title: Loud preimpact tones reduce the cervical multifidus muscle response during rear-end collisions: a potential method for reducing whiplash injuries.
abstract: BACKGROUND
  Neck muscle responses after unexpected rear-end collisions consist of a stereotypical combination of postural and startle responses. Prior work using surface electromyography (EMG) has shown that the superficial neck muscle responses can be attenuated when a loud tone (105 dB) is presented 250 milliseconds before impact, but the accompanying response of the deeper multifidus muscles remains unknown. Quantifying this response in multifidus is important because this muscle attaches directly to the cervical facet capsule and can potentially increase the strain in the capsule during an impact and contribute to whiplash injury.
  
  
  OBJECTIVE
  To investigate if a loud preimpact tone decreases the cervical multifidus muscle response during rear-end perturbations.
  
  
  METHODS
  After approval by the University Clinical Ethics Review Board, human volunteers experienced a series of three whiplash-like perturbations.
  
  
  METHODS
  Twelve subjects with no history of neurologic disorders or whiplash injury were recruited to participate in this experiment.
  
  
  METHODS
  Bilateral indwelling EMG of multifidus at the C4 and C6 levels, surface EMG of sternocleidomastoid (SCM) and C4 paraspinals (PARAs), and kinematics of the head/neck were measured.
  
  
  METHODS
  Subjects experienced three whiplash-like perturbations (peak acceleration of 19.5 m/s(2)) preceded by either no tone or a loud tone (105 dB) presented 250 milliseconds before sled acceleration onset.
  
  
  RESULTS
  The loud tone decreased the muscle activity of C6 multifidus (42%) and C4 PARAs (30%), but did not affect the C4 multifidus or SCM activity. Peak head kinematic responses (extension angle: 6%, retraction: 9%, linear forward acceleration: 9%, and angular acceleration in extension: 13%) were also decreased by the loud preimpact tone.
  
  
  CONCLUSIONS
  The attenuation of peak C6 multifidus activity and head kinematic responses suggests that a loud preimpact tone may reduce the strain in the cervical facet capsule, which may reduce the risk of whiplash injury during rear-end collisions.
authors.affiliation: School of Kinesiology, University of British Columbia (UBC), 210 - 6081 University Boulevard, Vancouver, Canada V6T 1Z1.
authors.forename: Daniel W H
authors.initials: DW
authors.lastname: Mang
authors.affiliation: School of Kinesiology, University of British Columbia (UBC), 210 - 6081 University Boulevard, Vancouver, Canada V6T 1Z1; MEA Forensic Engineers & Scientists, 11-11151 Horseshoe Way, Richmond, Canada V7A 4S5. Electronic address: gunter.siegmund@meaforensic.com.
authors.forename: Gunter P
authors.initials: GP
authors.lastname: Siegmund
authors.affiliation: School of Kinesiology, University of British Columbia (UBC), 210 - 6081 University Boulevard, Vancouver, Canada V6T 1Z1.
authors.forename: Harrison J
authors.initials: HJ
authors.lastname: Brown
authors.affiliation: School of Kinesiology, University of British Columbia (UBC), 210 - 6081 University Boulevard, Vancouver, Canada V6T 1Z1.
authors.forename: Samanthi C
authors.initials: SC
authors.lastname: Goonetilleke
authors.affiliation: School of Kinesiology, University of British Columbia (UBC), 210 - 6081 University Boulevard, Vancouver, Canada V6T 1Z1; Brain Research Centre, UBC, 2211 Wesbrook Mall, Vancouver, Canada V6T 2B5; Institute for Computing, Information and Cognitive Systems (ICICS), UBC, 289 - 2366 Main Mall, Vancouver, Canada V6T 1Z4.
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Blouin
mesh_terms: D000054:Acceleration; D000161:Acoustic Stimulation; D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009334:Neck Muscles / Q000503:physiopathology*; D064170:Paraspinal Muscles / Q000503:physiopathology*; D014911:Whiplash Injuries / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D055815:Young Adult
keywords: Head-neck control; Neck muscles; Neuromuscular response; Perturbation; Prestimulus inhibition; Whiplash