Itsuo Sakuramoto

Age‑related changes of the spinal cord: A biomechanical study

Although it is known that aging plays an important role in the incidence and progression of cervical spondylotic myelopathy (CSM), the underlying mechanism is unclear. Studies that used fresh bovine cervical spinal cord report the gray matter of the cervical spinal cord as being more rigid and fragile than the white matter. However, there are no reports regarding the association between aging an tensile and Finite Element Method (FEM). Therefore, FEM was used based on the data pertaining to the mechanical features of older bovine cervical spinal cord to explain the pathogenesis of CSM in elderly patients. Tensile tests were conducted for white and gray matter separately in young and old bovine cervical spinal cords, and compared with their respective mechanical features. Based on the data obtained, FEM analysis was further performed, which included static and dynamic factors to describe the internal stress distribution changes of the spinal cord. These results demonstrated that the mechanical strength of young bovine spinal cords is different from that of old bovine spinal cords. The gray matter of the older spinal cord was significantly softer and more resistant to rupture compared with that of younger spinal cords (P<0.05). Among the old, although the gray matter was more fragile than the white matter, it was similar to the white matter in terms of its rigidity (P<0.05). The in vitro data were subjected to three compression patterns. The FEM analysis demonstrated that the stress level rises higher in the old spinal cords in response to similar compression, when compared with young spinal cords. These results demonstrate that in analyzing the response of the spinal cord to compression, the age of patients is an important factor to be considered, in addition to the degree of compression, compression speed and parts of the spinal cord compression factor.

Simulation of Cervical Cord Compression Using Finite Element Method (FEM)

Cervical myelopathy results in loss of nerves functions along the spinal cord below the damage area as it is the result of spinal cord compression which nowadays always occur during traffic accidents. Patients with cervical myelopathy do not necessarily share the same symptoms. These vary according to the degree of cervical cord compression and cross sectional shape at every segment of cervical cord which caused difficulties in diagnosis. In this study, two dimension model of every cervical cord segment were built. Then, differences of compression results in every segment were verified. After that, to verify the effects of compression to other segments, three dimensions model of cervical cord model is built. From this study, we can see that cervical cord with flat shaped gray matter have higher stress distribution than cervical cord with hill shaped grey matter. Other than that, the injury start occurred in ventral column of white matter instead of gray matter during early injury stage.