SSR (Sympathetic Skin Response) Lower Limb

The sympathetic skin response (SSR) test measures changes in skin electrical potential after a stimulus to assess sympathetic (sudomotor) nerve function. Surface electrodes on palms/soles record latency and amplitude of sweat-related electrical responses triggered by electrical, auditory or deep-breathing stimuli. It’s noninvasive and helps detect autonomic dysfunction and small-fiber neuropathy in conditions such as diabetes, Parkinson’s disease and peripheral neuropathies.

SSR (sebum secretion rate) measures how much sebum the skin produces per unit area/time. Dermatologists use SSR to evaluate oily skin and acne risk, guide topical or systemic treatments, and monitor therapeutic response. It's measured with devices or absorbent strips and usually reported in µg/cm² or relative units. Abnormal SSR can reflect hormonal changes, dermatologic conditions, or medication effects.

The sympathetic response in skin includes vasoconstriction of cutaneous blood vessels (causing pallor and reduced heat loss), activation of arrector pili muscles (goosebumps), and stimulation of eccrine sweat glands (increased sweating) via sympathetic fibers. These changes support thermoregulation and the “fight-or-flight” response by conserving heat, redirecting blood flow, and promoting evaporative cooling during stress or increased sympathetic drive.

Yes. Sympathetic fibers innervate limbs and skin via thoracolumbar outflow (preganglionic neurons in T1–L2) that travel through the sympathetic chain and join spinal nerves via rami communicantes. Postganglionic fibers control cutaneous blood vessels (vasoconstriction), sweat glands (eccrine sweating), and arrector pili muscles, regulating temperature, blood flow distribution, and sympathetic responses like sweating and piloerection.

SSR testing (sympathetic skin response) is a noninvasive neurophysiology test measuring changes in skin electrical potential after a stimulus to evaluate sympathetic autonomic function. Electrodes on palms or soles record responses to electrical, auditory, or breathing stimuli; abnormal latency or amplitude can indicate autonomic neuropathy (e.g., diabetic neuropathy) or small‑fiber dysfunction. Results may be influenced by temperature, medications, and age.

SSR is not a universally standard blood‑test abbreviation; its meaning varies by laboratory. It’s sometimes used to indicate a serum separator tube or a lab/sample status code, but interpretations differ. If SSR appears on your report, check the laboratory’s abbreviation legend or ask your clinician or the lab directly for the exact definition and implications for your results.