Technical Nuances of Minimal Invasive Interlaminar Decompression in Lumbar Spinal Stenosis: The Role of Minimal Invasive Bilateral Approach

We report a series of patients operated for one or multilevel lumbar spinal stenosis (with and without spondylolisthesis) using the minimal invasive bilateral interlaminar decompression. We discuss our results, comparing this procedure (from a technical point of view) with the muscle-preserving interlaminar decompression (MILD) and the unilateral approach for bilateral decompression (ULBD). Clinical and outcome data of 62 consecutive patients were reviewed, using the Visual Analogue Scale for both low back pain (LBP) and legs pain and the Oswestry Disability Index (ODI) for the degree of disability. Mean age was 68.88 ± 9.54 years and mean follow-up (FU) was 16.38 ± 11.12 months. A statistically significant improvement of LBP, legs pain and ODI was globally observed. At latest FU, patients with multilevel lumbar spinal stenosis significantly improved all scores and patients with spondylolisthesis significantly decreased their disability. No major complications occurred. Two cerebrospinal fluid (CSF) collections were treated conservatively. No wound infection occurred. No progression of spondylolisthesis was observed. No reoperation was needed. Although efficacious in patients with lumbar spinal stenosis, MILD and ULBD can have both some limitations. MILD has been found to decrease lumbar function in multilevel decompression (increasing sagittal translation and lumbar lordosis probably due to the removal of half of the spinous processes) and ULBD shows some disadvantages due to the difficulty of manipulating instruments through a small portal and the inadequate decompression due to a minimal exposure. The minimal invasive bilateral interlaminar decompression (in this technique, the access is bilateral but the supraspinous and interspinous ligaments and the spinous processes are preserved) allows wide access (bilateral exposure) with minimal invasiveness and very low morbidity in patients with lumbar spinal stenosis at one or more levels.