The problem of utilizing the effect of thermal injury to the disc was how to deliver sufficient energy safely to the disc. Laser probes generate high temperatures that result in vaporization of the disc material. Pure radio frequency probes within the disc also fail to heat the disc as it has high resistance and any heating effect is rapidly lost. The Spine CATHTM however allows precise intradiscal navigation via a 17–gauge needle, of a resistive heating coil. Using the navigation capabilities of the catheter the coil can be placed within the posterior part of the annulus, the likely site of the painful inflammatory tissue associated with the painful spinal segment. The procedure is performed under intravenous sedation using fluoroscopic control. Needle insertion and the heating protocol take between half to one hour. Throughout the procedure any risk of misplaced catheters heating normal neural structures is reduced, as the patient is awake and can report radicular pain.
The pilot study performed at Stanford University by Saab and Saal, (NASS, 1998 and Spine, in press) included a group of thirty–six patients who were to undergo fusion surgery but instead elected Intradiscal Electrothermal Therapy. Results revealed 72% of patients achieved statistically significant improvement in function, as measured by the SF36 outcome assessment, and 80% of patients achieved statistically significant reductions in pain as measured utilizing VAS scores.
Spine CATHTM has been used in a clinical setting for three years and the early results are promising. As with any new device correct patient selection, surgeon training and careful follow–up are required. Joel and Jeff Saal from Stamford University, are the pioneers of this technique and their experience has been used to forward the use of this catheter. Although it requires a degree of technical skill, it remains a safe technique in trained hands, and one that will surely take it’s place as a standard method of treating painful degenerative disc disease affecting the lumbar spine.
From A Surgeons View!
For a spinal surgeon who is performing the Intradiscal Electrothermal Therapy procedure, it is technically only a little more difficult than discography. The procedure is tolerated well by patients, and the reduced bed occupancy, reduced implant costs and ease of nursing are making it a popular procedure. This is clearly an intervention that has to be reserved for patients who have a likely discogenic cause of their pain.