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Neural Response During a Mechanically Assisted Spinal Manipulation in an Animal Model

By |June 25, 2017|Instrument Adjusting|

Neural Response During a Mechanically Assisted Spinal Manipulation in an Animal Model: A Pilot Study

The Chiro.Org Blog


SOURCE:   J Nov Physiother Phys Rehabil. 2015 (Sep);   2 (2):   20–27 ~ FULL TEXT

William R. Reed, DC, PhD,
Michael A.K. Liebschner, PhD,
Randall S. Sozio, BS, LATG,
Joel G. Pickar, DC, PhD,
Maruti R. Gudavalli, PhD

Palmer Center for Chiropractic Research,
Davenport, IA, USA.


INTRODUCTION:   Mechanoreceptor stimulation is theorized to contribute to the therapeutic efficacy of spinal manipulation. Use of mechanically-assisted spinal manipulation (MA-SM) devices is increasing among manual therapy clinicians worldwide. The purpose of this pilot study is to determine the feasibility of recording in vivo muscle spindle responses during a MA-SM in an intervertebral fixated animal model.

METHODS:   Intervertebral fixation was created by inserting facet screws through the left L5-6 and L6-7 facet joints of a cat spine. Three L6muscle spindle afferents with receptive fields in back muscles were isolated. Recordings were made during MA-SM thrusts delivered to the L7 spinous process using an instrumented Activator IV clinical device.

RESULTS:   Nine MA-SM thrusts were delivered with peak forces ranging from 68-122N and with thrust durations of less than 5ms. High frequency muscle spindle discharge occurred during MA-SM. Following the MA-SM, muscle spindle responses included returning to pre-manipulation levels, slightly decreasing for a short window of time, and greatly decreasing for more than 40s.

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Characteristics of Paraspinal Muscle Spindle Response to Mechanically Assisted Spinal Manipulation

By |June 24, 2017|Instrument Adjusting|

Characteristics of Paraspinal Muscle Spindle Response to Mechanically Assisted Spinal Manipulation: A Preliminary Report

The Chiro.Org Blog


SOURCE:   J Manipulative Physiol Ther. 2017 (Jun 17) [Epub]

William R. Reed, DC, PhD,
Joel G. Pickar, DC, PhD,
Randall S. Sozio, BS, LATG,
Michael A.K. Liebschner, PhD,
Joshua W. Little, DC, PhD,
Maruti R. Gudavalli, PhD

Palmer Center for Chiropractic Research,
Palmer College of Chiropractic,
Davenport, IA


OBJECTIVES:   The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices.

METHODS:   L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAM thrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included   (a)   the time required post-thrust until the first action potential,   (b)   differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and   (c)   the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM.

RESULTS:   Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required >6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in <6 seconds after MAM. Nonparametric comparisons between the 22 N and 44 N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF.

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