Background: Microdecompression (MD) is a minimally invasive spine surgery for lumbar spinal stenosis (LSS). However, there was no long-term outcome study of this procedure in Thailand.
Objective: The aim of this study was to evaluate the safety, complications, and surgical outcomes in Thai patients who
underwent MD for LSS.
Material and Method: A single-institution database was reviewed for Thai patients with LSS who underwent MD during the 2005 to 2014 study period. We analyzed demographic data and clinical data, intraoperative and postoperative data, and immediate complications. Oswestry Low Back Disability Index (ODI) and EQ-5D-5L were used to measure outcomes.
Results: Seventy patients were enrolled (43 female and 27 male), with an average age of 64.1+10.6 years. Mean operative time was 99.5+31.6 minutes per level. Average length of stay was 5.2+2.8 days. Estimated blood loss was 90.5+65.6 ml. The most common level was L4-5. The average follow-up was 47.5+33.8 months. All postoperative patient-reported outcome measures were statistically significantly improved compared to preoperative measures (p<0.05). Average preoperative and postoperative ODI score was 60.8+20.6 and 15.9+15.7, respectively. Average pre-operative and postoperative EQ-5D-5L scores were 35.2+23.4 and 92.2+10, respectively. Immediate complications were found in 7 patients, including 5 incidental
dural tear, 1 epidural hematoma, and 1 superficial wound infection. Late complications were found in 5 patients, including 1 cerebrospinal fluid leakage and 4 additional fusion surgeries. Of note, 14 patients had grade I degenerative spondylolisthesis (DS) before surgery although none of these patients complained of significant back pain. However, 3 of 4 cases that underwent additional fusion had pre-operative DS.
Conclusion: Microdecompression surgery was found to be effective for treating patients with degenerative spinal stenosis. This procedure should be cautiously used in patients with spondylolisthesis, even in the absence of significant back pain.

Keywords: Spinal stenosis, Microdecompression, Surgical outcome, Complications, Decompression