Interactions between pain and the motor cortex : insights from research on phantom limb pain and complex regional pain syndrome

Abstract : Purpose: Pain is a significantly disabling problem that often interacts with other deficits during the rehabilitation process. The aim of this paper is to review evidence on interactions between pain and the motor cortex in order to attempt to answer the following questions: (1) Does acute pain interfere with motor cortex activity? (2) Does chronic pain interfere with motor cortex activity and, conversely, does motor cortex plasticity contribute to chronic pain? (3) Can the induction of motor plasticity by means of motor cortex stimulation decrease pain? (4) Can motor training result in both motor cortex reorganization and pain relief? Summary of Key Points: Acute experimental pain was clearly shown to exert an inhibitory influence over the motor cortex, which can interfere with motor learning capacities. Current evidence also suggests a relationship between chronic pain and motor cortex reorganization, but it is still unclear whether one causes the other. However, there is growing evidence to the effect that interventions that aim to normalize motor cortex organization can lead to pain relief. Conclusions: Interactions between pain and the motor cortex are complex, and more studies are needed to understand these interactions in our patients, as well as to develop optimal rehabilitative strategies