The effect of transcutaneous electrical nerve stimulation on local and distal cutaneous blood flow following a prolonged heat stimulus in healthy subjects

The aim of this study was to investigate the effects of transcutaneous electrical nerve stimulation (TENS) on blood flow and skin temperature following an elevation of baseline blood flow using infrared preheating. A randomized controlled approach was used whereby 66 healthy human subjects (33 male, 33 female) were allocated to one of three intervention groups (n = 22 per group, equal male and female): Control, Low frequency TENS (4 Hz/200 μs), or High frequency TENS (110 Hz/200 μs). TENS was applied just below motor threshold over the median nerve of the right forearm for 15 min immediately following an infrared preheating. Cutaneous blood flow and skin temperature were recorded at 3-min intervals from the forearm and fingertips during TENS and for 15 min following TENS. Analysis of data revealed no significant differences between High and Low frequency TENS for cutaneous blood flow or skin temperature at the forearm. A small and short lived increase in cutaneous blood flow at the index finger was observed on TENS groups compared with control when TENS was switched off. TENS reduced skin temperature when compared to control during the first 9 min of the 15-min stimulation period at the middle finger but not at the index finger. It was concluded that the effects of high and low frequency TENS when applied below motor threshold produced changes in blood flow and skin temperature that were transient and small. © 2007 The Authors Journal compilation 2007 Blackwell Publishing Ltd

The autonomic effects of deep brain stimulation-a therapeutic opportunity

Deep brain stimulation (DBS) is an expanding field in neurosurgery and has already provided important insights into the fundamental mechanisms underlying brain function. One of the most exciting emerging applications of DBS is modulation of blood pressure, respiration and micturition through its effects on the autonomic nervous system. DBS stimulation at various sites in the central autonomic network produces rapid changes in the functioning of specific organs and physiological systems that are distinct from its therapeutic effects on central nervous motor and sensory systems. For example, DBS modulates several parameters of cardiovascular function, including heart rate, blood pressure, heart rate variability, baroreceptor sensitivity and blood pressure variability. The beneficial effects of DBS also extend to improvements in lung function. This article includes an overview of the anatomy of the central autonomic network, which consists of autonomic nervous system components in the cortex, diencephalon and brainstem that project to the spinal cord or cranial nerves. The effects of DBS on physiological functioning (particularly of the cardiovascular and respiratory systems) are discussed, and the potential for these findings to be translated into therapies for patients with autonomic diseases is examined