Motor dysfunction in complex regional pain syndrome : the role of sensory processing and sensory-motor integration

Abstract

In the chronic stage of Complex Regional Pain Syndrome (CRPS), motor disturbances are common and cause significant disability. The motor dysfunction of CRPS is a poorly understood phenomenon that is characterized predominantly by a decrease or loss of voluntary muscle control. This thesis aims to obtain a better understanding of the pathophysiology underpinning the motor dysfunction of CRPS by examining the potential roles of decreased inhibition of the motor system, changes in sensory processing and problems in sensory-motor integration. In specific, characteristics of muscle activity recordings are scrutinized in order to determine whether the loss of voluntary motor control and abnormal postures in CRPS exhibit characteristics of dystonia that are associated with reduced inhibition of the motor system (i.e., excessive muscle activation and enhanced mirror activity). The potential role of impaired processing of proprioceptive information related to wrist orientation and force production is examined, as well as the involuntary and voluntary (sensory-)motor interactions between the affected and unaffected arm. Furthermore, a systematic review of the literature on the motor consequences of experimental pain in healthy humans is presented in order to gain insight into the potential role of pain-related processes in the motor and sensory and motor disturbances of CRPS.