The influence of transcutaneous electrical neurost

Authors: Mark ter Laan J Marc C van Dijk JanWillem J Elting Vaclav Fidler Michiel J Staal

Publish Date: 2010/05/15

Volume: 152, Issue: 8, Pages: 1367-1373

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Abstract

It has been shown that transcutaneous electrical neurostimulation TENS reduces sympathetic tone Spinal cord stimulation SCS has proven qualities to improve coronary peripheral and cerebral blood circulation Therefore we postulate that TENS and SCS affect the autonomic nervous system in analogous ways In this line of thought cervical application of TENS might be a useful and simple adjunct in the treatment of cerebrovascular disease by improving cerebral blood flow Experiments were performed in order to assess whether cervical TENS is safe and whether an effect on cerebral blood flow velocity CBFV can be shown in healthy subjectsA controlled nonrandomized phase 1 study was performed with 20 healthy volunteers Cervical TENS was applied in several frequencies with and without hyperventilation Continuous registration of blood pressure pulse CBFV estimated by transcranial Doppler sonography and endtidal carbon dioxide concentration was performedCervical TENS was welltolerated by all subjects Despite small effects on heart rate HR and mean arterial blood pressure MAP a significant effect on middle cerebral artery MCA blood flow velocity was not demonstrated No effect of age gender current or session order on MCA HR or MAP was found TENS did not influence the effect of hyperventilationSpinal cord stimulation SCS is widely used in the treatment of pain Although several mechanisms have been proposed its exact mechanism of action remains unclear 13 At least part of the effects of SCS is mediated by the autonomic nervous system as shown by the fact that sympathetically mediated pain eg visceral pain and complex regional pain syndromes responds better than nociceptive pain to SCS treatment 13 In addition it has been demonstrated that SCS has autonomic sideeffects such as increasing peripheral blood flow in Raynauds phenomenon peripheral ischemic pain coronary disease and complex regional pain syndromes 4 11 13 Since the sympathetic fibers are located ventrally in the spinal cord and SCS electrodes are placed dorsally these ventral fibers are not located within the electrical field Therefore these autonomic effect must be indirect eg via antidromic pathways 13Transcutaneous electrical neurostimulation TENS has been used since 1974 to test the tolerance for stimuli in the workup for SCS 1 Some of the effects seen in SCS can be produced by TENS as well Effects on peripheral blood flow have been shown as well as increased coronary perfusion 12 An experiment on autonomic cardiovascular reflexes demonstrated a decreased sympathetic response when using TENS 17 Since the sympathetic effects as shown by SCS must be indirect effects of the electrical stimulation we postulate that TENS produces these effects in the same wayIn several studies an increase of cerebral blood flow CBF has been described as a result of cervical SCS 2 3 9 10 The effects of SCS on CBF are most likely mediated through the sympathetic nervous system since cerebral vasculature is highly sympathetically innervated and the vascular diameter is related to sympathetic tone 18 Patel showed that this effect is mediated via a central pathway 15 This pathway involves brainstem vasomotor centers that connect with the cerebral microvasculature through intrinsic nerve pathways In experiments on rats he showed that surgical sympathectomy failed to influence the CBF response caused by cervical SCS while transsection of the spinal cord at the cervicomedullary junction completely abolished all increases in CBF Taking into account the proven effect of TENS on peripheral blood flow and its indirect effect on sympathetic tone TENS should be able to alter CBF an analog to SCS As such TENS could be a useful noninvasive adjunct in the treatment of cerebrovascular disease CVDTENS either has a direct effect on vascular diameter or has an effect on the sympathetic tone If the latter is true then in resting conditions there should be no effect on CBF Therefore in order to find out whether the sympathetic tone is reduced by TENS the effects of TENS on CBF in hyperventilating subjects is of interest Given that cerebral blood flow in response to hyperventilation might partially be sympathetically mediated 7 8 this response should be reduced by TENS

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