Manual Therapy
Volume 11, Issue 4 , Pages 241-242, November 2006

Adverse events and the vertebral artery: Can they be averted?

Discipline of Physiotherapy, School of Health Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia

Article Outline

 

Cervical spine manipulation continues to be the subject of much debate almost a century after the first manipulative complication was described in 1907. Essentially those who advocate abandoning cervical manipulation contend that despite it remaining a common treatment for neck pain and headache, there are safer and equally effective alternative interventions. However, is this indeed the case? While at this time there is only limited evidence for the efficacy of neck manipulation, there is even less for the most likely alternative intervention, passive joint mobilization (NHMRC, 2003). Similarly, cervical mobilization is not without its risks as recent reports have highlighted (Magarey et al., 2004). Nevertheless, the complications associated with cervical manipulation are more clearly established and in general more serious.

Of the various complications attributed to neck manipulation, stroke is arguably the most serious (Rivett, 2004). Despite some recent controversy as to whether the internal carotid artery is also at risk, the vertebral artery is unquestionably the most vulnerable vessel. The intimate relationship of the vertebral artery to the cervical vertebrae as it ascends through the transverse foraminae, the relative fixity of the segment between the atlas and the axis, together with the large excursion of rotation at the atlanto-axial articulation, may lead to ‘kinking’ (or other mechanical stressing) of the contralateral vessel during rotation. Vertebrobasilar insufficiency may result but the individual response largely depends on the calibre and patency of the opposite artery and its ability to maintain hindbrain perfusion. Certainly it is likely that any blood flow changes during neck rotation, whether manifest via symptomatic response or through some form of imaging such as duplex ultrasound, are the consequence of biomechanical stress imparted to the arterial wall (Haynes, 2000).

The actual risk of stroke associated with manipulation of the cervical spine is unknown as the event is relatively rare, rendering prospective epidemiological investigations impractical. Best estimates from retrospective studies of the medical (Dvorák et al., 1993, <1 per 150,450 manipulations), chiropractic (Rothwell et al., 2001, 1.3 per 100,000 patients <45 years) and physiotherapy professions (Rivett and Reid, 1998, 1 per 163,371 manipulations) tend to indicate that a practitioner would be unfortunate to encounter such an event even once in their career. Nonetheless, the potential for permanent disability or death from a vertebrobasilar stroke following neck manipulation obliges practitioners to undertake all reasonable precautions to prevent such an incident.

So what can be done to prevent such potentially tragic sequelae to the physical treatment of a relatively benign disorder? First, the practitioner should develop a high degree of clinical suspicion when a patient presents with a sudden onset of severe, sharp pain in the postero-superior neck and occipital region (Haldeman et al., 2002; Krespi et al., 2002; Thiel and Rix, 2005). This presentation is typical of a dissecting vertebral artery and may or may not be associated with a recent history of trauma to the cervical spine or with more recognizable neurological symptoms, such as hemianopia or dysphagia. Of course, there may be simple musculoskeletal causes for such pain, but extreme caution should be exercised in employing any form of manual therapy if there is no prior history of similar pain. It is a sobering thought that pain from a vertebral artery dissection may actually prompt the patient to seek manipulative treatment!

Second, do not consider using neck manipulation unless you have been properly trained in the application of the technique. There has been much recent debate about what is the appropriate level of education in spinal manipulation, but with no clear answer emerging (Refshauge et al., 2002; Boissonnault et al., 2004). What is clear however, is that many cases of manipulative complication are the result of poor clinical reasoning and the failure to recognize red flags or atypical clinical findings (Di Fabio, 1999; Rivett, 2004). In addition to technical training in manipulation to reduce hazardous practices such as overly vigorous thrusting forces, the thinking skills needed to appropriately and safely apply neck manipulation also require careful cultivation. To this end, the Australian Physiotherapy Association has produced an ‘at a glance’ colour flowchart to assist the practitioner in their clinical reasoning when considering cervical spine manipulation for a particular patient (Rivett et al., 2006).

Finally, the pre-manipulative use of provocative positional tests still has a role in the prevention of neurovascular manipulative complications (Rivett et al., 2006). Although the validity of tests involving sustained end-range rotation and/or extension of the neck has been seriously challenged of late (Thiel and Rix, 2005), provocative testing may still detect an occasional patient experiencing vertebrobasilar insufficiency related to positional occlusion of a vertebral artery, particularly when the opposite artery provides insufficient collateral flow. However the practitioner needs to be aware that dizziness is not the only possible positive response to provocative testing, but that other less recognized and indistinct symptoms may be elicited, including tinnitus, tremors, anxiety and nausea. The practitioner also needs to be mindful that the tests are limited in their predictive ability with false positive and false negative findings common, and with the number of ultrasonographic studies equally divided as to whether there are flow changes during neck rotation or not (Magarey et al., 2004).

Positional testing of the cervical spine in combination with the use of a hand-held Doppler velocimeter shows greater promise and may provide more valid clinical information as to blood flow changes and anomalies (Haynes, 2000). Further research is needed to clearly determine the clinical value of this tool in pre-manipulative screening, and to develop a means to detect patients at risk of vertebral artery dissection. Research is presently being conducted at the University of Newcastle in Australia in both these areas.

So can adverse events of the vertebral artery be averted? In many cases yes, if the practitioner is alert to the dissecting vertebral artery, thorough in their routine examination for vertebrobasilar insufficiency, and well trained technically and cognitively in cervical spine manipulation. Despite these precautions, a small number of unfortunate and unpredictable neurovascular complications will continue to occur for some time yet, at least until better screening procedures are developed and proven.

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References 

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PII: S1356-689X(06)00133-0

doi:10.1016/j.math.2006.08.001

Manual Therapy
Volume 11, Issue 4 , Pages 241-242, November 2006

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