Minimally Invasive Transtubular Endoscopic Decompression for L5 Radiculopathy Induced by Lumbosacral Extraforaminal Lesions

Abstract

Study design: Retrospective study.

Purpose: This study aimed to evaluate the efficacy of minimally invasive transtubular endoscopic decompression for the treatment of lumbosacral extraforaminal lesion (LSEFL).

Overview of literature: Conventional procedures for surgical decompression for the treatment of LSEFL involve certain technical challenges because the lumbosacral extraforaminal region has unique anatomical features. Moreover, the efficacy of minimally invasive procedures performed via the posterolateral approach for LSEFL has been reported.

Methods: Twenty-five patients who had undergone minimally invasive transtubular endoscopic decompression for the treatment of LSEFL and could be followed up for at least 1 year postoperatively were enrolled. Five of these patients had a history of lumbar surgery, and seven had concomitant adjacent-level spinal stenosis. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) lumbar score, numeric rating scale (NRS), and the JOA Back Pain Evaluation Questionnaire (JOABPEQ). The mean postoperative follow-up (FU) duration was 3.8 years.

Results: All procedures could be completed without any severe surgical complications, and all patients could resume their previous activity level within 1 month postoperatively. The JOA score significantly increased from 14.1±4.0 at baseline to 23.1±3.7 at the 1-year FU and 22.1±3.8 at the last FU. Similarly, there were significant improvements in the postoperative NRS and JOABPEQ scores. An additional surgery was performed in two patients (8%) during the FU period. Patients with degenerative scoliosis exhibited significantly poorer outcomes compared with those without this condition.

Conclusions: Transtubular endoscopic decompression can overcome certain technical challenges involved in the conventional procedures for LSEFL treatment; therefore, it can be recommended as a useful procedure for treating LSEFL. This procedure can provide some benefits to LSEFL patients and offer a well-illuminated surgical field and high surgical safety for the surgeon. However, the procedure should be carefully adapted for LSEFL patients with concomitant degenerative scoliosis.

Keywords: Extraforaminal lumbar disc herniation; Extraforaminal stenosis; Lumbosacral radiculopathy; Minimally invasive spine surgery.

Fig. 1. Minimally invasive transtubular endoscopic decompression using METRx MED system. (A) METRx MED system (Medtronic Sofamor Danek, Memphis, TN, USA). (B) Exposing the dorsal aspect of the extraforaminal area at the lumbosacral junction on the right side. (C) The lumbosacral ligaments are detached from the sacral ala and the L5 transverse process after the completion of bony resection by the partial resection of the S1 superior articular process and the sacral ala (arrows). (D) The L5 spinal nerve is identified at the extraforaminal zone by dissecting the overlying fat tissue and blood vessels after the resection of the lumbosacral ligaments (arrows). (E) An aggressive discectomy is performed. (F) Decompression is completed when the L5 spinal nerve is released from the foraminal portion to the depth of the lumbosacral tunnel where it enters the pelvic cavity.

Fig. 2. Measurement of the degree of coronal wedging at L5–S1. (A) The degree of coronal wedging at L5–S1 was noted as the angle between the lines drawn through the superior endplates of L5 and S1 (★). (B) When the superior endplate of S1 was unclear, a line joining the superior points on the sacral ala was used as a reference (☆).

Fig. 3. Assessments of surgical invasion of the facet joint on postoperative computed tomography scans. (A, B) Complete preservation of the facet joint (black arrows). (C, D) Partial resection of the cranial tip of the S1 superior articular process (black arrows) was performed to decompress the concomitant foraminal stenosis.