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Testing Sudomotor Function

Sudomotor testing has been created to enable a precise evaluation of sweat gland function, as it relates to the electrochemical reaction between electrodes and chloride, through stimulated sweat glands. SudopathThis simple method provides information and evidence of a sweat dysfunction that might otherwise not be detectable in physiological conditions. Disorders associated with dysfunction of the autonomic nervous system are quite common yet frequently unrecognized. Sudomotor function testing, measures the autonomic nerves that control sweating and, therefore, is a useful tool in assessing autonomic nervous system disorders.

Sudomotor dysfunction has been established as one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathies. Small unmyelinated C-fibers are responsible for the function of sweat glands. As an index of the severity and distribution of autonomic failure, quantitative assessment of sweat response is widely recommended. It also serves as an early indicator for regeneration of small fibers. Diabetic patients have been observed to experience a degeneration of small C-fiber innervating sweat glands. One of the major causes of nerve damage is diabetes. As diabetes patients suffer from metabolic impairment and related inflammatory processes, their non-myelinated axons of small fiber nerves are primarily affected, which is known as Diabetic Autonomic Neuropathy (DAN), a subtype of peripheral neuropathies. These results suggest that the peripheral autonomic nervous system plays a role in painful diabetic neuropathy. Sudomotor testing measures bio electrochemical sweat skin conductance’s (BEC), which are directly connected to the capability of the glands to transfer chloride ions and also reflects small-C fiber status. The Bioelectrical Conductance’s for the hands and feet, express quantitative results, while a risk score is derived from demographic data and the BEC values.

Sudomotor Testing Process

Sudomotor testing involves measuring the electrical potential difference caused by the electrochemical reaction of electrodes, which are applied to the skin and are stimulated by a low voltage of variable amplitude. The testing includes 5 independent electrodes for placement on the body, for example feet or palms and other areas with a high number of sweat glands.An independent review of Autonomic Nervous System Testing


  • Tests the peripheral autonomic nervous system, which plays a role in predicting painful diabetic neuropathy.

  • Analyzes and tests responsiveness and accuracy in detecting diabetic neuropathy and compares it with existing standardized tests for the diagnosis of diabetic neuropathy.

  • An innovative, sensitive tool for the detection of diabetic neuropathy, especially painful diabetic neuropathy.  As sweat glands are innervated by small c fibers, which are also involved in pain pathways, precise measuring of the sweat gland function can identify that cause.

  • Detects neuropathy in patients with diabetes mellitus; operates with a sensitivity of 80% and a specificity of 95%.

  • Sudomotor test results correlate significantly with clinical neuropathy scores, pain scores and measures of
    autonomic dysfunction.ANS 1


    Tests the electrochemical reaction between electrodes and chloride through low voltage stimulated sweat glands to evaluate sweat dysfunction.

An independent review of Autonomic Nervous System Testing

    Evaluates the integrity of the postganglionic sudomotor system along the axon reflex to define the distribution of sweat loss. Also measures the autonomic nerves that control sweating. The test is useful in assessing autonomic nervous system disorders, peripheral neuropathies and some types of pain disorders.

  • Sympathetic Skin Response (SSR)
    Measures change of the electrical potential of the skin. The recorded skin potential comes from the activated eccrine sweat gland. The amplitude and configuration are adjusted by sweat gland epithelium and the overlying epidermis.

  • Bioelectrical Impedance and Body Composition
    Fat, muscle, water and other important indicators are measured and provide accurate ratios to determine underlying medical conditions.