title: Changes in vertebral artery blood flow following normal rotation of the cervical spine.
abstract: BACKGROUND
  Extreme rotation of the cervical spine may cause compromised vertebral artery (VA) blood flow. This is of particular interest to manual therapists because of the potential risks associated with these movements. The question is whether the decreased blood flow is significant and therefore likely to cause vertebrobasilar insufficiency/ischemia (VBI) and whether contralateral and ipsilateral rotations are equally affected. Several studies measuring VA blood flow have been reported. However, different parts of the VA were studied, in small samples of normal subjects and patients over a wide range of ages. Hence, the results are controversial.
  
  
  OBJECTIVE
  To investigate intracranial VA blood flow in normal male subjects and female subjects, aged 20 to 30 years, in neutral and maximally rotated cervical spinal positions.
  
  
  METHODS
  Transcranial Doppler sonography was used to measure intracranial VA blood flow, with the cervical spine in neutral and then rotated maximally to the left and later to the right. The sample consisted of 60 male subjects and 60 female subjects (240 VAs). Comparisons between the neutral and rotated head positions were made within and between the groups.
  
  
  RESULTS
  There was a significant decrease (P =.001) in intracranial VA blood flow following cervical spine rotation, irrespective of side but greater on the contralateral side, in the total sample and in male subjects. Female subjects had a significantly higher blood flow than male subjects, and although they showed a significant decrease with contralateral rotation, there was no significant difference in blood flow on the ipsilateral side.
  
  
  CONCLUSIONS
  Maximal rotation of the cervical spine may significantly affect vertebral artery blood flow, particularly when used in the treatment of patients with underlying vascular pathology.
authors.affiliation: School of Allied Health Professions, Glenside Campus (Post-station 5), Faculty of Health and Social Care, University of the West of England, Blackberry Hill, Stapleton, Bristol BS16 1DD, England, United Kingdom. Jeanette.Mitchell@uwe.ac.uk
authors.forename: Jeanette A
authors.initials: JA
authors.lastname: Mitchell
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002574:Cervical Vertebrae / Q000098:blood supply*; D005260:Female; D006801:Humans; D008297:Male; D020393:Manipulation, Spinal / Q000379:methods; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012399:Rotation; D013314:Stress, Mechanical; D018615:Ultrasonography, Doppler, Color; D014711:Vertebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*