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Summary.Peripheral blood flow is known to be qualitatively increased in diabetic patients with neuropathy. We have measured the actual blood flow in the feet of diabetic patients with neuropathy using non-invasive mercury strain gauge plethysmography and Doppler sonogram techniques and shown that it is increased on average five times above normal at an ambient temperature of 20 ~ -22 ~ Moreover, reduction of this high flow by sympathetic arousal stimuli proved possible in those with severe painful neuropathy contrasting strongly with failure to reverse it in those with severe non-painful sensory neuropathy. Reduction of blood flow was associated with reduction in neuropathic pain. We studied 22 diabetic patients with severe sensory neuropathy and eight with painful neuropathy. High resting foot blood flows were demonstrated in both groups with neuropathy. The big toe flow in those with severe sensory neuropathy was 29.3 + 9.2 ml. rain-1. 100m1-1 (mean+-SD) and in the painful neuropathy group, 25.9+_7.5, compared with 5.2+2.4ml.min -1. 100m1-1 in the non-diabetic control subjects (p<0.001). High foot skin temperatures were also recorded in the groups with neuropathy, reflecting the high blood flow. The subjects with painful neuropathy retained the ability to constrict peripheral blood vessels in response to arousal stimuli, and reduce peripheral flow on average by 32% compared with the patients with sensory neuropathy who responded on average by only 10%. The demonstration of a peripheral sympathetic defect, responsible for the high blood flow and the potential reversal of such flow in painful neuropathy may be important in our further understanding of the aetiology of such pain and its treatment.Key words: Diabetes mellitus, peripheral blood flow, sensory neuropathy, painful neuropathy, peripheral sympathetic neuropathy.During the nineteenth century, the feet of diabetic patients with peripheral neuropathy were observed to be hot and erythematous [1] and the blood flow in such feet was considered to be increased. This increase is now thought to be due to the dilation of denervated arteriovenous shunts [2-9] normally controlled by sympathetic nerves.Measurement of actual blood flow in diabetic neuropathic feet has only been undertaken in one previous study [10]. Blood flow was not found to be increased in neuropathic subjects probably because the studies were conducted by waterbath plethysmography at 32~ causing vasodilatation and increased flow in the control subjects.The aim of this study was to measure the magnitude of resting foot blood flow in a group of diabetic patients with severe sensory neuropathy and to discover whether the hot, burning foot, so characteristic of distal painful neuropathy, also has a high resting flow resulting from a peripheral sympathetic defect. In addition, the sympathetic responses of both types of neuropathy were tested to discover whether either retained the ability to reduce peripheral flow by vasoconstriction, and whether any benefits might result from this. Subjects and metho...

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The objective of this study was to compute reference SEMG values for normal subjects of 13 parameters extracted in the time, frequency and bispectrum domain, from the Biceps Brachii (BB) muscle generated under isometric voluntary contraction (IVC). SEMG signals were recorded from 94 subjects for 5s at 10, 30, 50, 70 and 100% of maximum voluntary contraction (MVC). The Wilcoxon signed rank test was applied to detect significant differences or not at p<0.05 between force levels for each of the 13 parameters. The main findings of this study can be summarized as follows: (i) The time domain parameters turns per second and number of zero crossings per second increase significantly with force level. (ii) The power spectrum median frequency parameter decreases significantly with force level, whereas maximum power and total power increase significantly with force level. (iii) The bispectrum parameter, maximum amplitude, increases significantly with force level with the exception the transition from 30% to 50% MVC. Although, the tests for Gaussianity and linearity show no significant difference with force level, the SEMG signal exhibits a more Gaussian distribution with increase of force up to 70% MVC. The SEMG linearity test, which is a measure of how constant the bicoherence index is in the bi-frequency domain, shows that the signal's bicoherence index is less constant (hence, the signal is less linear) at 70% of MVC compared to 10, 30, 50 and 100% MVC. (iv) The time domain parameters have good correlation between them as well as, between each one of them and maximum and total power. The median frequency has a good (negative) correlation with the bispectrum peak amplitude. (v) No significant differences exist between values based on gender or age. The findings of this study can further be used for the assessment of subjects suffering with neuromuscular disorders, or in the rehabilitation laboratory for monitoring the elderly or the disabled, or in the occupational medicine laboratory.

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