Vertebral artery flow and cervical manipulation: An experimental study

Background: Spinal manipulation therapy is used by millions of patients eac h year to relieve symptoms caused by biomechanical dysfunction of the spine . Cerebrovascular accidents in the posterior cerebral circulation are a fea red complication, but little research has been done on vertebral artery hem odynamics during cervical manipulation. Objective: The purpose of this study was to develop an experimental model f or investigations of volume blood flow changes in the vertebral arteries du ring premanipulative testing of these vessels and during spinal manipulatio n therapy of the cervical spine. Design and Setting: An experimental study in a university biomedical labora tory. Material and Methods: The vertebral arteries were exposed in 8 adult pigs a fter extensive mediastinal dissection. Volume blood now was measured on bot h sides simultaneously by advanced transit-time flowmetry. Results: After cervical manipulation, the vertebral artery volume blood flo w increased significantly for 40 seconds before returning to baseline value s in less than 3 minutes. We found no significant changes in volume blood f low during premanipulative testing of the vertebral arteries (DeKleyn's tes t). Conclusion: We present an experimental model for investigations of vertebra l artery hemodynamics during biomechanical interventions. We found a modest and transient effect of cervical manipulation on vertebral artery Volume f low. The model may have further applications in future biomechanical resear ch, for example, to determine whether any of several spinal manipulative te chniques imposes less strain on the vertebral artery, thereby reducing poss ible future cerebrovascular accidents after such treatment.