Reorganization and preservation of motor control of the brain in spinal cord injury: a systematic review

Abstract

Reorganization of brain function in people with CNS damage has been identified as one of the fundamental mechanisms involved in the recovery of sensorimotor function. Spinal cord injury (SCI) brain mapping studies during motor tasks aim for assessing the reorganization and preservation of brain networks involved in motor control. Revealing the activation of cortical and subcortical brain areas in people with SCI can indicate principal patterns of brain reorganization when the neurotrauma is distal to the brain. This review assessed brain activation after SCI in terms of intensity, volume, and somatotopic localization, as well as preservation of activation during attempted and/or imagined movements. Twenty-five studies meeting the inclusion criteria could be identified in Medline (1980 to January 2008). Relevant characteristics of studies (level of lesion, time after injury, motor task) and mapping techniques varied widely. Changes in brain activation were found in both cortical and subcortical areas of individuals with SCI. In addition, several studies described a shift in the region of brain activation. These patterns appeared to be dynamic and influenced by the level, completeness, and time after injury, as well as extent of clinical recovery. In addition, several aspects of reorganization of brain function following SCI resembled those reported in stroke. This review demonstrates that brain networks involved in different demands of motor control remain responsive even in chronic paralysis. These findings imply that therapeutic strategies aimed at restoring spinal cord function, even in people with chronic SCI, can build on preserved competent brain control.

FIG. 1

Sequence of the selection process used to find articles describing brain plasticity following onset of SCI within inclusion criteria.

FIG. 2

Brain areas with increased activation during a motor task in SCI compared to controls. Increased activation was found in bilateral M1, S1, SMA, PM, CMA, parietal cortex, cerebellum, thalamus, and basal ganglia. (A) Medial view. (B) Lateral view. (C) Axial view.

FIG. 3

Depictions of the brain showing two types of spatial shift in activation described during a motor task in paraplegic and tetraplegic SCI subjects compared to controls. (A) Posterior shift of activation towards S1 during an upper limb motor task (activation represented by shading). (B) Activation of facial/upper limb movement is shifted in the direction of the deafferented upper/lower limb representation in para/tetraplegic SCI subjects.