Medical Policy: 07.01.63
Original Effective Date: February 2014
Reviewed: January 2018
Revised: January 2018
Benefit determinations are based on the applicable contract language in effect at the time the services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary based on contract, and individual member benefits must be verified. Wellmark determines medical necessity only if the benefit exists and no contract exclusions are applicable. This medical policy may not apply to FEP. Benefits are determined by the Federal Employee Program.
This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Image-guided minimally invasive lumbar decompression (IG-MILD) is a percutaneous procedure for decompression of the central spinal canal in patients with lumbar spinal stenosis (LSS). In this procedure, a specialized cannula and surgical tools (mild®) are used under fluoroscopic guidance for bone and tissue sculpting near the spinal canal. Image-guided minimally invasive lumbar decompression (IG-MILD) is proposed as an alternative to existing posterior decompression procedures.
Lumbar spinal stenosis (LSS) is a condition in which the space around the spinal cord narrows and causes compression of the spinal cord and its nerve roots. The most common symptoms of LSS is back pain with neurogenic claudication i.e. pain, numbness, or weakness in the lower extremities that often worsens with standing or walking and is alleviated by sitting or leaning forward. Compression of neural elements generally occurs from a combination of degenerative changes, 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 among the most common reasons for back surgery and the most common reason for lumbar spine surgery in adults over the age of 65. The goal of surgical treatment is to “decompress” the spinal cord and/or nerve roots.
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 surgical decompression may reduce perioperative morbidity without impairing long-term outcomes when performed in appropriately selected patients.
Decompressive laminectomy, the classic treatment for LSS, unroofs the spinal canal by extensive resection of posterior spinal elements, including the lamina, spinous process, 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 musculature can lead to instability with significant morbidity, both postoperatively and longer term. Spinal fusion, performed at the same time as laminectomy or after symptoms have developed, may be required to reduce resultant instability. Laminectomy may also be used for extensive multilevel decompression.
Hemilaminotomy and laminotomy, sometimes termed laminoforaminotomy, are less invasive then 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, ligmentum flavum, and the medial aspect of the facet joint. Unlike laminectomy, laminotomy 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), similar to laminotomy, uses endoscopic visualization. The position of the tubular working channel is confirmed by fluoroscopic guidance, and serial dilators are used to dilate the musculature and expand the fascia. For MEDL, an endoscopic curette, rongeur, and drill are used for the laminotomy, facetectomy and foraminotomy. The working channel may be repositioned from a single incision for multi-level and bilateral dissections.
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 image-guided minimally invasive lumbar decompression (IG-MILD) 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-guage cannula that is clamped in place with a back plate, single use tools (portal cannula, surgical guide, bone rongeur, tissue sculpter, 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 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.
For individuals who have lumbar spinal stenosis, the evidence includes a randomized controlled trial (RCT; N=302) the MiDAS ENCORE study, a systematic review of a small RCT (N=38), a number of prospective and retrospective cohort studies and case series, and an ongoing observational study (MILD Percutaneous Image-Guided Lumbar Decompression: A Medicare Claims Study; NCT03072927). The MiDAS ENCORE study compared minimally invasive lumbar decompression (MILD) procedure to epidural steroid injections in patients with painful lumbar spinal stenosis exhibiting neurogeneic claudication and having verified ligamentum flavum hypertrophy and who failed conservative therapy. Results at one year follow-up suggested reductions in pain and improvements in function in the MILD group versus the control group. The limitations related to this study included lack of patient blinding due to considerable differences in treatment protocols, resulting in a high risk of bias and a potentially higher non-responder rate for both groups versus standard-of-care due to adjunctive pain therapy study restrictions. Study enrollment was also not limited to patients that had never received epidural steroid injections (ESI). The Medicare Claims Study (NCT0307297) is an observational study, the control group includes all patients receiving interspinous process decompression (IPD) for the treatment of lumbar spinal stenosis with neurogenic claudication, and the treatment group includes all patients receiving MILD during the enrollment period. The study will compare incidence rates as well as harms associated with the MILD procedure. While image-guided minimally invasive lumbar decompression (IG-MILD) has been proposed as an alternative, less invasive treatment for central lumbar spinal stenosis, current clinical evidence is insufficient to permit conclusions about whether any beneficial effect from image guided minimally invasive lumbar decompression provides a significant advantage over surgical decompression. In addition, the complication rates and reoperation rates for this procedure compared with those of decompression surgery is unknown. There is a need for additional randomized controlled trials with sufficient follow up, sample size, and relevant comparative control groups to other established alternatives (i.e. surgical decompression) to determine the appropriateness of image-guided minimally invasive lumbar decompression for the treatment of central lumbar spinal stenosis. The evidence is insufficient to determine the effects of the technology on net health outcomes.
No guidelines or position statements were identified.
The mild® tool kit (Vertos Medical Inc., San Jose, CA) initially received 510(k) marketing clearance as the X-Sten MILD Tool Kit (X-Sten Corp.) from the US Food and Drug Administration (FDA) on December 19, 2006, as a class II device with intended use as a set of specialized surgical instruments to be used to perform percutaneous lumbar decompressive procedures for the treatment of various spinal conditions. A subsequent approval for the Vertos Medical mild® Device Kit (Vertos Medical Inc.) was given by the FDA on February 4, 2010.
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.
See also medical policy 07.01.39 Miscellaneous Surgical Treatment of Back Pain
Image-guided minimally invasive lumbar decompression (IG-MILD) is considered investigational for all indications.
While image-guided minimally invasive lumbar decompression (IG-MILD) has been proposed as an alternative, less invasive treatment for central lumbar spinal stenosis, current clinical evidence is insufficient to permit conclusions about whether any beneficial effect from image guided minimally invasive lumbar decompression provides a significant advantage over surgical decompression. In addition, the complication rates and reoperation rates for this procedure compared with those of decompression surgery is unknown. There is a need for additional randomized controlled trials with sufficient follow up, sample size, and relevant comparative control groups to other established alternatives (i.e. surgical decompression) to determine the appropriateness of image-guided minimally invasive lumbar decompression for the treatment of central lumbar spinal stenosis. The evidence is insufficient to determine the effects of the technology on net health outcomes.
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