A relatively new procedure is showing promise for patients suffering from lumbar spinal stenosis, according to Scott Kendrick, MD with Southside Pain Specialists.
MILD, minimally invasive lumbar decompression, debulks the ligamentum flavum, or the posterior ligament that gets enlarged and causes degenerative spinal stenosis.
"The procedure is technically experimental," Kendrick said. "MILD takes out a small amount of tissue, making room for spinal nerve roots. Even taking a small amount of tissue out tends to make a pretty significant difference in terms of the patient's ability to improve."
Patients who qualify under Medicare for the procedure must be at least 66 years old and have moderate to severe spinal stenosis with neurogenic claudication symptoms. "They should have intolerance for standing 15 minutes or less and have back and leg pain that is worsened with duration of standing and walking. Most patients who are candidates for MILD cannot walk 250 feet, or less than a football field. Typically, the patient is having to use assist devices such as a walker or cane and still have unsteadiness and even fall on occasion," Kendrick said.
MILD is an option for patients who are not otherwise considered good surgical candidates because of additional health problems. Only mild sedation is required.
"We use a trocar that allows access to the bone area, so underneath an x-ray machine or fluoroscope, I'm able to evaluate the lamina," Kendrick said. "I create a window, taking out a small amount of the ligamentum flavum underneath the fluoroscope. Then I create a window superiorly on the vertebral body above.
"Once I've adequately created the windows, I use a tissue sculptor to carve out a segment of the ligamentum flavum. The purpose of the procedure is to remove excess tissue, but it's important to leave the ligamentum flavum intact. We don't want to take out the whole thing. We're just trying to take out the back third. What makes the procedure very safe is by doing all the work from the back side, I can take out a significant amount of tissue, but I haven't opened up the epidural space to cause further destabilization, scarring and other problems that come with an open surgery."
The patient can expect post-procedure soreness for about two weeks, which is when Kendrick schedules follow-up visits. Even at that point, most patients are already reporting some change in their back symptoms and an improvement in balance and the time they are able to stand. The improvement generally continues for several months, with significant improvements within two months and slow, steady progress after that for up to nine months.
"Before the procedure, the patient has difficulty walking 250 feet," Kendrick said. "After nine months, patients are frequently able to walk at least three-quarters of a mile. So we see significant improvements in functional ability.
"One of our goals with this is to increase a patient's tolerance for exercise. When patients have had a chronic condition for while, they tend to get deconditioned. After two weeks, I send them for physical therapy to build them back up."
In addition to the improved functionality, patients report less pain. "They tend to be more comfortable across the board," Kendrick said. "They are able to stand and sit more comfortably. The patients tend to have lower levels of pain for the level of activity, and it tends to be a significant reduction in pain in addition to their ability to function. Typically we are talking about improvement in pain, not necessarily curing the pain."
Kendrick said MILD fits their treatment algorithm at Southside Pain Specialists. "Historically, we would give epidural steroids and patients would get relief, but frequently it was incomplete relief for a brief duration, and then the symptoms would return," he said. "MILD is a long-term option.
"This is a minimally invasive surgical option that we hope is going to decrease patient reliance on medications and other treatment modalities that sometimes are less effective, but it gives us a direction when a more open surgery is not necessarily going to be the treatment of choice."
MILD has been an option for about five years now. Medicare wanted further studies to evaluate the procedure. "Now we are seeing a reintroduction of MILD due to the good results of the studies," Kendrick said. "It still has a temporary code, so you have to stick to the protocols to have coverage. As a result, not many physicians are doing it aggressively, but we are seeing good results. It's going to become more frequently used over the next few years."