Painful view on motor actions

Imagine you sprained your wrist. It’s aching, swollen and reddish. You want to move the hand to see if it is ok, but the fear of pain makes you hesitate and it takes extra effort to do it. Even thinking about movement can be unpleasant and you focus on doing things with the healthy hand. After days and weeks, as the trauma heals, the pain passes and eventually you are back on track. In some people, however, these painful symptoms persist, start to spread and gain strength even though the initiating sprain itself has healed.

This is complex regional pain syndrome (CRPS). It begins typically after a small trauma, but then progresses into a devastating chronic painful condition with unpredictably variable daily symptoms. It has serious consequences for patients’ everyday life and is associated with disability and suffering. The affected limb becomes clumsy and weak, and the pain becomes annoying. People with chronic CRPS sometime start keeping their painful limb out of their field-of-vision [Lewis et al., 2007], as if trying to forget the limb and the pain. In addition, because moving the limb is painful, patients avoid movements and in the worst cases, find that a large amount of focus on the part is required to elicit even small movements. Nobody knows exactly how CRPS evolves, but the central nervous system seems to play a role.

In our recently published study ‘Patients with complex regional pain syndrome overestimate applied force in observed hand actions‘ [Hotta et al., 2015], we showed that CRPS patients feel unpleasantness and an increase in pain intensity when they observe others’ motor actions. The painfulness of observing the actions was associated with the painfulness of performing similar actions. Intriguingly, patients estimated that a greater force was applied during the observed actions than the healthy control subjects did. This overestimation of force was associated with unpleasantness and painfulness of observing the actions, but not with the amount of force patients themselves could apply when performing similar movements. The painfulness, unpleasantness and the force overestimation were stronger when patients observed motor actions of the limb corresponding to their painful limb than of the limb corresponding to their healthy limb.

Observation and execution of motor actions are known to activate overlapping brain areas (for a review, see Rizzolatti et al., 2009). We suggest that the association between pain and movement is so strong in CRPS, that plain visual information of actions might be enough to also activate brain areas underpinning pain. In theory, such a strong association might also encourage patients to avoid visual control over their own actions, making already diminished motor skills even worse.

Healthy people overestimate the force they apply if the performed movement is painful [Weerakkody et al., 2003]. We speculate that in CRPS the varying pain levels might disturb patients’ estimate of applied force. This, together with the increased sensation of effort for movements, might explain our findings of patients misestimating the force others apply.

One of the main targets in treatment of CRPS is to ease the pain so that patients may start practicing their lost motor skills. Unfortunately pain in CRPS is highly resistant to drugs. One popular treatment protocol is the so called “graded motor imagery” [Moseley, 2004]. In this therapy patients are encouraged using sequential steps to proceed from hand-laterality-recognition practice to imagined movements and further, to mirror therapy, and actual movements. In CRPS, even the imagined movements can cause pain [Moseley et al., 2008] and action observation has been suggested as an even more gentle exposure to motor actions [Moseley et al., 2009]. Based on our results it seems that in CRPS action-observation truly tickles the affected motor pathways in the brain and it could thus be of use in therapy.

Complex regional pain syndrome is not just a disease of a limb but it affects the lives of patients in numerous ways. Our study gives insight into how one aspect of CRPS modulates the patient’s world view, and suggests that pain is in the eye of the beholder.

About Jaakko Hotta

Jaakko HottaJaakko is a licensed physician graduated in 2004 from Faculty of Medicine in University of Helsinki. At the moment he is working partly in the Department of Neurology at Helsinki University Hospital, trying to get his degree in neurology done by the end of the year, and at the same time doing research in the Department of Neuroscience and Biomedical Engineering at Aalto University, trying to complete his doctoral thesis on CRPS. His special interests are in the couplings of brain and CRPS. His research is done in close collaboration with the Pain Clinic at Helsinki University Hospital.


Hotta J, Harno H, Nummenmaa L, Kalso E, Hari R, Forss N (2015): Patients with complex regional pain syndrome overestimate applied force in observed hand actions. Eur J Pain. Epub ahead of print.

Lewis JS, Kersten P, McCabe CS, McPherson KM, Blake DR (2007): Body perception disturbance: a contribution to pain in complex regional pain syndrome (CRPS). Pain 133:111–9.

Moseley GL (2004): Graded motor imagery is effective for long-standing complex regional pain syndrome: a randomised controlled trial. Pain 108:192–8.

Moseley GL, Zalucki N, Birklein F, Marinus J, van Hilten JJ, Luomajoki H (2008): Thinking about movement hurts: the effect of motor imagery on pain and swelling in people with chronic arm pain. Arthritis Rheum 59:623–31.

Moseley GL, Birklein F, van Hilten JJ, Marinus J (2009): Reply. Arthritis Care Res (Hoboken) 61:140–141.

Rizzolatti G, Fabbri-Destro M, Cattaneo L (2009): Mirror neurons and their clinical relevance. Nat Clin Pract Neurol 5:24–34.

Weerakkody NS, Percival P, Canny BJ, Morgan DL, Proske U (2003): Force matching at the elbow joint is disturbed by muscle soreness. Somatosens Mot Res 20:27–32.


  1. Nice post (and paper!), Jaakko. We did a study (presenting these findings at EFIC, but still working on writing up) asking 45 persons with CRPS about their symptoms and experience using a new condition-specific tool – and one of the questions specifically addressed this. For this item, participants rated how much they agreed with the statement: “I need to concentrate in order to make my affected limb(s) move”. Not surprisingly, folks with more symptoms that had a greater impact on their daily activities agreed more strongly with this statement. Interestingly, they expressed this was a different idea than guarding, where they also needing to pay attention to where their painful limb was during movement for protection.

    So my ongoing issue is, what are the practical strategies to address this in rehabilitation? The kinesiology literature tells us that when we concentrate on movement (internal focus) rather than the task (external focus) our muscles work less efficiently and with less precision (see G. Wulf’s line of work on this). This suggests that guarding likely compounds the poor quality and/or use of proprioceptive information in CRPS. So when we take this beyond a lab task and out into everyday life for our CRPS patients, we need to think about grading the level of demand/threat to the nervous system (hmm, sounds suspiciously neuromatrix again) and tease out these individual pieces.

    One of my ‘go-to’ patient recommendations is to consciously pay attention to the hand or foot (correlating to their affected limb, of course) of any actor appearing during a commercial when they are watching the TV. I ask them to concentrate on how that hand/foot moves throughout the ad – action observation. This encourages short bursts of practice while they themselves are not in motion (and hopefully in a comfy seat). It seems to be a strategy they can follow through with, but sadly no RCTs on TV watching yet.

    EG Reply:


    Jaakko just told us in this article that “CRPS patients feel unpleasantness and an increase in pain intensity when they observe others’ motor actions”.

    Then you say “I ask them to concentrate on how that hand/foot moves throughout the ad – action observation”, whilst sitting on a couch watching ads on TV.

    This is your “go to” recommendation? Doing something which has been shown to be pain-provoking whilst watching TV in a comfortable chair?

  2. Or maybe employ ‘utilization’ if there’s a lot of resistance.

    [In the subconscious, a house is often used to represent the self. And family members can be used here to symbolize competing aspects of the personality]….

    “There were a few family members who really didn’t want to move house. My children – they were against it. I was keen for them to change their minds, and I pointed out all the benefits. But actually…. when I listened to them… when I saw things from their angle…I could see exactly why they didn’t want to move. I had a complete change of perspective and we decided to call it off, the whole thing. We stopped going to inspections. It was strange because I was so set on it… so set on it being a good thing, but I really hadn’t seen things from my kids’ angle at all…. it was too much for them.

    The old house isn’t that bad…. I mean it needs constant maintenance… [sigh] …but it is what we have come to call home. Change isn’t always a good thing and it does involve a lot of risk… at least I think it does”.

    Conversation… just conversation. Then maybe next visit you could introduce some splitting of associated themes as above.

  3. Thanks,

    So if ‘imagined movement’ and ‘movement observation’ are problematic, we need a way to shut down the fear and then practice some type of movement – actual, observed or imagined.

    Movement’s association needs to be split and re-linked to something either 1) pleasurable or 2) safe.

    It’s obvious from these studies that an altered state of consciousness is going to be required for any meaningful progress (after all, ‘movement observation’ is an attempt to split and re-link the association).

    So an example treatment might go like this:

    1) induce trance. Absolutely essential. For a CRPS sufferer, I’d go with a confusion induction.
    2) Deepen it as much as possible
    3) Start chatting about how you just moved house last weekend.

    “… it was the strangest thing… we’d been anticipating a lot of stress… you know everyone says it’s hard moving house, but just an hour or so into the day the sun came out and I thought…. oooh that’s so nice, and I knew it was a good sign. And it was. At the end of the day we found it quite hard to believe how trouble-free it was. Of course we had a few little hiccups during the day, but it didn’t bother us, because we knew it wouldn’t be absolutely perfect….. and it made me think… if I did this every weekend…. imagine how easy it would become …a few weeks of practice and it would become quite painless, quite natural… that move”

    I really hope I’m not the only physio who would use this sort of proven approach. I really hope physios are using proven techniques rather than stuff that makes no difference whatsoever.