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Abstract: Knowledge of the position of one’s limbs is an essential component of daily function and relies on complex interactions of sensorimotor body schema-related information. Those with Complex Regional Pain Syndrome (CRPS) express difficulty in knowing where their affected limb is positioned. The aim of this study was to determine the degree to which experimental data supported the reported difficulty in limb position sense. A controlled experimental design was used to measure upper limb position accuracy amongst those with CRPS of one arm. Position accuracy was individually measured in both arms and compared to a known target position. Video captured each of 36 trials (half with arm in full view and half with vision obscured). The error in degrees between actual and known targets was determined using video analysis software. The Brief Pain Inventory measured pain. A subjective mental image representation of both upper limbs was documented. The CRPS group had moderate pain intensity and were significantly less accurate in positioning both the affected and unaffected limbs compared to controls (p <0.001). Position accuracy of the CRPS affected limb significantly improved with vision (8.3° in view, 10.7° not in view). Subjective mental representations of the affected limb were visualised as distorted. Evidence of bilateral arm positioning impairments in unilateral arm CRPS suggests that central mechanisms are involved. Cortical reorganisation in regions associated with the body schema (i.e. primary somatosensory and parietal cortices) is proposed as an explanation. The exact relationship between pain and limb position deficits requires further exploration. [Copyright &y& Elsevier]

Abstract: In spite of pain in the CRPS limb, clinical observations show patients pay little attention to, and fail to care for, their affected limb as if it were not part of their body. Literature describes this phenomenon in terms of neurological neglect-like symptoms. This qualitative study sought to explore the nature of the phenomenon with a view to providing insights into central mechanisms and the relationship with pain. Twenty-seven participants who met the IASP CRPS classification were interviewed using qualitative methods to explore feelings and perceptions about their affected body parts. These semi-structured interviews were analysed utilising principles of grounded theory. Participants revealed bizarre perceptions about a part of their body and expressed a desperate desire to amputate this part despite the prospect of further pain and functional loss. A mismatch was experienced between the sensation of the limb and how it looked. Anatomical parts of the CRPS limb were erased in mental representations of the affected area. Pain generated a raised consciousness of the limb yet there was a lack of awareness as to its position. These feelings were about the CRPS limb only as the remaining unaffected body was felt to be normal. Findings suggest that there is a complex interaction between pain, disturbances in body perception and central remapping. Clinically, findings support the use of treatments that target cortical areas, which may reduce body perception disturbance and pain. We propose that body perception disturbance is a more appropriate term than ‘neglect-like’ symptoms to describe this phenomenon. [Copyright &y& Elsevier]