NEURAL BASES OF IMPLICIT MOTOR IMAGERY IN PATIENTS WITH ORTHOPEDIC DISEASES

As motor execution and motor imagery share the same brain correlates, it is possible to hypothesize that immobilization and disuse may cause deficits in both domains. Although the effect of immobilization was extensively studied in amputees or in subjects who were wearing a cast after a traumatic injury or in experimental immobilization, little is known about the effect of immobilization and disuse in subjects affected by chronic limitations of hand use due to chronic joint degenerative pathologies. We find chronic trapeziometacarpal joint osteoarthritis a perfect model to study mechanisms of neurofunctional and behavior changes resulted from long disuse of a hand due to pain. We studied 13 patients with rhizarthrosis and 13 healthy subjects who underwent both behavioural and fMRI measures of brain activity during the hand laterality task. No difference was found between patients and controls in behavior task, indicating that the Motor Imagery is preserved in rhizarthrosis. Both patients with rhizarthrosis and controls showed slower RTs for back view than the palm view and lateral position compared to the medial position, which indicates participants implicitly used a motor imagery strategy to execute the task. The fMRI measures showed reduced activation in the inferior parietal gyrus for the patient group compared to controls and the hypoactivation of the premotor cortex when the patients were seeing the left hand. The results of our study showed for the first time the presence of significant effects of hand disuse due to chronic trapeziometacarpal joint osteoarthritis on the neural correlates of implicit motor imagery.