Cervical artery dissection refers to a tear in the internal carotid or the vertebral artery that results in an intramural haematoma and/or an aneurysmal dilatation. Although cervical artery dissection is thought to occur spontaneously, physical trauma to the neck, especially hyperextension and rotation, has been reported as a trigger. Headache and/or neck pain is the most common initial symptom of cervical artery dissection. Other symptoms include Horner’s syndrome and lower cranial nerve palsy. Both headache and/or neck pain are common symptoms and leading causes of disability, while cervical artery dissection is rare. Patients often consult their general practitioner for headache and/or neck pain, and because manual-therapy interventions can alleviate headache and/or neck pain, many patients seek manual therapists, such as chiropractors and physiotherapists. Cervical mobilization and manipulation are two interventions that manual therapists use. Both interventions have been suspected of being able to trigger cervical artery dissection as an adverse event. The aim of this review is to provide an updated step-by-step risk–benefit assessment strategy regarding manual therapy and to provide tools for clinicians to exclude cervical artery dissection.

Key messages

  • Cervical mobilization and/or manipulation have been suspected to be able to trigger cervical artery dissection (CAD). However, these assumptions are based on case studies which are unable to established direct causality.
  • The concern relates to the chicken and the egg discussion, i.e. whether the CAD symptoms lead the patient to seek cervical manual-therapy or whether the cervical manual-therapy provoked CAD along with the non-CAD presenting complaint.
  • Thus, instead of proving a nearly impossible causality hypothesis, this study provide clinicians with an updated step-by-step risk–benefit assessment strategy tool to (a) facilitate clinicians understanding of CAD, (b) appraise the risk and applicability of cervical manual-therapy, and (c) provide clinicians with adequate tools to better detect and exclude CAD in clinical settings.


This review outlines a systematic approach to exclude a serious and potential life-threatening disorder, such as CAD, within primary care and, especially, the manual-therapy clinical settings. The risk–benefit analysis tool is based on the most recent evidence and should benefit clinicians to help them better understand the many warning signs, especially if the presenting complaint deviates from what they consider to be the usual musculoskeletal presentation. Thus, this approach should help clinicians refer patients to medical examinations and treatment immediately upon a suspicion of CAD.

Considering the rarity of CAD, which reportedly constitutes as few as 1 per 8.1 million chiropractic office visits and 1 per 5.9 million cervical manipulations by practising chiropractors in Canada [38], conducting sufficiently powered clinical manual-therapy randomized controlled trials to evaluate causality is nearly impossible. Naturally, one can suggest that to scientifically establish the prevalence of CAD as a direct trigger of cervical mobilization and/or manipulation intervention, a prospective study would need to include 1000 manual therapists treating the cervical spine 100 times per week for 52 weeks. As a consequence, most manual-therapy randomized controlled trials have abundant type II errors.

The assumption that the cervical manual-therapy intervention triggers CAD in rare cases has been dominated by single-case reports and retrospective case series or surveys from neurologists who naturally lack substantial methodological quality to establish definitive causality [87]. These neurological case reports have probably contributed to an over-reporting of serious and catastrophic AEs compared to minor and moderate AEs, which are likely to occur more frequently [55,88]. In light of the evidence provided in this comprehensive review, the reality is (a) that there is no firm scientific basis for direct causality between cervical SMT and CAD; (b) that the ICA moves freely within the cervical pathway, while 74% of cervical SMTs are conducted in the lower cervical spine where the VA also moves freely; (c) that active daily life consists of multiple cervical movements including rotations that do not trigger CAD, as is true for a range of physical activities; and (d) that a cervical manipulation and/or grade C cervical mobilization goes beyond the physiological limit but remains within the anatomical range, which theoretically means that the artery should not exceed failure strain. These factors underscore the fact that no serious AE was reported in a large prospective national survey conducted in the UK that assessed all AEs in 28,807 chiropractic treatment consultations, which included 50,276 cervical spine manipulations [50].

While no mechanical event is reported in one-third of patients, spontaneous CAD has been reported to be caused by minor traumas to the neck from various activities, namely, skating, tennis, basketball, volleyball, swimming, scuba diving, weight lifting, dancing, yoga, jumping on a trampoline, roller coaster rides, sexual intercourse, coughing or sneezing and dental procedures, while traumatic CAD, a major trauma is present, namely, neck fractures, spinal cord injuries, and muscular tears [36,37,89]. Minor traumas together with a recent infection may contribute to the hypothesized direct injury or weakness in the vessel wall, respectively, while increased systolic blood pressure can contribute to arterial stiffness [90]. Thus, these factors must be incorporated in the risk–benefit assessment and in the evaluation of the true musculoskeletal problem presentation versus a latent CAD.

An intervention with a proven effect for a range of musculoskeletal disorders cannot be without risk. However, instead of proving a nearly impossible causality hypothesis that today is based on insufficient and poorly descriptive case studies, focus should be directed to the early detection and exclusion of CAD, and questions should be raised on how to minimize the risk.

History taking, especially regarding the time of symptom onset, is the single most important factor for detecting subtle symptoms of CAD; thus, primary care clinicians and, especially, manual therapists should dedicate enough time during the first consultation to allow for thorough history taking and physical examination. During history taking, follow-up of the patient’s answers in relation to his or her (new) neck pain and/or headache is extremely important to obtain sufficient knowledge and understanding, and one must not accept a simple yes or no answer. In cases with suspicion of high-risk CAD, which contain a combination of several warning signs, there should be an immediate referral to the medical emergency department. If time allows, this referral can include a short description of the clinician’s report of his or her findings. In time, this vigilant act by a professional may contribute to closer cooperation and mutual respect between physicians and manual therapists, which is highly important for improving the efficiency of today’s healthcare and ultimately benefits patients.

There is no sufficient evidence to support cervical VA tests to identify patients with a higher risk, and the validity and reliability of these tests are low [91]. A recent guideline by the Australian Physiotherapy Association suggests that sustained cervical rotation might be an alternative test to assess for blood flow insufficiency in a controlled way [92]. However, the validity and reliability of this new test conforms to the same uncertainties as previous tests for vascular insufficiency [91]. Thus, in the absence of a physical vascular screening test, manual therapists would need to rely on a thorough history and clinical reasoning to follow the principles of do-no-harm.

Although the chiropractic profession evolved in the early nineteen hundreds as an art, philosophy, and science, neck manipulation should not resemble a martial art. Thus, when cervical manipulation techniques are being conducted, one must be specific when manipulating a single spinal segment, minimizing the end range in cervical techniques, especially rotational techniques, and minimizing force, all of which have been recommended to reduce the risk of serious AEs [93].

We propose that considering the risk–benefit assessment tool outlined in Figure 3, clinicians will consequently enhance decision-making with respect to differential diagnoses and enable the detection of a larger number of latent and possible progressive CADs, regardless of the actual manual intervention.

Keywords: Cervical artery dissection, vertebral artery dissection, carotid artery dissection, stroke, manual-therapy, manipulation

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