Sensorimotor Cortical Plasticity During Recovery Following Spinal Cord Injury: A Longitudinal fMRI Study

Background. Although the consequences of spinal cord injury (SCI) within the spinal cord and peripheral nervous system have been studied extensively, the influence of SCI on supraspinal structures during recovery remains largely unexplored. Objective. To assess temporal changes in cortical sensorimotor representations beginning in the subacute phase following SCI and determine if an association exists between the plastic changes within cortical sensorimotor areas and recovery of movement postinjury. Methods. Functional magnetic resonance imaging (fMRI) was used to study 6 SCI patients for 1 year, beginning shortly postinjury, and 10 healthy control individuals. During fMRI, individuals performed a simple self-paced wrist extension motor task. Recovery of movement was assessed using the American Spinal Injury Association (ASIA) Standard Neurological Classification of SCI. Results. In the subacute period post-SCI, during impaired movement, little task-related activation within the primary motor cortex (M1) was present, whereas activation in associated cortical sensorimotor areas was more extensive than in controls. During motor recovery, a progressive enlargement in the volume of movement-related M1 activation and decreased activation in associated cortical sensorimotor areas was seen. When movement was performed with little to no impairment, the overall pattern of cortical activation was similar to that observed in control individuals. Conclusions . This study provides the first report of the temporal progression of cortical sensorimotor representational plasticity during recovery following traumatic SCI in humans and suggests an association between movement-related fMRI activation and motor recovery postinjury. These findings have implications on current and future rehabilitative interventions for patients with SCI.