Reducing Scar Tissue After Lumbar Disc Surgery
Scar tissue formation after lumbar disc surgery is a major cause of failed-back surgery syndrome. One in four patients are affected. Surgeons are looking for ways to keep this from occurring.
Different drugs and topical agents applied to the surgical area have been studied. These substances may act as a barrier to fibrosis (scar tissue). They may inhibit the development of scar tissue. So far, nothing has been found that works well.
In this study, an antibiotic called mitomycin C was tested. It has been used successfully to prevent fibrosis in eye surgery for glaucoma and after tracheal reconstructive surgery. Animal studies have shown it works after back surgery involving laminectomy. A laminectomy is the removal of vertebral bone from around the spinal cord.
Two groups of patients were included in this study. The ages and gender (male versus female) were matched between the two groups. The first group had mitomycin applied at the site of their discectomies (removal of herniated disc).
The antibiotic solution was applied to the space where the disc was removed. The surgeon was careful not to touch any of the nerve tissue with the mitomycin. Application time was limited to five minutes to avoid any toxic effects of the drug on nearby tissue. The second group just had the discectomy without the mitomycin application.
Results were measured three ways. First, postoperative neurologic function was assessed. Each patient filled out the Lumbar Spine Outcomes Questionnaire (LSOQ). The LSOQ scores pain, symptoms, and activities of daily living (ADLs). A neurologic exam was done to evaluate leg (motor) weakness.
Second, severity of pain and other physical symptoms such as numbness, tingling, and problems with bowel or bladder function were also measured. Each patient rated the degree that function and activities were impaired by pain. Objective measures included the number of days each month they couldn't complete daily or work activities. Number of hours spent resting each day was recorded and compared between the two groups.
The first two measures were performed one week after surgery. The measures were repeated three, six, and 12 month after surgery. The third measurement of outcomes was by magnetic resonance images (MRIs) taken six months after surgery.
MRIs showed the presence and extent of fibrotic tissue forming in the area where the disc was removed. This is called peridural fibrosis. The amount of peridural fibrosis was graded on a scale from zero (none) to four (75 to 100 per cent filled with scar tissue). Grade two indicated 25 to 50 per cent of the space was filled with scar tissue. Grade three referred toan area that was 51 to 74 per cent filled.
After reviewing all of the data and MR images, the authors concluded there was no benefit to using mitomycin C to prevent peridural fibrosis. The two groups had equal results in all areas. One group did not have fewer complications or better results than the other. Scores on all the tests for pain and function were comparable between the two groups.
More study is needed to identify a biological or inert material that can be implanted in the peridural space to prevent fibrosis. Other factors as a cause of peridural fibrosis after discectomy should also be explored.
For example, would the mitomycin C work better if/when applied to a different site? Perhaps using it at the area where bone is removed (laminotomy or laminectomy) would work better. Or maybe the spine is overloaded when patients walk so soon after surgery. The load and pressure on healing tissue may start a series of steps that cause the formation of scar tissue. The authors suggest multicenter trials to further study this problem.
Suat E. Ãelik, MD, et al. Mitomycin Protection of Peridural Fibrosis in Lumbar Disc Surgery. In Journal of Neurosurgery: Spine. September 2008. Vol. 9. No. 3. Pp. 243-248.