Neck pain is a common problem, with two-thirds of the population having neck pain at some point in their lives.
Neck pain, although felt in the neck, can be caused by numerous other spinal problems. Neck pain may arise due to muscular tightness in both the neck and upper back, or pinching of the nerves emanating from the cervical vertebrae. Joint disruption in the neck creates pain, as does joint disruption in the upper back.
The head is supported by the lower neck and upper back, and it is these areas that commonly cause neck pain. The top three joints in the neck allow for most movement of your neck and head. The lower joints in the neck and those of the upper back create a supportive structure for your head to sit on. If this support system is affected adversely, then the muscles in the area will tighten, leading to neck pain.
Neck pain may also arise from many other physical and emotional health problems.
A study on Neck Pain and the Adjustment
Currently, the Cochrane Review and the work of Bronfort form the standard for evaluating the evidence for the treatment of neck pain by manipulation or mobilization. Our review differed from these works in several ways. With respect to the studies included, our review included not only studies of manipulation and mobilization but also of massage and other manual therapies as well. Our review included several studies that Gross and Bronfort had excluded because they were not studies comparing manipulation or mobilization to another form of therapy. Rather, these studies compared one form of these therapies with another form. In our review, each of these study groups was appropriate because they included selected, randomized subjects receiving one of the therapies of interest.
With respect to exclusions, we did not include studies involving subjects with acute neck pain, neck and arm pain, neck pain due to whiplash injury, or those with headache, whether clearly cervicogenic in nature or not. Thus, our review has remained within the boundaries of studies of chronic neck pain treated with one or more forms of manual therapy.
Our review did not include several studies that reported on subjects with neck pain that had been included in larger spine pain groups but did not clearly separate the results of the subjects with neck pain nor did they provide separate results for those with chronic neck pain.
The primary difference between these reviews and our review lies in the analysis of change scores within groups so as to identify levels of improvement as opposed to determining whether differences between groups occurred as a measure of the “effectiveness” of the experimental treatment. Interestingly, Bronfort specifically endorse this line of inquiry; however, they do not pursue it in their review. In fact, they reported only the percentage differences between groups in their review of studies of manipulation and mobilization for spinal pain (including chronic neck pain). They do not even provide the outcome data for the study groups so that the reader might make these intragroup determinations.
Gross conclusions were that, “The evidence did not favor manipulation and/or mobilization done alone or in combination with various other physical medicine agents; when compared to one another, neither was superior”
As noted above, they did find supportive evidence for a multimodal approach of manipulation and/or mobilization combined with exercises for subacute/chronic mechanical neck disorders.
With respect to our approach to subgroup analysis, it could be asked if it is appropriate to conduct intragroup analyses from a set of published random control studies. In none of the manipulation or mobilization trials included in this review was there a comparison between a form of manual therapy and a placebo control procedure. These trials are more properly seen as randomized comparative trials in which none of the subjects in these trials were blinded as to the form of treatment they received. Interestingly, both trials of massage are placebo-controlled clinical trials.
Results from All Trials
From the baseline pain scores, it is evident that this body of trials involves patients with chronic neck pain, with mild to moderately severe neck pain. Most studies included outcome assessments up to 6 to 10 weeks. Several studies provided long-term outcomes up to 52 weeks, with one providing outcomes to 104 weeks. There was considerable variance in the format of reporting the outcomes in these trials. Most studies reported pre- to posttreatment changes in primary outcomes. Some trials, reported only change scores, whereas others only reported the percentage of subjects achieving a criterion level of outcome.
The largest number of trial reports is available for manipulation. All groups showed positive changes. Effect sizes could be calculated from 7 of 9 trials of a course of manipulation. These effect sizes are maintained up to 12 weeks posttreatment. For long-term outcome, the data from 2 trials are less conclusive but still shows large effect sizes for up to 104 weeks.
The other 2 trials of a course of manipulative therapy reported change scores differently. In the first trial of Giles and Muller, 4-week mean reductions of scores on a 10-point VAS were reported as statistically significant for only the manipulation group as compared with the groups receiving non-steroidal anti-inflammatory drugs or acupuncture. Hurwitz did not report change scores per se and only indicated that none of their contrasts between manipulation and mobilization achieved statistical significance at any outcome point. In all, 8 of 9 trials of a course of spinal manipulation reported statistically significant or clinically important changes in the group receiving manipulation. No trial group was reported to remain unchanged, and no trial group was reported to have worsened. In none of these trials were any major adverse reactions reported.
Five studies are available to determine the outcome of a course of mobilization therapy, one of which did not provide pre- and posttreatment pain scores. All groups showed positive changes. Two studies provide data up to the 6- to 7-week outcome point. Only one of these permits the calculation of an effect size, which was found to be large and at the upper end of the range found in the manipulation studies for the same period. Two studies provided data on the percentage of subjects achieving a clinically important improvement or full recovery. From these, it appears that approximately 70% of patients achieve this level of improvement at the 6- to 7-week point. Only 1 study provided long-term data, showing full recovery in approximately 70% of subjects at 13 and 52 weeks.
Only 2 trials of massage for chronic neck pain were retrieved. An effect size was calculated from Gam for a group receiving massage and exercises of 0.03 at the 6-week outcome point. Irnich et al reported the change scores in 100 mm VAS points at 1 week (7.89) and at 12 weeks (14.4), neither of which exceeds the 20 mm (2 of 10 points) level established by Brodin and others as a clinically important difference in chronic pain patients.
There are several ways to assess the clinical relevance of change scores. They can be compared with what is known as the “minimum clinically important change.” However, this value is properly derived from an analysis of patients’ minimum expectations of change on a specific instrument as compared with a global or objective standard of change. To our knowledge, this has not specifically been done for pain scores for chronic neck pain patients.
More generally, Farrar have reviewed the change scores on the 11-point pain scale in 10 clinical trials for a variety of chronic pain complaints (2724 subjects) and have determined that a 2-point or 20 of 100 mm change is clinically relevant for patients with chronic pain.
It could be argued that these change scores represent the natural history of chronic neck pain or the placebo effect within a trial and therefore do not reflect the influence of the treatments provided. We have investigated the average change scores in a separate group of controlled clinical trials of conservative treatments for chronic neck pain and found that these are not generally greater than 15 mm on a 100 mm VAS (around 25% improvement). In several of these studies, there was no change at all in the control groups over up to 10 weeks posttreatment. Given these findings, the changes obtained in this review would appear to exceed what could be ascribed to either the natural history or the placebo affect.
Notwithstanding these comparisons with published benchmarks for clinical change, there is an urgent need for placebo- or sham-controlled clinical trials of manual therapies for chronic neck pain. Until such trials are performed, it will not be possible to accurately determine the attributable effect of these therapies over and above the nonspecific effects that are generally present in all clinical trials but even more strongly present during manual therapies in particular.
ConclusionThere is moderate- to high-quality evidence that subjects with chronic neck pain not due to whiplash and without arm pain and headaches who are randomized to receive a course of spinal manipulation or mobilization show clinically important improvements at 6, 12, and up to 104 weeks posttreatment. The current evidence does not support a similar level of benefit from massage therapy. There is a need for controlled studies of these therapies for chronic neck pain.