LIGAMENT ROLE ON THE CERVICAL SPINAL-CORD

Study Design. Laminectomy was performed on cats to destroy the posteri or epidural ligament. Evoked potentials and spinal cord blood flows qu antified the spinal cord function before and after cervical flexion. O bjectives. This work describes a relationship between the loss of the posterior epidural ligaments and cervical spinal cord injury. Summary of Background Data. The posterior epidural ligaments of the human cerv ical spine have been recently described. These ligaments theoretically prevent injury to the spinal cord by resisting collapse of the dura d uring cervical flexion. Methods. The animals were divided into three e xperimental groups: 1) control: no laminectomy and standard position, 2) flexion control: no laminectomy and known imposed flexion, 3) lamin ectomy (C3-C7) and flexion. Motor-evoked potentials and evoked spinal cord potentials were recorded to quantify the spinal cored functions. Radioactive microspheres were used to quantify ischemia in the spinal cord. Results. Control subjects showed blood flows of 36 mL/100 g/min (C3-C4) to 46 mL/100 g/min (C7-C8). flexion control subjects did not e xperience significant reductions in blood flows or substantial changes in evoked potentials The laminectomy plus flexion group experienced r educed blood flows and substantial motor-evoked potentials with 50 deg rees, 60 degrees, and 70 degrees flexion. Blood flow reduction was gre ater in the anterior half of the C7-C8 segments compared with the post erior half at 60 degrees flexion. Evoked spinal cord potentials were l ess vulnerable than motor-evoked potentials. Conclusion. The role of t he posterior cervical epidural ligaments is to anchor the posterior du ra mater to the ligamentum flavum. Loss of the ligaments allows anteri or displacement of the posterior dura mater in flexion. Abnormal distr ibution of or lack of the cervical posterior epidural ligaments may le ad to flexion myelopathy.