Thursday, November 29, 2012

Yoga for Chronic Neck Pain Tested

Neck PainNeck pain is a common malady affecting a third to half of all adults in any given year, with up to 70% suffering nonspecific neck pain at some point during their lifetimes. The prevalence of persistent, chronic neck pain is between 6% and 22%, increasing with age. There are various causes and relatively few effective therapies; however, a recent study found that yoga was significantly helpful for many patients.

A team of German researchers — led by Andreas Michalsen, MD, at Charité-University Medical Center, Berlin, Germany — evaluated the effectiveness of Iyengar yoga for chronic neck pain by means of a randomized, comparative efficacy clinical trial [Michalsen et al. 2012]. They enrolled 77 patients (average age 48, range 29-61 years; 87% female) with at least moderate chronic neck pain (>40mm on a 100mm visual analog scale, or VAS). Subjects were randomized to either a 9-week Iyengar yoga program with weekly 90-minute classes (N=38) or to a self-care/home exercise program (N=39).

The patients — who had suffered from nonspecific neck pain for about 6.6 years on average — were examined at baseline and after 4 and 10 weeks. The primary outcome measure was change of mean pain at rest from baseline to week 10 (measured via 100mm VAS). Secondary outcomes included pain during motion (on VAS), functional disability, quality of life (QOL), and psychological outcomes.

Statistical analyses used intention-to-treat procedures (ie, drop-outs were considered as failures). Thirteen patients in the yoga group and 11 patients in the self-care/exercise group were lost to follow-up, with higher study nonadherence in the self-care group (5 vs 10 patients).

Writing in the November edition of the Journal of Pain, Michalsen and colleagues report significantly favorable effects of yoga at 10 weeks:

  • The mean pain score at rest was reduced from 44.3 to 13.0 by yoga and from 41.9 to 34.4 by self-care/exercise. The difference between groups = −20.1 points; 95% confidence interval, −30.0 to −10.1; P<0.001).

  • Pain during motion was reduced from 53.4 to 22.4 by yoga and from 49.4 to 39.9 by self-care/exercise. Between-group difference = −18.7; 95% CI, −29.3 to −8.1; P<0.001).

Significant treatment effects favoring yoga also were found for pain-related apprehension, disability, QOL, and psychological outcomes. Sensitivity analyses — eg, using per-protocol data only or last observation carried forward to account for missing data — suggested that dropout rates had minimal influence on relative effect sizes.

Both yoga and the home-exercise program were well tolerated. There were no serious events in either group, although some yoga participants experienced transient back pain or muscle soreness.

The researchers concluded that this preliminary trial demonstrated yoga to be an effective treatment in chronic neck pain with possible additional positive effects on psychological well-being and QOL. However, the clinical effectiveness of yoga for chronic neck pain should be further tested via comparative efficacy trials involving other modalities and with longer observation periods.

COMMENTARY: Chronic neck pain poses a clinical challenge for patients and practitioners, and this topic has been discussed in prior UPDATES articles. One epidemiological survey in the United States found a 2.2% annual prevalence rate of nonspecific chronic neck pain, primarily affecting middle-aged (mean age 49) white females [see UPDATE here]. On average those surveyed had suffered disabling neck pain for nearly 7 years, and during that time had consulted 5 different healthcare providers, underwent 2 diagnostic tests, and received 16 different treatments.

Those population demographics are remarkably similar to subjects in the above study by Michalsen et al. conducted in Germany; however, patient selection was an important factor. The German researchers excluded prospective participants if they had recently undergone invasive treatment for their neck pain (eg, surgery, joint nerve blocks, epidural injections), or whose neck pain was complicated (eg, spinal stenosis or herniated vertebral disk) or attributable to specific underlying diseases (eg, congenital spine anomalies or fractured bones), as well as those who had whiplash injury, frozen shoulder syndrome, or other serious comorbidity.

Whether or not yoga also might benefit persons with the excluded conditions is unknown. [Yoga has been variously discussed in other UPDATES here.] Essentially, yoga was tested in this current study among persons who had uncomplicated nonspecific chronic neck pain and were otherwise sufficiently healthy to participate in physical activity.

YogaThe form of yoga selected for study also was of consequence. Iyengar yoga — named after its developer, B.K.S. Iyengar — is a form of Hatha yoga that emphasizes detail and precision in the performance of postures (asanas) and breath control (pranayama). In the German trial, the yoga group participated in weekly 90-minute yoga classes led by a certified instructor and physician adhering to the Iyengar style, with classical yoga poses adapted specifically to address neck pain.

A wide range of poses employed by this method are thought to enhance flexibility, alignment, stability, and mobility in muscles, joints, and tendons. The use of props such as belts, blankets, benches, and chairs is thought to minimize risks of injury or strain, while making the poses accessible to both young and old. [A list of poses used in the study is available as a supplement to the journal article.] Subjects were requested to practice selected poses at home for 10 to 15 minutes, 2 to 3 times a week, and 70% of patients reported practicing >2 times each week.

Although, yoga appeared to be safe as practiced in this study, it is not entirely without risks. As we noted in a prior UPDATE [here], persons with bone loss — whether osteopenia or osteoporosis — should be especially warned and educated on safe techniques. Of particular concern might be spinal flexion exercises, which case reports have suggested may lead to compression fractures in older women.

Michalsen and colleagues portray their study as a pilot trial due to its relatively small size. However, with 77 enrolled and 53 total subjects available for final analysis, it is somewhat typical in size of much research in the pain field overall and particularly studies examining complementary and alternative medicine (CAM) interventions. Still, there are methodological limitations of size here that may tend to favor the experimental therapy of interest.

Adjusting for small sample size, we calculated the effect sizes (Standardized Mean Difference, SMD, or Cohen’s d) favoring yoga for pain at rest as 1.18, and 1.15 for pain during motion — both of which are significantly large and clinically meaningful outcomes. [Effect sizes were discussed in an UPDATE here, and a calculator to derive SMD from a mean difference with CI is available via our PTCalcs Excel worksheet here.]

Those effect sizes are support by absolute improvements in pain. According to established criteria [Dworkin et al. 2008], pre- versus posttreatment changes of 20 points (or 30%–36%, on a 100mm VAS) generally denotes subjects feeling “much better” or “meaningfully improved”; a decrease of ≥40 points or ≥50% represents their feeling substantially (“very much”) improved.

In the present trial, for the yoga group compared with the control group, there was a statistically significant and clinically important adjusted reduction of pain intensity at rest of ≈20 points on the VAS. Within the yoga group itself, the pre- to posttreatment reduction of ≈30 points (or ≈68%) also represents a significant and important effect. For pain during motion, the comparable reductions were ≈19 points between groups and 58% within the yoga group.

Many patients in this German study were taking medications at baseline (50% in yoga group, 41% in self-care/exercise group, P=0.42) and/or had received physical therapy (60% and 56.4%, respectively; P=0.81). Although these factors were equitably balanced between groups at the outset, the researchers do not comment on whether there were between group differences in these factors as a result of the interventions.

Furthermore, the design of this trial does not help to distinguish the mechanisms by which yoga induces such physical and psychological improvements. According to Michalsen et al., the practice of Hatha yoga (of which Iyengar is a form) encompasses physical movements that enhance isometric muscle strengthening, stretching, and flexibility, along with a mental focus. Therefore, yoga might enhance both muscle toning and a release of muscle tension, while the induced relaxation response may further reduce stress-related muscle tension and modify pain perception.

Outcomes of this study suggest that yoga merits consideration as a component of therapy for chronic neck pain — if properly conducted in appropriately selected patients. Studies of other therapies for chronic neck pain also have been discussed in UPDATES articles:

  • A review and meta-analysis of the literature found that low-level laser therapy can effectively reduce nonspecific acute neck pain immediately after treatment and for several months in patients with chronic neck pain. In some cases, there may be advantages of this approach over traditional pharmacotherapies, if laser therapy is properly applied [UPDATE here].

  • A comparative clinical trial found that spinal manipulation therapy (chiropractic) or home exercises were equally better than medications for relieving chronic neck pain. However, there were a number of limitations of this research and effect sizes were small [UPDATE here].

  • Researchers in Germany conducted a small, short-term randomized controlled trial of the traditional East Asian healing technique Gua sha — sometimes referred to as “spooning” or “coining” — in patients with chronic neck pain. While favorable pain-relief results were observed, there were questions about whether healthcare providers should recommend this therapy for their patients [UPDATE here].

Finally, it should be noted that in much of the research to date, including the present study by Michalsen et al., there have been inadequate controls to assess the influences of possible placebo effects and the natural course of painful nonspecific neck disorders. At the least, these factors might diminish the favorable effects found in the studies and this is an element of some concern with most investigations of CAM therapies.

Most of the literature suggests that CAM therapies are best considered as part of a multimodal biopsychosocial approach to pain management. Yoga might have a particular appeal — for suitably qualified patients and if properly administered — due to its potential benefits for overall physical well-being and mental health.

> Dworkin RH, Turk DC, Wyrwich KW, et al. Interpreting the clinical importance of treatment outcomes in chronic pain clinical trials: IMMPACT recommendations. J Pain. 2008;9:105–121 [
abstract here].
> Michalsen A, Traitteur H, Lüdtke R, et al. Yoga for Chronic Neck Pain: A Pilot Randomized Controlled Clinical Trial. J Pain. 2012(Nov);13(11):1122–1130 [
abstract here].

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