THE ASSOCIATION BETWEEN CERVICAL SPINE MANIPULATION AND CAROTID ARTERY DISSECTION: A SYSTEMATIC REVIEW OF THE LITERATURE Chadwick L.R. Chung, DC, a Pierre Côté, DC, PhD, b, c, d Paula Stern, DC, e and Georges L'Espérance, MD f
ABSTRACT Objective: Controversy surrounds the safety of cervical spine manipulation. Ischemic stroke secondary to cervical spine manipulation is a hypothesized adverse event. In Canada, the seriousness of these events and their perceived association to cervical spine manipulation has led some members of the public to call for a ban of the procedure. The primary objective of this study was to determine the incidence of internal carotid artery (ICA) dissection after cervical spine manipulation in patients who experience neck pain and its associated disorders. The secondary objective was to determine whether cervical spine manipulation is associated with an increased risk of ICA dissection in patients with neck pain, upper back pain, or headaches. Methods: We systematically searched MEDLINE, CINAHL, Alternative Health, AMED, Index to Chiropractic Literature, and EMBASE from 1970 to November 2012. Two independent reviewers used standardized criteria to screen the eligibility of articles. We considered cohort studies, case-control studies, and randomized clinical trials that addressed our objectives. We planned to critically appraise eligible articles using the Scottish Intercollegiate Guideline Network methodology. Results: We did not find any epidemiologic studies that measured the incidence of cervical spine manipulation and ICA dissection. Similarly, we did not find any studies that determined whether cervical spine manipulation is associated with ICA dissection. Conclusions: The incidence of ICA dissection after cervical spine manipulation is unknown. The relative risk of ICA dissection after cervical spine manipulation compared with other health care interventions for neck pain, back pain, or headache is also unknown. Although several case reports and case series raise the hypothesis of an association, we found no epidemiologic studies that validate this hypothesis. (J Manipulative Physiol Ther 2013;xx:1-5) Key Indexing Terms: Manipulation; Spinal; Chiropractic; Carotid Artery; Injuries
a Tutor, Graduate Education Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. b Canada Research Chair in Disability Prevention and Rehabilitation, Canada Research Chairs, Canadian Federal Government. c Associate Professor, Health Sciences Department, University of Ontario Institute of Technology, Oshawa, Ontario, Canada. d Director, UOIT-CMCC Centre for the Study of Disability Prevention and Rehabilitation, Institute of Technology, Oshawa, Ontario, Canada. e Director, Graduate Education Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. f President, Quebec Society of Experts in Medicolegal Evaluation, Montreal, Quebec, Canada. Submit requests for reprints to: Chadwick L.R. Chung, DC, Tutor, Graduate Education Research Programs, Canadian Memorial Chiropractic College, 6100 Leslie St, Toronto, ON, Canada M2H 3J1 (e-mail: [email protected]). Paper submitted April 15, 2013; in revised form September 18, 2013; accepted September 20, 2013. 0161-4754/$36.00 Copyright © 2013 by National University of Health Sciences. http://dx.doi.org/10.1016/j.jmpt.2013.09.005
nternal carotid artery (ICA) dissection is a rare cause of ischemic stroke. Epidemiologic studies suggest that most dissections of the ICA are spontaneous. 1,2 In the United States and in France, the annual incidence of spontaneous ICA dissection varies from 1.72 to 1.89 per 100 000 residents in Minnesota 3 to 2.9 per 100 000 residents in Dijon. 4 Internal carotid artery dissections result from tearing of the internal lining of the artery followed by displacement of the internal lining due to the pulsatile blood flow between the internal and medial layers. 5 The separation of the arterial layers usually occurs in the direction of blood flow and leads to an obstruction of blood flow in the distal carotid artery with secondary ischemia in the anterior and/or middle cerebral artery territories in the brain. Little is known about the etiology of spontaneous ICA dissection. It is more common in women and individuals in their fifth decade of life. 3,4 The hypothesized risk factors include the
I
1
2
Chung et al Manipulation and Carotid Artery Dissection
following: collagen vascular disease 6–10; blunt trauma such as in motor vehicle collisions 11,12; mild traumas such as childbirth, vomiting, coughing, and rhythmic neck movements 13–15; and cervical spine manipulation. 16,17 Some examples of other risk factors hypothesized to be involved in the etiology of cervical artery dissections include infection, elevated plasma homocysteine, aortic diameter greater than 34 mm, atherosclerosis, diabetes mellitus, hypercholesterolemia, hypertension, tobacco use, and migraine headaches. 18–25 To our knowledge, only one review has investigated the association between cervical spine manipulation and ICA dissection. 26 However, the review was not systematic, and it relied on case reports and case series to comment on the association between cervical spine manipulation and ICA dissection. Therefore, the results of this review lack validity because case reports and case series cannot be used to determine whether cervical spine manipulation is associated with ICA dissection. To date, no systematic review has investigated the association between cervical spine manipulation and ICA dissection. Our primary objective was to determine the incidence of ICA dissection after cervical spine manipulation in patients who experience neck-related complaints. Our secondary objective was to determine whether cervical spine manipulation is associated with an increased risk of ICA dissection in patients with neck pain, upper back pain, or headaches.
METHODS Protocol and Registration Our systematic review was registered with PROSPERO, the international prospective register of systematic reviews (CRD42012003289) and can be accessed at http://www.crd.york.ac.uk/prospero/display_record.asp? ID=CRD42012003289.
Eligibility Criteria Articles eligible for the review met the following inclusion criteria: (1) English or French language; (2) studies of human subjects; (3) published in a peer-reviewed journal; (4) randomized controlled trial, cohort study, casecrossover, or case-control study; (5) cervical spine manipulation was explicitly stated as the treatment or exposure under investigation; and (6) carotid artery dissection was a primary or secondary outcome. We excluded studies that combined carotid and vertebral arteries into one category (cervical arteries), unless a stratified analysis was conducted for carotid artery dissections. We also excluded cross-sectional studies, biomechanical studies, case reports, case series, reviews, opinions, editorials, and conference proceedings.
Journal of Manipulative and Physiological Therapeutics Month 2013
Information Sources We systematically searched 6 electronic databases (MEDLINE, CINAHL, Alternative Health, AMED, Index to Chiropractic Literature [ICL], EMBASE) from 1970 to November 2012. The search strategy combined terms relevant to manipulation and the carotid artery (Musculoskeletal Manipulations [Mesh], Chiropractic [Mesh], Carotid Artery Injuries [Mesh], Chiroprac* [All Terms], Manipulat* [All Terms], Carotid Artery [All Terms], Spinal Manipulation [All Terms]). The outlined search strategy can be viewed in Appendix A. The ICL was searched using search terms in “All Fields” and limited to peer-reviewed journals. All identified abstracts were retrieved and reviewed for relevance by at least 2 of the authors, and upon consensus, full-text articles were retrieved for critical appraisal. The references of the retrieved articles were hand searched for further articles that may have been missed in the systematic search.
Study Selection We used a 2-phase screening process to select eligible studies. In phase 1, random pairs of independent reviewers screened citation titles and abstracts to determine the eligibility of studies. Phase 1 screening resulted in studies being classified as relevant, possibly relevant, or irrelevant. In phase 2, the same paired reviewers independently reviewed the articles of possibly relevant studies to make a final determination of eligibility. Reviewers met to resolve disagreements and reach consensus on the eligibility of studies. If consensus could not be reached, then a third reviewer was used.
Risk of Bias Assessment We had planned to critically appraise the eligible articles using the Scottish Intercollegiate Guidelines Network criteria. 27 The Scottish Intercollegiate Guidelines Network criteria assist with the evaluation of selection bias, measurement bias, and confounding in epidemiologic and clinical studies.
Data Collection We planned for one reviewer to independently extract data from scientifically admissible studies. Similarly, we had planned for a second reviewer to validate the data extracted by the first reviewer. However, these steps were not undertaken because we did not identify studies relevant to our purpose.
Synthesis We planned to qualitatively synthesize results from scientifically admissible studies according to principles of best-evidence synthesis. 28 Specifically, we planned to build
Journal of Manipulative and Physiological Therapeutics Volume xx, Number x
Chung et al Manipulation and Carotid Artery Dissection
Fig 1. Flowchart showing the study selection process for this systematic review.
evidence tables to describe the best evidence. According to the best-evidence synthesis principles, more emphasis would be put on scientifically admissible studies judged to have the highest internal validity.
RESULTS Study Selection Our systematic search identified 151 studies; however, no studies met our inclusion criteria (Fig 1). We excluded a study by Dittrich et al 29 because it did not provide a stratified analysis for the association between cervical spine manipulation and carotid artery dissection. We excluded the remaining articles because they were case reports and case series, literature reviews, or not directly related to the ICA. Therefore, we found no epidemiologic studies that describe the incidence of ICA dissection after cervical manipulation or the association between cervical spine manipulation and ICA dissection.
Study Characteristics and Results and Risk of Bias We did not critically appraise any of the articles identified in our search because none were epidemiologic studies that addressed our research question. Of the 99 articles identified in our review, 37% were case reports or case series, 28% were literature reviews, 27% were trials, 4% were commentaries, and 3% were epidemiologic studies that were not related to the ICA.
DISCUSSION Our review aimed to describe the incidence of ICA dissection after cervical manipulation and to evaluate the association between cervical manipulation and ICA dissec-
tion. However, we did not find valid epidemiologic evidence that informed these objectives. We found that the literature on the topic remains in its early development and only includes case reports and case series. These designs are not useful to measure incidence, and consequently, they cannot be used to describe the association between an exposure and an outcome. Moreover, case reports and case series are susceptible to publication bias. 30 Understanding the risks associated with the delivery of health care interventions is necessary to ensure the safety of the public. 31 In Canada, concerns about cervical arterial dissection have led to public campaigns by some neurologists and patient advocates calling for a ban of cervical spine manipulation. 32 Therefore, it is important that possible adverse events of interventions be studied in well-designed epidemiologic studies. To date, no valid studies of the association between cervical spine manipulation and ICA dissection have been published. Therefore, statements about the safety or risks remain speculative and subject to opinion rather than scientific evidence. Previous work on the association between chiropractic care and posterior circulation stroke suggests that the association is noncausal. 33–35
CONCLUSION Our review did not identify valid evidence that can be used to support or refute the presence of an association between cervical spine manipulation and ICA dissection. Of the articles identified in this review, 97% of the published articles on this topic were not epidemiologic studies and cannot be used to make causal or noncausal inferences about the presence of an association. The remaining 3% of studies were epidemiologic studies that did not directly relate to the ICA. Epidemiologic studies are
3
4
Chung et al Manipulation and Carotid Artery Dissection
Practical Applications • This study did not find any epidemiologic studies that measured the incidence of cervical spine manipulation and carotid artery dissection. • This study did not find any literature quantifying the association between cervical spine manipulation and carotid artery dissection. • The incidence of carotid artery dissection after cervical spine manipulation is unknown.
needed to understand the hypothesized relationship between cervical manipulation and internal carotid dissection.
FUNDING SOURCES AND POTENTIAL CONFLICTS OF INTEREST No funding sources or conflicts of interest were reported for this study.
CONTRIBUTORSHIP INFORMATION Concept development (provided idea for the research): CC, PC. Design (planned the methods to generate the results): CC, PC. Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): PC. Data collection/processing (responsible for experiments, patient management, organization, or reporting data): CC, PC, PS, GL. Analysis/interpretation (responsible for statistical analysis, evaluation, and presentation of the results): CC, PC, PS, GL. Literature search (performed the literature search): CC Writing (responsible for writing a substantive part of the manuscript): CC, PC. Critical review (revised manuscript for intellectual content, this does not relate to spelling and grammar checking): CC, PC, PS, GL.
REFERENCES 1. Schievink WI, Mokri B, Whisnant JP. Internal carotid artery dissection in a community. Rochester, Minnesota, 1987-1992. Stroke 1993;24:1678-80.
Journal of Manipulative and Physiological Therapeutics Month 2013
2. Schievink WI, Wijdicks EF, Kuiper JD. Seasonal pattern of spontaneous cervical artery dissection. J Neurosurg 1998;89: 101-3. 3. Lee VH, Brown RD, Mandrekar JN, Mokri B. Incidence and outcome of cervical artery dissection: a population-based study. Neurology 2006;67:1809-12. 4. Giroud M, Fayolle H, Andre N, et al. Incidence of internal carotid artery dissection in the community of Dijon. J Neurol Neurosurg Psychiatry 1994;57:1443. 5. Zetterling M, Carlstrom C, Konrad P. Internal carotid artery dissection. Acta Neurol Scand 2000;101:1-7. 6. van den Berg JS, Limburg M, Kappelle LJ, Pals G, Arwert F, Westerveld A. The role of type III collagen in spontaneous cervical arterial dissections. Ann Neurol 1998;43:494-8. 7. Pelkonen O, Tikkakoski T, Leinonen S, Pyhtinen J, Sotaniemi K. Intracranial arterial dissection. Neuroradiology 1998;40: 442-7. 8. Lomeo RM, Silver RM, Brothers M. Spontaneous dissection of the internal carotid artery in a patient with polyarteritis nodosa. Arthritis Rheum 1989;32:1625-6. 9. Guillon B, Levy C, Bousser MG. Internal carotid artery dissection: an update. J Neurol Sci 1998;153:146-58. 10. Brandt T, Hausser I, Orberk E, et al. Ultrastructural connective tissue abnormalities in patients with spontaneous cervicocerebral artery dissections. Ann Neurol 1998;44:281-5. 11. Cogbill TH, Moore EE, Meissner M, et al. The spectrum of blunt injury to the carotid artery: a multicenter perspective. J Trauma 1994;37:473-9. 12. Watridge CB, Muhlbauer MS, Lowery RD. Traumatic carotid artery dissection: diagnosis and treatment. J Neurosurg 1989; 71:854-7. 13. Ast G, Woimant F, Georges B, Laurian C, Haguenau M. Spontaneous dissection of the internal carotid artery in 68 patients. Eur J Med 1993;2:466-72. 14. Sturzenegger M. Spontaneous internal carotid artery dissection: early diagnosis and management in 44 patients. J Neurol 1995;242:231-8. 15. Kumar SD, Kumar V, Kaye W. Bilateral internal carotid artery dissection from vomiting. Am J Emerg Med 1998;16: 669-70. 16. Nadgir RN, Loevner LA, Ahmed T, et al. Simultaneous bilateral internal carotid and vertebral artery dissection following chiropractic manipulation: case report and review of the literature. Neuroradiology 2003;45:311-4. 17. Peters M, Bohl J, Thomke F, et al. Dissection of the internal carotid artery after chiropractic manipulation of the neck. Neurology 1995;45:2284-6. 18. D'Anglejan-Chatillon J, Ribeiro V, Mas JL, Youl BD, Bousser MG. Migraine—a risk factor for dissection of cervical arteries. Headache 1989;29:560-1. 19. Etminan M, Takkouche B, Isorna FC, Samii A. Risk of ischaemic stroke in people with migraine: systematic review and meta-analysis of observational studies. BMJ 2005;330:63. 20. Pezzini A, Grassi M, Del ZE, et al. Interaction of homocysteine and conventional predisposing factors on risk of ischaemic stroke in young people: consistency in phenotype-disease analysis and genotype-disease analysis. J Neurol Neurosurg Psychiatry 2006;77:1150-6. 21. Pezzini A, Caso V, Zanferrari C, et al. Arterial hypertension as risk factor for spontaneous cervical artery dissection. A casecontrol study. J Neurol Neurosurg Psychiatry 2006;77:95-7. 22. Rubinstein SM, Peerdeman SM, van Tulder MW, Riphagen I, Haldeman S. A systematic review of the risk factors for cervical artery dissection. Stroke 2005;36:1575-80. 23. Schievink WI. Spontaneous dissection of the carotid and vertebral arteries. N Engl J Med 2001;344:898-906.
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24. Spector JT, Kahn SR, Jones MR, Jayakumar M, Dalal D, Nazarian S. Migraine headache and ischemic stroke risk: an updated meta-analysis. Am J Med 2010;123:612-24. 25. Tzourio C, Cohen A, Lamisse N, Biousse V, Bousser MG. Aortic root dilatation in patients with spontaneous cervical artery dissection. Circulation 1997;95:2351-3. 26. Haneline MT, Croft AC, Frishberg BM. Association of internal carotid artery dissection and chiropractic manipulation. Neurologist 2003;9:35-44. 27. Harbour R, Miller J. A new system for grading recommendations in evidence based guidelines. BMJ 2001;323:334-6. 28. Slavin RE. Best evidence synthesis: an intelligent alternative to meta-analysis. J Clin Epidemiol 1995;48:9-18. 29. Dittrich R, Rohsbach D, Heidbreder A, et al. Mild mechanical traumas are possible risk factors for cervical artery dissection. Cerebrovasc Dis 2007;23:275-81. 30. Easterbrook PJ, Berlin JA, Gopalan R, Matthews DR. Publication bias in clinical research. Lancet 1991;337:867-72.
31. Macintyre S. Evidence based policy making. BMJ 2003; 326:5-6. 32. Group wants provincial ban on some neck manipulation by chiropractors. Winnipeg Free Press. October 4, 2012. http:// www.winnipegfreepress.com/breakingnews/Group-wantsprovincial-ban-on-some-neck-manipulation-by-chiropractors172692471.htm. 33. Cassidy JD, Boyle E, Cote P, et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. J Manipulative Physiol Ther 2009;32(2 Suppl):S201-8. 34. Boyle E, Cote P, Grier AR, Cassidy JD. Examining vertebrobasilar artery stroke in two Canadian provinces. Spine (Phila Pa) 2008;33(4 Suppl):S170-5. 35. Choi S, Boyle E, Cote P, Cassidy JD. A population-based case-series of Ontario patients who develop a vertebrobasilar artery stroke after seeing a chiropractor. J Manipulative Physiol Ther 2011;34:15-22.
APPENDIX A
17) 18) 19) 20) 21) 22)
PUBMED 1) chiropractic [Mesh] 2) chiropractic [All Fields] 3) chiroprac* [All Fields) 4) 1 OR 2 OR 3 5) manipulation [All Fields] 6) manipulate* [All Fields] 7) manipulation, spinal [Mesh] 8) spinal manipulation [All Fields] 9) 4 OR 5 OR 6 OR 7 10) Musculoskeletal manipulation [Mesh] 11) 8 OR 9 12) carotid artery [Mesh] 13) carotid [All Fields] 14) artery [All Fields] 15) common [All Fields] 16) 11 AND 12 AND 13 And 14
10 OR 15 carotid artery injuries [Mesh] 16 OR 17 10 AND 18 19 AND 3 18 OR 19
Alternative Health Watch, AMED, CINAHL, ICL, EMBASE 1) chiroprac* 2) chiropractic 3) 1 OR 2 4) manipulate* 5) manipulation 6) 4 OR 5 7) carotid artery 8) 7 AND 6 9) 8 AND 3 10) 7 AND 3 11) 9 OR 10
5
ABSTRACT Objective: Controversy surrounds the safety of cervical spine manipulation. Ischemic stroke secondary to cervical spine manipulation is a hypothesized adverse event. In Canada, the seriousness of these events and their perceived association to cervical spine manipulation has led some members of the public to call for a ban of the procedure. The primary objective of this study was to determine the incidence of internal carotid artery (ICA) dissection after cervical spine manipulation in patients who experience neck pain and its associated disorders. The secondary objective was to determine whether cervical spine manipulation is associated with an increased risk of ICA dissection in patients with neck pain, upper back pain, or headaches. Methods: We systematically searched MEDLINE, CINAHL, Alternative Health, AMED, Index to Chiropractic Literature, and EMBASE from 1970 to November 2012. Two independent reviewers used standardized criteria to screen the eligibility of articles. We considered cohort studies, case-control studies, and randomized clinical trials that addressed our objectives. We planned to critically appraise eligible articles using the Scottish Intercollegiate Guideline Network methodology. Results: We did not find any epidemiologic studies that measured the incidence of cervical spine manipulation and ICA dissection. Similarly, we did not find any studies that determined whether cervical spine manipulation is associated with ICA dissection. Conclusions: The incidence of ICA dissection after cervical spine manipulation is unknown. The relative risk of ICA dissection after cervical spine manipulation compared with other health care interventions for neck pain, back pain, or headache is also unknown. Although several case reports and case series raise the hypothesis of an association, we found no epidemiologic studies that validate this hypothesis. (J Manipulative Physiol Ther 2013;xx:1-5) Key Indexing Terms: Manipulation; Spinal; Chiropractic; Carotid Artery; Injuries
a Tutor, Graduate Education Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. b Canada Research Chair in Disability Prevention and Rehabilitation, Canada Research Chairs, Canadian Federal Government. c Associate Professor, Health Sciences Department, University of Ontario Institute of Technology, Oshawa, Ontario, Canada. d Director, UOIT-CMCC Centre for the Study of Disability Prevention and Rehabilitation, Institute of Technology, Oshawa, Ontario, Canada. e Director, Graduate Education Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada. f President, Quebec Society of Experts in Medicolegal Evaluation, Montreal, Quebec, Canada. Submit requests for reprints to: Chadwick L.R. Chung, DC, Tutor, Graduate Education Research Programs, Canadian Memorial Chiropractic College, 6100 Leslie St, Toronto, ON, Canada M2H 3J1 (e-mail: [email protected]). Paper submitted April 15, 2013; in revised form September 18, 2013; accepted September 20, 2013. 0161-4754/$36.00 Copyright © 2013 by National University of Health Sciences. http://dx.doi.org/10.1016/j.jmpt.2013.09.005
nternal carotid artery (ICA) dissection is a rare cause of ischemic stroke. Epidemiologic studies suggest that most dissections of the ICA are spontaneous. 1,2 In the United States and in France, the annual incidence of spontaneous ICA dissection varies from 1.72 to 1.89 per 100 000 residents in Minnesota 3 to 2.9 per 100 000 residents in Dijon. 4 Internal carotid artery dissections result from tearing of the internal lining of the artery followed by displacement of the internal lining due to the pulsatile blood flow between the internal and medial layers. 5 The separation of the arterial layers usually occurs in the direction of blood flow and leads to an obstruction of blood flow in the distal carotid artery with secondary ischemia in the anterior and/or middle cerebral artery territories in the brain. Little is known about the etiology of spontaneous ICA dissection. It is more common in women and individuals in their fifth decade of life. 3,4 The hypothesized risk factors include the
I
1
2
Chung et al Manipulation and Carotid Artery Dissection
following: collagen vascular disease 6–10; blunt trauma such as in motor vehicle collisions 11,12; mild traumas such as childbirth, vomiting, coughing, and rhythmic neck movements 13–15; and cervical spine manipulation. 16,17 Some examples of other risk factors hypothesized to be involved in the etiology of cervical artery dissections include infection, elevated plasma homocysteine, aortic diameter greater than 34 mm, atherosclerosis, diabetes mellitus, hypercholesterolemia, hypertension, tobacco use, and migraine headaches. 18–25 To our knowledge, only one review has investigated the association between cervical spine manipulation and ICA dissection. 26 However, the review was not systematic, and it relied on case reports and case series to comment on the association between cervical spine manipulation and ICA dissection. Therefore, the results of this review lack validity because case reports and case series cannot be used to determine whether cervical spine manipulation is associated with ICA dissection. To date, no systematic review has investigated the association between cervical spine manipulation and ICA dissection. Our primary objective was to determine the incidence of ICA dissection after cervical spine manipulation in patients who experience neck-related complaints. Our secondary objective was to determine whether cervical spine manipulation is associated with an increased risk of ICA dissection in patients with neck pain, upper back pain, or headaches.
METHODS Protocol and Registration Our systematic review was registered with PROSPERO, the international prospective register of systematic reviews (CRD42012003289) and can be accessed at http://www.crd.york.ac.uk/prospero/display_record.asp? ID=CRD42012003289.
Eligibility Criteria Articles eligible for the review met the following inclusion criteria: (1) English or French language; (2) studies of human subjects; (3) published in a peer-reviewed journal; (4) randomized controlled trial, cohort study, casecrossover, or case-control study; (5) cervical spine manipulation was explicitly stated as the treatment or exposure under investigation; and (6) carotid artery dissection was a primary or secondary outcome. We excluded studies that combined carotid and vertebral arteries into one category (cervical arteries), unless a stratified analysis was conducted for carotid artery dissections. We also excluded cross-sectional studies, biomechanical studies, case reports, case series, reviews, opinions, editorials, and conference proceedings.
Journal of Manipulative and Physiological Therapeutics Month 2013
Information Sources We systematically searched 6 electronic databases (MEDLINE, CINAHL, Alternative Health, AMED, Index to Chiropractic Literature [ICL], EMBASE) from 1970 to November 2012. The search strategy combined terms relevant to manipulation and the carotid artery (Musculoskeletal Manipulations [Mesh], Chiropractic [Mesh], Carotid Artery Injuries [Mesh], Chiroprac* [All Terms], Manipulat* [All Terms], Carotid Artery [All Terms], Spinal Manipulation [All Terms]). The outlined search strategy can be viewed in Appendix A. The ICL was searched using search terms in “All Fields” and limited to peer-reviewed journals. All identified abstracts were retrieved and reviewed for relevance by at least 2 of the authors, and upon consensus, full-text articles were retrieved for critical appraisal. The references of the retrieved articles were hand searched for further articles that may have been missed in the systematic search.
Study Selection We used a 2-phase screening process to select eligible studies. In phase 1, random pairs of independent reviewers screened citation titles and abstracts to determine the eligibility of studies. Phase 1 screening resulted in studies being classified as relevant, possibly relevant, or irrelevant. In phase 2, the same paired reviewers independently reviewed the articles of possibly relevant studies to make a final determination of eligibility. Reviewers met to resolve disagreements and reach consensus on the eligibility of studies. If consensus could not be reached, then a third reviewer was used.
Risk of Bias Assessment We had planned to critically appraise the eligible articles using the Scottish Intercollegiate Guidelines Network criteria. 27 The Scottish Intercollegiate Guidelines Network criteria assist with the evaluation of selection bias, measurement bias, and confounding in epidemiologic and clinical studies.
Data Collection We planned for one reviewer to independently extract data from scientifically admissible studies. Similarly, we had planned for a second reviewer to validate the data extracted by the first reviewer. However, these steps were not undertaken because we did not identify studies relevant to our purpose.
Synthesis We planned to qualitatively synthesize results from scientifically admissible studies according to principles of best-evidence synthesis. 28 Specifically, we planned to build
Journal of Manipulative and Physiological Therapeutics Volume xx, Number x
Chung et al Manipulation and Carotid Artery Dissection
Fig 1. Flowchart showing the study selection process for this systematic review.
evidence tables to describe the best evidence. According to the best-evidence synthesis principles, more emphasis would be put on scientifically admissible studies judged to have the highest internal validity.
RESULTS Study Selection Our systematic search identified 151 studies; however, no studies met our inclusion criteria (Fig 1). We excluded a study by Dittrich et al 29 because it did not provide a stratified analysis for the association between cervical spine manipulation and carotid artery dissection. We excluded the remaining articles because they were case reports and case series, literature reviews, or not directly related to the ICA. Therefore, we found no epidemiologic studies that describe the incidence of ICA dissection after cervical manipulation or the association between cervical spine manipulation and ICA dissection.
Study Characteristics and Results and Risk of Bias We did not critically appraise any of the articles identified in our search because none were epidemiologic studies that addressed our research question. Of the 99 articles identified in our review, 37% were case reports or case series, 28% were literature reviews, 27% were trials, 4% were commentaries, and 3% were epidemiologic studies that were not related to the ICA.
DISCUSSION Our review aimed to describe the incidence of ICA dissection after cervical manipulation and to evaluate the association between cervical manipulation and ICA dissec-
tion. However, we did not find valid epidemiologic evidence that informed these objectives. We found that the literature on the topic remains in its early development and only includes case reports and case series. These designs are not useful to measure incidence, and consequently, they cannot be used to describe the association between an exposure and an outcome. Moreover, case reports and case series are susceptible to publication bias. 30 Understanding the risks associated with the delivery of health care interventions is necessary to ensure the safety of the public. 31 In Canada, concerns about cervical arterial dissection have led to public campaigns by some neurologists and patient advocates calling for a ban of cervical spine manipulation. 32 Therefore, it is important that possible adverse events of interventions be studied in well-designed epidemiologic studies. To date, no valid studies of the association between cervical spine manipulation and ICA dissection have been published. Therefore, statements about the safety or risks remain speculative and subject to opinion rather than scientific evidence. Previous work on the association between chiropractic care and posterior circulation stroke suggests that the association is noncausal. 33–35
CONCLUSION Our review did not identify valid evidence that can be used to support or refute the presence of an association between cervical spine manipulation and ICA dissection. Of the articles identified in this review, 97% of the published articles on this topic were not epidemiologic studies and cannot be used to make causal or noncausal inferences about the presence of an association. The remaining 3% of studies were epidemiologic studies that did not directly relate to the ICA. Epidemiologic studies are
3
4
Chung et al Manipulation and Carotid Artery Dissection
Practical Applications • This study did not find any epidemiologic studies that measured the incidence of cervical spine manipulation and carotid artery dissection. • This study did not find any literature quantifying the association between cervical spine manipulation and carotid artery dissection. • The incidence of carotid artery dissection after cervical spine manipulation is unknown.
needed to understand the hypothesized relationship between cervical manipulation and internal carotid dissection.
FUNDING SOURCES AND POTENTIAL CONFLICTS OF INTEREST No funding sources or conflicts of interest were reported for this study.
CONTRIBUTORSHIP INFORMATION Concept development (provided idea for the research): CC, PC. Design (planned the methods to generate the results): CC, PC. Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): PC. Data collection/processing (responsible for experiments, patient management, organization, or reporting data): CC, PC, PS, GL. Analysis/interpretation (responsible for statistical analysis, evaluation, and presentation of the results): CC, PC, PS, GL. Literature search (performed the literature search): CC Writing (responsible for writing a substantive part of the manuscript): CC, PC. Critical review (revised manuscript for intellectual content, this does not relate to spelling and grammar checking): CC, PC, PS, GL.
REFERENCES 1. Schievink WI, Mokri B, Whisnant JP. Internal carotid artery dissection in a community. Rochester, Minnesota, 1987-1992. Stroke 1993;24:1678-80.
Journal of Manipulative and Physiological Therapeutics Month 2013
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Chung et al Manipulation and Carotid Artery Dissection
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APPENDIX A
17) 18) 19) 20) 21) 22)
PUBMED 1) chiropractic [Mesh] 2) chiropractic [All Fields] 3) chiroprac* [All Fields) 4) 1 OR 2 OR 3 5) manipulation [All Fields] 6) manipulate* [All Fields] 7) manipulation, spinal [Mesh] 8) spinal manipulation [All Fields] 9) 4 OR 5 OR 6 OR 7 10) Musculoskeletal manipulation [Mesh] 11) 8 OR 9 12) carotid artery [Mesh] 13) carotid [All Fields] 14) artery [All Fields] 15) common [All Fields] 16) 11 AND 12 AND 13 And 14
10 OR 15 carotid artery injuries [Mesh] 16 OR 17 10 AND 18 19 AND 3 18 OR 19
Alternative Health Watch, AMED, CINAHL, ICL, EMBASE 1) chiroprac* 2) chiropractic 3) 1 OR 2 4) manipulate* 5) manipulation 6) 4 OR 5 7) carotid artery 8) 7 AND 6 9) 8 AND 3 10) 7 AND 3 11) 9 OR 10
5
