CRPS Research

CRPSKeep up to date with some of the recent CRPS research papers. You can click on the title link for the full text version. My comments are posted ‘RS’ in italics.

Pain exposure physical therapy (PEPT) compared to conventional treatment in complex regional pain syndrome type 1: a randomised controlled trial


To compare the effectiveness of pain exposure physical therapy (PEPT) with conventional treatment in patients with complex regional pain syndrome type 1 (CRPS-1) in a randomised controlled trial with a blinded assessor.

The study was conducted at a level 1 trauma centre in the Netherlands.

56 adult patients with CRPS-1 participated. Three patients were lost to follow-up

Patients received either PEPT in a maximum of five treatment sessions, or conventional treatment following the Dutch multidisciplinary guideline.

Outcomes were assessed at baseline and at 3, 6 and 9 months after randomisation. The primary outcome measure was the Impairment level Sum Score—Restricted Version (ISS-RV), consisting of visual analogue scale for pain (VAS-pain), McGill Pain Questionnaire, active range of motion (AROM) and skin temperature. Secondary outcome measures included Pain Disability Index (PDI); muscle strength; Short Form 36 (SF-36); disability of arm, shoulder and hand; Lower Limb Tasks Questionnaire (LLTQ); 10 m walk test; timed up-and-go test (TUG) and EuroQol-5D.

The intention-to-treat analysis showed a clinically relevant decrease in ISS-RV (6.7 points for PEPT and 6.2 points for conventional treatment), but the between-group difference was not significant (0.96, 95% CI −1.56 to 3.48). Participants allocated to PEPT experienced a greater improvement in AROM (between-group difference 0.51, 95% CI 0.07 to 0.94; p=0.02). The per protocol analysis showed larger and significant between-group effects on ISS-RV, VAS-pain, AROM, PDI, SF-36, LLTQ and TUG.

We cannot conclude that PEPT is superior to conventional treatment for patients with CRPS-1. Further high-quality research on the effects of PEPT is warranted given the potential effects as indicated by the per protocol analysis.


High-frequency repetitive sensory stimulation as intervention to improve sensory loss in patients with CRPS type 1


Achieving perceptual gains in healthy individuals or facilitating rehabilitation in patients is generally considered to require intense training to engage neuronal plasticity mechanisms. Recent work, however, suggested that beneficial outcome similar to training can be effectively acquired by a complementary approach in which the learning occurs in response to mere exposure to repetitive sensory stimulation (rSS). For example, high-frequency repetitive sensory stimulation (HF-rSS) enhances tactile performance and induces cortical reorganization in healthy subjects and patients after stroke. Patients with complex regional pain syndrome (CRPS) show impaired tactile performance associated with shrinkage of cortical maps. We here investigated the feasibility and efficacy of HF-rSS, and low-frequency rSS (LF-rSS) to enhance tactile performance and reduce pain intensity in 20 patients with CRPS type I. Intermittent high- or low-frequency electrical stimuli were applied for 45 min/day to all fingertips of the affected hand for 5 days. Main outcome measures were spatial two-point-discrimination thresholds and mechanical detection thresholds measured on the tip of the index finger bilaterally. Secondary endpoint was current pain intensity. All measures were assessed before and on day 5 after the last stimulation session. HF-rSS applied in 16 patients improved tactile discrimination on the affected hand significantly without changes contralaterally. Current pain intensity remained unchanged on average, but decreased in four patients by ≥30%. This limited pain relief might be due to the short stimulation period of 5 days only. In contrast, after LF-rSS, tactile discrimination was impaired in all four patients, while detection thresholds and pain were not affected. Our data suggest that HF-rSS could be used as a novel approach in CRPS treatment to improve sensory loss. Longer treatment periods might be required to induce consistent pain relief.

RS: This is an interesting finding. Stimulation that brings about changes in the cortical maps is not a new notion, and indeed is part of normal learning. We stimulate with movement and/or touch under day to day circumstances, and in fact that is what we need to employ moment to moment at home to overcome CRPS and other painful conditions. Most people will not have access to equipment but are able to use simple touch, two point discrimination and movement, all of which form a vital part of the training and self-coaching programme. Pain is a lived experience and the programme must become part of life and hence be as simple as possible, which it can.


Motor imagery and its effect on complex regional pain syndrome: an integrative review


The motor imagery (MI) has been proposed as a treatment in the complex regional pain syndrome type 1 (CRPS-1), since it seems to promote a brain reorganization effect on sensory-motor areas of pain perception. The aim of this paper is to investigate, through an integrative critical review, the influence of MI on the CRPS-1, correlating their evidence to clinical practice. Research in PEDro, Medline, Bireme and Google Scholar databases was conducted. Nine randomized controlled trials (level 2), 1 non-controlled clinical study (level 3), 1 case study (level 4), 1 systematic review (level 1), 2 review articles and 1 comment (level 5) were found. We can conclude that MI has shown effect in reducing pain and functionality that remains after 6 months of treatment. However, the difference between the MI strategies for CRPS-1 is unknown as well as the intensity of mental stress influences the painful response or effect of MI or other peripheral neuropathies.

RS: motor imagery does have an impact on our ability to move, and often rapidly so after a few repetitions. Using imagery and visualisation to assess mental representations, body sense and integrity alongside other simple tests gives an insight into the different hierarchical levels of contribution to the brain’s best guess about this moment for the individual. What we are experiencing now is our brain’s prediction (or best guess) when it has chosen from a number of hypotheses. Using imagery and visualisation, we can impact on the predictions as well as our own expecations that feed such predictions and our own conscious sense of what is to come. Pain is worse when we expect something to hurt, so what if we do not expect this and indeed anticipate something different, new and healthy?


Fear and reward circuit alterations in padeiatric CRPS


In chronic pain, a number of brain regions involved in emotion (e.g., amygdala, hippocampus, nucleus accumbens, insula, anterior cingulate, and prefrontal cortex) show significant functional and morphometric changes. One phenotypic manifestation of these changes is pain-related fear (PRF). PRF is associated with profoundly altered behavioral adaptations to chronic pain. For example, patients with a neuropathic pain condition known as complex regional pain syndrome (CRPS) often avoid use of and may even neglect the affected body area(s), thus maintaining and likely enhancing PRF. These changes form part of an overall maladaptation to chronic pain. To examine fear-related brain circuit alterations in humans, 20 pediatric patients with CRPS and 20 sex- and age-matched healthy controls underwent functional magnetic resonance imaging (fMRI) in response to a well-established fearful faces paradigm. Despite no significant differences on self-reported emotional valence and arousal between the two groups, CRPS patients displayed a diminished response to fearful faces in regions associated with emotional processing compared to healthy controls. Additionally, increased PRF levels were associated with decreased activity in a number of brain regions including the right amygdala, insula, putamen, and caudate. Blunted activation in patients suggests that (a) individuals with chronic pain may have deficits in cognitive-affective brain circuits that may represent an underlying vulnerability or consequence to the chronic pain state; and (b) fear of pain may contribute and/or maintain these brain alterations. Our results shed new light on altered affective circuits in patients with chronic pain and identify PRF as a potentially important treatment target.

Pain Coach ProgrammeRS: we know that fear provokes on-going and more protection as we are perceiving a threat. Pain is also about perceived threat that is being predicted by our brain’s best guess about a particular situation or context base on what has happened before. This is one of the reasons why pain can be so specifically associated with a particular movement, a place or a thought. Many are puzzled by the changeable nature of pain and how it can exists one minute and not the next. Understanding pain allows people to realise that this is exactly the lived experience, especially in youngsters who can appear to be moving normally and then be in agony. Their brains have predicted a need for protection and hence they are in pain. The perceived threat passes and the new prediction is ‘no threat’ and hence no pain. This is how it works and unfortunately many people are not believed as a consequence and a really important reason why society needs to understand pain. Fear of pain being eradicated results in positive change and is a key step towards overcoming pain, starting with a working knowledge. I use UBER-M as a self-coaching tool that I give to individuals: U (understand pain; working knowledge), B (breathing & mindfulness), E (exercises – specific and general), R (re-charge energy to engage); M (movement for health and expression); the question to ask is this: ‘Are these thoughts and actions taking me towards my vision of a healthy me?’

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