Research Review By Dr. Josh Plener©

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Date Posted:

January 2020

Study Title:

Spinal manipulation for the management of cervicogenic headache: a systematic review and meta-analysis

Authors:

Fernandez M, Moore C, Tan J et al.

Author's Affiliations:

Macquarie University, Sydney, Australia; University of Technology, Sydney, Australia; Chiropractic Academy for Research Leadership (CARL); McGill University, Quebec, Canada; Université du Québec à Trois Rivières, Quebec, Canada

Publication Information:

European Journal of Pain 2020 Oct;24(9):1687-1702. doi: 10.1002/ejp.1632.

Background Information:

Cervicogenic headache is believed to arise as a secondary disorder from pain or dysfunction in the cervical spine (1). Cervicogenic headache has an estimated population prevalence of 4.1%, affecting approximately 15-20% of all headache patients (2, 3).

Clinically, cervicogenic headache typically presents as head pain that is worsened by neck movement or sustained positions (or postures), restricted cervical ranges of motion and ipsilateral shoulder and arm pain (4). Typically, pain experienced during these headaches begins in the neck or occipital region, and travels to the face and head (5, 6). This referred pain is thought to result from the unique confluence of inputs in the trigeminocervical complex, which receives input from both the upper cervical segments and trigeminal nociceptive afferents (7).

The diagnosis of cervicogenic headache may be challenging due to the symptom similarity between cervicogenic headache and other conditions. For example, sharp pain in the occipital region may be the result of occipital neuralgia (8), and overlapping signs such as neck pain, nausea, vomiting, photophobia and phonophobia may be the result of other headaches such as migraines (9, 10).

Treatment options for cervicogenic headache typically include spinal mobilization, spinal manipulative therapy (SMT), massage and endurance-based cervico-scapular exercises (11, 12). Specifically pertaining to SMT, a number of systematic reviews have demonstrated that SMT might be beneficial in pain reduction when administered within a multimodal treatment approach (13-16). However, in 2019, Cote et al. demonstrated that there was no added benefit in offering combined treatment consisting of SMT, spinal mobilization and exercise compared to providing either one of these interventions in isolation (17).

Since prior systematic reviews did not compare SMT in isolation to other manual therapies in a meta-analytic fashion, it is not known whether SMT is superior to other manual therapy interventions for cervicogenic headache. Therefore, the objective of this review is to compare SMT to other manual therapies for the management of cervicogenic headache.

Pertinent Results:

Seven studies were included in the meta-analysis, comprising a total of 403 participants. The included studies examined SMT delivered to the cervical spine, thoracic spine or ribs (1-9). The comparison manual therapy interventions consisted of spinal mobilization and cranio-cervical flexion exercises, light massage, deep flexor exercises, deep friction massage with laser, and sham interventions consisting of light touch to specific cervical spine segments or manipulation at the lateral edge of the scapula and/or the gluteal region.

The methodological quality assessment using PEDro scale revealed an average score of 6.9 (SD = 0.6) with five studies being considered “high quality” and two studies considered “moderate quality”. A key problem identified from the quality assessment was the lack of blinding of therapists, which is expected for this type of intervention.

Three follow-up times were examined, with the quality of the evidence determined for each outcome at each follow-up.

Short term follow-up:
  • Low quality evidence: Significant, small effect favoring SMT over other manual therapies for pain intensity.
  • Low quality evidence: Non-significant effect for pain duration.
  • Moderate quality evidence: Significant, small effect favouring SMT over other manual therapies for disability.
  • Moderate quality evidence: Significant, small effect favouring SMT over other manual therapies for pain frequency.
Intermediate term follow-up:
  • Low quality evidence: Non-significant difference between SMT and other manual therapies for pain intensity.
  • Moderate quality evidence: Significant, small effect favouring SMT over other manual therapies for pain frequency.
Long term follow-up:
  • Low quality evidence: Non-significant difference between SMT and other manual therapies for pain intensity.
  • Moderate quality evidence: Small, but non-significant effect favouring SMT over other manual therapies for pain frequency.
Not all studies reported on adverse events, but no major adverse events were reported for either group. Minor adverse events that were reported included neck pain or soreness, stiffness, transient upper extremity pain/tingling, increased headache intensity, nausea and dizziness (18).

Clinical Application & Conclusions:

The results of this systematic review and meta-analysis demonstrate that compared to other manual therapies, SMT provides small but significant short-term effects for pain intensity, frequency and disability, but not pain duration among cervicogenic headache sufferers. In particular, the small but statistically significant benefit seen in the short and intermediate term for headache frequency is of interest, as this is reported to be the most important primary outcome measure in efficacy studies (19).

Discussing and communicating the findings of this review with patients will help in the shared decision-making process between the clinician and patient. This will allow patients to consider the potential treatment benefits such as positive improvement in quality of life, which can be weighed against the potential harms such as mild to moderate adverse events (20). Patients can then determine the best treatment options that align with their preferences and values (21).

An important aspect to consider is the clinical utility of the results, which requires a comparison to the known minimal clinically important change (MCID). The MCID is the smallest difference that patients perceive as beneficial with respect to the treatment they receive. For cervicogenic headaches patients, MCID threshold for self-reported pain intensity is 2.5 points on a 10-point scale, and 5.5 points on 0-50 Neck Disability Index Scale at the short term (22). The treatment effect seen in the meta-analysis demonstrated that despite SMT being superior for pain intensity in the short-term, the treatment effect falls below the MCID. However, the treatment effect on disability in the short term is greater than the MCID. Therefore, compared to pain intensity, the improvement in disability may provide greater clinical justification for providing SMT for cervicogenic headache patients. This being said, the evidence surrounding MCID for cervicogenic headache is limited, therefore a discussion with patients to determine their individual minimally important difference would be beneficial.

The results of this review are interesting and provide useful clinical information. However, research is lacking in this patient population and further research is required. Future trials should evaluate the intermediate to long term impact of SMT for cervicogenic headache, and examine cost-effectiveness and subgrouping of patients to determine who is most likely to benefit from SMT.

Study Methods:

The following databases were searched with the MeSH terms cervicogenic; headache; spinal manipulation; manual therapy; and randomised control trial: Medline, Mantis, PEDro, Cochrane Central Register of Controlled Trials, and Embase.

Eligibility for study inclusion:

In order to be eligible for the review, studies needed to enrol patients who experience and report cervicogenic headache and fulfill the following criteria:
  1. Adults with cervicogenic headache that were diagnosed by a certified medical or allied health practitioner using the International Headache Society 3rd edition or Cervicogenic Headache International Study Group (4).
  2. The primary treatment administered was SMT.
  3. The comparison group received some other form of manual therapy including spinal mobilization, light massage, deep friction massage, low-level laser, cervico-scapular exercise, and sham treatments.
  4. Outcome measures were pain intensity, pain frequency, pain duration or disability.
  5. The study design was a randomised controlled trial.
Studies were excluded from the review if patients were diagnosed with other types of headaches such as migraine and/or tension-type headache, treated primarily with pharmacological interventions or if SMT was combined with spinal mobilization and/or exercises.

Data extraction:
 
Four reviewers independently assessed the risk of bias for each study using the Physiotherapy Evidence Database (PEDro) scale, which assesses the internal validity of a RCT. A PEDro score of 4 or less was considered ‘poor quality’, 5-6 was considered ‘moderate quality’ and 7-10 was considered ‘high quality’. Five reviewers independently extracted characteristics of the included studies.

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the overall quality of the evidence and strength of recommendations (23).

The quality of the evidence is graded as:
  • High quality – further research is unlikely to change our confidence in the estimate of effect
  • Moderate quality – further research is likely to have an important impact on our confidence in the estimate of effect and might change the estimate
  • Low quality – further research is likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate
  • Very low quality – we are uncertain about the estimate
Since only randomized controlled trials were included, initially the overall quality of the evidence was regarded as ‘high’ but was reduced by 1 level for each of the following factors: limitations in the design as demonstrated by > 25% of the studies considered to have a risk of bias, inconsistency of results as demonstrated by large heterogeneity between trials and imprecision as noted by < 400 patients in total for each outcome (24).

Data Synthesis: Outcome data was extracted for the following time intervals: Short term (> 2 weeks but  3 months), intermediate term (> 3 months but < 12 months), and long term ( 12 months).

Meta-analyses were conducted calculating the mean difference with 95% confidence intervals for all point estimates for pain intensity and disability measures. In addition, heterogeneity was evaluated using the I2 statistic.

Study Strengths / Weaknesses:

Strengths:
  • This systematic review and meta-analysis provides an up-to-date summary of the impact of SMT among cervicogenic headache sufferers.
  • Most of the trials included were of high methodological quality (PEDro score of 7 or greater).
  • Authors provided clinically interpretable estimates, which provides clinicians and patients the ability to consider whether SMT will be considered meaningful and important to them.
Limitations:
  • A small number of trials (n = 7) were included, therefore the overall quality of the evidence for the meta-analyses were downgraded for reasons of imprecision as less than 400 patients were included in the analysis (24).
  • Some outcomes had a high between-trial heterogeneity, most likely due to the use of different outcome measures and methodologies used in the trials.
  • Co-occurring conditions may have been present, such as migraine and/or tension-type headache, as anaesthetic blockade procedures would be needed to make a definitive cervicogenic headache diagnosis.
  • Different forms of SMT techniques were included in the studies and treatment frequency also varied between trials.
  • Studies were limited to the English language.
  • There is a lack of high-quality evidence according to the GRADE approach, which results in some degree of uncertainty in the results.

Commentary from Dr. Matthew Fernandez (lead author):

Current evidence supports the role of manual therapies, such as spinal manipulation therapy (SMT) in the management of cervicogenic headache. Previous systematic reviews on this topic have shown that SMT might be a beneficial modality, but have combined massage, spinal mobilization and exercise, with and without SMT. We therefore undertook the task of comparing SMT as a solo intervention to other manual therapies for the management of cervicogenic headache. By conducting a meta-analysis, we aimed to make our recommendations based on the pooled treatment effects and therefore provided clinically interpretable estimates. This can assist clinicians and patients as to whether they would consider SMT for cervicogenic headache as meaningful or important.

Our review showed short-term (> 2 weeks but < 3 months), superior effects in favour of SMT over other manual therapies for pain intensity, pain frequency and disability but not pain duration. Additionally, the positive SMT effect for pain frequency extended into the intermediate term (> 3 months but < 12 months). By reporting the estimate of the size of effects (as opposed to simply the presence of effects), we can now better inform clinicians and patients about whether or not the treatment is worth undertaking (i.e. is it clinically meaningful).

Presently, it remains unknown whether some patients may consider the small, superior short-term effects in our review as clinically worthwhile. It may well be best for clinicians to discuss the estimated effect with patients, who can then set their own individual ‘cut off’ points as the smallest worthwhile effect. In doing so, the patient can then weigh up the perceived benefits and potential risks as part of the treatment decision-making process.

While these results are positive for SMT, our findings must be cautiously interpreted. Across all eligible trials, there were small sample sizes, and different headache classification criteria were utilised. In addition, not all components within the chosen criteria were adopted by researchers. Finally, there was only low-to-moderate quality evidence according to the GRADE classification. Together, these shortcomings reduce the confidence in our results. Ultimately, robust randomized controlled trials with adequate sample sizes are necessary to increase certainty and inform whether SMT is effective for cervicogenic headache.

Matt Fernandez is a chiropractor and exercise physiologist, awarded his PhD in 2017. He is currently a full-time lecturer at the Department of Chiropractic, Macquarie University in the area of rehabilitation and orthopaedics, and has presented at numerous back pain conferences both nationally and internationally. His current research interest includes physical activity and exercise promotion within the chiropractic setting and is exploring these topics, including GLA:D Back Australia, as a Program Fellow of the Chiropractic Academy for Research Leadership (CARL)

Additional References:

  1. Zito G, Jull G, et al. Clinical tests of musculoskeletal dysfunction in the diagnosis of cervicogenic headache. Manual Therapy 2006; 11(2): 118-129.
  2. Haldeman S, Dagenais S. Cervicogenic headaches: a critical review. The Spine Journal 2001; 1(1): 31-46.
  3. Sjaastad O, Bakketeig LS. Prevalence of cervicogenic headache: Vågå study of headache epidemiology. Acta Neurologica Scandinavica 2008; 117(3): 173-180.
  4. Sjaastad O, Fredriksen TA, et al. Cervicogenic Headache: Diagnostic Criteria. Headache: The Journal of Head and Face Pain 1998; 38(6): 442-445.
  5. Bogduk N. The anatomical basis for cervicogenic headache. Journal of Manipulative and Physiological Therapeutics 1992; 15(1): 67-70.
  6. Bogduk N, Govind J. Cervicogenic headache: an assessment of the evidence on clinical diagnosis, invasive tests, and treatment. The Lancet Neurology 2009; 8(10): 959-968.
  7. Bogduk N. The Neck and Headaches. Neurologic Clinics 2014; 32(2): 471-487.
  8. Barmherzig R, Kingston W. Occipital Neuralgia and Cervicogenic Headache: Diagnosis and Management. Current Neurology and Neuroscience Reports 2019; 19(5): 20.
  9. Fredriksen TA, Antonaci F, et al. Cervicogenic headache: too important to be left undiagnosed. The Journal of Headache and Pain 2015; 16(1): 6.
  10. Sjaastad O. Cervicogenic Headache: Comparison with Migraine Without Aura; Vågå study. Cephalalgia 2008; 28(1suppl): 18-20.
  11. Jull G, Trott P, et al. A randomized controlled trial of exercise and manipulative therapy for cervicogenic headache. Spine 2002; 27(17): 1835-1843.
  12. Wells RE, Bertisch SM, et al. Complementary and Alternative Medicine Use Among Adults With Migraines/Severe Headaches. Headache: The Journal of Head and Face Pain 2011; 51(7): 1087-1097.
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  14. Coelho M, Ela N, et al. The effectiveness of manipulation and mobilization on pain and disability in individuals with cervicogenic and tension-type headaches: a systematic review and meta-analysis. Physical Therapy Reviews 2019; 24(1-2): 29-43.
  15. Garcia JD, Arnold S, et al. Mobilization and Manipulation of the Cervical Spine in Patients with Cervicogenic Headache: Any Scientific Evidence? Frontiers in Neurology 2016; 7(40).
  16. Racicki S, Gerwin S, et al. Conservative physical therapy management for the treatment of cervicogenic headache: a systematic review. Journal of Manual & Manipulative Therapy 2013; 21(2): 113-124.
  17. Côté P, Yu H, et al. Non-pharmacological management of persistent headaches associated with neck pain: A clinical practice guideline from the Ontario protocol for traffic injury management (OPTIMa) collaboration. European Journal of Pain 2019; 23(6): 1051- 1070.
  18. Haas M, Bronfort G, et al. Dose-response and efficacy of spinal manipulation for care of cervicogenic headache: a dual-center randomized controlled trial. The Spine Journal 2018; 18(10): 1741-1754.
  19. Bendtsen L, Bigal ME, et al. Guidelines for controlled trials of drugs in tension-type headache: second edition. Guidelines for controlled trials of drugs in tension-type headache: second edition. Cephalalgia 2009; 0(0).
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  21. Hoffmann TC, Lewis J, et al. Shared decision making should be an integral part of physiotherapy practice. Physiotherapy 2019.
  22. Young IA, Dunning J, et al. Psychometric properties of the Numeric Pain Rating Scale and Neck Disability Index in patients with cervicogenic headache. Cephalalgia 2019; 39(1): 44-51.
  23. Group GW. Grading quality of evidence and strength of recommendations. BMJ: British Medical Journal 2004; 328(7454): 1490.
  24. Guyatt GH, Oxman AD, et al. GRADE guidelines 6. Rating the quality of evidence imprecision. Journal of Clinical Epidemiology 2011; 64(12): 1283-1293.