was assessed with the analysis of Bland-Altman plots, mean absolute error (MAE), and root mean squared error (RMSE) calculations. The repeatability of the measurements was also compared between the two devices.

Results

A total of 147 patients (52% men, mean age 59 years old, 76% diabetic) were included in the analysis. The sensitivity and specificity to detect at least moderate or severe SFN were: Se70 = 0.91 ([0.83, 0.96]), Sp70 = 0.97 ([0.88, 0.99]), Se50 = 0.91 ([0.80, 0.98]), and Sp50 = 0.99 ([0.94, 1]), respectively. The bias and 95% limits of agreement were 1.5 [-5.4, 8.4]. The MAE was 2.9 and the RMSE 3.8. The intra-sample variability was 2.0 for the Body Scan® and 2.3 for the Sudoscan®.

Conclusion

The ESC measurements provided by the Body Scan® were in almost perfect agreement with those provided by the reference device, the Sudoscan®, which validates the accuracy of the Body Scan® for the detection of SFN. By enabling simple, rapid, and autonomous use by the patient at home, this new technique will facilitate screening and monitoring of SFN in daily practice.

Clinical trial registration

ClinicalTrials.gov, identifier NCT05178459.

Circadian-like patterns in electrochemical skin conductance measured from home-based devices: a retrospective study

In this study, we investigated the potential of electrochemical skin conductance (ESC) measurements gathered from home-based devices to detect circadian-like patterns. We analyzed data from 43,284 individuals using the Withings Body Comp or Body Scan scales, which provide ESC measurements. Our results highlighted a circadian pattern of ESC values across different age groups and countries. Our findings suggest that home-based ESC measurements could be used to evaluate circadian rhythm disorders associated with neuropathies and contribute to a better understanding of their pathophysiology. However, further controlled studies are needed to confirm these results. This study highlights the potential of digital health devices to generate new scientific and medical knowledge.