Changes of blood flow velocity indicating mechanical compression of the vertebral arteries during rotation of the head in the normal human measured with transcranial Doppler sonography

Abstract

The dynamical changes of blood flow velocity of the intracranial vertebral arteries (VA's) and proximal basilar artery (BA) provoked by rotation of the head in normal volunteers were measured using pulsed-wave transcranial Doppler sonography (TCD). In another group both VA's were examined simultaneously with 2-channel TCD. Blood flow velocities diminished compared to the neutral position in all vessels, independently of the side. Total obstruction of the flow was not observed. Our findings reveal a definitive decrease of blood flow velocity at the vertebrobasilar artery system provoked by rotation of the head in normal humans. This physiological phenomenon is suggested to have an impact on the cerebral blood flow in patients with impaired autoregulation of the cerebral vessels, low volume flow reserve in the contralateral VA or insufficient collateral channels because of normal anatomical variation, especially those patients under general anesthesia or comatose.

Comparison of 4D Phase-Contrast MRI Flow Measurements to Computational Fluid Dynamics Simulations of Cerebrospinal Fluid Motion in the Cervical Spine

“…The healthy subjects were considerably older than the CM patients and thus were also likely to have different flow characteristics [9], [43]. In addition, several factors were not controlled including neck angulation that might have had an impact on CSF dynamics [44], [45], [46], [47]. Future studies should be performed in a larger population with age-matched controls.…”

Manual Therapy and Cervical Arterial Dysfunction, Directions for the Future: A Clinical Perspective

“…Many blood fl ow studies have demonstrated a change (reduction) in blood fl ow in the contralateral VA during rotation [20][21][22][23][24][25][26][27][28] . Other studies, however, have found no change in blood fl ow [29][30][31][32] .…”

“…Some fl ow studies have insonated the vessel as it enters the lower part of the vertebral column (the pre-transverse level) 22,[76][77][78][79][80] . Few studies have measured blood fl ow in the intracranial VA 21,23,24,28 where it may be argued that VA blood fl ow related to the upper cervical spine would be a more accurate measure of fl ow change 24,32,73,74 . It has also been shown that VA atherosclerotic plaques do exist throughout the course of the VA 64 .…”

Vertebral Artery Blood flow Velocity Changes Associated with Cervical Spine rotation: A Meta-Analysis of the Evidence with implications for Professional Practice

“…The majority of these studies report compromised contralateral VA blood flow 15,16,19,22,25,[27][28][29]39,42,43 . however, some authors found no associated change in VA blood flow 10,18,21,32,35,38,41 , while a few reports indicated an increase, in some cases, in contralateral 15,30,40,44 and in ipsilateral 25 blood flow.…”