A Histologic and Functional Study on Cauda Equina Adhesion Induced by Multiple Level Laminectomy

STUDY DESIGN: A histologic and functional study on cauda equina adhesion induced by multiple-level laminectomy was performed using rats. OBJECTIVE: To assess the relation between the extent of laminectomy and histologic and functional changes of the cauda equina induced by laminectomy. SUMMARY OF BACKGROUND DATA: It has been demonstrated that laminectomies may induce cauda equina adhesion, transiently or permanently. However, the relation between the extent of laminectomy and histologic and functional changes of the cauda equina induced by laminectomy is still unclear. METHODS: Sprague-Dawley rats (250-300 g) were used. They were divided into four groups: no-laminectomy group (n = 5) and single, double, and triple level laminectomy groups (n = 20, respectively). At 24 hours and 1, 3, and 6 weeks after laminectomy, rats in each group were killed, and specimens were obtained from L4 to L6. The histologic changes were assessed using the classification of Yamagami. Walking durations on treadmill test and ascending spinal nerve-evoked potential were assessed in laminectomy groups before laminectomy, then weekly for 1 to 6 weeks after laminectomy. RESULTS: With the greater extent of laminectomy, the decrease in cauda equina adhesions was more delayed. There was no difference in walking durations and ascending spinal nerve-evoked potential between pre- and postlaminectomy. CONCLUSIONS: The extent of laminectomy was related to recovery time of induced cauda equina adhesion. However, a delay in recovery from cauda equina adhesion may not produce a recognizable delay in recovery from clinical symptoms.