April 2008

Research shows adjustment's impact on brain function

According to a study conducted by Dr. Heidi Haavik-Taylor, director of research at New Zealand College of Chiropractic, chiropractic adjustments may alter cortical somatosensory processing and sensorimotor integration, that is, the way the brain and nervous system function.

"The process of a spinal adjustment is like rebooting a computer. The signals that these adjustments send to the brain, via the nervous system, reset muscle behaviour patterns," said Dr. Haavik-Taylor.

"By stimulating the nervous system we can improve the function of the whole body. This is something that chiropractors and their patients have known for years; and now we have some scientific evidence to prove it."

According to a press release from the New Zealand Chiropractors Association, Haavik-Taylor has spent the last seven years researching the effects of chiropractic adjustments on the nervous system. In her latest research, carried out in conjunction with fellow New Zealander, Dr. Bernadette Murphy, she was able to measure how brain waves are altered before and after spinal adjustments.

"This is the first time that anyone has used EEGs to prove that there are definite changes to the way the brain processes information after chiropractic care," she said in the release.

The research report, "Altered Sensorimotor Integration With Cervical Spine Manipulation," was published in the Journal of Manipulative and Physiological Therapeutics (Volume 31, Issue 2, February 2008, Pages 115-126).

According to the abstract of the report, the objective of the research was to investigate changes in the intrinsic inhibitory and facilitatory interactions within the sensorimotor cortex subsequent to a single session of cervical spine manipulation using single- and paired-pulse transcranial magnetic stimulation protocols.

Twelve subjects with a history of reoccurring neck pain participated in this study. Short interval intracortical inhibition, short interval intracortical facilitation (SICF), motor evoked potentials, and cortical silent periods (CSPs) were recorded from the abductor pollicis brevis and the extensor indices proprios muscles of the dominant limb after single- and paired-pulse transcranial magnetic stimulation of the contralateral motor cortex. The experimental measures were recorded before and after spinal manipulation of dysfunctional cervical joints, and on a different day after passive head movement. To assess spinal excitability, F wave persistence and amplitudes were recorded after median nerve stimulation at the wrist.

After cervical manipulations, there was an increase in SICF, a decrease in short interval intracortical inhibition, and a shortening of the CSP in abductor pollicis brevis. The opposite effect was observed in extensor indices proprios, with a decrease in SICF and a lengthening of the CSP. No motor evoked potentials or F wave response alterations were observed, and no changes were observed after the control condition.

The researchers conclusion was that "spinal manipulation of dysfunctional cervical joints may alter specific central corticomotor facilitatory and inhibitory neural processing and cortical motor control of 2 upper limb muscles in a muscle-specific manner. This suggests that spinal manipulation may alter sensorimotor integration. These findings may help elucidate mechanisms responsible for the effective relief of pain and restoration of functional ability documented after spinal manipulation."

Haavik-Taylor is the recipient of two grants from the Australian Spinal Research Foundation to further her studies on how chiropractic care affects the function of the nervous system and alters muscle function.

Earlier this year Haavik-Taylor was recognized by her peers and she received the New Zealand College of Chiropractic Alumni Chiropractor of the Year 2007 award in recognition of her research and her passion for the discipline.

"(Dr. Haavik-Taylor's) work is ground-breaking on an international level by proving that chiropractic adjustments do alter and benefit the nervous system," said Dr. James Burt, president of the New Zealand Chiropractors Association.