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.

Acknowledgments:
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.
Reference:
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.
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