This study aims to evaluate the representation of action peripersonal space (PPS) in subjects suffering from unilateral segmental exclusion syndrome of the upper limb compared to healthy control subjects. Segmental exclusion is defined by non-use or under-use of a limb segment without central nervous system damage. The study hypothesizes that this syndrome leads to a modification (shrinkage) of the PPS representation. Participants will perform reachability judgments in a Virtual Reality (VR) environment.
Age ≥ 18 years.
Presenting unilateral exclusion symptom of the upper limb or part of the hand evolving for > 3 months.
No contraindication to force work in daily activities.
For patients with finger exclusion: at least 2 perturbed items related to exclusion on tests 3 and 4 of the "Bilan 400 points".
Visual impairments.
Central neurological pathology.
Unstabilized psychiatric pathology.
Communication or comprehension difficulties.
he study population consists of two groups recruited at the Institut Régional de Réadaptation (Centre Louis Pierquin, UGECAM Nord-Est) in Nancy, France. Patients with Exclusion: Participants are selected from patients receiving routine care (full hospitalization or day hospital) at the center. They are identified based on a functional assessment ("Bilan 400 points") showing specific impairments related to unilateral upper limb exclusion evolving for more than 3 months. Healthy Controls: Asymptomatic volunteers are recruited through the social or family network of the investigators and current participants, as well as via posters displayed in the UGECAM centers.
Case-control
Cross-sectional
Reachability Judgment Task in VR.
BehavioralParticipants wear an Oculus Quest 2 VR headset. They first perform a motor task to measure Real Reachable Distance (DMA-r). Then, they perform a perceptual task where they must judge, without moving, if a virtual object is reachable (DMA-p). The test evaluates different spatial planes (front, 45° right, 45° left) and heights (shoulder, navel).
Judgment Error of Reachability
The Judgment Error of Reachability is a single composite metric calculated as: ((DMA-p - DMA-r) / DMA-r) × 100, expressed as a percentage (%). Both DMA-p (Perceived Maximum Reachable Distance) and DMA-r (Real Maximum Reachable Distance) are measured in centimeters, and their ratio yields a single dimensionless percentage score.
Body Perception Disturbance Score
Assessed using the Bath CRPS Body Perception Disturbance Scale (French version). Scores range from 0 to 57, with higher scores indicating greater disturbance.
Functional Impairment Score (400-Point Hand Assessment)
Evaluated using the 400-Point Hand Assessment, which measures functional hand use. The score ranges from 0 to 400, where higher scores indicate better functional performance (better outcome).
Anxiety and Depression Score (HAD)
Hospital Anxiety and Depression Scale. Scores range from 0 to 21 for each dimension (Anxiety and Depression).
Kinesiophobia Score (Tampa Scale)
Tampa Scale for Kinesiophobia (TSK). Assesses fear of movement. Scores range to 68; \>40 indicates significant kinesiophobia.
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