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Activator Methods International Ltd.
2950 N. Seventh Street, Suite 200
Phoenix, AZ 85014
ofc 602-224-0220
fax 602-224-0230
toll free 1-800-598-0224
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Subject: Neurophysiological Research |
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| Title: Neurophysiological Response to Intraoperative Lumbosacral Spinal Manipulation |
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| Reference: Christopher J. Colloca, D.C., Tony S. Keller, Ph.D., Robert Gunzburg, M.D., Ph.D., Katelijne Vandeputte, M.D., Arlan W. Fuhr, D.C. in press. |
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Abstract: Background: Although the mechanisms of spinal manipulation (SM) are poorly understood, clinical effects are thought to be related to mechanical, neurophysiologic, and reflexogenic processes. Animal studies have identified mechanosensitive afferents in animals and clinical studies in humans have measured neuromuscular responses to SM. Few, if any, studies have identified the basic neurophysiologic mechanisms of SM in humans or animals.
Objectives: The purpose of this clinical investigation was to determine the feasibility of obtaining intraoperative neurophysiological recordings and to quantify mixed-nerve root action potentials in response to lumbosacral SM in a human subject undergoing lumbar spinal surgery.
Materials and Methods: An L4-L5 laminectomy was performed in a 62 year-old male subject. Short duration (<0.1 ms) mechanical force, manually assisted spinal manipulative thrusts (SMTs) (500 N) were delivered to the lumbosacral spine
with an Activator® II Adjusting Instrument (AAI II). With the spine exposed, SMTs were delivered internally to the L5 mammillary process, L5-S1 joint, and to the sacral base using various force vectors. This protocol was repeated by contacting the skin overlying respective anatomical landmarks. Mixed-nerve root recordings were obtained from gas sterilized platinum bipolar hooked electrodes attached to the S1 nerve root at the level of the dorsal root ganglion during the SMTs and during a 30-second baseline period during which no SMTs were applied.
Results: During the active trials, mixed-nerve root action potentials were observed in response to both internal and external SMTs. Differences in the amplitude and discharge frequency were noted in response to varying segmental contact points and force vectors, and similarities were noted for internal and externally applied SMTs. Amplitudes of mixed-nerve root action potentials for internal thrusts ranged from 200-2600 mV, and 800-3500 mV for external thrusts.
Conclusions: Monitoring mixed-nerve root discharges in response to SMTs in human subjects in vivo undergoing lumbar surgery is feasible. Neurophysiological responses appeared sensitive to contact point and applied force vector of the SMT. Further study of the neurophysiological mechanisms of spinal manipulation in humans and animals is needed to more precisely identify the mechanisms and neural pathways involved.
Support for this study was from the National Institute of Chiropractic Research |
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