One-year follow-up of patients with lumbar spinal stenosis treated with a novel spine surgery procedure has shown sustained improvements in pain and mobility with no serious adverse events.

Timothy Deer, MD, of the Center for Pain Relief in Charleston, West Virginia, presented those findings in a plenary session at the American Academy of Pain Medicine 27th Annual Meeting, held in Washington, DC.

"The goal of this procedure is to debulk the ligamentum flavum," Dr. Deer said, "and the reason we think this may be an important advancement in the field of minimally invasive spine techniques is that, unlike fusion, laminectomy, and spacers, it involves very little change in the stability or biomechanical aspects of the spine."

This is the first prospective, one-year, evidence-based study of this procedure, Dr. Deer said. "And that's very encouraging since there hasn't been much one-year data on spine surgery in the recent literature."

MILD Procedure

The procedure, known as MILD — for minimally invasive lumbar decompression — uses special instrumentation and percutaneous decompression laminotomy, with guidance from epidurography and fluoroscopy. The MILD devices use a 5.1-mm portal, so the trauma induced by the technique is comparatively minimal, Dr. Deer explained.

The MILD procedure uses a posterior approach. "Fluoroscopic imaging is critical and local anesthesia, with mild sedation, is all that's required," he said. Average time for a bilateral single-level procedure is about 40 minutes.

In this study Dr. Deer and his colleagues assessed outcomes of the procedure at one year after treatment in 58 patients, which included 170 procedures. Most of the procedures were bilateral, performed at one or two affected levels of the spine, Dr. Deer said. Average age of the patients was 70 years.

The researchers used four different outcomes instruments to validate their findings, including the visual analog scale (VAS), Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ), and the 12-item Short-Form Health Survey (SF-12v2).

Dr. Deer said that at one-year follow-up patients showed significant improvement in pain scores — an overall 40% reduction. VAS scores improved in 79% of the patients, from a mean of 7.4 before the procedure to 4.5 at one-year follow-up.

Functional mobility also improved in 71% of study participants, with overall mean ODI scores improving from 48.6 (severe disability) to 36.7 (moderate disability). Measures of ZCQ and SF-12v2 also improved, with decreased pain and increased physical function.

The procedure got good marks for safety, with no reports of dural tear, need for blood transfusion, nerve root damage, or hematoma. Dr. Deer pointed out that conventional open spinal surgery has been shown to be associated with up to 20% incidence of significant adverse effects.

"This is a meaningful study since we were able to gather our data directly from our patients in real time," Dr. Deer said. "That allowed us to avoid the bias that's often associated with retrospective studies."

He added that the results of the study are also noteworthy in that significant positive responses were achieved in all 4 outcome measurements. "Many of the spinal studies look at two of these measurements, and a few have looked at three, but none we know of has looked at all four. And in this study all four were significant to a major degree," he said.

Exciting Technique

Commenting on the study, Jeffrey Tiede, MD, of the Columbia Interventional Pain Center in Columbia, Missouri, said he thinks the technique may have significant advantages even for younger patients in that they don't have to undergo more invasive surgery — with the associated sequelae that may occur years later.

"But the majority of these patients are elderly and don't tolerate extensive invasive back surgery," he said. "So this technique is truly exciting in offering these patients a new treatment that's minimally invasive and safe. I think it's going to really change how we treat patients with spinal stenosis."

Dr. Deer reports that he is a paid researcher and speaker for Vertos Medical of Aliso Viejo, California. Dr. Tiede has disclosed no relevant financial relationships.

American Academy of Pain Medicine (AAPM) 27th Annual Meeting: Poster 286. Presented March 26, 2011.

Steven Fox • Medscape Medical News © 2011 WebMD, LLC