Remarkable hand grip steadiness in individuals with complete spinal cord injury
Although no damage occurs in the brains of individuals with spinal cord injury, structural and functional reorganization occurs in the sensorimotor cortex because of the deafferentation of afferent signal input from below the injury level. This brain reorganization that is specific to individuals with spinal cord injury is speculated to contribute to the improvement of the motor function of the remaining upper limbs. However, no study has investigated in detail the motor function above the injury level. To clarify this, we designed an experiment using the handgrip force steadiness task, which is a popular technique for evaluating motor function as the index of the variability of common synaptic input to motoneurons. Fourteen complete spinal cord injury (cSCI) individuals in the chronic phase, fifteen individuals with lower limb disabilities, and twelve healthy controls participated in the study. We clarified that the force steadiness in the cSCI group was significantly higher than that in the control groups, and that sports years were significantly correlated with this steadiness. Furthermore, multiple analyses revealed that force steadiness was significantly predicted by sports years. These results suggest that brain reorganization after spinal cord injury can functionally affect the remaining upper limb motor function. These findings may have implications in the clinical rehabilitation field, such as occupational rehabilitation of the upper limbs. They also indicate that individuals with complete spinal cord injury, based on their enhanced force adjustment skills, would excel at fine motor tasks such as manufacturing and handicrafts.
KeywordsSpinal cord injury Force steadiness Hand grip Brain reorganization
This work was supported by JSPS KAKENHI Grant Numbers 18H04082 and Japanese Physical Therapy Association (JPTA H30-A50).
TN, HK, and KeN designed the study. TN, HK, and HO collected the data. TN analyzed and interpreted the data and wrote the article. All authors have revised the article for intellectual content and approved the final manuscript.
This project was funded by the Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI, 18H04082) and Japanese Physical Therapy Association (JPTA H30-A50).
Compliance with ethical standards
Conflicts of interest
We declare that we have no conflicts of interest.
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