IN YOUR PRACTICE
As a healthcare professional, incorporating SUDOSCAN® into your practice can provide significant benefits in managing patients with diabetes and other conditions that can lead to neuropathies.
The non-invasive procedure assesses the function of small nerve fibers innervating sweat glands, allowing for early detection and monitoring of neuropathies caused by diabetes complications.
What is SUDOSCAN®?
The SUDOSCAN® device is a revolutionary and cutting-edge technology that utilizes a simple and non-invasive approach to detect and monitor small fiber neuropathy. Traditional tools are often unable to detect these neuropathies, but with SUDOSCAN®, they can be easily detected and tracked. This innovative device provides a unique solution for physicians to accurately diagnose and monitor small fiber neuropathy in their patients.
How to use SUDOSCAN®?
SUDOSCAN is a user-friendly and non-invasive medical device that measures sudomotor function through sweat gland activity. To use the device, the patient places their hands and feet on the designated sensors, and a small electrical current is applied to stimulate the sweat glands. The device then measures the conductance of the sweat on the palms of the hands and soles of the feet, which is linked to the status of small nerve fibers that innervate sweat glands. The results are displayed on the device's touchscreen within three minutes, providing physicians with valuable information about a patient's sudomotor function and small fiber neuropathy.
The SUDOSCAN® device assesses the release of chloride ions from sweat glands by applying an electrical stimulus to the palms of the hands and soles of the feet, which are areas with a high density of sweat glands.
The utility of SUDOSCAN® has been demonstrated in:
Neurology : SUDOSCAN® is useful in evaluating and monitoring various conditions related to neuropathies such as neuropathic pain management, Gougerot Sjögren syndrome, idiopathic neuropathies, Fabry disease, amyloidosis, and more. It provides a non-invasive and easy way to assess sudomotor function and detect early signs of small fiber neuropathy caused by diabetes and prediabetes. SUDOSCAN's patented technology measures sweat gland activity through sweat conductance on the palms and soles, allowing physicians to detect and monitor peripheral neuropathies, track the progression of the disease, and tailor treatments accordingly.
Diabetology :SUDOSCAN® is useful in diabetology for the early detection of sweat gland dysfunction and peripheral neuropathy, which can aid in the prevention of diabetic foot complications.
Oncology : SUDOSCAN® is useful for the quantitative evaluation of chemotherapy-induced neuropathy, enabling more informed decision-making.
Follow-up: SUDOSCAN® is useful for patient management, monitoring treatment progress over time, and implementing lifestyle interventions.
SUDOSCAN® has been extensively validated and demonstrated similar results to reference tests such as skin biopsy, QSART, and clinical scores like NIS-LL. The technology is supported by over 150 publications in international scientific journals.
The device is manufactured in France and the test is both highly sensitive and reproducible.
SUDOSCAN® is CE certified, cleared for use by the US FDA, and registered and distributed in 34 countries with over 3000 devices sold.
SUDOSCAN® has proven to be effective in detecting sudomotor dysfunction, which is a common early finding in various peripheral and autonomic neuropathies. The device has been extensively tested for small fiber neuropathies and compared to reference diagnostic tests in the following conditions:
Diabetes [Prevent and manage diabetes complications]
Diseases with neurological complications
SUDOSCAN® has been utilized for various diseases with neurological complications, including but not limited to Hereditary Amyloidosis, Idiopathic Neuropathies, COVID-19, Fabry Disease, Parkinson’s Disease, Autoimmune Small Fiber Neuropathy, Fibromyalgia, Sjörgen’s Syndrome, Pure Autonomic Failure, and Hepatitis C.
Chemotherapy induced peripheral neuropathy
SUDOSCAN® is a useful tool for monitoring patients with Chemotherapy-induced peripheral neuropathy (CIPN). It can be easily conducted in the Oncology department both before and after treatment to ensure optimal patient follow-up. SUDOSCAN results are highly correlated with clinical evaluation scores such as the Total Neuropathy Score (TNSc). The results have been shown to be reduced for patients with a TNSc score greater than 6.
Monitoring of patient outcomes
SUDOSCAN® has a significant role in patient management, treatment follow-up, and lifestyle impact evaluation. The device has been used to monitor the effect of physical activity on metabolic diseases and cardiovascular risk.
New area development
SUDOSCAN® is actively participating in the e-PREDICE (Early PRevention of Dlabetes Complications in people with hyperglycaemia in Europe) European project. The project's goal is to evaluate the long-term effectiveness of various treatment regimens for the early prevention of diabetic complications in people with hyperglycemia who are currently undergoing lifestyle interventions. The project, which involves 15 centers throughout Europe, was developed in collaboration with Pr. Jaakko TUOMILEHTO.
By measuring the Electrochemical Skin Conductance (ESC) and the level of asymmetry between the right and left sides, SUDOSCAN test results can serve as indicators for patients who are at risk of autonomic dysfunction.
A test of the sudoral function
The SUDOSCAN® works by using a small direct current to both hand and foot sensor plates to test sweat gland function. The stratum corneum acts as a capacitor at low voltage, which causes the sweat ducts to become the only channel for the transmission of Cl- ions. This process allows for the assessment of the sweat gland's ability to release chloride ions in response to the electrical stimulus, which is measured and analyzed to provide valuable information about peripheral and autonomic neuropathies.
SUDOSCAN® provides a quantitative measure of chloride conductance (measured in microsiemens) and its results serve as a biomarker to assess sweat gland function in relation to sweat gland innervation.
What happens during a scan?
The SUDOSCAN® scan involves the transmission of a mild electrical current through the electrodes during the test, which is not painful for the patient and is kept under 4V. Despite its mildness, the current is strong enough to stimulate the sweat glands, triggering the release of naturally present Chloride ions. The entire scan takes only 3 minutes, and quantitative and objective results for both hands and feet are immediately displayed. These results are helpful in evaluating small C fibers and provide a simple, fast, and non-invasive way to detect Small Fiber Peripheral Autonomic Neuropathy.
Backed up by science
Due to its endorsement by key opinion leaders worldwide, awareness of SUDOSCAN® technology is rapidly increasing, making it a reference test in many countries. It has been incorporated into various guidelines, such as the European Network for TTR-FAP Amyloidosis, the German guidelines for diabetes management, and the Latin America Diabetes Association. With over 3000 devices sold worldwide, SUDOSCAN® is commercially available and registered in 34 countries. Moreover, it has been certified by CE and cleared for use by the US FDA.
How to use SUDOSCAN®?
SUDOSCAN® is a precise evaluation tool for sweat function that targets the small nerve fibers in the peripheral nervous system responsible for the innervation of sweat glands. The test involves a computer and four electrodes on which patients place their bare feet and hands. Within just three minutes, SUDOSCAN® triggers the sweat glands, allowing for the evaluation of small nerve fibers, also known as C fibers.
Simple results obtained in 3 minutes
The results are displayed automatically.
If the score is high, this indicates no sign of sudomotor dysfunction and no autonomic neuropathy.
If the score is low, this indicates a sudomotor dysfunction and a neuropathy.
Easy to read results
During a SUDOSCAN® scan, the polarity of the stainless steel sensor plates is alternated to measure individual conductance values of the right and left sides. The patient's results are available immediately after the scan. The level of asymmetry between the conductance values can indicate the type of peripheral neuropathy. Additionally, physicians can track the patient's progress over time by comparing multiple SUDOSCAN® scans.
SUDOSCAN® results compared to Skin Biopsy and QSART
Several scientific publications have compared the effectiveness of SUDOSCAN® with other main assessment techniques for small fiber neuropathy. For example, G. Smith et al  found that SUDOSCAN® had comparable diagnostic performance to Intraepidermal Nerve Fiber Density (IENFD) and QSART in detecting neuropathy.
IENFD distal leg and foot QSART sweat volumes had similar area under the curve (AUC) to SUDOSCAN® values (ESC).
IENFD: lntraepidermal Nerve Fiber Density from a skin biopsy
QSART: Quantitative Sudomotor Axon Reflex Testing- sudomotor function testing
Reference values assessed in large adult population
SUDOSCAN® was used to test a large population of adults for neuropathy, allowing for the establishment of reference values based on three ESC zones. These zones indicate normal sudomotor function (green), moderate sudomotor dysfunction (yellow), and severe sudomotor dysfunction (red).
 Smith G et al. The diagnostic utility of Sudoscan® for distal symmetric peripheral neuropathy. Journal of Diabetes and its Complications. 2014;28(4):511-516.
 Vinik AI, Nevoret ML, Casellini C . The New Age of Sudomotor Function Testing: A Sensitive and Specific Biomarker for Diagnosis, Estimation of Severity, Monitoring Progression, and Regression in Response to Intervention. Front Endocrinol (Lausanne). 2015 Jun 11;6:94.
- No patient preparation
- No fasting
- Results in 3 minutes
- Easy-to-read critical data points to help physicians reach a diagnosis
- No fasting
- Easy to operate
- CE and FDA approvals
- Reproducible quantitative results
- Independent from environmental conditions
- Backed by evidence-based research
- 150 peer-reviewed journals publications
SUDOSCAN results compared to Skin Biopsy and QSART
SUDOSCAN effectiveness have been compared to main small fiber neuropathy assessment technics in several scientific publications. G. Smith et al  have demonstrated SUDOSCAN’s diagnostic performance was comparable to Intraepidermal Nerve Fiber Density (IENFD) and QSART in detecting Neuropathy.
IENFD distal leg and foot QSART sweat volumes had similar area under the curve (AUC) to SUDOSCAN values (ESC).
0:01 / 1:36SUDOSCAN - Interview with Dr Smirnoff, M.D., Neurologist - Use of SUDOSCAN
SUDOSCAN - Interview with Dr Smirnoff, M.D., Neurologist - Early detection
SUDOSCAN - Interview with Dr Smirnoff, M.D., Neurologist - Diagnostic work up
SUDOSCAN - Interview with Dr Smirnoff, M.D., Neurologist - Patient Followup
The assessment of sudomotor function can serve as a quick and precise means of identifying initial stages of distal small fiber neuropathy. Small blood vessels extensively supply the eccrine glands responsible for sweat response, which receive innervation from the autonomic nervous system's sympathetic C nerve fibers. As these fibers are thin and lengthy, they may become impaired during the early stages of various metabolic disorders. Research publications suggest that "sweat response may be the most sensitive test in detecting distal small fiber neuropathy" (Low PA and Gibbons CH).
SUDOSCAN® is a non-invasive test that measures sudomotor function on the palms of the hands and soles of the feet, which have the highest density of sweat glands. The technology works by applying a low DC voltage ≤ 4 volts to generate a current relative to the chloride ion flow in the sweat glands and ducts, which is then used to calculate an Electrochemical Skin Conductance (ESC) for each hand and foot. This electrical stimulus captures information about sweat dysfunction that cannot be diagnosed under normal conditions. The skin's stratum corneum acts as an electrical capacitor, ensuring that the movement of chloride to the electrodes only occurs via the sweat ducts, targeting the underlying sweat gland and its sympathetic innervations. This theory is supported by a comparative study on patients with Cystic Fibrosis and controls. For a better understanding, an animation video is available on the website.
SUDOSCAN® provides test results for both the hands and feet, with the average conductance of both the left and right sides being reported. Various studies have found that higher conductances are indicative of normal sweat function and healthy nerve innervation, particularly in small C-fibers. In contrast, lower conductances have been associated with peripheral or autonomic neuropathy.
SUDOSCAN® provides physicians with simple and immediate information on small autonomic fiber status, which can be used in various medical settings. With the trend towards prevention and early detection of disease and complications, physicians can use SUDOSCAN® results to obtain an objective evaluation of sudomotor function in a patient with signs or symptoms suggestive of developing disease. Additionally, SUDOSCAN® can be used to assess the level of intensive glycemic control for diabetics before prescribing treatment. By detecting autonomic dysfunction, SUDOSCAN® may alert physicians to refer a patient for further autonomic function testing. Moreover, SUDOSCAN® allows physicians to quickly determine sudomotor functioning as a biomarker for peripheral nerve integrity, which can help in evaluating patient drug or lifestyle compliance. Worsening sudomotor function may signal poor patient response to treatment or lack of compliance, and initiate a discussion between physician and patient on a change in therapy. The quantitative results obtained from SUDOSCAN® offer a precise follow-up with no subjectivity introduced via patient verbal responses, making it an excellent complementary tool to traditional blood tests, while providing extremely fast and immediate results.
With the exception of specific contra-indications, anyone is eligible for SUDOSCAN testing to evaluate their sudomotor function. As mentioned earlier, the assessment of sudomotor function using SUDOSCAN is valuable for monitoring and follow-up of peripheral autonomic and small fiber neuropathies that may arise from various medical conditions such as diabetes, amyloidosis, Fabry disease, and Parkinson's disease.
The American Academy of Neurology (AAN), American Diabetic Association (ADA), and American Academy of Clinical Endocrinologists (AACE) recognize sudomotor dysfunction as a symptom of autonomic neuropathy, a common complication of diseases such as diabetes, Parkinson's disease, and amyloidosis. Sudomotor tests like SUDOSCAN are utilized to evaluate autonomic and small fiber neuropathies. SUDOSCAN is a rapid and non-invasive test that can establish a patient's baseline, detect sub-clinical nerve damage, and evaluate clinically significant changes in medical status. Studies suggest that simple lifestyle changes can substantially improve sudomotor function as measured with SUDOSCAN and are associated with cardio-metabolic improvement (Raisanen et al., Int J Environ Res Public Health, 2014).
Evaluation of sudomotor function using other tests such as Quantitative Sudomotor Axon Reflex Test (QSART) has revealed that women generally have lower results (sweat output) than men. This can be explained by lower sweat rates in women. Measurements performed by SUDOSCAN do not depend on sweat rate. A study performed on more than 500 women and more than 200 men showed no significant differences in hand or feet ESC. This will be confirmed in future pending studies on larger group populations.
The variability of sweat rates among individuals does not impact the accuracy of SUDOSCAN results. Nonetheless, sweat gland physiology can differ by ethnicity, and research is being conducted to examine the potential impact of this on SUDOSCAN outcomes. Future studies involving large and diverse populations are expected to establish normative ranges for different ethnic groups.
A substantial dataset of healthy volunteers has indicated that SUDOSCAN® conductances are not correlated with age.
Clinical tests conducted at different temperatures, varying by more than 5°C, have shown that SUDOSCAN® test results are not affected by temperature. As the hands and feet have a limited role in thermoregulation due to their small surface area, their sweat rate is less temperature dependent than other areas of the body. Nevertheless, it is advisable not to conduct a SUDOSCAN® test if the electrodes are too cold or if the patient has just come in from an extremely cold environment.
To assess the impact of exercise on SUDOSCAN® tests, a study was conducted on 112 healthy individuals before and after a VO2max test. The study found a correlation coefficient of 0.814 (p<0.0001) and a mean percentage change of 1.15% for feet ESC, indicating good test-retest reliability (Casellini et al. Diab Tech & Ther 2013). These results suggest that SUDOSCAN® measurements are not influenced by changes in sweat rate due to exercise.
To ensure its usefulness, a medical device must be reproducible. Several clinical studies have evaluated the reproducibility of SUDOSCAN®, and the results have been positive. Paired Spearman correlation coefficients among tests on three different SUDOSCAN® devices were >0.96 (p<0.0001), and the correlation coefficients between measurements performed with two different devices in diabetic patients were 0.85 for hands and 0.93 for feet, with p < 0.001. (Schwarz et al., Br J Diab & Vasc Dis 2011; Calvet et al., Exp Clin Endo Diab 2012). As mentioned earlier, the reproducibility between measurements performed before and after exercise is also excellent. Dynamic analysis of chloride-ionic flow in sweat glands (as opposed to sweat volume) provides more informative results, as chloride levels remain constant regardless of sweat rate (see Quinton et al. article on the website).
Testing children on SUDOSCAN® is considered safe and initial data from clinical studies conducted on pediatric patients have shown promising results. However, until FDA clearance is obtained for pediatric age groups, the use of SUDOSCAN in clinical practice is limited to the adult population.
SUDOSCAN® and HbA1c are complementary tests as they focus on different aspects of diabetes assessment. While HbA1c is a blood-based test, SUDOSCAN® assesses sweat gland function and its sympathetic innervation. Small fiber neuropathy in type 2 diabetes is influenced by various metabolic disturbances, including hyperlipidemia, in addition to hyperglycemia. Thus, there is no strict correlation between HbA1c and SUDOSCAN® results. In research studies, it has been observed that ESC results decreased significantly over time in some cases, while no significant difference in HbA1c was observed.
The frequency of retesting with SUDOSCAN depends on various factors, including the patient's initial test results, the underlying medical condition, changes in the patient's medical status or response to treatment, and the clinical judgment of the physician. In general, SUDOSCAN retesting is usually done no more than once every 12 months.
Differentiating between a progressive and a non-progressive peripheral small fiber or autonomic neuropathy can be challenging due to changes in symptoms that may indicate either a response to therapy or ongoing nerve loss. However, the quantitative and highly reproducible assessment of sweat gland function using SUDOSCAN® may aid in this differentiation. Changes in SUDOSCAN results may indicate whether the neuropathy is progressive or non-progressive.
SUDOSCAN® applies only direct current during the test, which means it does not interfere with pacemaker electronics. Therefore, it is considered safe to use in subjects with pacemakers. Safety tests were performed to meet the Electromagnetic Compatibility requirements specified in the ANSI/AAMI PC69:2007 guidelines for implantable cardiac pacemakers and implantable cardioverter. The Laboratoire Centrale des Industries Electriques (LCIE, Fontenay aux Roses, France) performed these tests and concluded that "SUDOSCAN® is compliant according to ANSI/AAMI PC69:2007 (Annexe M) standard" (Report October, 2012). However, it is recommended that patients with pacemakers undergo SUDOSCAN® testing under the supervision of a medical doctor.
Further studies are necessary to verify whether other cardiovascular medications affect SUDOSCAN® measurements; however, cardioselective beta-blockers are not expected to interfere with the test.
Since SUDOSCAN® measures sweat gland activity through cholinergic small C fibers, medications that have significant anti-cholinergic effects can impact the test results. Tricyclic antidepressants, especially amitriptyline, have been found to significantly reduce ESC measurements obtained by SUDOSCAN®. Therefore, caution must be exercised when interpreting results in patients using anti-cholinergic agents. The effect of medications on ESC measurements is a crucial factor and is being continuously investigated in ongoing studies.
Preliminary findings from an observational study conducted in a German outpatient clinic on two groups of patients with type 2 diabetes, one receiving insulin and the other receiving other anti-diabetic drugs, suggest that after one year of follow-up, patients receiving insulin showed an improvement in their conductances, while the second group experienced a slight decrease. However, these results are preliminary, and further research is needed with a larger study population to confirm these findings.
SUDOSCAN® results in patients with skin conditions that affect their palms and/or soles, such as atopic dermatitis, have not been fully investigated, so it is uncertain how these conditions may affect test outcomes. It should be noted that for SUDOSCAN® results to be accurate, the skin on the palms and soles must be intact, without any open sores, ulcers, or lacerations.
Before testing with SUDOSCAN®, it is necessary to ensure that the palms and soles are clean and free of any dirt, ointments, or lotions. The recommended method of cleaning is to wash the skin with soap and water. It is important that the palms and soles are thoroughly dried before placing them on the electrodes. It is also important to note that the manufacturer-approved cleaning solution for the electrodes is intended for Sensor Plate cleaning only and should not be applied directly or indirectly to a patient's skin before testing.
SUDOSCAN® test results are not affected by the size of a patient's hands or feet. However, if a hand or foot has a significantly reduced surface area due to an injury such as a second or third-degree burn or amputation, with the loss of sweat glands, it can impact SUDOSCAN® results.
The sensor plates used in SUDOSCAN® are manufactured from high-grade stainless steel, making them resistant to corrosive influences. The lifespan of the plates is dependent on how frequently they are used and how well they are maintained. After each patient, the plates must be cleaned with a manufacturer-approved solution to ensure hygiene and safety standards are maintained, to halt the electrochemical reaction that occurs during each test, and to guarantee the most accurate test results. As a result, the sensor plates are replaced after every 100 successful tests to ensure the physician that the test results obtained are of the highest quality.