The loss can mean gelatinous disk innards start bulging out, pressing on nearby nerves and causing pain in the lower back and legs, says Dr. Jeffrey A. Stone, chief of the Section of Interventional Neuroradiology at the Medical College of Georgia.
"What happens is over time, just because we stand upright and put a lot of abuse on our spines, the disks go through the aging process. So as you get 35 or 40, simple trauma, even a twisting motion like tennis or golf, sometimes will stretch it and sometimes you will get a tear in the disk's outer covering called the annulus," says Dr. Stone, who likens that cover to a leather sack.
The good news is that today many painful bulges can be treated without even an incision, says Dr. Stone, who will give an update on percutaneous diskectomy May 2 during the 44th annual meeting of the American Society of Neuroradiology in San Diego.
This latest approach to treating disk herniation uses X-ray to guide insertion of a needle through skin and muscle directly into the offending disk and eliminate the portion of the bulging nucleus that is causing pain, Dr. Stone says. Patients receive local pain relief at the injection site and enough anesthesia to relax but remain awake so they can report any pain they experience. After accessing the disk, the puncturing stylet is removed so the needle then functions as a cannula through which devices are inserted to vaporize or suction out excess gelatinous substance. "The goal is to reduce the pressure and inflammatory factors in the disk with a minimal amount of removal," says Dr. Stone.
"As we remove nucleus, the pressure inside goes down so the pressure on the outside of the disk decompresses," he says. "You are basically making a smaller disk so it's not pushing on surrounding structures. So, there is a degree of immediate relief."
Within two weeks, most patients say they are 50 percent to 60 percent better and by three months, they are 80 percent to 90 percent better. Although doctors can't definitively explain this secondary improvement, they suspect it's related to a change in the mix of inflammatory factors over time that results in more healing factors and fewer destructive ones.
The approach is similar when doctors inject inflammation-reducing steroids and anesthetic as a more short-term solution to pain. It's less invasive than the endoscopic approach that requires a small incision in the back, drilling out a small piece of bone to access the disk and remove the herniated portion, then closing the incision in the back, Dr. Stone says.
He notes that percutaneous diskectomy does not preclude surgery if still needed for pain relief and said it is not a panacea for back pain – a leading cause of disability and doctor visits – which can have multiple causes.
Ideal candidates for percutaneous diskectomy typically have more leg pain than back pain because the bulging disk is pressing on a nearby nerve and/or causing inflammation that results in referred leg pain, Dr. Stone says.
To identify the best candidates, he may do a procedure that puts pressure on the disk to see if that causes pain or try the approach of locally injecting steroids and anesthetic to see if that relieves pain. He notes that some patients experience long-term relief from just the injections. In fact, a national study is comparing the long-term effectiveness of the minimally invasive surgery to injections alone.
The lower, or lumbar, disks are the most common area of herniation. "The spine isn't a straight up-and-down structure so pressure is not equally exerted on all disks," says Dr. Stone. Consequently the lower back is a big stress area best suited for percutaneous diskectomy.
He will teach other physicians how to perform the procedure at the July summer workshop of the American Society of Interventional and Therapeutic Radiology.
Dr. Stone, a paid consultant and instructor for a company that makes devices used in this procedure, regularly teaches the technique across the country.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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