Interlaminar endoscopic lateral recess decompression-surgical technique and early clinical results

Abstract

Background: Lateral recess stenosis is a common pathology causing de-novo or residual radicular pain following lumbar spine surgery. Diagnostic criteria and treatment strategies for symptomatic lateral recess stenosis are not well established.

Methods: We identified ten patients in our prospective patient database (n=146) who underwent endoscopic interlaminar decompression for unilateral symptomatic lateral recess stenosis. Lateral recess height and angle were measured on axial T2-weighted MRI. Values from the symptomatic side were compared to the contralateral side which served as asymptomatic control. Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) for back and leg pain were collected preoperatively, postoperatively and at last follow-up.

Results: Preoperative MRI revealed that both lateral recess angle and height were significantly smaller on the symptomatic compared to the asymptomatic side (angle: 19.3° vs. 35.7°; height: 2.9 vs. 5.7 mm; P<0.01). All patients tolerated endoscopic interlaminar decompression well and half of the patients were discharged on the day of surgery. At last follow-up (12.6±1.7 months), 8 out of 10 patients experienced a minimally clinically important improvement of their VAS for ipsilateral leg pain, which improved from 7.2±0.5 preoperatively to 2.5±0.8 postoperatively (P=0.001). The back pain VAS also improved (preoperatively 5.1±1.1 vs. postoperatively 1.7±0.9, P<0.05). The ODI improved from 50±5.8 preoperatively to 22.2±5.1 at last follow-up (P=0.001). One patient experienced persistent leg pain.

Conclusions: Lateral recess height and angle correlate with symptomatic lateral recess stenosis which is effectively treated utilizing interlaminar endoscopic lateral recess decompression.

Keywords: Endoscopic spine surgery; lateral recess; radiculopathy; stenosis.

Figure 1

Intraoperative view of a stenotic contralateral L4/5 lateral recess. (A) The traversing L5 nerve root (arrow) is seen within the lateral recess bordered posteriorly by the yellow ligament (y) which covers the anterior portion of the facet joint; (B) partial removal of the yellow ligament (y) reveals the L4/5 facet joint formed by the inferior (i) and superior (s) articular processes. The traversing nerve root is marked with an arrow.

Figure 2

Illustration of lateral recess measurements on an axial T2-weighted image at L4/5. Traversing nerve roots are outlined red. The lateral recess angle is drawn between tangents of the disc annulus and the facet joint centered in middle of the traversing nerve root. The lateral recess height is measured along a sagittal plane at the medial margin of the traversing nerve root.

Figure 3

Interlaminar approach. (A) Intraoperative AP X-ray depicting marking for the skin incision for a L4/5 medial facetectomy; (B) cartoon illustrating the lumbar spine; (C) boxed area in panel B depicts a close up of the lateral recess. The green area indicates bone removal of the inferior articular process and the blue area indicated the area of bony resection of the superior articular process. Note that an attempt is made to undercut the inferior articular process.

Figure 4

Intraoperative steps for lateral recess decompression. (A) Following resection of the medial portion of the inferior articular process (i) the superomedial aspect of the superior articular process is exposed; (B) resection of the yellow ligament is carried out using micropunches; (C) following resection of the yellow ligament the traversing nerve root (t) is exposed. A small synovial cyst (arrow head) is seen along the medial aspect of the superior articular process (s); (D) complete decompression of the traversing nerve root (t) is achieved by resecting the synovial cyst and medial portion of the superior articular process.

Figure 5

Graphs depicting clinical outcomes following endoscopic medial facetectomy. (A) Reduction of the visual analog score for ipsilateral leg pain and back pain are recorded; (B) patients experience alleviation of their disability as measured by the Oswestry disability index.