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Intradiscal Electrothermal Coagulation Therapy
(IDET)


Few minimally invasive procedures have burst upon the scene with as much good press, hoopla and hype as IDET (since the advent of chemonucleolysis with chymopapain).

The image above from the March 15, 1999 issue of Newsweek on IDET does an excellent job of illustrating the procedure but is IDET really an alternative to fusion as the article suggests?
There is no question but that intradiscal electrothermal coagulation therapy (IDET) is minimally invasive and carries with it significantly less patient risk than many other "minimally invasive" therapeutic modalities.  With IDET the major liability is that it won't really accomplish adequate pain relief and its associated small risk of intradiscal infection (discitis).  These risk factors are certainly minimal if compared to the potential risks of other so-called "minimally invasive" procedures:

Epidural Steroid Injection- if injected materials are neurotoxic (i.e. contain glycols) and these get into the subarachnoid space a lifetime of agonizing pain due to adhesive arachnoiditis is possible.  Epidural steroid injection with neurotoxic agents has not yet ( remarkably) "fallen into disuse."

Chemonucleolysis with Chymopapain- if chymopapain is inadvertently injected into nerves or the subarachnoid space nerve injury, paraplegia and stroke are possible.  It was because of complications such as this that the use of chymopapain "fell into disuse."
The image to the left (below) shows an area of disc degeneration (high intensity zone annular tear) shown on MRI which is reflected in the pathologic specimen to the right.
 When normal healing occurs there is ingrowth of granulation tissue accompanied by C class pain conducting fibers which are not normally present.
Courtesy of Wm. Kirkaldy-Willis
The four images above are direct intradiscal endoscopic photographs of tears and fissures within degenerated discs into which granulation tissue has grown.  The the lat image to the right a green dye has been used to identify the granulation tissue.  Special staining for C fibers documents their ingress into the disc with the granulation tissue.  The images shown are from the Editor's collection.


The purposeful coagulation of abnormal C pain fibers in discs is something which has been practiced for many years.  Dr. Steven Vitaly, Moscow, Russia reported on a series of 5,000 cases in which intradiscal alcohol was injected to produce C fiber coagulation.  The use of a RF catheter electrode intradiscally simply extends well-established RF coagulation of facets into a new territory.  IDET may also have some benefit in constricting deranged collagen fibers.  It's real value however, clearly seems  to be directed to the management of discogenic pain in individuals where significant segmental dysfunction or instability is not present warranting a stabilization procedure.

Is IDET a Primary Procedure?

Although minimally invasive, IDET is still a very expensive and invasive procedure and has the liability of not yet being associated with long-term data on efficacy.  Because of this it is not a primary treatment modality as long as there are alternatives where less will suffice and cost is significantly less.  When these other modalities have failed IDET might then become a reasonable next step in addressing single level discogenic pain.  Often provocative discography will not only help in identifying the good IDET candidate (as well as the IDET failure patient whose next step may be stabilization by surgery).  For those in whom there is also significant pain being generated by an associated facet syndrome IDET might be better used in association with facet injections or RF Facet blocks. 

Does IDET replace Fusion?

The key to attempt to answer this question relates to the criteria under which a stabilization procedure is considered or performed and what the surgeon means by the term fusion? At one end of the scale are surgeons who consider any degenerated disc appropriate grounds for rigid multi-level instrumented surgery as the primary form of patient therapy. 
 Some routinely even perform 5 level 360o fusions on patients with juvenile discogenic disease.  The majority of patients with degenerative disc problems can be effectively treated without invasive procedures.  Most certainly, the use of acute health measures followed by self-administered health maintenance programs allows the natural healing processes to progress in most cases.  It is when these fail that interventional measures such as IDET may become reasonable.  For spine surgeons who exercise judgment based on the patient's best interest, rather than their own IDET has value in helping to screen potential surgical candidates.  In the final analysis however persistent significant segmental dysfunction and/or instability can only be corrected in today's spine care with some sort of stabilization procedure be it rigid or flexible.  The day of the artificial disc is not yet upon us and, if early indications can serve as a guide, there is a great deal of homework remaining to be done in this area before the concept becomes a practical reality.

     Summary
IDET may be a reasonable procedure to consider in a selected patient with single-level discogenic pain who has not responded to more cost-effective non-invasive care.  IDET is not the treatment of choice for disc herniation, significant segmental dysfunction or instability or spinal stenosis.  IDET's efficacy is less in previously operated discs, "transitional" syndromes, and in multilevel discogenic problems.  Because IDET is a relatively expensive (about $6-10,000.00)  procedure cost-effectiveness must also be carefully considered.

IDET addresses discogenic pain.  Patients with degenerated segments typically also have pain related to facet joint dysfunction.  IDET combined with PRFFNB may be the most effective non-operative treatment combination.  This may be particularly true for "high-intensity zone" annular discal tears.  A emerging concern with IDET, however,  has been the attempt, by "feral" practitioners to misrepresent this therapy as a means of achieving procedure payment.  Shown below is an actual operative report from a non-surgeon pain management specialist which was represented as, and billed for, "surgery."

The patient needs to look at these procedures as if they were paying for them out of their own pocket and become a discrimination consumer.  Many patients who undergo invasive procedures have not adequately experienced true non-invasive "conservative care" combined with adequate following preventive measures.

As of 2003 it is clear that IDET isn't an alternative to "fusion", hasn't yet gained the acceptance of third party payors, and has not yet established itself as a cost-effective generally accepted therapy for back pain.  As one specialist stated: "The reason IDET has gotten a bad name in the community is that people are doing it on everyone" (McGough: Health Journal, Wall Street Journal, February 11, 2003).