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The Stroke Perspective
October 11, 2014 by Dr Matthew D. Long
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October 11, 2014 by Dr Matthew D. Long
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The Stroke Perspective
October 11, 2014 by Dr Matthew D. Long
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'If you don’t believe in the messenger, you won’t believe the message’
James Kouzes and Barry Posner
The topic of chiropractic, neck manipulation and stroke just refuses to die (no pun intended). Although the literature has now assembled a reasonable framework to understand the issue, there remains much disinformation and inaccuracy. Indeed, the perception that there is a significantly elevated risk of cardiovascular accident after neck manipulation is still a major impediment to greater acceptance of chiropractic care.
But why is this so?
Why has chiropractic treatment been singled out in this manner? After all, the use of NSAIDs, particularly the highly selective COX-2 inhibitors, has also shown a significant increase in risk of stroke. One study demonstrated a nearly threefold increase in the risk of ischaemic stroke when using selective versus nonselective agents (1). Another study looked at a broader cross-section of NSAIDS and also found elevated risk (2),
But why is this so?
Why has chiropractic treatment been singled out in this manner? After all, the use of NSAIDs, particularly the highly selective COX-2 inhibitors, has also shown a significant increase in risk of stroke. One study demonstrated a nearly threefold increase in the risk of ischaemic stroke when using selective versus nonselective agents (1). Another study looked at a broader cross-section of NSAIDS and also found elevated risk (2),
"The present study findings in general support results from prior observational studies that a greater risk of stroke was not limited to the use of COX-2 inhibitors but also some traditional nonselective NSAIDs. Our study results were consistent with the reports by Haag and colleagues suggesting NSAID use was associated with increased risk of both ischemic and hemorrhagic stroke. We found the hazards for stroke associated with most oral NSAIDs were small with ORs between 1.2 and 1.9 in contrast to >2.6-fold increased risk in hemorrhagic stroke for oral ketorolac. Our frequency-response analysis suggested that the risks might become elevated even for use <15 days. The risks were evident among all subgroups of patients with or without cardiovascular risk factors."
However, there is barely a murmur from the wider medical community to abandon or moderate their use. A recent review paper published in Vascular Health and Risk Management (3) simply suggested that,
"Although the evidence from the initial prospective trials suggested an association with coronary ischemic events, the evidence for a link between NSAIDs and stroke events remains a source of debate. As the evidence here has been presented, no definitive recommendations can be made regarding the use of NSAIDs with respect to stroke risk.”
That’s it. So is there a statistical association between vertebral artery dissection and neck manipulation? Sure. But association doesn’t prove causation. This topic was extensively reviewed by Tuchin recently in The International Journal of Clinical Practice (4),
"There is lack of compelling evidence that SMT is causally associated with stroke. Physical triggers, including SMT, can serve as plausible final link between the underlying disease and stroke (for instance, in case of arterial dissection with existing connective tissue weakness). It appears few of Hill’s criteria for causality appear connected with vertebral artery dissection (VAD) and chiropractic. There may be some links or association with SMT and VAD in untrained practitioners, but this has not been established with chiropractors. The quality of evidence suggesting causation between chiropractic and VAD is mostly weak. Therefore, causality between chiropractic and vascular accidents has not been determined. It is possible that healthcare practitioners are not taking a thorough history to determine the cause of the VAD after SMT. Healthcare practitioners are probably missing many clinical facts, because they now only record the patient having SMT. They should enquire about other possible causes or circumstances for VAD. This may include minor neck trauma, a change in chronic neck pain or headache, recent infection or other predisposing lifestyle factors such as smoking, hyperlipidaemia, hypertension, and hyperhomocysteinaemia. Therefore, it is important that healthcare practitioners take a thorough clinical history to determine the cause of VAD."
Indeed, the most convincing evidence now suggests that the primary role of the chiropractor in such situations is one of concerned bystander, not causal agent. In other words, it appears that the statistical association between stroke and chiropractic arises from the fact that patients suffering from vertebral artery dissection typically experience neck pain and sub-occipital headache prior to their stroke, driving them to seek out help and thus drawing chiropractors into the pool of known possible triggers. Cassidy and colleagues recently addressed the topic in a published debate (5) about the merits of neck manipulation and whether it should be abandoned in the face of limited evidence for efficacy. They cited their influential 2008 study (6) that examined all case of vertebral artery-related stroke that presented to Ontario hospitals between 1993 and 2002 finding,
"... a strong association between chiropractic care and subsequent vertebrobasilar stroke in people under 45 years old using both case-control and case-crossover designs (odds ratio 3.60, 1.46 to 10.84) for those consulting a chiropractor in the previous month. However, they found a similar association between family physician care and vertebrobasilar strokes (odds ratio 2.99, 1.81 to 4.96). Furthermore, the estimates for previous chiropractic or family physician care were similar when investigating different hazard periods up to 30 days before the stroke. Both associations increased when the analyses were limited to neck related diagnoses (such as cervical pain, strain, sprain, and headaches). This suggests that the association between manipulation and stroke is confounded by indication - that is, the disease (early dissection related neck pain or headache) is causing the exposures (visits to chiropractors and family doctors). Neck pain and headache are the most common presenting complaints in people with cervical artery dissections and are common reasons for seeking care. This evidence raises doubt about any causal relation between manipulation and stroke."
Interestingly, the fact that the risk of stroke following chiropractic treatment, and the risk following a GP visit, are about the same doesn’t seem to reduce the anxiety associated with neck manipulation. Furthermore, the negligible nature of the risk also does little to dissuade opponents who are convinced that neck manipulation has no benefit. They argue that if there is no clinical advantage to the procedure then no amount of risk is acceptable (7), even if it is tiny.
"Given the equivalence in outcome with other forms of therapy, manipulation seems to be clinically unnecessary. The potential for catastrophic events and the clear absence of unique benefit lead to the inevitable conclusion that manipulation of the cervical spine should be abandoned as part of conservative care for neck pain. In the interests of patient safety, the regulatory and professional bodies associated with professions that use manual therapy should consider adopting this as a formal policy."
But this argument does not stand up in the face of any decent literature review, which confirms a useful role for cervical manipulation in the treatment of neck pain (8,9). A recent study by Bronfort and colleagues in the Annals of Internal Medicine demonstrated greater efficacy for neck manipulation in the management of acute and sub-acute neck pain over both short and long-term periods than the use of NSAIDs (10).
So why does opposition to neck manipulation remain so ill-considered and vocal? To answer, we should revisit the quote at the top of this piece.
So why does opposition to neck manipulation remain so ill-considered and vocal? To answer, we should revisit the quote at the top of this piece.
'If you don’t believe in the messenger, you won’t believe the message.’
It all comes down to perspective. Unfortunately the common view of chiropractors amongst the general scientific community is somewhat jaundiced. Even the best chiropractic research often goes unnoticed, whilst poor quality studies that support established bias receive significant attention. Such attentional bias is very 'human', but it certainly isn't helpful when one is trying to create new understanding and alter an out-of-date perspective. It isn't limited to chiropractic research either.
In 1981 Dr Barry Marshall was a 30 year old trainee gastroenterologist in Western Australia who had teamed up with pathologist J. Robin Warren to investigate the possibility that the bacterium helicobacter pylori was the cause of stomach ulcers. Given his relative youth and inexperience, his initial study findings were rejected out of hand by the Australian Gastroenterological Society. After all, the stomach was understood to be sterile and such infections were ‘impossible’. Furthermore, peptic ulcers were ‘known’ to occur as a consequence of acid imbalance or psychosomatic mechanisms. They were certainly not infectious. But Marshall persisted with his research, ultimately resorting to drinking a cultured cocktail of h. pylori to create his own stomach ulcer, which he then cured with antibiotics. His results were published in 1985. However, this was just the beginning of the road to acceptance. After all, what would a young doctor from Perth know that the medical establishment didn't?
Even after years of diligent research and multiple publications most physicians still refused to treat stomach ulcers with antibiotics. A study by Munnangi and Sonnenberg writes, "In 1995, about 75% of ulcers were still treated primarily with antisecretory medications, and only 5% received antibiotic therapy”. Surely the science was enough? Unfortunately we give ourselves too much credit as humans and assume that our decisions are untainted by bias. But this is clearly not the case. As stated by Thagard (12), "The hypothesis that ulcers are caused by bacteria requires reclassification of [peptic ulcer] disease as an infectious disease", a process that "involves moving a concept from one branch in the tree of concepts to another branch.” Such mental reimagining becomes a huge burden for us, particularly when we are already strongly invested in a particular worldview. It requires a considerable investment in cognition and emotional restructuring to undo deeply entrenched beliefs and practices.
Is this why some of our medical colleagues still subscribe to old-fashioned ideas about stroke and neck manipulation? Do the historical medical perspectives about chiropractic prevent others from adopting a more reasoned and rational viewpoint about stroke? A recent survey of North American orthopaedic surgeons' attitudes towards chiropractors revealed a number of critical themes that were seen as a barrier to increased inter-professional collaboration (13). These included concerns about variability between practitioners, the treatment of non-musculoskeletal complaints, misleading terminology, false or exaggerated claims, lack of standardisation in training, unethical behaviour and concerns about the scientific basis of chiropractic. This was summed up nicely by one quoted orthopaedic surgeon within the article who stated that they were “Unclear at this point what their role is”.
With such a distinct lack of understanding about the dimensions of chiropractic practice it should not be a surprise that any new perspective upon stroke has gained little traction with the medical community. However, all is not lost. Quality chiropractic research is a relatively new phenomenon, and wider integration is slowly occurring. It took the best part of 20 years for Marshall and Warren’s findings to be widely accepted, and they were operating from within the medical community. Thankfully Marshall and Warren did eventually receive the recognition they deserved, with both awarded the Nobel Prize in Physiology of Medicine in 2005, and their theory of an infectious basis to stomach ulcer ultimately become mainstream.
In 1981 Dr Barry Marshall was a 30 year old trainee gastroenterologist in Western Australia who had teamed up with pathologist J. Robin Warren to investigate the possibility that the bacterium helicobacter pylori was the cause of stomach ulcers. Given his relative youth and inexperience, his initial study findings were rejected out of hand by the Australian Gastroenterological Society. After all, the stomach was understood to be sterile and such infections were ‘impossible’. Furthermore, peptic ulcers were ‘known’ to occur as a consequence of acid imbalance or psychosomatic mechanisms. They were certainly not infectious. But Marshall persisted with his research, ultimately resorting to drinking a cultured cocktail of h. pylori to create his own stomach ulcer, which he then cured with antibiotics. His results were published in 1985. However, this was just the beginning of the road to acceptance. After all, what would a young doctor from Perth know that the medical establishment didn't?
Even after years of diligent research and multiple publications most physicians still refused to treat stomach ulcers with antibiotics. A study by Munnangi and Sonnenberg writes, "In 1995, about 75% of ulcers were still treated primarily with antisecretory medications, and only 5% received antibiotic therapy”. Surely the science was enough? Unfortunately we give ourselves too much credit as humans and assume that our decisions are untainted by bias. But this is clearly not the case. As stated by Thagard (12), "The hypothesis that ulcers are caused by bacteria requires reclassification of [peptic ulcer] disease as an infectious disease", a process that "involves moving a concept from one branch in the tree of concepts to another branch.” Such mental reimagining becomes a huge burden for us, particularly when we are already strongly invested in a particular worldview. It requires a considerable investment in cognition and emotional restructuring to undo deeply entrenched beliefs and practices.
Is this why some of our medical colleagues still subscribe to old-fashioned ideas about stroke and neck manipulation? Do the historical medical perspectives about chiropractic prevent others from adopting a more reasoned and rational viewpoint about stroke? A recent survey of North American orthopaedic surgeons' attitudes towards chiropractors revealed a number of critical themes that were seen as a barrier to increased inter-professional collaboration (13). These included concerns about variability between practitioners, the treatment of non-musculoskeletal complaints, misleading terminology, false or exaggerated claims, lack of standardisation in training, unethical behaviour and concerns about the scientific basis of chiropractic. This was summed up nicely by one quoted orthopaedic surgeon within the article who stated that they were “Unclear at this point what their role is”.
With such a distinct lack of understanding about the dimensions of chiropractic practice it should not be a surprise that any new perspective upon stroke has gained little traction with the medical community. However, all is not lost. Quality chiropractic research is a relatively new phenomenon, and wider integration is slowly occurring. It took the best part of 20 years for Marshall and Warren’s findings to be widely accepted, and they were operating from within the medical community. Thankfully Marshall and Warren did eventually receive the recognition they deserved, with both awarded the Nobel Prize in Physiology of Medicine in 2005, and their theory of an infectious basis to stomach ulcer ultimately become mainstream.
But how long will it be before chiropractors are truly accepted for the expertise that they possess? I think that this is dependent upon two driving forces. The first, is the ongoing growth of a quality research base. The currency of influence in the health care system is science, and we certainly need more of it. However, we must also win over the hearts and minds of our local medical community - one practitioner at a time. A person’s worldview is shaped and maintained by emotional factors, and only personal relationships can influence at this level. Individual chiropractors would do well to foster such relationships, and demonstrate their science, efficacy and ethics by communicating directly with every patient’s GP. Only then will the perspective on stroke change.
Something to think about...
Dr Matthew D. Long
BSc (Syd) M.Chiro (Macq)
Something to think about...
Dr Matthew D. Long
BSc (Syd) M.Chiro (Macq)
References:
1. Haag MD, Bos MJ, Hofman A, Koudstaal PJ, Breteler MM, Stricker BH. Cyclooxygenase selectivity of nonsteroidal anti-inflammatory drugs and risk of stroke. Arch Intern Med. 2008;168(11):1219–1224.
2. Chang CH, Shau WY, Kuo CW, Chen ST, Lai MS. Increased risk of stroke associated with nonsteroidal anti-inflammatory drugs: a nationwide case-crossover study. Stroke 2010;41:1884-90.
3. Bavry, A., & Park, K. (2014). Risk of stroke associated with nonsteroidal anti-inflammatory drugs. Vascular Health and Risk Management, 25. doi:10.2147/VHRM.S54159
4. Tuchin, P. (2013). Chiropractic and stroke: association or causation? International Journal of Clinical Practice, 67(9), 825–833. doi:10.1111/ijcp.12171
5. Cassidy, J. D., Bronfort, G., & Hartvigsen, J. (2012). Should we abandon cervical spine manipulation for mechanical neck pain? No. BMJ (Clinical Research Ed), 344(jun07 3), e3680–e3680. doi:10.1136/bmj.e3680
6. Cassidy JD, Boyle E, Cote P, He Y, Hogg-Johnson S, Silver FL, et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. Spine 2008;33(suppl 4):S176-83.
7. Wand, B. M., Heine, P. J., & O'Connell, N. E. (2012). Should we abandon cervical spine manipulation for mechanical neck pain? Yes. BMJ (Clinical Research Ed), 344(jun07 3), e3679–e3679. doi:10.1136/bmj.e3679
8. Hurwitz EL, Carragee EJ, van der Velde G, Carroll LJ, Nordin M, Guzman J, et al. Treatment of neck pain: noninvasive interventions: results of the Bone and Joint Decade 2000-2010 Task Force on neck pain and its associated disorders. Spine 2008;33(suppl 4):S123-52. 2
9. Leaver AM, Refshauge KM, Maher CG, McAuley JH. Conservative interventions provide short-term relief for non-specific neck pain: a systematic review. J Physiotherapy 2010;56:73-85.
10. Bronfort G, Evans R, Anderson AV, Svendsen KH, Bracha Y, Grimm RH. Spinal manipulation, medication, or home exercise with advice for acute and subacute neck pain: a randomized trial. Ann Intern Med 2012;156:1-10.
11. Munnangi S and S Amnon. (1997). Time Trends of Physician Visits and Treatment Patterns of Peptic Ulcer Disease in the United States. Archives of Internal Medicine. 157: 1489-94.
12. Thagard P. (1998). Ulcers and Bacteria I: Discovery and Acceptance. Studies in History and Philosophy of Science. Part C: Studies in History and Philosophy of Biology and Biomedical Sciences. 29:107-36.
13. Busse, J. W., Jim, J., Jacobs, C., Ngo, T., Rodine, R., Torrance, D., et al. (2011). Attitudes towards chiropractic: an analysis of written comments from a survey of north american orthopaedic surgeons. Chiropractic & Manual Therapies, 19(1), 25. doi:10.1186/2045-709X-19-25
1. Haag MD, Bos MJ, Hofman A, Koudstaal PJ, Breteler MM, Stricker BH. Cyclooxygenase selectivity of nonsteroidal anti-inflammatory drugs and risk of stroke. Arch Intern Med. 2008;168(11):1219–1224.
2. Chang CH, Shau WY, Kuo CW, Chen ST, Lai MS. Increased risk of stroke associated with nonsteroidal anti-inflammatory drugs: a nationwide case-crossover study. Stroke 2010;41:1884-90.
3. Bavry, A., & Park, K. (2014). Risk of stroke associated with nonsteroidal anti-inflammatory drugs. Vascular Health and Risk Management, 25. doi:10.2147/VHRM.S54159
4. Tuchin, P. (2013). Chiropractic and stroke: association or causation? International Journal of Clinical Practice, 67(9), 825–833. doi:10.1111/ijcp.12171
5. Cassidy, J. D., Bronfort, G., & Hartvigsen, J. (2012). Should we abandon cervical spine manipulation for mechanical neck pain? No. BMJ (Clinical Research Ed), 344(jun07 3), e3680–e3680. doi:10.1136/bmj.e3680
6. Cassidy JD, Boyle E, Cote P, He Y, Hogg-Johnson S, Silver FL, et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. Spine 2008;33(suppl 4):S176-83.
7. Wand, B. M., Heine, P. J., & O'Connell, N. E. (2012). Should we abandon cervical spine manipulation for mechanical neck pain? Yes. BMJ (Clinical Research Ed), 344(jun07 3), e3679–e3679. doi:10.1136/bmj.e3679
8. Hurwitz EL, Carragee EJ, van der Velde G, Carroll LJ, Nordin M, Guzman J, et al. Treatment of neck pain: noninvasive interventions: results of the Bone and Joint Decade 2000-2010 Task Force on neck pain and its associated disorders. Spine 2008;33(suppl 4):S123-52. 2
9. Leaver AM, Refshauge KM, Maher CG, McAuley JH. Conservative interventions provide short-term relief for non-specific neck pain: a systematic review. J Physiotherapy 2010;56:73-85.
10. Bronfort G, Evans R, Anderson AV, Svendsen KH, Bracha Y, Grimm RH. Spinal manipulation, medication, or home exercise with advice for acute and subacute neck pain: a randomized trial. Ann Intern Med 2012;156:1-10.
11. Munnangi S and S Amnon. (1997). Time Trends of Physician Visits and Treatment Patterns of Peptic Ulcer Disease in the United States. Archives of Internal Medicine. 157: 1489-94.
12. Thagard P. (1998). Ulcers and Bacteria I: Discovery and Acceptance. Studies in History and Philosophy of Science. Part C: Studies in History and Philosophy of Biology and Biomedical Sciences. 29:107-36.
13. Busse, J. W., Jim, J., Jacobs, C., Ngo, T., Rodine, R., Torrance, D., et al. (2011). Attitudes towards chiropractic: an analysis of written comments from a survey of north american orthopaedic surgeons. Chiropractic & Manual Therapies, 19(1), 25. doi:10.1186/2045-709X-19-25