The present study investigates by means of the rubber hand illusion body image stability and sense of body ownership in patients with CRPS of the upper limb compared to patients with unilateral pain of origin other than CRPS and age and sex-matched healthy subjects.
In patients with CRPS of the upper limb distortions of body representation and impairments of sense of body ownership are well-known. To investigate the body schema and body image stability of these patients in comparison to patients with upper limb pain of origin other than CRPS and healthy subjects, we conducted a series of rubber hand illusions. This well - established paradigm is elicited by visuo-tactile stimulation of one´s own real hand and a visible hand and forearm prosthesis. The present study investigates 1) if and how far patients with CRPS are susceptible to experience the illusion 2) how far the illusion strength differs between CRPS and patients with unilateral pain of the upper limb of other origin and healthy subjects 3) how far parameters, e.g. neglect-like severity symptoms, body plasticity, empathy, duration of disease and pain intensity influence the illusion strength.
Study Type
OBSERVATIONAL
Enrollment
69
There were three consecutive trials of the RHI: 1. one control trial: asynchronous condition (3 Min.) 2. two experimental trials (conducted on both hands):synchronous condition (3 Min.),additionally watching the prosthesis being threatened (20 sec.)
Pain clinic of the Bergmannsheil University Hospital
Bochum, Germany
subjective illusion strength by a validated questionnaire
The illusion strength was measured subjectively by a validated questionnaire on a 7- point Likert scale,ranging from 0 (= disagree strongly) to 7 (= agree strongly). The questionnaire encompassed five slightly modified items of the German-translated questionnaire by Ocklenburg et al.(2011), following Botvinick \& Cohen (1998).In the experimental conditions the questionnaire was additionally augmented by three further statements regarding the perception of the needle threat.
Time frame: 1 hour
objectified illusion strength by measure of skin conductance response (SCR)
The SCR represents an objective measure of participant´s identification with the artificial limb, indicating the autonomic nervous system arousal in anticipation of pain, while watching the prosthesis being harmed (Armel \& Ramachandran, 2003; Ehrsson, Wiech, Weiskopf, Dolan \& Passingham, 2007). In every trial, the SCR was recorded with Ag-AgCl electrodes from the thenar and hypothenar eminence of the non-tested hand. Conductivity was measured in micro-Siemens (1/Ohm).
Time frame: 1 hour
Measurement of influences of the illusion strength
Several questionnaires were used to assess current and average pain intensity (NRS 0-10), neglect-like severity symptoms (Frettloeh et al. 2006), Handedness (Oldfield,1971), body plasticity (TABP) (Desmond, Horgan et al., 2001), empathy (IRI) ( Davis, 1980) and DASH-score (German, Wind et al. 1999).
Time frame: half an hour
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