The immediate effect of osteopathic cervical spine mobilization on median nerve mechanosensitivity

Authors: Gary Whelan, M.Ost (Osteopath), Ross Johnston, M.Sc. B.Sc. (Hons) Ost Med, DO (Senior Lecturer), Charles Millward, ND DO (Lecturer), Darren J. Edwards, B.Sc. M.Sc. Ph.D. (Lecturer)

Published in: J Bodyw Mov Ther. 2018 Apr;22:252-260. doi: 10.1016/j.jbmt.2017.05.009. Epub 2017 May 18.

Abstract

BACKGROUND:

Neurodynamics is a clinical medium for testing the mechanical sensitivity of peripheral nerves which innervate the tissues of both the upper and lower limb. Currently, there is paucity in the literature of neurodynamic testing in osteopathic research, and where there is research, these are often methodologically flawed, without the appropriate comparators, blinding and reliability testing.

AIMS:

This study aimed to assess the physiological effects (measured through Range of Motion; ROM), of a commonly utilized cervicalmobilization treatment during a neurodynamic test, with the appropriate methodology, i.e., compared against a control and sham. Specifically, this was to test whether cervical mobilization could reduce upper limb neural mechanical sensitivity.

METHODOLOGY:

Thirty asymptomatic participants were assessed and randomly allocated to either a control, sham or mobilization group, where they were all given a neurodynamic test and ROM was assessed.

RESULTS:

The results showed that the mobilization group had the greatest and most significant increase in ROM with Change-Left p < 0.05 and Change-Right p < 0.05 compared against the control group, and Change-Left p < 0.01 and Change-Right p < 0.05 compared against the sham group.

CONCLUSIONS:

This study has highlighted that, as expected, cervical mobilization has an effect at reducing upper limb neural mechanical sensitivity. However, there may be other factors interacting with neural mechanosensitivity outside of somatic influences such as psychological expectation bias. Further research could utilize the methodology employed here, but with other treatment areas to help develop neural tissue research. In addition to this, further exploration of psychological factors should be made such as utilizing complex top-down cognitive processing theories such as the neuromatrix or categorization theories to help further understand cognitive biases such as the placebo effect, which is commonly ignored in osteopathic research, as well as other areas of science, and which would further complete a holistic perspective.

Impact of Spinal Manipulation on Cortical Drive to Upper and Lower Limb Muscles.

Authors: Haavik H, Niazi IK, Jochumsen M, Sherwin D, Flavel S, Türker KS.

Published in: Brain Sci. 2016 Dec 23;7(1). pii: E2. doi: 10.3390/brainsci7010002.

Abstract

This study investigates whether spinal manipulation leads to changes in motor control by measuring the recruitment pattern of motor units in both an upper and lower limb muscle and to see whether such changes may at least in part occur at the cortical level by recording movement related cortical potential (MRCP) amplitudes. In experiment one, transcranial magnetic stimulation input-output (TMS I/O) curves for an upper limb muscle (abductor pollicus brevis; APB) were recorded, along with F waves before and after either spinal manipulation or a control intervention for the same subjects on two different days. During two separate days, lower limb TMS I/O curves and MRCPs were recorded from tibialis anterior muscle (TA) pre and post spinal manipulation. Dependent measures were compared with repeated measures analysis of variance, with p set at 0.05. Spinal manipulation resulted in a 54.5% ± 93.1% increase in maximum motor evoked potential (MEPmax) for APB and a 44.6% ± 69.6% increase in MEPmax for TA. For the MRCP data following spinal manipulation there were significant difference for amplitude of early bereitschafts-potential (EBP), late bereitschafts potential (LBP) and also for peak negativity (PN). The results of this study show that spinal manipulation leads to changes in cortical excitability, as measured by significantly larger MEPmax for TMS induced input-output curves for both an upper and lower limb muscle, and with larger amplitudes of MRCP component post manipulation. No changes in spinal measures (i.e., F wave amplitudes or persistence) were observed, and no changes were shown following the control condition.

These results are consistent with previous findings that have suggested increases in strength following spinal manipulation were due to descending cortical drive and could not be explained by changes at the level of the spinal cord. Spinal manipulation may therefore be indicated for the patients who have lost tonus of their muscle and/or are recovering from muscle degrading dysfunctions such as stroke or orthopaedic operations and/or may also be of interest to sports performers. These findings should be followed up in the relevant populations.