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Image-Guided Minimally Invasive Decompression for Spinal Stenosis

Policy Number: MP-419

Latest Review Date: May 2022

Category: Surgery                                                                       



Image-guided minimally invasive spinal decompression is considered investigational. 


Spinal Stenosis

Image-guided minimally invasive lumbar decompression (IG-MLD) describes a percutaneous procedure for decompression of the central spinal canal with spinal stenosis and hypertrophy of the ligamentum flavum. In this procedure, a specialized cannula and surgical tools (mild®) are used under fluoroscopic guidance for bone and tissue sculpting near the spinal canal. IG-MLD is proposed as an alternative to existing posterior decompression procedures.

In spinal stenosis, the space around the spinal cord narrows, compressing the spinal cord and the nerve roots. The goal of surgical treatment is to “decompress” the spinal cord and/or nerve roots.

The most common symptoms of lumbar spinal stenosis (LSS) are back pain with neurogenic claudication (i.e., pain, numbness, or weakness) in the legs that worsens with standing or walking and is alleviated with sitting or leaning forward. Compression of neural elements generally occurs from a combination of degenerative change including ligamentum flavum hypertrophy, bulging of the intervertebral disc, and facet thickening with arthropathy. Spinal stenosis is often linked to age-related changes in disc height and arthritis of the facet joints. LSS is one of the most common reasons for back surgery and the most common reason for lumbar spine surgery in adults over 65 years of age.

The most common symptoms of cervical/thoracic spinal stenosis are neck pain and radiculopathy of the shoulder and arm. The most common cause of cervical radiculopathy is degenerative changes, including disc herniation.

Conventional Posterior Decompressive Surgery

For patients with LSS, surgical laminectomy has established benefits in reducing pain and improving quality of life. For patients with cervical or thoracic stenosis, surgical treatment includes discectomy or foraminal decompression.

A 2009 systematic review of surgery for back pain, commissioned by the American Pain Society (APS), was conducted by the Oregon Health Sciences University Evidence-Based Practice Center. Four higher-quality randomized trials were reviewed that compared surgery with nonsurgical therapy for spinal stenosis, including two studies from the multicenter Spine Patient Outcomes Research Trial (SPORT) evaluating laminectomy for spinal stenosis (specifically with or without degenerative spondylolisthesis). All four trials found that initial decompressive surgery (laminectomy) was slightly to moderately superior to initial nonsurgical therapy (e.g., average 8- to 18-point difference on the SF-36 and Oswestry Disability Index [ODI]). There was insufficient evidence to determine the optimal adjunctive surgical methods for laminectomy (i.e., with or without fusion, and instrumented versus non-instrumented fusion) in patients with or without degenerative spondylolisthesis. The SPORT trials continue to be referenced as the highest quality evidence that has been published on decompressive surgery.

Less invasive surgical procedures include open laminotomy and microendoscopic laminotomy. In general, the literature comparing surgical procedures is limited.  The literature has suggested that less invasive procedures may reduce perioperative morbidity without impairing long-term outcomes when performed in appropriately selected patients. Posterior decompressive surgical procedures include: decompressive laminectomy, hemilaminotomy and laminotomy, and microendoscopic decompressive laminotomy (MEDL).

Decompressive laminectomy, the classic treatment for LSS, which unroofs the spinal canal by extensive resection of posterior spinal elements, including the lamina, spinous processes, portions of the facet joints, ligamentum flavum, and the interspinous ligaments. Wide muscular dissection and retraction is needed to achieve adequate surgical visualization. The extensive resection and injury to the posterior spine and supporting muscles can lead to instability with significant morbidity, both post-operatively and longer-term. Spinal fusion performed at the same time as laminectomy or after symptoms have developed, may be required to reduce the resultant instability. Laminectomy may be used for extensive multi-level decompression.

Hemilaminotomy and laminotomy, sometimes termed laminoforaminotomy, are less invasive than laminectomy. These procedures focus on the interlaminar space, where most of the pathologic changes are concentrated, minimizing resection of the stabilizing posterior spine. A laminotomy typically removes the inferior aspect of the cranial lamina, superior aspect of the subjacent lamina, ligamentum flavum and the medial aspect of the facet joint. In contrast to laminectomy, laminectomy does not disrupt the facet joints, supra-and interspinous ligaments, a major portion of the lamina or the muscular attachments. Muscular dissection and retraction are required to achieve adequate surgical visualization.

Microendoscopic decompressive laminotomy (MEDL) is similar to laminotomy, but utilizes endoscopic visualization. The position of the tubular working channel is confirmed by fluoroscopic guidance, and serial dilators (METRx™ lumbar endoscopic system, Medtronic) are used to dilate the musculature and expand the fascia.  For MEDL, an endoscopic curette, rongeur, and drill are used for the laminotomy, fasciectomy, and foraminotomy. The working channel may be repositioned from a single incision for multilevel and bilateral dissections.

Image-Guided Minimally Invasive Lumbar Decompression

Posterior decompression for LSS has been evolving toward increasingly minimally invasive procedures in an attempt to reduce postoperative morbidity and spinal instability. Unlike conventional surgical decompression, the percutaneous mild® decompressive procedure is performed solely under fluoroscopic guidance (e.g., without endoscopic or microscopic visualization of the work area). This procedure is indicated for central stenosis only, without the capability of addressing nerve root compression or disc herniation, should either be required.

Percutaneous IG-MLD using a specially designed tool kit (mild®) has been proposed as an ultra-minimally invasive treatment of central LSS. In this procedure, the epidural space is filled with contrast medium under fluoroscopic guidance. Using a 6-gauge cannula that is clamped in place with a back plate, single use tools (portal cannula, surgical guide, bone rongeur, tissue sculptor, and trocar) are used to resect thickened ligamentum flavum and small pieces of lamina. The tissue and bone sculpting is conducted entirely under fluoroscopic guidance, with additional contrast media added throughout the procedure to aid visualization of the decompression. The process is repeated on the opposite side for bilateral decompression of the central canal. The devices are not intended to be used near the lateral neural elements and are contraindicated for disc procedures.


This policy was created in 2010 and updated periodically using the MEDLINE database. The most recent literature review was performed through March 4, 2022. Following is a summary of key references to date.

Summary of Evidence

For individuals who have lumbar spinal stenosis who receive image-guided minimally invasive lumbar decompression, the evidence includes a large, randomized controlled trial (n=302), a systematic review of a small randomized controlled trial (n=38), and a number of prospective and retrospective cohort studies and case series. Relevant outcomes are symptoms, functional outcomes, health status measures, and treatment-related morbidity. The largest randomized controlled trial compared image-guided minimally invasive lumbar decompression with epidural steroid injections (control) in patients who had ligamentum flavum hypertrophy and who failed conservative therapy. Results suggested reductions in pain and improvements in function scores in the image-guided minimally invasive lumbar decompression group vs the control group. The trial was unblinded and there is evidence of differing expectations and follow-up in the 2 groups, suggesting a high-risk of bias. The available evidence is insufficient to determine the efficacy of mild® compared with placebo or to determine the efficacy of image-guided minimally invasive lumbar decompression compared with open decompression. Trials with relevant control groups could provide greater certainty on the risks and benefits of this procedure. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

For individuals who have cervical or thoracic spinal stenosis who receive image-guided minimally invasive spinal decompression, no evidence was identified. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Practice Guidelines and Position Statements

North American Spine Society

In 2011, the North American Spine Society revised clinical practice guidelines on the diagnosis and treatment of degenerative lumbar spinal stenosis. Treatment recommendations included:

  • Interlaminar ESI for short-term (two weeks to six months) symptom relief in patients with neurogenic claudication or radiculopathy; however, there is conflicting evidence regarding long-term efficacy. (Grade of Recommendation: B)
  • A multiple injection regimen of radiographically-guided transforaminal ESI or caudal injection for medium-term relief of pain. (Grade of Recommendation: C)
  • Decompressive surgery to improve outcomes in patients with moderate to severe symptoms of lumbar spinal stenosis. (Grade of Recommendation: B)

No specific recommendations on percutaneous image-guided lumbar decompression were provided.

Lumbar Spinal Stenosis Consensus Group MIST Guidelines

In 2018, the Lumbar Spinal Stenosis Consensus Group, composed of a panel of nationally recognized spine experts, convened to evaluate the available literature and develop guidelines for minimally invasive spine treatment. Based on a systematic review of the available literature on percutaneous image-guided lumbar decompression, the consensus committee determined there is sufficient support to warrant Level I evidence (Grade A, Level I, Consensus strong). Grade A evidence is defined as "extremely recommendable (good evidence that the measure is effective and that benefits outweigh the harms."

U.S Preventive Services Task Force Recommendations

Not Applicable


Image-guided minimally invasive lumbar decompression, mild®, image-guided percutaneous minimally invasive lumbar decompression, IG-MILD, lumbar spinal stenosis, LSS, posterior lumbar decompression, microendoscopic decompressive laminotomy, MEDL, X-Sten MILD Vertos’s mild®


In 2006, the X-Sten MILD Tool Kit now the mild® device kit (X-Sten Corp. renamed Vertos Medical) was cleared for marketing by the U.S. Food and Drug Administration through the 510(k) process for treatment of various spinal conditions. This set of specialized surgical instruments is used to perform percutaneous lumbar decompressive procedures.

Vertos’ mild® instructions for use state that the devices are not intended for disc procedures but rather for tissue resection at the perilaminar space, within the interlaminar space and at the ventral aspect of the lamina.  These devices are not intended for use near the lateral neural elements and remain dorsal to the dura using image guidance and anatomical landmarks.

Note:  The abbreviation MILD has also been used for microscopic muscle-preserving interlaminar decompression, which involves a small skin incision at the interspinous level and partial drilling of the spinous process, with decompression performed under microscopic visualization.


Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP:  Special benefits may apply.  Refer to member’s benefit plan.  FEP does not consider investigational if FDA approved and will be reviewed for medical necessity.


CPT Codes:


Percutaneous laminotomy/laminectomy (intralaminar approach) for decompression of neural elements, (with or without ligamentous resection, discectomy, facetectomy and/or foraminotomy) any method under indirect image guidance (e.g., fluoroscopic, CT), with or without the use of an endoscope, single or multiple levels, unilateral or bilateral; cervical or thoracic


Percutaneous laminotomy/laminectomy (intralaminar approach) for decompression of neural elements, (with or without ligamentous resection, discectomy, facetectomy and/or foraminotomy) any method under indirect image guidance (e.g., fluoroscopic, CT), with or without the use of an endoscope, single or multiple levels, unilateral or bilateral; lumbar


HCPC Codes:


Blinded procedure for lumbar stenosis, percutaneous image-guided lumbar decompression (PILD) or placebo-control, performed in an approved coverage with evidence development (CED) clinical trial.


The procedure utilizes an epidurogram so CPT code 72275 (epidurography, radiological supervision and interpretation) would probably also be reported.  Effective 01/01/2022, CPT 72275 has been deleted.


  1. Benyamin RM, Staats PS, Mi DASEI. MILD(R) is an effective treatment for lumbar spinal stenosis with neurogenic claudication: MiDAS ENCORE randomized controlled trial. Pain Physician. May 2016; 19(4):229-242.
  2. Brown LL. A double-blind, randomized, prospective study of epidural steroid injection vs. the mild(R) procedure in patients with symptomatic lumbar spinal stenosis. Pain Pract. Jun 2012; 12(5):333-341.
  3. Chopko BW. A novel method for treatment of lumbar spinal stenosis in high-risk surgical candidates: pilot study experience with percutaneous remodeling of ligamentum flavum and lamina. J Neurosurg Spine. Jan 2011; 14(1):46-50.
  4. Chopko BW. Long-term Results of Percutaneous Lumbar Decompression for LSS. Clinical Journal of Pain. Nov 2013; 29(11): 939-943.
  5. Chou R, Baisden J, Carragee EJ, et al.  Surgery for low back pain: A review of the evidence for an American Pain Society clinical Practice Guideline. Spine, May 2009; 34(10): 1094-1109.
  6. Chou R, Loeser JD, Owens DK, et al. Interventional therapies, surgery, and interdisciplinary rehabilitation for low back pain: An evidence-based clinical practice guideline from the American Pain Society. Spine, May 2009; 34(10): 1066-1077.
  7. Deer TR, Grider JS, Pope JE et al. The MIST Guidelines: The Lumbar Spinal Stenosis Consensus Group Guidelines for Minimally Invasive Spine Treatment. Pain Pract. 2019 Mar;19(3).
  8. Lingreen R, Grider JS. Retrospective review of patient self-reported improvement and post-procedure findings for mild (minimally invasive lumbar decompression). Pain Physician. Nov-Dec 2010; 13(6):555-560.
  9. North American Spine Society (NASS). Evidence-Based Clinical Guidelines for Multidisciplinary Spine Care: Diagnosis and Treatment of Degenerative Lumbar Spinal Stenosis. 2011;
  10. Staats, PS, Chafin, TB, Golovac, S et al. 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. Reg Anesth Pain Med. 2018 Oct;43(7):789-794.
  11. Staats PS, Benyamin RM. MiDAS ENCORE: randomized controlled clinical trial report of 6-month results. Pain Physician. Feb 2016; 19(2): 25-38.
  12. Weinstein JN, Lurie JD, et al.  Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis.  NEJM, May 2007; 356(22): 2257-2270.
  13. Weinstein JN, Tosteson RD, et al.  Surgical versus nonsurgical therapy for lumbar spinal stenosis.  NEJM, Feb 2008; 358(8): 794-810.


Medical Policy Group, March 2010 (1)

Medical Policy Administration Committee, April 2010

Available for comment April 7-May 21, 2010

Medical Policy Group, March 2011 (1): Updated Coding, Key Points and References

Medical Policy Administration Committee, April 2011

Available for comment April 4 – May 18, 2011

Medical Policy Group, March 2012 (1): Update to Key Points and References related to MPP update; no change to policy statement

Medical Policy Group, June 2013 (4): Update to Key Points and References related to IG-MLD. No policy change.

Medical Policy Group, January 2014 (4): References related to IG-MLD. No policy change.

Medical Policy Panel April 2014

Medical Policy Group April 2014 (4): Updated Key Points, Key Words and References. No change to the policy at this time.

Medical Policy Group, February 2015: 2015 Annual Coding Update.  Added HCPC codes section to include G0276.

Medical Policy Panel, April 2015.

Medical Policy Group, April 2015 (2): 2015 Updates to Description, Key Points, and References; no change to policy statement.

Medical Policy Panel, April 2016.

Medical Policy Group, April 2016 (7): 2016 Updates to Key Points and References; no change in policy statement.

Medical Policy Group, December 2016: 2017 Annual Coding Update. Updated verbiage for revised cpt code 0275T.

Medical Policy Panel, April 2017

Medical Policy Group, April 2017 (7): Updates to Description, Key Points, Coding and References. Added CPT code 0274T (has always been investigational) to Current Coding and removed Previous Coding section as it pertained to changes made in 2011. Policy statement updated to state “spinal” decompression rather than lumbar decompression.

Medical Policy Panel, April 2018

Medical Policy Group, May 2018 (7): Updates to Description and Key Points. No change to Policy Statement.

Medical Policy Panel, April 2019

Medical Policy Group, April 2019 (7): Minor update to Key Points, no new literature to add. No change to Policy Statement.

Medical Policy Panel, April 2020

Medical Policy Group, May 2020 (7): Update to Key Points and References. No change to Policy Statement.

Medical Policy Panel, April 2021

Medical Policy Group, April 2021 (7): Minor update to Key Points. No new references added. Policy section updated to remove “not medically necessary” statement. No change in intent.

Medical Policy Group, December 2021 (7): 2022 Annual Coding Update. Updated note regarding deletion of CPT 72275, effective 01/01/2022. 

Medical Policy Panel, April 2022

Medical Policy Group, May 2022 (7): Minor update to Key Points. No new references added. No change to Policy Statement.



This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.


This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

  1. The technology must have final approval from the appropriate government regulatory bodies;
  2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;
  3. The technology must improve the net health outcome;
  4. The technology must be as beneficial as any established alternatives;
  5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

  1. In accordance with generally accepted standards of medical practice; and
  2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and
  3. Not primarily for the convenience of the patient, physician or other health care provider; and
  4. 4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.