To the Editor:
I read with interest the following recommendation of the guidelines1 under Section 1.3.3. Noting predispositions during physical examination; impaired vertebral artery flow:
“Do not use Doppler ... to identify impaired vertebral artery flow, the presence of dissection, or patients with greater or lesser risk of symptomatic (ischemia-provoking) dissection subsequent to manipulation.”
To support this recommendation the guidelines1 state that: “The evidence of an extensive review of the literature suggests that a positive (impaired) Doppler “flow test” does not predict impaired vertebral artery blood flow” {L-5}.146 <http://www.ccachiro.org/Client/cca/cca.nsf/web/JCCA-References?OpenDocument>
The reference number 146 relates to a survey study by Magarey et al.2 of Australian physiotherapists about guidelines regarding cervical manipulation. Included in this paper was, as alluded to by the guideline1 authors, a supposedly extensive review of the literature about Doppler ultrasound of vertebral arteries (VAs). In reality, Doppler was discussed mainly in the context of the provocational tests, rather than as a separate subject, and in insufficient detail to make any legitimate conclusions about its effectiveness.
It seems that, while Magarey et al.2 did make a passing mention of some technical difficulties with Doppler, there was an absence of any suggestion that a positive Doppler test is unable to indicate or predict markedly impaired VA blood flow. The discrepancies in the results between the studies of positional stenosis of VAs that are listed in their paper,2 are understandable, because most of the Doppler studies had flawed experimental designs, as explained in an analysis of the literature by Haynes.3 Hence, it is inappropriate to use these discrepancies to cast doubt about the usefulness of Doppler. Properly designed validity and reliability trials are required to make decisions about the capabilities of a test, but their review2 omitted mentioning any of the relevant trials that have been published. The literature review by Haynes3 included 8 published original studies, which found that vertebral artery Doppler, has high capability.
What scientific justification was there for the authors of the guidelines1 to choose the Margarey et al.2 review, which omitted any reference to validity and reliability studies of VA Doppler, to form a conclusion about the efficacy of Doppler, and then to use this to make a recommendation about Doppler? Was there any scientific rationale for their lack of recognition of the Haynes’ literature review, which did discuss the validity and reliability trials of VA Doppler? Considering that there are at least 8 validity or reliability trials supporting VA Doppler that have been published between 1977 and 2001,3 what evidence is there to support the guidelines’ recommendation to refrain from using Doppler in pre-manipulative screening of vertebral arteries?
References
- 1.Anderson-Peacock E, Blouin JS, Bryans R, Danis N, Furlan A, Marcoux F, et al. Clinical practice guideline: Evidence-based treatment of adult neck pain not due to whiplash. J Can Chiropr Assoc. 2005;49(3):158–209. http://www.ccachiro.org/Client/cca/cca.nsf/web/CPG-sep-05?OpenDocument. [PMC free article] [PubMed] [Google Scholar]
- 2.Magarey M, Rebbeck T, Coughlan B, Grimmer K, Rivett DA, Refshauge K. Premanipulative testing of the cervical spine review, revision, and new clinical guidelines. Man Ther. 2004;9:95–108. doi: 10.1016/j.math.2003.12.002. [DOI] [PubMed] [Google Scholar]
- 3.Haynes MJ. Vertebral arteries and cervical movement: Doppler ultrasound velocimetry for screening before manipulation. J Manipulative Physiol Ther. 2002;25:556–67. doi: 10.1067/mmt.2002.127077. [DOI] [PubMed] [Google Scholar]