Changes in vertebral artery blood flow following various head positions and cervical spine manipulation.
OBJECTIVE
The objective of the study was to investigate the cerebrovascular hemodynamic response of cervical spine positions including rotation and cervical spine manipulation in vivo using magnetic resonance imaging technology on the vertebral artery (VA).


METHODS
This pilot study was conducted as a blinded examiner cohort with 4 randomized clinical tasks. Ten healthy male participants aged 24 to 30 years (mean, 26.8 years) volunteered to participate in the study. None of the participants had a history of disabling neck, arm, or headache pain within the last 6 months. They did not have any current or history of neurologic symptoms. In a neutral head position, physiologic measures of VA blood flow and velocity at the C1-2 spinal level were obtained using phase-contrast magnetic resonance imaging after 3 different head positions and a chiropractic upper cervical spinal manipulation. A total of 30 flow-encoded phase-contrast images were collected over the cardiac cycle, in each of the 4 conditions, and were used to provide a blood flow profile for one complete cardiac cycle. Differences between flow (in milliliters per second) and velocity (in centimeters per second) variables were evaluated using repeated-measures analysis of variance.


RESULTS
The side-to-side difference between ipsilateral and contralateral VA velocities was not significant for either velocities (P = .14) or flows (P = .19) throughout the conditions. There were no other interactions or trends toward a difference for any of the other blood flow or velocity variables.


CONCLUSIONS
There were no significant changes in blood flow or velocity in the vertebral arteries of healthy young male adults after various head positions and cervical spine manipulations.
Chiropractor, Private Practice, Division of Graduate Studies, Clinical Sciences, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.. Electronic address: jquesnele@gmail.com.
Jairus J
JJ
Quesnele
Professor, Dean of Graduate Studies and Research, Graduate Education and Research, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.
John J
JJ
Triano
Associate Professor, Electrical and Computer Engineering School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Director, Imaging Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada.
Michael D
MD
Noseworthy
Assistant Professor, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada.
Greg D
GD
Wells
D000293:Adolescent; D000328:Adult; D002560:Cerebrovascular Circulation; D006257:Head; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020393:Manipulation, Spinal / Q000379:methods*; D009333:Neck; D056888:Patient Positioning; D010865:Pilot Projects; D012039:Regional Blood Flow; D014711:Vertebral Artery / Q000502:physiology*; D055815:Young Adult
Blood Flow Velocity; Chiropractic; Head Movements; Hemodynamic; Manipulation Spinal; Vertebral Artery; Vertebrobasilar Insufficiency