Title:

THE ACUTE NEUROPHYSIOLOGICAL

CHANGES BEFORE AND AFTER CHIROPRACTIC

ADJUSTMENTS OF THE CERVICAL SPINE.

Authors:

Diane Sherwin, Teiva Livine, Frosini Konidaris, Rosalyn Tansey, Heidi Haavik-Taylor,

Place of completion:

University of Auckland

College/Institution:

New Zealand College of Chiropractic

Address correspondence to:

Heidi Haavik Taylor, Human Neurophysiology and Rehabilitation Laboratory, Tamaki Campus, University of Auckland, Private Bag 92019, 200 Morrin Rd, Glen Innes, Auckland, New Zealand.

Phone number: (649) 3737599 extn 82544

Fax number: (649) 3737043

Email address: h.taylor@auckland.ac.nz

Acknowledgment:

Heidi Taylor was supported by a Bright Futures Top Achievers Doctoral Scholarship

Key words: Chiropractic, adjustment, transcranial magnetic stimulation, manipulation

Abstract

Background. Chiropractic adjustments have been shown to cause clinical changes lasting weeks to months. There is however, a lack of understanding of its neurophysiological mechanism. Research has shown that chiropractic adjustments increase pain tolerance, affect afferent responses from paraspinal muscles, and affect reflex neuronal output to both motor and visceral organs.

Objective. The purpose of the proposed research is to study the neurophysiological changes occurring in two targeted muscles, abductor pollicis brevis (APB) and extensor indicis proprius (EIP), after stimulation over the motor cortex non-invasively with transcranial magnetic stimulation (TMS), before and after a single session of cervical spine adjustment(s). Short interval intracortical inhibition (SICI) and I wave facilitation (IwF) will be the TMS techniques utilized. This may help to elucidate the neural mechanisms that occur following chiropractic adjustments.

Methods. Twelve healthy volunteers between the ages of 18-40 were used in this study. Short interval intracortical inhibition (SICI) and I-wave facilitation (IwF) was measured with a paired TMS protocol (SICI measured with interstimulus interval (ISI) of 2.5ms, and IwF with ISI of 1.5ms). The dependent variables were measured before and after two interventions (the order of which was randomized); passive head movement and cervical spinal manipulations. To assess spinal excitability, F wave persistence and amplitudes were recorded following median nerve stimulation at the wrist.

Results: The IwF data revealed a significant effect following cervical spinal manipulation for both the APB and EIP data. The one-way repeated measures ANOVA revealed a significant effect for both the APB and EIP data following cervical spinal manipulation while the two-tailed paired t-tests revealed a significant increase of IwF in the APB muscle following spinal manipulation and a decrease of IwF in the EIP muscle following spinal manipulation. No significant effect was observed for any of the measures for either muscle following the passive head movement control intervention. No significant effect following cervical spinal manipulation intervention was observed for the SICI data or F wave parameters.

Conclusions: This study suggests that cervical spine manipulation can alter corticomotor facilitatory central neural effects.