Non-invasive tests of neurovascular function

This paper describes the value of non-invasive neurovascular function tests in the clinical setting. Painful transcutaneous electrical nerve stimulation (TENS) of the dorsum of the foot evoked axon reflex vasodilatation, measured by laser Doppler flowmetry. In addition, acetylcholine and sodium nitrite (NaNO2) were iontophoresed to cause vasodilatation by endothelium-dependent and -independent mechanisms, respectively. Compared with healthy volunteers, diabetic patients with clinically diagnosed neuropathy showed reduced electrical axon reflex flare responses. These responses in one additional subject were absent in a region of denervated skin. Acetylcholine responses, but not NaNO2 responses, were also depressed in patients with diabetic neuropathy. Such reduced cutaneous nocifensor functions may contribute to some symptoms and complications of diabetes mellitus.