Neurophysiological Responses of Chiropractic Adjustments

Christopher J. Colloca, D.C.

"Although ligament has been traditionally considered only as a mechanical structure, there is increasing evidence to suggest that ligaments are innervated and can participate in active neuromuscular reflexes."

-Jiang H, Russell G, Raso J, Moreau MJ, Hill DL, Bagnall KM. The Nature and Distribution of the Innervation of Human Supraspinal & Interspinal Ligaments. Spine 1995; 20:869-876.

Reflex assessments that are made from the skin overlying the spinal musculature using surface electromyography (sEMG) are of value in determining the electrical activity of the muscles or neuromuscular reflex responses of chiropractic adjustments.

Some of the fundamental questions that remain, however, are the origin of the reflex responses.

What tissues are being stimulated during spinal adjustment - The disc? The facet capsule? The ligaments? The muscles? Some or all of these structures?

Could it be that the advantageous results of spinal manipulation can be attributed to stimulation of the deep tissue discoligamentous and muscular tissues - tissues not affected by passive therapeutic modalities?

Such questions are difficult to answer and require sophisticated neurophysiological recording techniques.

However, these important questions deserve attention as they may hold the answers to explain the mechanisms underlying chiropractic adjustments.

(L to R) Chris Colloca, DC, Robert Gunzburg, MD, PhD, Arlan Fuhr, DC, and Tony Keller, PhD represent a unique collaboration combining the sciences of chiropractic, orthopaedics, neurology, and engineering to investigate neurophysiological responses of chiropractic adjustments.

Spinal adjusting instrument in place with segmental contact internally upon the L5 spinous process as recordings are made from the S1 spinal nerve root. Electrode lead is shown exiting the surgical wound.

We have had the opportunity on two occasions to measure mixed nerve root responses to internal mechanical stimulation and chiropractic adjustments.

By cradling a biplolar platinum electrode around the spinal nerve root and measuring its response during spinal thrusts, we have been able to quantify nerve root responses to adjustments in this manner.

Dr. Colloca delivers a chiropractic adjustment while nerve root recordings are being obtained in a patient undergoing lumbar spine surgery.

S1 spinal nerve root potential in response to spinal manipulation delivered to L5.
Specifically, we have assessed the nerve root's response dependent upon segmental contact point, force, and applied vector (line of drive).

We have found significant differences in nerve root responses when considering these variables.

Typical neurophysiological response to a chiropractic adjustment shown. The temporal relationship between the mechanical stimulus (adjustment) and the action potential generation can be examined in this manner.
More recently, Dr. Keller and I designed a study and have collected data on an additional 9 patients with an improved design.

We designed a specific protocol where we could deliver chiropractic adjustments again with varying segmental contact points, vectors, and excursions, but this time simultaneously measure spinal motions (using implanted bone pins), obtain neurophysiological recordings from the spinal nerve roots bilaterally, and measure electromyographic reflex responses from the spinal musculature (using needle Currently we are analyzing the data from this new research and preparing to present our results and publish the manuscripts.


The NICR, and especially Dr. William Harris (Foundation for the Advancement of Chiropractic Education), and Dr. Jack Donovan (Carroll, IA) are thanked for their generous support of this research through financial support.


Colloca CJ, Keller TS, Gunzburg R, Van de Putte K, Fuhr AW. Neurophysiological response to intraoperative lumbosacral spinal manipulation. J Manipulative Physiol Ther 2000: 23(7):447-57.

Related Research on Neurophysiological Responses of Mechanical Stimulation

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