RRS Education Chiropractic BLOG - Musculoskeletal Research Reviews

High-velocity, low amplitude cervical spine manipulation (CSM) is an effective treatment for neck pain that is commonly used by patients and is recommended in numerous clinical practice guidelines. Nonetheless, some are concerned about the safety of CSM, especially about CSM that involves head and neck extension/rotation and possible stretch and damage to the inner lining of the vertebral artery (VA) resulting in arterial dissection and subsequent stroke. 

Prior studies have shown that head angular displacements during CSM are small and do not exceed the normal physiological range of motion (references contained in the Review). However, one study reported that angular head displacements at the pre-manipulative position approached the extent of upper cervical active range of motion. 

The elongation response of the VA to CSM and passive ranges of motion has been investigated in several studies, with reports of arterial length changes for specific regions or along the full length of the artery. Head and neck rotation contralateral to the side of VA instrumentation resulted in the greatest changes in VA length at the V3 segment (C1/C2 level) during both CSM and passive ranges of motion. These changes in VA length during CSM were typically lower than changes measured during passive range of motion testing, and they did not approach published length changes that result in failure (which is about 12% elongation on average). 

However, the kinematics of the head relative to the sternum along with associated VA length changes during the thrust phase of CSM delivered at each level of the cervical spine have not been investigated. Therefore, it is not known whether VA length changes vary when CSM thrusts are applied to different levels of the cervical spine. 

Because of gaps identified in previous research, the purpose of this cadaveric study was to systematically quantify the angular displacements of the head relative to the sternum and the associated VA length changes during the thrust phase of two types of CSM (rotation and lateral flexion), applied bilaterally, to each level of the cervical spine (C1–C7). The authors hypothesized that there would be no differences in VA length changes during CSM applied to the different vertebral levels. 

THIS WEEK'S RESEARCH REVIEW: “Head Kinematics & Associated Vertebral Artery Length Changes During Neck Manipulation”

This paper was published in Chiropractic & Manual Therapies (2022) and this Review is posted in Recent Reviews, Spinal Manipulation - Adverse Events & Safety and the 2022 Archive.


Vertebral artery

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