What is OMT’s Effect on the Autonomic Nervous System?
Medicine and Health Sciences
Paraspinal inhibition is an osteopathic manipulative treatment (OMT) purported to work via the sympathetic nervous system and aid in restoring autonomic homeostasis. Despite clinical anecdotal evidence, the mechanism of action has not been robustly evaluated. This study tested the hypothesis that OMT acutely alters the autonomic nervous system (ANS) and that the effects of OMT would be more pronounced in excited states. Because direct measures of ANS are difficult to assess in human in vivo studies, static and dynamic measures of ANS-mediated end-organ responses were quantified. These included beat-by-beat heart rate, arterial blood pressure, arm and forehead skin blood flow, and stroke volume as well as calculations of systemic and cutaneous vascular resistance/conductance and cardiac output. To determine if the excited state modulates ANS effects or restores autonomic homeostasis, participants were tested in a resting supine position and a 60° head-up tilt. Head-up tilt was performed via a tilt table to reduce physiological adjustments associated with volitional standing. Nineteen apparently healthy (health history and vital sign assessment) individuals participated in this randomly assigned cross-over designed study. The protocol consisted of supine baseline, OMT, and recovery for one session then supine baseline, tilt baseline, tilt OMT, and supine recovery for the other. Each data segment was recorded for 6 minutes to allow for fast Fourier and transfer function analysis of beat-by-beat data. No differences were noted between variables when comparing the supine baselines, indicating baselines were similar for both trials. During neutral conditions OMT decreased the heart rate and increased stroke volume but did not alter the cardiac output or any other measured variable. Excitation was observed with head-up tilt as identified by a) increases in arterial blood pressure and heart rate, b) decreases in stroke volume and cutaneous vascular conductance, and c) no change in systemic vascular resistance and cardiac output. During sympathoexcitatory conditions no static differences were observed during OMT. Dynamic analysis of systolic blood pressure, R-to-R, and skin blood flow interval yielded some condition and treatment trends and effects in both the low and high frequency ranges. Low frequency ranges are often linked to sympathetic nervous system, while high frequency changes are often linked to the parasympathetic nervous system, or a combination of the two branches of the ANS. This may indicate that the ANS is being altered by OMT, but these control system changes are complex and not always manifested in static averages. Thus, studies involving OMT influences on the ANS and associated variables need to account for these complexities, especially with regard to background sympathetic tone, hemostasis, and neural reflexes when evaluating mechanisms of action and associated physiological effects.
Copyright 2019 all authors
Waldherr, Alexander OMS-2, "What is OMT’s Effect on the Autonomic Nervous System?" (2019). MU-COM Research Day. 164.