Table 2. Summary of invasive management techniques.

No.	Article title	Authors	Journal of publication	Year of publication	Main findings
1.	Surgery of the Lumbar Spine for Spinal Stenosis in 118 Patients 70 Years of Age or Older [15]	Ragab AA, Fye MA	Spine	2003	This retrospective study collected data from 118 subjects who had undergone surgical treatment for lumbar spinal stenosis. Patients were assessed for post-surgical morbidity and their satisfaction with surgery. Overall morbidity was approximately 20%, while 109 patients were satisfied with their surgical outcome and were able to continue their daily life routine post-operatively.
2.	Predominant Leg Pain is Associated With Better Surgical Outcomes in Degenerative Spondylolisthesis and Spinal Stenosis: Results From the Spine Patient Outcomes Research Trial (Sport) [16]	Pearson A, Blood E, Lurie J, Abdu W, Sengupta D, Frymoyer JW, Weinstein J	Spine	2011	In this study, two patient groups were organized: the degenerative spondylolisthesis group (591) and spinal stenosis group (615). About 62% of cases from each group underwent surgical intervention. The patients in either cohort were further classified into three categories with respect to their symptoms: leg pain predominant, lower back pain predominant, and mixed symptoms. The researchers subsequently demonstrated that leg pain symptoms were more likely relieved by surgical intervention.
3.	Functional and Patient‐Reported Outcomes in Symptomatic Lumbar Spinal Stenosis Following Percutaneous Decompression [17]	Mekhail N, Costandi S, Abraham B, Samuel SW	Pain Practice	2012	Forty patients were recruited for percutaneous lumbar spinal decompression. The Pain Disability Index and Roland-Morris Questionnaire were used to assess the patients’ status. Both tools demonstrated significant progress with respect to the overall functional profile and a decrease in pain intensity and disability.
4.	A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis [18]	Försth P, Ólafsson G, Carlsson T, et al.	The New England Journal of Medicine	2016	A total of 247 patients with spinal stenosis aged between 50 and 80 years were randomly categorized to undergo either of the following two operations; spinal decompression with fusion surgery or decompression only. The data collection tool used was the Oswestry Disability Index. The findings demonstrated no statistically significant difference between the two groups with regard to patient recovery rates. However, hospital-stay duration of fusion surgery individuals was almost twice that of those who underwent decompression only. Moreover, bleeding complications were more likely to be seen in the former group.
5.	Long-Term Safety and Efficacy of Minimally Invasive Lumbar Decompression Procedure for the Treatment of Lumbar Spinal Stenosis With Neurogenic Claudication 2-Year Results of MiDAS ENCORE [19]	Staats PS, Chafin TB, Golovac S, et al.	Regional Anesthesia and Pain Medicine	2018	In this trial, two groups of patients were formed: the first (143)  were treated with MILD surgery (minimally invasive lumbar decompression), while the second (131) were treated with epidural steroid injections. The Oswestry Disability Index and other scores showed high improvement rates for surgically treated cases. Only 1.3% of the patients experienced surgical complications.
6.	Clinical Outcome After Surgery for Lumbar Spinal Stenosis in Patients With Insignificant Lower Extremity Pain. A Prospective Cohort Study From the Norwegian Registry for Spine Surgery [20]	Hermansen E, Myklebust TÅ, Austevoll IM, et al.	BMC Musculoskeletal Disorders	2019	In this study, data obtained from 3,181 patients who underwent spine decompression surgery were assessed. They divided patients into four groups with respect to pain status: Group 1 with 154 cases, group 2 with 753 cases, group 3 with 1,766 patients, and group 4 with 528 patients. The pain status of the four groups varied from group 1 to 4 as insignificant, mild to moderate, severe, and extremely severe pain. The Oswestry Disability Index was used to monitor post-surgical outcomes. At 12 months' follow-up, the group 1 members reported minimum improvement from pre-surgical evaluation as compared to all the other groups.
7.	Minimally Invasive Treatment of Lumbar Spinal Stenosis With a Novel Interspinous Spacer [21]	Shabat S, Miller LE, Block JE, Gepstein R	Clinical Interventional Aging	2011	In this study, 53 patients with LSS (lumbar spinal stenosis) were treated with the Superior (®) Interspinous Spacer (Vertiflex Inc.) and follow-up visits at five weeks, one year, and two years. The study endpoints utilized axial and extremity pain severity with an 11-point numeric rating scale, Zurich Claudication Questionnaire (ZCQ), and back function with the Oswestry Disability Index. Axial and extremity pain decreased by 54% over the two-year follow-up period. ZCQ symptom severity scores improved by 43%, and ZCQ function improved by 44% from pre-treatment to two years post-treatment.  Moderate LSS can be effectively treated with a minimally invasive interspinous spacer. The device is appropriate for certain patients who have failed nonoperative treatment measures for LSS and strict anatomical criteria.
8.	Minimally Invasive Lumbar Decompression: A Review of Indications, Techniques, Efficacy, and Safety [22]	Jain S, Deer T, Sayed D, et al.	Pain Management	2020	This study utilized an extensive literature review of two randomized controlled trials, together with 11 other controlled clinical studies, to establish the efficacy of MILD surgery (minimally invasive lumbar decompression). This study recommended that MILD should be considered as the first intervention after failure of conservative measures for patients diagnosed with lumbar spinal stenosis (LSS) and ligamentum flavum hypertrophy (LFH) ≥2.5 mm.