title: 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, low-amplitude 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Associate Professor, Palmer Center for Chiropractic Research, Davenport, IA. Electronic address: william.reed@palmer.edu.
authors.forename: William R
authors.initials: WR
authors.lastname: Reed
authors.affiliation: Research Associate, Palmer Center for Chiropractic Research, Davenport, IA.
authors.forename: Randall
authors.initials: R
authors.lastname: Sozio
authors.affiliation: Professor Emeritus, Palmer Center for Chiropractic Research, Davenport, IA.
authors.forename: Joel G
authors.initials: JG
authors.lastname: Pickar
authors.affiliation: Associate Professor, Palmer Center for Chiropractic Research, Davenport, IA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Onifer
mesh_terms: D000818:Animals; D020647:Lateral Thalamic Nuclei / Q000166:cytology*; D008297:Male; D020393:Manipulation, Spinal / Q000379:methods*; D009619:Nociceptors / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
keywords: Chiropractic; Lumbar Vertebrae; Manipulation; Nociceptive Neuron; Spinal; Thalamus