"Median paralyzing dose" and "multiple regression analysis", a new viewpoint to the research method of spinal cord injury

Protective effect of extended laminectomy on spinal cord injury induced by spinal shortening

This study aims to investigate the effect of extended laminectomy (EL) on spinal cord injury (SCI) caused by spinal shortening and further the best time for performing this operation and the optimal length of the additional lamina to remove. Dogs were allocated to 6 groups and all received spinal column shortening at T13 segment. Animals in the control group received non-extended laminectomy following shortening. Those in the "1-lamina EL 6h" group underwent laminectomy with an additional 1-lamina length removed 6h post shortening. For the "1.5-lamina EL 6h" and "1.5-lamina EL 12h" groups, the animals had an extra 1.5-lamina length of lamina resected at 6h and 12h, respectively, post shortening. In the "2-lamina EL 6h" and "2-lamina EL 12h" groups, an extra 2-lamina length was removed at 6h and 12h post shortening, respectively. Somatosensory evoked potential (SSEP) and neurological function were recorded periodically; spinal cord blood flow (SCBF) and nerve cell apoptosis were detected. We have discovered that resection of an additional 1-lamina length appeared not adequate to relieve the sharp kinking of the spinal cord, whereas the kinking disappeared when the laminectomy extended to an additional 2-lamina length. The "1-lamina EL 6h" and "1.5-lamina EL 12h" groups showed no significant difference, as compared with the control, in latency of SSEP, SCBF, hind-limb function and apoptosis. By contrast, significant recovery of SSEP, SCBF and hind-limb function as well as reduction of apoptosis presented in other three experimental groups. The "2-lamina EL 6h" group, in particular, showed the most prominent recovery. In conclusion, in the case of shortening of 2/3 vertebral body length with 2 laminae resected, an additional resection of two laminae at 6 h post shortening showed the best performance in alleviating SCI. Timely and adequately extended laminectomy could be a potential therapeutic strategy for SCI due to spinal shortening.