Does the number of drain tubes influence the formation of postoperative spinal epidural hematoma following biportal endoscopic unilateral laminotomy for bilateral decompression (BE-ULBD) in patients with two-level adjacent lumbar spinal stenosis? a prospective randomized study

Abstract

Background: The formation of postoperative spinal epidural hematoma (POSEH) following lumbar spinal surgery is a potentially serious complication. The efficacy and necessity of prophylactic postoperative drain tubes in preventing symptomatic postoperative spinal epidural hematoma (SPOSEH) after lumbar spinal decompression remain subjects of ongoing debate. The objective of this study is to investigate the potential impact of the number of drain tubes on POSEH following biportal endoscopic unilateral laminotomy for bilateral decompression (BE-ULBD) in patients of two-level adjacent lumbar spinal stenosis.

Methods: A prospective randomized study was conducted involving 89 patients with two-level adjacent lumbar spinal stenosis who underwent BE-ULBD. Patients were divided into two groups: Group A (one drain tube) and Group B (two drain tubes). Demographic data were collected, including preoperative visual analog scale (VAS) scores for leg pain and preoperative blood pressure (BP). Postoperative BP was recorded. The primary outcome was the cross-sectional area (CSA) of POSEH assessed at 72 h postoperatively. Secondary outcomes included postoperative VAS scores for leg pain, volume of drainage output, and length of hospital stay.

Results: A total of forty-three patients were assigned to Group A, while forty-six patients were assigned to Group B. The demographic characteristics of the patients in both groups were comparable. No significant differences were observed between the two groups regarding the CSA of POSEH. However, a significantly greater volume was noted in Group B (P = 0.015). There were no significant differences between the groups for other secondary outcomes, including postoperative VAS scores for leg pain (P = 0.584), and length of hospital stay (P = 0.428).

Conclusions: More drain tubes may result in statistically significant output but not clinically significant differences in influencing the formation of POSEH following BE-ULBD for two-level adjacent lumbar spinal stenosis.

Trial registration: The study was retrospectively registered in ClinicalTrials.gov on March 1, 2024, with the registration number NCT06290791.

Keywords: Decompression surgery; Drain tube; Lumbar spinal stenosis; Spinal epidural hematoma.

Fig. 1

The flowchart illustrates the process of enrollment and randomization for the randomized controlled trial. Legend: A total of forty-three patients were assigned to Group A, while forty-six patients were assigned to Group B

Fig. 2

The bar charts illustrate the comparative BP data between Group A and Group B. Legend: No statistically significant differences were observed between the two groups concerning these BP metrics

Fig. 3

An 81-year-old female in Group A presented with SPOSEH. Legend: Preoperative MR images revealed lumbar canal stenosis at the L3-L4 and L4-L5 levels (a-b, red arrows). Subsequent postoperative MR images following drain tube removal demonstrated minimal compression of the dural sac by spinal epidural hematomas at the L3-L4 and L4-L5 level (c-d, red arrows). POSEH enlarged after resuming daily activities and caused more severe compression of the dural sac with folded ground margin, particularly at the L4-L5 level (e-f, red arrows). Three weeks after surgery, spinal epidural hematomas remained stable (g-h, red arrows). Percutaneous catheter drainage under ultrasound guidance was then performed. Four weeks after surgery, spinal epidural hematomas decreased in size and the dural sac expanded further (i-j, red arrows). Five weeks after surgery, spinal epidural hematomas were nearly absorbed (k-l, red arrows)

Fig. 4

A 73-year-old female in Group B presented with SPOSEH. Legend: Lumbar stenosis at the L3-L4 and L4-L5 levels were demonstrated by preoperative MR images (a-b, red arrows). Subsequent postoperative MR images following drain tubes removal revealed formation of POSEH at the L3-L4 and L4-L5 level, but no obvious compression of dural sac (c-d, red arrows). POSEH enlarged after resuming daily activities and caused obvious compression of the dural sac with folded ground margin, particularly at the L4-L5 level (e-f, red arrows). Bedside puncture under ultrasound guidance was then conducted to extract the hematomas. Seven weeks after surgery, spinal epidural hematomas were nearly absorbed and the dural sac expanded further (g-h, red arrows)

Fig. 5

The presence of a purple potato sign was showed. Legend: A purple potato sign indicates the presence of a severe spinal canal hematoma with blood infiltration into the subcutaneous tissue (white arrows)