When someone tells you that they have a painful knee, it makes sense to have a look at the joint to see what has gone wrong.Perhaps an x-ray or a scan would help to determine the state of the cartilage, bone and surrounding soft tissue. An assessment of the range of motion, motor control and the responses to sensory testing reveal any functional limitations and adaptations. Is this enough to truly understand where pain really sits? Is it enough to decide where to intervene? In some cases yes is the answer, but not always!
Important that this kind of evaluation maybe, we must consider the significant pile of literature that points out pain is not an accurate indicator of tissue damage, as so eloquently concluded by Lorimer Moseley. One has only to think about phantom limb pain to realise that there is no need to have an arm, or a leg, or indeed any body part, for there to be pain in that location.
Phantom limb pain is the condition that illustrates the concept that pain is allocated a space. This space could be the knee as in our example above, any other body region or regions, or even outside of the body. A study by Lorimer Moseley also suggested that pain is felt in a space and not within the tissues. Subjects were asked to cross their arms, placing the affected hand into the space usually occupied by the unaffected hand. The effect? Pain relief. This is of course one study, however there was an impact that needs to be further investigated. Assuming that pain is allocated a space, this would explain why, when you position the hand in that of the non-painful side, both the pain and movement quality improve.
This is easily tested in the clinic with both hands and feet. The demonstration is a potent one for the individual as their limb experience can change. Seemingly there is an ease of the tension and guarding as well as the sensitivity. It can be profound, especially when someone has been suffering with a nasty pain such as in complex regional pain syndrome (CRPS) or neuropathic pain. The caveat is that this is not a cure, and it does not work every time, however in those that the effect is apparent, the ability to move more normally promotes healthy tissue and perception by the brain, especially if you are looking at the movement — extra sensory feedback via the visual system.
In summary, as best we know, pain is allocated a space. This can be a space that is occupied by a body region that why we feel pain in the tissues, the place where the pain emerges. The actual location of the pain is determined by the brain as it decides where we need to attend for protection. Recall that pain is a protective device involving a widespread network of neurons within the brain. There is no higher pain centre, but rather a network that monitors the sensory situation and responds as needed. On the basis that the sensory feedback suggests something dangerous is happening, the network will create an output that we experience in the body via a space that is deemed to need protection. Unfortunately, this output can occur without sensory input in some cases of persisting pain as the neuroimmune system becomes very sensitised and responsive to a range of stimuli including those that are not actually dangerous, hence why normal activities can hurt.
On this basis, when considering where to treat pain, we have to consider the space where the brain feels we need protecting. With the emergent property that is pain, the sensation is at the end of a process and it is therefore wise to target the entire biology from top to bottom and bottom to top. This means we need to address the higher centres, for example developing the individual’s understanding of their pain, reducing fears and using strategies for the brain maps of the body concurrent with using techniques within the space, i.e. the body area where the pain is felt.
Contrbuted by Richmond Stace, The Specialist Pain Physio