Clinical results of XMR-assisted percutaneous transforaminal endoscopic lumbar discectomy

Abstract

Background: Although percutaneous endoscopic lumbar discectomy (PELD) has shown favorable outcomes in the majority of lumbar discectomy cases, there were also some failures. The most common cause of failure is the incomplete removal of disc fragments. The skin entry point for the guide-needle trajectory and the optimal placement of the working sleeve are largely blind, which might lead to the inadequate removal of disc fragments. The objective of this study was to present our early experiences with image-guided PELD using a specially designed fluoroscope with magnetic resonance imaging-equipped operative suite (XMR) for the treatment of lumbar disc herniation.

Methods: This prospective study included 89 patients who had undergone PELD via the transforaminal approach using an XMR protocol. Pre- and postoperative examinations (at 12 weeks) included a detailed clinical history, visual analogue scale (VAS), Oswestry disability index (ODI), and radiological workups. The results were categorized as excellent, good, fair, and poor according to MacNab's criteria. At the final follow-up, the minimum follow-up time for the subjects was 2 years. The need for revision surgeries and postoperative complications were noted on follow-up.

Results: Postoperative mean ODI decreased from 67.4% to 5.61%. Mean VAS score for back and leg pain improved significantly from 4 to 2.3 and from 7.99 to 1.04, respectively. Four (4.49%) patients underwent a second-stage PELD after intraoperative XMR had shown remnant fragments after the first stage. As per MacNab's criteria, 76 patients (85.4%) showed excellent, 8 (8.89%) good, 3 (3.37%) fair, and 2 (2.25) poor results. Four (4.49%) patients had remnant disc fragments on XMR, which were removed during the same procedure. All of these patients had either highly migrated or sequestrated disc fragments preoperatively. Four (4.49%) other patients needed a second, open surgery due to symptomatic postoperative hematoma (n = 2) and recurrent disc herniation (n = 2).

Conclusions: This prospective analysis indicates that XMR-assisted PELD provides a precise skin entry point. It also confirms that decompression occurs intraoperatively, which negates the need for a separate surgery and thus increases the success rate of PELD, particularly in highly migrated or sequestrated discs. However, further extensive experience is required to confirm the advantages and feasibility of PELD in terms of cost effectiveness.

Figure 1

XMR suite: arrows indicating (from left to right) the MRI, fluoroscope, and sliding table. The glass door between the MRI and the sliding table can also be seen.

Figure 2

Patient with attached skin markers (MR-SPOTS, Beekley Corp, Bristol, CT, USA). Based on the markers, the exact trajectory for the entry guide pin can be decided.

Figure 3

Preoperative planning for XMR-guided skin entry point and subsequent needle trajectory (all skin markers - arrows). Different markers at position C are placed during XMR, and one of these markers was selected as the correct entry point, as shown in the picture. Line AB is the midline; CD is the proposed entry point to reach the target; and BC is the distance of the skin entry point from the midline.

Figure 4

Intraoperative XMR confirming the remnant fragments and final MRI showing complete decompression.

Figure 5

Preoperative XMR confirming the change in location and size of the herniated fragment. Postoperative MR showing a decompressed fragment.

Figure 6

Intraoperative XMR indicating a hematoma, which was symptomatic and treated with percutaneous drainage through the transforaminal approach.