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.

Inclusion Criteria:

every participant:

• aged > 18 years
• written informed consent
• free to withdraw participation at any time
• adequate understanding of the german language

Patients with CRPS:

• patients with CRPS type 1 of the upper limb
• clinical symptoms were diagnosed on the basis of the recently modified diagnostic research criteria (Harden, Bruehl et al., 2007)
• proved by typical enhancement in the late phase of the 99m-technetium-triple-phase bone skeleton scintigraphy (Wüppenhorst, Maier et al., 2010)

Patients with unilateral pain of the upper limb:

• unilateral pain
• pain of origin other than CRPS

Healthy subjects:

• age and sex matched to patients with CRPS
• checked by the DFNS IMI questionnaire

Exclusion Criteria:

every participant:

• inadequate understanding of the german language
• missing informed consent
• diabetes mellitus

Patients with CRPS:

-CRPS Type 2

The study sample consists of three groups:

1. Patients with CRPS of the upper limb type 1 ( n=24)
2. Patients with unilateral pain of the upper limb origin other than CRPS (n=21)
3. Healthy subjects, age and sex-matched to patients with CRPS Patients with unilateral pain of the upper limb of origin other than CRPS serve as controls. Recruitment for all CRPS and the majority of patients in the control group took place in the pain clinic of the Bergmannsheil University Hospital in Bochum. The remaining patients were recruited from the Neurological respectively Surgical department of the Bergmannsheil University Hospital.