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SUDOSCAN TESTING measures electrochemical skin conductance of hands and feet through reverse iontophoresis.  Basically, SUDOSCAN testing evaluates the sweat gland function, which can reflect the health of small nerve fibers.  By testing sweat function, SUDOSCAN allows physicians to follow the health of these nerves to better personalize and monitor patient treatment plans.


The Science

SUDOSCAN is a test that provides an accurate evaluation of sweat gland function.  The test focuses on small nerve fibers that innervate the sweat glands.  The degeneration of small nerve fibers reduces sweat gland innervation and impairs sudomotor function.

SUDOSCAN measures the ability of the sweat glands to release chloride ions in response to an electrical stimulus on the palms of the hands and soles of the feet, areas with the highest sweat gland density.

SUDOSCAN provides a quantitative measure of chloride conductance (measured in microsiemens, µS) and its results serve as a biomarker to assess sweat gland function.  The test results can be used as indicators for patients at risk of autonomic dysfunction through the measurement of Electrochemical Skin Conductance (ESC).


An Innovative Technology

SUDOSCAN is a patented technology that evaluates sweat gland function, which is controlled by small nerves like some of those involved in pain sensation.

The polarity of the stainless steel sensor plates is swapped during a scan to record individual right and left side conductance values.  The amount of observed asymmetry can sometimes help the physician in determining a diagnosis.


SUDOSCAN and Type 2 Diabetes

Small nerve fibers are the very first targets of diabetes.  For a substantial number of patients, irreversible tissue damage (peripheral vascular disease, nephropathy, retinopathy, neuropathy) have already set in at the time of diagnosis [1]. 60-70% of patients with diabetes have neuropathies.

Early identification of these complications, which may be asymptomatic in up to 50% of diabetic patients, has the potential to reduce or delay their complications with timely preventative treatment.

The American Diabetes Association (ADA) mandates that all patients with diabetes be screened annually for peripheral and autonomic neuropathy.


Simply Put: Less Invasive and More Reliable.

The use of skin biopsy (IENFD) is an accepted diagnostic measure of small fiber neuropathy, but it has certain limitations: invasiveness, risk of infection, poor healing process for diabetic patients, and a limited number of labs that can process the samples.

Nerve conduction studies (NCS) are the gold standard for the diagnosis of peripheral neuropathy, but can only assess large myelinated fibers.  Therefore, for symptomatic patients with normal NCS, small nerve fiber evaluation is recommended.

SUDOSCAN’s diagnostic performance (ESC) is comparable to ENFD/SGNFD and QSART in detecting Neuropathy.


Why test sudomotor function?

Testing sudomotor function can be a fast and accurate method for detecting early stages of neuropathies. Sweat gland nerve fibers are thin and long and are susceptible to damage at a very early stage of disease, such as diabetes.


SUDOSCAN is a medical device that has been cleared by the FDA as a galvanic skin response (GSR) test and sudomotor function test. In GSR, changes in the voltage measured from the surface of the skin are recorded. These voltage changes are thought to arise from activation of sweat glands (sudomotor function).

How is the test performed?

You will be asked to take your shoes and socks off; then you will stand on the sensor plates for the feet and place your hands on the hand sensor plates. If you are unable to stand still for 3 minutes on the plates, your physician will ask you to sit for the test.

What does SUDOSCAN measure?

SUDOSCAN evaluates sudomotor function on the palm of the hands and soles of the feet. It uses a very low DC voltage ≤ 4 volts to activate the sweat glands and measures the current of chloride ions that flow out of the sweat glands in response to the electric impulse.

How long is the test and is it painful?

The test runs for 2 to 3 minutes. You may feel slight tingling in your hands and/or feet, or you may feel nothing at all.

What information does SUDOSCAN provide?

SUDOSCAN test results are provided as hands and feet conductances measured in microSiemens (μS). In studies, high conductances have been found to correlate with normal sweat function and healthy innervation (small C-fibers). Low conductances were associated with peripheral or autonomic neuropathy.

How can the physician use this information to help me?

Physicians get simple and immediate information on small autonomic fiber status and can use it to:
–       Confirm whether your symptoms may be due to a neuropathy
–       Assess a change in your medical status
–       Evaluate why your treatment may or may not be working.

Who should get tested on SUDOSCAN?

Anyone can get tested on SUDOSCAN to assess their sudomotor function unless they have a specific contra-indication.

What are the reasons to get tested with SUDOSCAN?

Abnormal sweating (also known as sudomotor dysfunction) is recognized by the American Academy of Neurology (AAN), American Diabetic Association (ADA), and American Academy of Clinical Endocrinologists (AACE) as a symptom of autonomic neuropathy, a common complication of diabetes, Parkinson Disease, and amyloidosis for example. Sudomotor tests such as SUDOSCAN are used in the evaluation of autonomic and small fiber neuropathies.

Does gender play a factor in the results?

A large study performed on healthy individuals showed no significant differences in hand or feet ESC between men and women.

Does ethnicity play a role?

Sweat gland function can vary by ethnicity and produce minor differences in hands and feet ESC among African Americans, Asians, and Caucasians. Your doctor will interpret your SUDOSCAN results based on available research data.

Can my age influence the SUDOSCAN reading?

A large database of healthy individuals demonstrated that SUDOSCAN conductances do not change significantly with age in adults.

Does room temperature affect the test results?

Clinical tests demonstrated that temperature does not impact test results. However, it is recommended not to perform a SUDOSCAN test if the electrodes are too cold or on a patient immediately after coming in from an extremely cold environment.

Does exercising just before being evaluated impact test results?

Measurements were performed before and after high impact exercise on more than 100 subjects. Tests showed a non-significant variation between these two measurements.

Can I use SUDOSCAN for type 1 diabetes?

Yes. SUDOSCAN can be used to measure peripheral sudomotor function, which can be impaired in various disease states, such as type 1 diabetes.

How does SUDOSCAN correlate with HbA1c?

HbA1C is used to monitor blood glucose levels over the preceding 3-month period, whereas SUDOSCAN measures sweat gland function. Therefore, there is no strict correlation between HbA1c and SUDOSCAN results, but they can each provide very important and different information about your medical condition.

How do nerve conduction studies or EMG correlate with SUDOSCAN?

Nerve conduction studies (NCS, also known as EMG) measure the function of large, myelinated nerves, and SUDOSCAN measures the function of small sweat gland nerve fibers. The two tests are therefore not likely to correlate since they measure 2 different types of nerves.

How should I wash my hands and feet prior to SUDOSCAN testing?

Palms and soles must be free of dirt, ointments, or lotions prior to testing. Washing with soap and water is always the best option. Make sure that your hands and feet are DRY before placing them on the electrodes.

Can some medications affect my SUDOSCAN test results?

Most medications should not influence the results of your test. Your doctor will review the drugs you take and determine their interactions prior to testing.

Can I get tested if I have a pacemaker?

Safety tests have concluded that SUDOSCAN meets the electrical standards for active implantable medical devices. Patients with pacemakers may perform a SUDOSCAN test with a medical doctor present.

How often can you or should you retest?

Retesting with SUDOSCAN can safely be done any time. Your physician can decide with you if another test is necessary based on changes in your treatment or your condition.