People with chronic pain have some pretty odd perceptual disturbances – the affected area might feel swollen when it is not,[1] it might be difficult to ‘find’ in the mind’s eye,[2] it might feel foreign, displaced, stuck, full, hot, thin, floating or heavy,[3]. People with chronic pain also have proprioceptive difficulties, blood flow changes, sensory problems, spatial processing deficits and motor abnormalities. In an attempt to integrate this smorgasboard of body-related dysfunction, we recently proposed the idea of a cortical body matrix[4]. This body matrix is a network of multisensory and homeostatic brain areas. That is, it is a dynamic neural representation that not only extends beyond the body surface to integrate both somatotopic and peripersonal sensory data, but also integrates body-centred spatial sensory data and then integrates the whole lot with homeostatic and motor functions. Our proposal is based on a whole heap of experimental and clinical data – experiments that use illusions to modulate perception of the body and patients who report consistent disturbances across efferent systems, disturbances that can be modulated using illusions[5]. The obvious sequelae of having a body matrix, is that it can become disrupted and we reckon that disruption of this body matrix might explain many of the problems we see in patients – blood flow, perceptual, sensory and motor dysfunction. Clearly these multiple system disruptions are common in chronic pain, but they are also observed in other conditions, for example schizophrenia. Of course, our main interest is in chronic pain and we reckon that this disruption might contribute to the problem. If this reckoning is correct, then we should be able to improve the situation by correcting the disruption. Time will tell.
About Lorimer Moseley
Lorimer is NHMRC Senior Research Fellow with twenty years clinical experience working with people in pain. After spending some time as a Nuffield Medical Research Fellow at Oxford University he returned to Australia in 2009 to take up an NHMRC Senior Research Fellowship at Neuroscience Research Australia (NeuRA). In 2011, he was appointed Professor of Clinical Neurosciences & the Inaugural Chair in Physiotherapy at the University of South Australia, Adelaide. He runs the Body in Mind research groups. He is the only Clinical Scientist to have knocked over a water tank tower in Outback Australia.
References
[1] Moseley, G. (2005). Distorted body image in complex regional pain syndrome Neurology, 65 (5), 773-773 DOI: 10.1212/01.wnl.0000174515.07205.11
[2] Moseley GL (2008). I can’t find it! Distorted body image and tactile dysfunction in patients with chronic back pain. Pain, 140 (1), 239-43 PMID: 18786763
[3] Lotze M, & Moseley GL (2007). Role of distorted body image in pain. Current rheumatology reports, 9 (6), 488-96 PMID: 18177603
[4] Moseley GL, Gallace A, & Spence C (2011). Bodily illusions in health and disease: Physiological and clinical perspectives and the concept of a cortical ‘body matrix’ Neuroscience and biobehavioral reviews PMID: 21477616
[5] Moseley, G., Parsons, T., & Spence, C. (2008). Visual distortion of a limb modulates the pain and swelling evoked by movement Current Biology, 18 (22) DOI: 10.1016/j.cub.2008.09.031