Extraforaminal compression of the L-5 nerve root at the lumbosacral junction: clinical analysis, decompression technique, and outcome

Abstract

Object Extraforaminal compression of the L-5 nerve encompasses multiple pathological entities and may result from disc herniations as well as bony (osteophytes or sacral ala) or ligamentous (sacroiliac ligament and lumbosacral band) compression. Several other factors, such as disc space collapse or coronal wedging, can also contribute to narrowing of the extraforaminal space. The extraforaminal space at L5–S1 has unique anatomical features compared with the upper lumbar levels, which makes surgical access to this region difficult. Minimally invasive techniques offer easier access to the region. The purpose of this study was to analyze the contributing factors for extraforaminal compression of the L-5 nerve and assess clinical outcome following surgical decompression. Methods Fifty-two consecutive patients who underwent a minimally invasive far-lateral approach for extraforaminal compression of the L-5 nerve were retrospectively analyzed for clinical data, outcomes, and imaging features (type of disc prolapse, coronal wedging, degree of disc and facet degeneration, facet tropism, foraminal stenosis, osteophytes, and adjacent-level disease). The authors describe the surgical technique used in this study. Results The mean age of the patient sample was 57 years. Sixteen patients each had an extraforaminal ruptured disc or contained protrusion, and the remaining 20 patients had disc protrusions extending into the foraminal region or the lateral recess. Associated foraminal stenosis was found in 38.5%, and adjacent-level stenosis was noted in 22 cases (42.3%) and spondylolisthesis in 4 (7.7%). Osteophytes were noted in 18 cases. A coronal wedging angle ≥ 3° was found in 46.2%, and the laterality of wedging corresponded to the symptomatic side in 91% of cases. Fifteen patients (28.8%) complained of postoperative dysesthesias, which completely resolved in all cases within 6 months. The incidence of dysesthesias was more common in the ruptured disc group. There were no differences in clinical outcome among the different types of disc prolapses. The mean preoperative and postoperative visual analog scale scores were 7.6 and 3.6, respectively. The mean preoperative and postoperative Japanese Orthopaedic Association (JOA) scores were 6.4 and 13.8, respectively. The mean JOA recovery rate was 86.1%. According to the Macnab functional grading system, 96% of the patients had excellent or good grades at follow-up. Conclusions A minimally invasive far-lateral approach to L5–S1 requires a good understanding of the regional anatomy and can provide good to excellent clinical results in properly selected cases. This approach is effective in decompressing the far-lateral and foraminal zones. Adequate preoperative diagnosis and tailoring the surgical procedure to address the relevant compressive element in each case is essential to achieving good clinical results.

Minimally invasive pars approach for foraminal disc herniation

“…Good to excellent outcomes in nearly 90% of FDH have been shown with the MIS endoscopic technique in the 11 patients described by Foley et al [18] Equally good results have been shown in subsequent reports with the MIS technique for FDH as well as degenerative foraminal stenosis [5,16,23]. Perlier et al [23] described the MIS approach in 46 patients with results comparable to ours and without complications.…”

“…Their average hospitalization was 3 days compared to our 1 ± 1 days. Lee et al [5] used the MIS technique in 52 patients with L5-S1 foraminal disc herniations only. The results were as good as those described above, also without complications.…”

“…Far lateral lumbar disc herniations, or foraminal disc herniations (FDH), account for up to 12% of lumbar disc herniations [1][2][3][4][5][6][7][8][9]. The discs are found lateral to the pedicle causing foraminal stenosis with compression of the exiting nerve root.…”

“…The second approach is that of partial pars resection with unroofing of the foramen, exposing the nerve root and offending disc [4,7,[14][15][16][17]. More recently, the method of choice is increasingly shifting towards minimally invasive surgery (MIS) with a tube to achieve decreased operative time, lessen blood loss, make smaller surgical incisions, reduce postoperative pain and hasten return to activities of daily living [5,11,14,[16][17][18][19][20][21][22][23][24][25][26].…”

Percutaneous full endoscopic lumbar foraminoplasty for adjacent level foraminal stenosis following vertebral intersegmental fusion in an awake and aware patient under local anesthesia: A case report

“…As being reported before, degenerative change such as facet hypertrophy can appear at the adjacent level following spinal fusion (4,5). Foraminal stenosis can also occur due to facet hypertrophy (4, 5) and disc collapse (22). Orita et al (6) reported a series of patients with foraminal stenosis at the adjacent level following spinal fusion in whom symptoms appeared on average 13.3 months after surgery.…”