Intradiscal Electrothermal Therapy Promising in Select Patients with Chronic Lower Back PainA common technique used to treat chronic lower back pain (CLBP) is intradiscal electrothermal therapy (IDET), also called intradiscal electrothermal annuloplasty. IDET is chosen for select patients in an attempt to avoid surgical interventions to treat CLBP.
Using heat to treat intervertebral discs is supported by the success of using heat in shoulder repairs, making shoulders more stable. Although the mechanism is not completely understood, theories of its function include alteration of biomechanical properties of the vertebral segment from the heat, decreasing stiffness; contraction of collagen leading to decrease in disc herniation size; sealing of annular tears; denervation; and decreased intradiscal pressure.
IDET is accomplished with a few different techniques. In general, a catheter is introduced into the annular fissure and heat is applied. Following treatment, patients are generally monitored for one to three hours and are warned that a slight increase in pain may occur, lasting from two to seven days. In some cases, this may be longer. Patients often wear braces and, although they are encouraged to do exercise, such as walking, they are not given physical therapy for at least one to two months. Maximal improvement seems to be by three months following procedure, but may take up to six months. Many patients are still experiencing some sort of relief as late as two years after the procedure.
The authors of this article searched the literature for studies and reviews of studies examining the efficacy of IDET in the treatment of CLBP. One meta-analysis of 17 studies involving IDET, with a follow up of six to 24 months following the procedure, there was a mean decrease in pain as measured by the Visual Analog Scale (VAS), which measures pain on a scale from zero to 10, with zero being no pain and 10 being the worst pain possible. In this meta-analysis, pain was reported to drop by 2.9 points. Using the Short Form 36 (SF-36) to measure function, the researchers found a decrease in pain of 18 (out of 100), as well as a mean decrease in the Oswestry Disability Index (ODI) of 7.0 (out of 100). The authors of this meta-analysis concluded that there was compelling evidence of IDET's efficacy and safety in treating CLBP.
However, another meta-analysis, which has since come under criticism, looked at the same studies but came to a different conclusion. Although these authors found a mean improvement in the VAS of 3.4 and an ODI improvement of 5.2, plus the notation that only 13 percent to 23 percent of the patients went on to have surgery, the author concluded "the evidence for efficacy of IDET remains weak and has not passed the standard of scientific proof."
Other reviews agreed with the first mentioned above. One found that measurements of 18 IDET studies had similar outcomes to patients in 33 studies of patients who underwent spinal fusion.
When looking at randomized, controlled trials, the authors found that carefully selected patients, those with SF-36 pain scores of 36 and disc protrusions that did not exceed 4 mm, did show a statistical difference in VAS (7.4) to the control group (4.9) There was no statistical difference in the SF-36, however, 33 percent of patients in the control group worsened, compared with only six percent in the IDET group.
Observational studies report a mixture of findings. In some studies, there was a decrease in VAS among IDET patients, while in others were more positive.
Complications to IDET are a possibility but are not frequent. One retrospective study of 1675 IDET procedures plus an analysis of data from 35,000 catheters, found only six nerve root injuries were reported, six cases of post-IDET disc herniation, 19 cases of catheter breakage, 8 cases of superficial burns at the entry point and one case of post-IDET bladder function. Infections and neural injury have been reported as well.
The authors conclude that IDET is a minimally invasive technique that provides a modest improvement but in a safe method than other invasive therapies.
Richard Derby, MD, et al. Evidence-informed management of chronic low back pain with intradiscal electrothermal therapy. In The Spine Journal. January/February 2008. Vol. 8. Issue 1. Pp. 80-95.
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