‘Sympathetic Slump’: The Effects of a Novel Manual Therapy Technique on Peripheral Sympathetic Nervous System Function

Abstract

The present study examined the physiological effects of the ‘sympathetic slump’ on measures of peripheral sympathetic nervous system (SNS) function in normal volunteers. ‘Sympathetic slump’ has been proposed (1) as a technique to load the sympathetic trunk (ST). It is suggested that mechanical stimulation of the ST will result in alterations in peripheral SNS function and/or target tissue sensitivity. This technique forms part of an overall examination and treatment protocol for patients with features of sympathetically maintained pain (2 = 13). The present study evaluated the effect of ‘sympathetic slump’ on two measures (skin conductance and skin temperature) of peripheral SNS function.Twenty-two normal, asymptomatic subjects with no previous experience of manual therapy participated in the study. A randomised, repeated measures, double-blind, placebo controlled protocol was used to evaluate the effects of ‘sympathetic slump’, placebo and control conditions on skin conductance and skin temperature in the upper limbs.‘Sympathetic slump’ produced a significantly greater increase in skin conductance than either placebo or control. A greater increase in skin conductance was observed in the right upper limb compared to the left upper limb, in keeping with the fact that the technique used in this study was intended to bias the right ST. Significant changes in skin temperature occurred for both ‘sympathetic slump’ and placebo compared to control, however there was no significant difference between ‘sympathetic slump’ and placebo. ‘Sympathetic slump’ did however appear to exert a greater differential effect between sides (R < L) than did the placebo technique.The results of this study demonstrate that the ‘sympathetic slump’ technique influences peripheral SNS function. The technique has the capacity to differentially increase sympathetic activity in the ipsilateral upper limb.