Extent of decompression and incidence of postoperative epidural hematoma among different techniques of spinal decompression in degenerative lumbar spinal stenosis

Abstract

Study design: Prospective radiographic cohort study.

Objective: To study the extent of bony decompression and dural sac expansion after laminectomy (including subtotal laminectomy and laminotomy with midline resection), bilateral fenestration, and unilateral fenestration with contralateral undercutting in lumbar spinal canal stenosis. Further, to investigate differences of incidence and extent of early postoperative epidural hematoma in these approaches.

Summary of background data: There are different techniques of decompression in lumbar spinal stenosis. An overall good clinical outcome has been reported with different biomechanical consequences, but no morphometric comparative reports exist on these approaches.

Methods: Using the data of a previous prospective study of 30 patients, who underwent lumbar decompression for degenerative stenosis, 49 levels treated with 3 different kinds of surgical approaches were analyzed: (1) laminectomy (including subtotal laminectomy, laminotomy with midline resection); (2) bilateral fenestration; and (3) unilateral fenestration with contralateral undercutting. In all 3 groups, the cross-sectional area of the maximum bony stenosis and dural sac compression (bony margins and dural sac expansion) were measured in each operated level before and after the operation. Occurrence of epidural hematoma and its size were noted in the 3 groups.

Results: Median postoperative bony stenosis was not significantly different in the groups, being 330 mm(2), 333.5 mm(2), and 261.5 mm(2), respectively, in groups 1, 2, and 3. There was no statistically significant difference between the median postoperative extension of dural sac areas in the 3 groups, measuring 125 mm(2), 123 mm(2), and 137 mm(2). The incidence of epidural hematoma was similar in the 3 groups. Levels where postoperative epidural hematoma was detected had larger bony decompression independent of the surgical approach compared with the whole group.

Conclusions: Unilateral and bilateral approaches achieve a similar amount of dural sac extension by a lesser extent of bony resection in comparison with the laminectomy approach. There is a tendency of increased postoperative hematoma in approaches with greater bony decompression area.