VBI – Decision Making in the Presence of Uncertainty

Some estimates related to the risk of VBI when manipulating the spine range from 6 in 10 million[i] to 1 in 400,000.[ii] Although the spectrum of risk in these figures differs, the technique of performing low-amplitude high-velocity thrusts on the cervical spine is real.

It is a little disheartening to me, knowing that the tests we use to screen cervical spine patients for vertebro-basilar insufficiency (VBI) may not in fact be as accurate as I initially thought.  Although our governing body supports the use of screening procedures and guidelines to indentify patients at risk for VBI, Childs et al (2005) attest that recent research does not support the idea that practitioners can assess risk in VBI patients accurately. Furthermore, Di Fabio (1999) and Halderman et al (1999) believe that there is not great evidence for ultrasound, diagnostic testing or clinical examination findings to identify patients with VBI risk.

Evidence over the past 10 or so years has confirmed cases of patients who sustained VBI after cervical manipulation. Huffnagel et al (1999) reported on 10 such patients that had no signs or symptoms predicting them for increased risk of VBI.

Despite the inaccuracy of testing, from a legal standpoint, it would still be jurisprudent for physical therapists to use the guidelines for pre-manipulative testing with appropriate patients, so that they do not place themselves at risk for litigation.

Why should we bother testing patients at all if this lack of specificity for testing exists, and there is a high likelihood that practitioners may report false negative findings when testing for VBI?  Despite this being a difficult area to research, due to the occurrence of VBI being rare, we must strive to develop either safer manipulation skills or better testing measures for VBI.

Is it the manipulative procedure itself, or the position of the neck holds risk of VBI?  Interestingly, Symons et al (2002) found that the strain on the vertebral arteries during thrusting is lower in some cases than range of motion testing of the cervical spine. In contrast, Kuether et al (1997) found the positions of terminal neck rotation, and neck rotation plus cervical extension reduce vertebral artery blood flow significantly.

I then ask the question, are the pre-manipulative testing positions potentially more dangerous than the high-velocity thrust performed during the manipulation? I am aware of (but not proficient in) certain cervical manipulative techniques done in supine, with the absence of any rotation performed to the neck. Perhaps these advanced techniques should be taught to physical therapy schools, rather than the current rotation/extension manipulation techniques that may be putting patients at risk.

Cleland et al (2007) and Childs et al (2005) suggest we try another approach altogether – thoracic spine manipulation to address patients with neck pain. Cleland et al (2007) reported positive preliminary results with their initial study. I will reserve judgement until the results of a validation trial are performed on their clinical prediction rule.

References

Childs J, Flynn T, Fritz J, et al. Screening for vertebrobasilar insufficiency in patients with neck pain: manual therapy decision-making in the presence of uncertainty. The Journal Of Orthopaedic And Sports Physical Therapy. 2005;35(5):300-306.

Cleland J, Childs J, Fritz J, Whitman J, Eberhart S. Development of a clinical prediction rule for guiding treatment of a subgroup of patients with neck pain: use of thoracic spine manipulation, exercise, and patient education. Physical Therapy. 2007;87(1):9-23.

Di Fabio, R. Manipulation of the cervical spine: risks and benefits. Physical Therapy. 1999; 79(1): 50-65

Hladerman S, Kohlbeck F, McGregor M. Unpredictibility of cerebrovascular ischemia associated with cervical spine manipulation therapy: a review of sixty-four cases after cervical spine manipulation. Spine. 2002; 27:49-55.

Hufnagel A, Hammers A, Schönle P, Böhm K, Leonhardt G. Stroke following chiropractic manipulation of the cervical spine. Journal Of Neurology. 1999;246(8):683-688.

Kuether T, Nesbit G, Clark W, Barnwell S. Rotational vertebral artery occlusion: a mechanism of vertebrobasilar insufficiency. Neurosurgery. 1997;41(2):427-432.

Symons B, Leonard T, Herzog W. Internal forces sustained by the vertebral artery during spinal manipulative therapy. Journal of Manipulative & Physiological Therapeutics. 2002;25(8):504-510.

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[i] Klougart N, Leboeuf-Yde C, Rasmussen L. Safety in chiropractic practice. Part II: Treatment to the upper neck and the rate of cerebrovascular incidents. Journal Of Manipulative And Physiological Therapeutics. 1996; 19(9):563-569.

[ii] Magarey M, Rebbeck T, Coughlan B, Grimmer K, Rivett D, Refshauge K. Pre-manipulative testing of the cervical spine review, revision and new clinical guidelines. Manual Therapy. 2004;9(2):95-108.