Sensory disturbances induced by sensorimotor conflicts are higher in complex regional pain syndrome and fibromyalgia compared to arthritis and healthy people, and positively relate to pain intensity

Chronic pain and psychiatric disorders frequently co-occur. However, estimates of the magnitude of these associations have been biased by the use of select clinical samples. The present study utilized the National Comorbidity Survey [Arch. Gen. Psychiatry 51 (1994) 8-19] Part II data set to investigate the associations between a chronic pain condition (i.e. arthritis) and common mood and anxiety disorders in a sample representative of the general US civilian population. Participants (N=5877) completed the Composite International Diagnostic Interview [World Health Organization (1990)], a structured interview for trained non-clinician interviewers based on the revised third edition of the Diagnostic and Statistical Manual of Mental Disorders [American Psychiatric Association (1987)], and provided self-reports of pain and disability associated with a variety of medical conditions. Significant positive associations were found between chronic pain and individual 12-month mood and anxiety disorders [odds ratios (OR) ranged from 1.92 to 4.27]. The strongest associations were observed with panic disorder (OR=4.27) and post-traumatic stress disorder (OR=3.69). The presence of one psychiatric disorder was not significantly associated with pain-related disability, but the presence of multiple psychiatric disorders was significantly associated with increased disability. The findings of the present study raise the possibility that improved efforts regarding the detection and treatment of anxiety disorders may be required in pain treatment settings.

Illusions that induce a feeling of ownership over an artificial body or body-part have been used to explore the complex relationships that exist between the brain's representation of the body and the integrity of the body itself. Here we discuss recent findings in both healthy volunteers and clinical populations that highlight the robust relationship that exists between a person's sense of ownership over a body part, cortical processing of tactile input from that body part, and its physiological regulation. We propose that a network of multisensory and homeostatic brain areas may be responsible for maintaining a 'body-matrix'. That 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. The existence of such a 'body-matrix' allows our brain to adapt to even profound anatomical and configurational changes to our body. It also plays an important role in maintaining homeostatic control over the body. Its alteration can be seen to have both deleterious and beneficial effects in various clinical populations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pain without accompanying tissue pathology poses a classic puzzle, presented in extreme form by phantom pain in a non-existent amputated limb. A clue to the origin of such pain is given by the recent discovery of a region of cortex active in response to incongruence between motor intention, awareness of movement, and visual feedback. Phantom-limb sensation, and repetitive strain injuries or focal hand dystonias in writers, musicians, or keyboard operators, are accompanied by plastic changes in sensorimotor cortex and by pathological pain. Disorganised or inappropriate cortical representation of proprioception may falsely signal incongruence between motor intention and movement, which results in pathological pain in the same way that incongruence between vestibular and visual sensation results in motion sickness.