The human spine is a wondrous piece of machinery and a balky one. Most of us suffer back problems at one time or another, but f or the million or more Americans with damaged spinal discs, the pain is no mere annoyance. Some disc problems can make the act of sitting in a desk chair or car seat unbearable . And the traditional remedy-a costly surgical procedure called spinal fusion-is fraught with complications. Nearly 300,000 people endured the procedure last year alone, but the prospects for relief are improving. Early studies suggest that a new treatment called IDET (intradiscal electrothermal annuloplasty) works at least as well as fusion. The difference is that it takes about 15 minutes under local anesthetic. It costs $7,000 instead of $50,000. And patients walk out of the operating suite when it’s over. Says one veteran, “It’s not much worse than having a tooth filled.”
To understand the new treatment, you need a sense of how spinal discs work. Think of a healthy disc as a car tire made of tightly woven ligaments and filled with soft putty (chart). Sandwiched between two vertebrae, it makes a good cushion. Unfortunately, the ligaments encasing a disc can loosen and tear after several decades of service. And when that happens, outside blood vessels can invadde the disc, accompanied by nerve fibers that don’t belong in such a high-pressure environment. The problem is more complicated than a rupture, or “herniation, ” because the pain originates inside the disc, not in the adjacent nerves it touches. The standard treatment involves destroying the disc and using bone grafts to fuse the two vertebrae it separated.
IDET aims to achieve more by doing less. “We don’t throw out the tire, ” says Dr. Jeffrey Saal, a Stanford spine specialist and coinventor of the technique. “We patch it.” The secret is an instrument called SpineCath. Designed by Saal and his brother, Dr. Joel Saal, it consists of a six-inch needle and fine catheter with a heating element on the end. After tracing a patient’s pain to a particular disc, doctors insert the catheter through the needle and heat it to 194 degrees for 14 to 17 minutes. The heat not only kills the invading nerves but also tightens the surrounding ligaments, creating a new seal.
The technique is still in its infancy-only 700 patients have been treated-but the early results look promising. In small studies, roughly 80 percent of the recipients have enjoyed reduced pain and greater mobility, and half of those taking narcotic painkillers have ended up drug-free. No one knows how long the benefits will last; heat-treated discs may develop new tears over time. The beauty of IDET is that most patients will probably try it again.
March 15, 1999