Effect of Spinal Manipulation Thrust Duration on Trunk Mechanical Activation Thresholds of Nociceptive Specific Lateral Thalamic Neurons

Abstract

Objective-The objective of this preliminary study was to determine if high-velocity, lowamplitude spinal manipulation (HVLA-SM) thrust duration alters mechanical trunk activation thresholds of nociceptive-specific (NS) lateral thalamic neurons.Methods-Extracellular recordings were obtained from 18 NS neurons located in 2 lateral thalamic nuclei (ventrolateral [n = 12] and posterior [n = 6]) in normal anesthetized Wistar rats. Response thresholds to electronic von Frey anesthesiometer (rigid tip) mechanical trunk stimuli applied in 3 lumbar directions (dorsal-ventral, 45° caudal, and 45° cranial) were determined before and immediately after the delivery of 3 HVLA-SM thrust durations (time control 0, 100, and 400 milliseconds). Mean changes in mechanical trunk activation thresholds were compared using a mixed model analysis of variance.Results-High-velocity, low-amplitude spinal manipulation duration did not significantly alter NS lateral thalamic neurons' mechanical trunk responses to any of the 3 directions tested with the anesthesiometer.Copyright © 2014 by National University of Health Sciences.Submit requests for reprints to: William R Reed, DC, PhD, 741 Brady St, Davenport, IA 52803. (william.reed@palmer.edu). Potential Conflicts of Interest No conflicts of interest were reported for this study Contributorship Information Concept development (provided idea for the research): W.R.R. Design (planned the methods to generate the results): W.R.R., J.G.P., R.S.S. Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): W.R.R. Data collection/processing (responsible for experiments, patient management, organization, or reporting data): W.R.R., R.S.S. Analysis/interpretation (responsible for statistical analysis, evaluation, and presentation of the results): W.R.R., J.G.P., S.M.O., R.S.S. Literature search (performed the literature search): W.R.R., S.M.O., R.S.S. Writing (responsible for writing a substantive part of the manuscript): W.R.R., S.M.O. Critical review (revised manuscript for intellectual content, this does not relate to spelling and grammar checking): W.R.R., J.G.P., S.M.O., R.S.S.The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusions-This study is the first to examine the effect of HVLA-SM thrust duration on NS lateral thalamic mechanical response thresholds. High-velocity, low-amplitude spinal manipulation thrust duration did not affect mechanical trunk thresholds. Key Indexing TermsManipulation; Spinal; Thalamus; Nociceptive Neuron; Lumbar Vertebrae; ChiropracticSpinal manipulation has been shown to be effective in treating neck and low back pain. [1][2][3] Not only are the neurophysiological mechanisms by which this occurs unknown, but a lack of knowledge also exists regarding the effects of clinician-controlled mechanical application parameters o...