Biomechanical analysis of the spinal cord in Brown-Séquard syndrome

Complete Brown-Sequard syndrome (BSS) resulting from chronic compression is rare and the majority of patients present with incomplete BSS. In the present study, we investigated why the number of cases of complete BSS due to chronic compression is limited. A 3-dimensional finite element method (3D-FEM) spinal cord model was used in this study. Anterior compression was applied to 25, 37.5, 50, 62.5 and 75% of the length of the transverse diameter of the spinal cord. The degrees of static compression were 10, 20 and 30% of the anteroposterior (AP) diameter of the spinal cord. When compression was applied to >62.5 or <37.5% of the length of the transverse diameter of the spinal cord, no increases in stress indicative of complete BSS were observed. Compression of 50% of the length of the transverse diameter of the spinal cord resulted in a stress distribution that may correspond to that in complete BSS cases, when the degree of compression was 30% of the AP diameter of the spinal cord. However, compression within such a limited range rarely occurs in clinical situations and, thus, this may explain why the number of cases with complete BSS is low.