Doppler insonation of vertebral artery blood flow changes associated with cervical spine rotation: Implications for manual therapists

Abstract

The controversy related to changes in vertebral artery (VA) blood flow associated with rotation of the cervical spine and the implications for professional practice is still of concern to manual therapists. The aim of this review of the literature is, first, to assess current evidence of altered VA blood flow following cervical spine rotation in persons with and without signs and symptoms of vertebrobasilar ischemia/insufficiency (VBI). Second, any reported, related alterations in blood flow that may have consequences for the individual will be discussed to assist manual therapists in pretreatment risk assessment of patients. The most commonly used noninvasive, in vivo technique for measuring blood flow is Doppler ultrasonography. Of the 88 relevant papers retrieved by a systematic literature search covering the past 50 years, 20 studies reported measurement of VA blood flow related to cervical spine rotation. A critical analysis of these reports revealed that there is no standardization of methods used (heterogeneous samples, small sample sizes, various measurement positions and instruments, and different parts of the VA measured); no consensus of findings (no change, and a significant reduction in contralateral VA blood flow, with or without VBI); and no correlations found between rotation, blood flow, and VBI. Nevertheless, this review is of value in increasing our knowledge of the possible mechanisms and consequences of repeated minor arterial trauma and of blood flow changes related to rotational movements used in cervical manual therapy. It highlights, too, the need for caution in the interpretation of pretreatment risk assessment outcome measures.

Manipulative practice in the cervical spine: a survey of IFOMPT member countries

“…Two MOs commented that they no longer used positional tests involving extension, but continued to use rotation. This finding is notable as there is conflicting evidence in the literature from Doppler ultrasound studies regarding the validity of these tests; 28 however, evidence suggests that rotation does influence blood flow in the vertebral artery in some individuals. 12,26 There are also published reports of (false) negative tests despite known dysfunction.…”

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

“…Traditionally, the upper cervical spine is believed to carry a greater risk because of the tortuous course of the VA between C2 and the occiput. Most blood fl ow studies have concentrated on the C1/C2 and cervical anatomical area 25,29,30,32,[73][74][75] . 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] .…”

“…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 .…”

The immediate effect of atlanto-axial high velocity thrust techniques on blood flow in the vertebral artery: A randomized controlled trial

“…The mechanistic reasoning for measuring blood flow in relation to adverse events is principled initially in the idea of altered haemodynamics being a fundamental component of vessel pathology (Cecchi et al, 2011). Further, flow change is considered to be indicative of the sorts of mechanical stresses responsible for the type of micro-trauma in question (Mitchell, 2007). Thus blood flow measurement remains a valid procedure to understand vascular tissue stress in the VA.…”

“…Although blood flow volume is the primary measure affecting brain perfusion (Ganong, 2005), the measure of interest in this study was blood flow velocity. Changes in blood flow velocity may be used to reflect changes in volume (Aaslid et al, 1986;Newell and Aaslid, 1992;Mitchell, 2007). Blood flow velocity and volume vary proportionally (Aaslid et al, 1986;Newell and Aaslid, 1992) in part due to the low pulsatility index of the VA, and during normal laminar blood flow the VA internal diameter does not change (Mitchell, 2009).…”