LD TECHNOLOGY
SUDOMOTOR FUNCTION / SWEATC
The SweatC Model A001 is a galvanic skin response technology related to the sweat gland function. It uses the sympathetic skin response (SSR) method to assess the sudomotor function via foot skin disposable electrodes following a predetermined electrical stimulations and specific sequence of measurement.
The SweatC measures the absorption of the induced sweat on the bulk of the cloth electrodes. As perspiration increases, more sweat glands are stimulated which increases the voltage amplitude in a given area of skin covered by the disposable cloth electrodes.
The test is performed in the supine position on an exam table and the patient needs to be relaxed at least 5 minutes.
Per the last published clinical study performed at the University of Miami:
The SweatC marker NO Sweat Peak had a sensitivity of 88% and a specificity of 68% (Area Under the Curve = 0.81,p< 0.0001) to detect retinopathy.
The NO Sweat Peak response marker inversely correlated with BUN (ρ=−0.41,p< 0.0001), homocysteine(ρ=−0.44,p< 0.0001), fibrinogen (ρ=−0.41,p< 0.0001), the Cardiac Autonomic Neuropathy score (ρ=−0.68,p<0.0001), and the heart rate variability Total Power (ρ=−0.57,p< 0.0001), and it positively correlated with the Photoplethysmography Index (PTGi;ρ=0.53p< 0.0001).
The SweatC markerSweat Peak inversely correlated with the severity of symptoms on the peripheral neuropathy scale (ρ=−0.56,p< 0.0001).
THE SUDOMOTOR TEST SWEATC
REVIEW
The Sudomotor testing clinical data suggest it may be the most sensitive means to detect peripheral small fiber neuropathy (Low, et al.,2006).
Sudomotor function is controlled by part of the sympathetic nervous system (post sympathetic cholinergic fiber) and it relates to skin microcirculation and small demyelinated nerve fibers (C-Fibers).
Microcirculatory disorders and Small fiber neuropathy could be the earliest stages of peripheral distal neuropathy in diabetic patients.
In addition, sudomotor dysfunction has been found in different diseases or as medication side effects such as cancer treatment, antihypertensive treatment (in particular beta and alpha blockers and calcium antagonists), metformin treatment, vitamin deficiency, Parkinson’s disease, AIDS, amyotrophic lateral sclerosis, hypothyroidism, kidney and liver diseases, alcoholism, Alzheimer’s disease and Guillain-Barre syndrome.
Traditional and recognized neurophysiologic measurements of sudomotor function include thermoregulatory sweat testing (TST), quantitative sudomotor axon reflex testing (QSART), silicone impressions and sympathetic skin response (SSR).
Sudomotor dysfunction is used to define a decreased sudomotor activity.
Impaired response of autonomic C-Fiber ( low level or absence or acetylcholine production) or of capillaries vasodilation ( low or absence of response to Nitric Oxide) lead to sudomotor dysfunction.
The autonomic C-fiber response (Sweat Peak) is measured at the positive electrode.
The vasodilation response (NO Peak) is measured at the negative electrode.
ELECTRODE PLACEMENT
DISPOSABLE ELECTRODE ADVANTGES:
- No disinfection and no maintenance
- Increased reproducibility (no ageing of the electrodes)
- Prevent cross contamination
- Prevent biased measurement from the temperature
- Prevent biased measurement from the size of the feet