Intradiscal Electrothermal Annuloplasty (IDET) is a minimally invasive treatment for chronic low back pain that results from certain types of painful degenerative disc disease or contained disc herniation. Successful IDET treatment may allow some patients to experience good or excellent pain relief without having to undergo major spinal surgery for disc removal and spinal fusion, or disc replacement.
The IDET treatment was first introduced in 1997 and has been performed extensively since then. The procedure involves inserting a catheter into the disc and heating it up. It takes about an hour and can be readily performed on an outpatient basis (with no overnight hospital stay). Several disc levels may be treated in a single session.
The exact mechanism by which IDET reduces disc pain is still under investigation. Proposed mechanisms include: thermal destruction of pain sensitive nerve endings in the posterior disc wall; heat induced contraction of collagen tissue within the disc wall that may seal up painful tears; stimulation of new collagen formation, and; destruction or alteration of inflammatory or pain mediators within the disc tissue.
The IDET Procedure
Prior to undergoing an IDET procedure, patients usually have a preliminary discogram test in which the lumbar disc or discs that are abnormal (as seen on an MRI scan) and thought to be the cause of a patient’s back pain are injected with dye. Discogram tests that reproduce the patient’s pain and demonstrate tears or small herniations on the posterior wall (in the back of the disc) may signify a disc that may respond to IDET treatment. Recent improvements in the discogram test utilizing pressure controlled injection equipment have allowed physicians to more accurately identify truly symptomatic disc levels.
More Back Pain Info
Once the symptomatic disc or discs have been identified, the patient is brought to the procedure suite and placed face down on the operative table. Intravenous sedation is usually given to relax the patient and relieve any discomfort during the procedure. A flexible catheter is inserted into the target disc under x-ray guidance and navigated into the proper position. The terminal portion of the catheter is placed along the posterior disc wall (the area of the disc that is thought to be painful), and then slowly heated to 90 degrees Celsius for 15 to 16 minutes. The catheter is then removed and the disc is injected with a small amount of antibiotic and anesthetic medication to lessen discomfort and the risk of infection. If the catheter cannot be fully advanced along the entire posterior disc wall, the thermal treatment is performed and then a second catheter is inserted from the opposite side and a second thermal treatment is carried out.
After the operation, patients are typically placed in a low back brace and advised to avoid activities that stress the low back. Analgesic medications may be given to control discomfort in the early recovery period. After two months of low back protection, patients typically undergo four weeks of physical therapy, emphasizing exercises that strengthen the supporting musculature of the lower back, and are then encouraged to resume their regular activities.
IDET Success Rates
Numerous studies have demonstrated that 50 to 60% of patients undergoing IDET experience good or excellent pain relief. A recent blinded, placebo-controlled study (the gold standard in medicine for determining the unbiased success rate of a given treatment) by Pauza, Howel, Dreyfuss, et al showed that 40% of patients undergoing IDET achieved greater than 50% relief of their pain. This was more than the 32% of patients who experienced greater than 50% pain relief after undergoing the sham treatment.
It is important to note that careful patient selection and meticulous placement of the IDET catheter appear to lead to higher success rates. Patients with less severe disc degeneration are thought to respond better to the IDET procedure than those patients with severe disc degeneration.
Potential Risks and Complications with IDET
There are minimal risks associated with IDET when it is performed by an experienced physician. Initially, it was thought that disc space infection, nerve root injury, post treatment disc degeneration or herniation, and post treatment increase in back pain were significant concerns. However, most published studies of IDET therapy have not reported any significant complications and the real risk of complications is now felt to be quite low.
Contraindications to IDET
Patient factors or anatomical features that have been associated with poor response to IDET treatment include:
- Significant reliance on narcotic pain medications either before or after IDET treatment
- Significant disc space narrowing
- Large disc herniations
- Diffuse disc degeneration
- Three or more symptomatic discs
While the exact mechanism of pain relief achieved by IDET therapy is still to be fully determined, and the treatment is not successful in all patients, the IDET treatment has been established as a safe, minimally invasive treatment that may provide a select group of patients with painful disc disorders pain relief without the risks of a major spinal surgery (such as a spine fusion or disc replacement). Careful patient selection and meticulous placement of the IDET catheter appear to lead to higher success rates in providing pain relief for patients.