Mayo Clinic performs minimally invasive treatment for degenerative disc disease

Monday, January 08, 2001

JACKSONVILLE, Fla., Jan. 8, 2001 — Physicians at Mayo Clinic in Jacksonville, Fla., have begun performing a new, minimally invasive treatment to relieve lower back pain caused by degenerative disc disease. Called IntraDiscal ElectroThermal Therapy, or IDET, the outpatient procedure is an alternative to spinal fusion.

Trauma or repeated stress on intervertebral discs can cause tears, or fissures, to develop in the outer portion of the disc. These fissures allow tiny blood vessels and nerve endings to grow into the damaged area. This doesn't happen in healthy discs. Standing, sitting or even bending forward puts pressure on these new nerves and may cause pain.

During the IDET procedure, the patient is awake but mildly sedated, and the involved area of his or her back is numbed with anesthetic. A physician inserts an X-ray-guided needle through the patient's back and into the damaged disc. The physician then threads a special catheter through the needle into the disc. Once in place, the doctor gradually heats the catheter to 90 degrees Celsius over 16.5 minutes. The thermal energy generated causes two reactions. It destroys nerve fibers that have grown into the outer portion of the disc, and it changes the structure of the outer disc, thickening it and essentially closing the tiny fissures.

Dr. Todd Sitzman, an anesthesiologist in the Division of Pain Management at Mayo Clinic, is part of a multidisciplinary team of physicians that evaluates patients who are candidates for IDET. He says patients must meet strict selection criteria that include: persistent back pain for six or more months; no pain radiating, or only minimally radiating, down the leg; unresponsive to aggressive nonsurgical treatments; a normal neurological examination; and no prior disc surgery.

Most importantly, patients must undergo radiologic studies to verify a damaged disc is the source of their low back pain. Dr. Douglas Fenton is a neuroradiologist at Mayo Clinic who performs these studies and the IDET procedure itself. "One of the key issues is that the disc being a source of pain is not well understood by the medical community," he says. "For a time, they didn't believe discogenic pain existed at all. It's been proven to exist, but we have to rule out all other causes of low back pain before entertaining this diagnosis."

A person's age also plays a role, directly and indirectly, in determining whether he or she is eligible for IDET. "Disc space narrowing is part of the aging process," Sitzman says. "And older patients can have further narrowing following trauma. Once the disc loses more than 50 percent of its height, it's hard to navigate the catheter within the disc. So procedurally, you might not be able to perform IDET."

"Discs are the cushions between the vertebrae," Fenton says. "Without these discs, you're a solid piece of bone. You don't have movement. What we're trying to do with IDET, especially in young patients and those with fairly well-preserved discs, is keep them from having possibly unnecessary surgical fusion so we can preserve that mobility."

Charles Allen, a factory supervisor who spends most of his day walking a concrete floor, suffered from low back pain for years. About the time the Nahunta, Ga., man turned 43, he says his pain got worse. "I had injections and medicine that worked for awhile," he says. "I like to farm when I'm not working, but I hadn't been able to in two years."

Allen was referred to Mayo Clinic where the team evaluating him concluded he was a candidate for IDET. Last August, Fenton performed the procedure on two of Allen's intervertebral discs. Five months after IDET Allen says, "I'm way better than before I had it done. I was living on pain medicine to work. I couldn't go without it."

Sitzman and Fenton both say it's important that patients like Allen be motivated and have realistic expectations about IDET. Pain may worsen for seven to 10 days following the therapy as the heated disc heals. Sitzman says postoperative pain should subside then, and patients should begin to feel the benefits of IDET within six to 10 weeks. Patients should achieve the maximum benefit from IDET six to nine months after it's performed.

"Even though it was just placement of a needle and a catheter, patients really have to think as if they've had surgery," Fenton says, explaining the postoperative requirements. If patients don't follow these postprocedural instructions, Fenton says they may have complications, including traumatic disc herniation.

Patients must rest for the first 24 hours and limit time on their feet to 15 minutes. They should apply ice to reduce local swelling and continue taking any preprocedural medications. In addition, they may take nonsteroidal anti-inflammatory medications. Over the course of the next few weeks to few months, patients may resume activities as instructed by their physician.

Those interested in the IDET procedure should call their primary care physician for a referral to the Division of Pain Management at Mayo Clinic.

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Media contact: Erik Kaldor 904-953-2299 kaldor.erik@mayo.edu

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