Ellen Vandyck
Research Manager
People with pain lasting more than six months often display characteristics of central sensitization where no nociceptive processes but more features of nociplastic pain are present. Previously it turned out that approximately one in four musculoskeletal shoulder pain patients display sensitization characteristics. (Previtali et al. 2021) Often, these people are resistant to usual care, despite having tried otherwise effective treatment strategies. Graded motor imagery has been shown to activate areas related to movement execution in the brain. By using the same neural pathways of real movement, activating these brain regions may allow to activate movement-specific central activation patterns without actually provoking pain. Since earlier studies have shown promising results regarding the usefulness of graded motor imagery but mostly in the short term, the current investigates mid- and long-term results.
This study set up a pre-post intervention single-group study including people over 60 years of age affected by at least 6 months of shoulder pain secondary to tendinopathy and/or partial rotator cuff tear. The eligible candidates were recruited from the physiotherapy department in a private clinic in Chile. An orthopedic surgeon was involved in establishing the diagnosis.
All participants were offered usual care, which consisted of nonsteroidal anti-inflammatory drugs (celecoxib 200mg, 2x/d for 14 days), standard medical education, and physiotherapy treatment.
Along with the usual care, a graded motor imagery program was designed based on Mosely et al. (2012). This program was conducted three times per week for six consecutive weeks. Three main concepts of graded motor imagery were used:
The primary outcome of interest was pain intensity, assessed using the 0-10 visual analog scale (VAS). According to the authors, a reduction of 1.1 centimeters is the minimal clinically important difference (MCID). Secondary outcomes included the 17-item Tampa Scale of Kinesiophobia (TSK) with a minimal detectable change (MDC) of 5.6 points, the Pain Catastrophization Scale (PCS) with a MDC of 9.1 points, shoulder active range of motion (AROM) measured with the use of a universal goniometer and a MDC of 8°, and the Central Sensitization Inventory (CSI). The outcomes were assessed at baseline, 6, and 12 months.
148 participants were enrolled in this pre-post study. The population was approximately equally divided into men and women. At baseline they had a CSI score of 48.3 points, meaning that these participants had moderate levels of central sensitization features (threshold >40 points). They reported symptoms for a mean of 61.2 months!
The analysis of the primary outcome revealed a decrease of 3.2 points on the VAS and this effect was held over the one-year follow-up.
All of the secondary outcome measures were significantly better after following the graded motor imagery program, with all passing the MCID.
The calculated effect size at 12 months showed a large effect.
This study found an important and worthwhile reduction in pain intensity sustained over 12 months after the end of the trial. The confidence interval confirmed the findings, with reductions in the primary outcome all above the threshold of the MCID. Moreover, all secondary outcomes confirmed the primary analysis and their confidence intervals also all surpassed the threshold of the MCIDs. Most remarkable was that the graded motor imagery program was only held for 6 weeks, but improvements were sustained up to 6 and 12 months. That is an achievement not every study succeeds in. In 2020, the same authors had already conducted a short-term study, which was also indicative of important improvements beyond the thresholds of clinically worthwhile improvements. Therefore, I am curious to see if these effects would also be achieved in further research and more rigorous designs.
No information was provided on the timeline between the last graded motor imagery treatment session and the first follow-up. It could have been possible that the included participants continued to exercise the learned motor imagery, switched to other treatments or did nothing in particular. An RCT follows a more strict methodology, in which confounding factors can be taken along in the analyses.
An interesting point to consider about this study is that no dropout or loss to follow-up occurred, despite that these people with chronic complaints were asked to engage in a 6-week intensive study period. This also may be indicative of treatment efficiency, since people would probably not remain in a trial when they achieve no progress, especially when they are already suffering from their pain for more than 5 years.
An improvement between 20° and 36° in shoulder flexion active range of motion is a remarkable achievement for a treatment that is solely based on practicing imaginary movements and activating motor patterns. If you are not familiar with graded motor imagery, it may even seem like magic or sorcery. But when diving a bit more in the research, you can see that this is a well-established treatment option, developed by a well-known name: Lorimer Mosely. It is been used for decades, for instance in phantom-limb recovery and post-stroke, but also people with complex regional pain syndrome (CRPS) have been studied extensively and goes back to the years 2000 already.
This was not a randomized controlled trial (RCT), which is the gold standard for measuring treatment effectiveness. (Hariton et al., 2018) Before the current study emerged, already evidence on graded motor imagery was available. For example in 2020, a systematic review by Suso-Martí et al. concluded “Movement representation techniques in combination with usual care are capable of producing a decrease in pain intensity compared with conventional treatment, in both post-surgical and chronic pain. However, the very low-quality evidence found regarding these techniques showed that more research is needed for their application in a clinical context”. Since then, research emerged:
As this was a pre-post single-group study, you should be aware that there was no comparison with another treatment as is the case in gold-standard randomized controlled trials. Therefore, the conclusions of this study can not be considered evidence-based practice yet but can merely shed light on future steps. This study can maybe inspire you to help people who present with similar characteristics in practice. This study included participants older than 60 years who had chronic RCRSP and were suffering from their condition for at least 6 months. Patients in your practice who are comparable and who have been resistant to routine care and display signs of central sensitization might be suitable candidates for this protocol of graded motor imagery. However, in the absence of a rigor randomized controlled trial showing effectiveness for graded motor imagery for RCRSP, routine best-practice care should be followed first.
When considering the already-known evidence, not including a control group in the 2024 study by Araya-Quintanilla et al. is a limitation. However, as this study followed their participants for 12 consecutive months, it gives an innovative viewpoint and an indication of the possibilities for future research and long-term possibilities of graded motor imagery.
This pre-post single-group study inspired the possibility of graded motor imagery on long-term follow-up outcomes in people suffering from chronic shoulder pain with features of central sensitization. As no control group was included, evidence is not conclusive, yet may guide treatment for patients with similar pain characteristics who are resistant to usual care.
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