Relationship between sensorimotor cortex reorganization and post-injury time in patients with spinal cord injury

• DOI: https://doi.org/10.22533/at.ed.6422501108

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• Abstract: Traumatic spinal cord injury (TSCI) is a widely discussed in the literature due to its high incidence and substantial socioeconomic impacts. Cortical motor reorganization is a particularly discussed area due to its importance in the rehabilitation of patients. Knowing the reorganization process is highly complex and is affected by several factors, such as the cortical level involvement, when the rehabilitation began, and the time after the injury itself. Thus, the aim of this study was to evaluate the changes in the spatial patterns of cortical motor activation associated with functional recovery after an TSCI. Our main objective was to explore the relationship between cerebral cortical reorganization and post-injury time. Ten patients with TSCI and paraplegia grade A or B according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS) were evaluated, along with ten control subjects, through functional magnetic resonance imaging (fMRI) related to the same task, using the BOLD technique, comparing the sensory-motor ratios (SMRs), which are estimated by the activation ratio of the post-central and pre-central gyrus. The tasks performed for the upper limbs were the execution of hand flexion/extension for all participants. The tasks performed for the lower limbs were the execution of dorsiflexion of the ankles for the control group and attempted dorsiflexion movement for individuals with spinal cord injury. Subjects with TSCI showed reduced sensorimotor ratios (SMRs) in the left ankle compared to controls, while there were no differences observed in right ankle SMRs. In contrast, the SMRs related to motor execution of the right-hand increased compared to the controls, but no differences were found in the left-hand SMRs. The increase in SMRs for the right hand and the reduction in the left ankle SMRs may be associated with recruitment of the corresponding limbs; the increase in SMRs may be directly related to limb dominance, a factor that could have influenced this reorganization. A relationship between the right ankle SMRs and injury time was evidenced, indicating an increase in reorganization of the dominant limb over time. Thus, comparing the SMRs with respect to the time since the injury may help characterize the cortical patterns post-injury, which are currently not well understood, and be used to guide neurorehabilitation training protocols and the use of brain-machine interfaces.