Recovery of 0.1 Hz microvascular skin blood flow in dysautonomic diabetic (type 2) neuropathy by using Frequency Rhythmic Electrical Modulation System (FREMS)

Synchronized oscillation of smooth muscle cells tension in arterioles is the main control system of microvascular skin blood flow. An important autogenic vasomotion activity is recognized in 0.1 Hz oscillations through power spectrum analysis of laser Doppler flowmetry. Severe dysautonomia in diabetic neuropathy is correlated with loss of 0.1 Hz vasomotor activity, hence with impaired blood microcirculation. FREMS is a novel transcutaneous electrotherapy characterized by sequences of electrical stimuli of high voltage and low pulse duration which vary both in frequency and duration. We have evaluated the changes in laser Doppler flow in the volar part of the forearm before, during and after FREMS. Normal controls ( n = 10 , 6 females, age range 21–39 years) demonstrated significant 0.1 Hz vasomotion power spectra at baseline conditions associated with large oscillations of adrenergic cutaneous sweat activity sampled from the hand; people with diabetes type 2 and severe dysautonomia ( n = 10 , 5 females, age range 63–75 years) displayed a significant decrease of 0.1 Hz vasomotion power spectra. During FREMS application we observed an increase ( p < 0.05 ) of 0.1 Hz vasomotion power spectra only in the diabetic group, despite persistence of adrenergic cutaneous sweat activity suppression in this group. However, after the application of the stimuli, the relative energy values around the 0.1 Hz peak remained significantly higher than preapplication values in the diabetic group ( p < 0.05 ). From these findings, we suggest that FREMS is able to synchronize smooth cell activity, inducing and increasing 0.1 Hz vasomotion, independently from the autonomic nervous system.