Intradiscal Modulation

Treatment of Discogenic Low Back Pain (link to Degenerative Disc Disease) has traditionally been limited to either conservative medical management or open surgery. Surgical treatment including lumbar fusion or disc replacement surgery has yielded mixed results. Given the prevalence (very common) of this problem and the limited treatment options, the development of alternative treatment methods is the logical advancement of care. This has lead to the evolution of minimally invasive, fluoroscopically-guided, procedures as another step in the treatment algorithm for chronic discogenic pain. There are three types of minimally invasive intradiscal procedures discussed in the treatment of discogenic low back pain:

Thermal

 

Simply put, this involves the insertion of a radiofrequency probe into the posterior of your disc where the painful nerve endings are located. Then electrical energy is used to 'turn off' the nerve endings, thus decreasing the sensation of pain from your disc. For the lumbar and thoracic spine, there are currently three types of Intradiscal Thermal Modulation procedures available in North America:

1. Intradiscal Thermal Annuloplasty (IDTA); better known as Intradiscal Electrothermal Therapy (IDET)
2. Posterior Radiofrequency Ablation (PRFA)
3. Biacuplasty; otherwise known as Transdiscal

Traditionaly, the eligibility criteria for each mentioned thermal modulation procedure are as follows:

1. Age 18 to 65 years;
2. Low back greater than leg pain present for greater than 6 months duration
3. Failure to improve after at least 6 weeks of non-operative care (e.g. anti-inflammatory and analgesic medications and a physical therapy and/or home directed lumbar exercise program)
4. Low back pain exacerbated by sitting or standing and relieved by lying down
5. Less than 20% disc height narrowing on lateral plain film radiographs. In general, the disc pathology of IDDS is more appropriate than DDD.
6. Facet joint pain ruled out by a negative response to diagnostic blockade of these spinal joints under direct x-ray guidance.
7. Confirmation of “disc” pain at 1 or 2 levels by provocative discography.

Despite early promising results, no single approach has proven itself to be the definitive minimally invasive solution to internal disc disruption. The current leading technologies are IDET and biacuplasty. Each offers a modest rate of success for relieving severe low back pain associated with IDDS while avoiding the risks of major surgery. However, it should be noted that some patients do not experience any pain relief, and the long-term results of these procedures are not yet known.

IDET

The IDET procedure takes 30 minutes to one hour to complete. A specialized needle is inserted into thedamaged disc with the guidance of an x-ray machine. A special wire, called an electrothermal catheter, is then threaded down through the needle and into the disc. The wire is heated through electrical current over the course of about 16 minutes. The high heat destroys the small nerve fibers that have grown into the cracks of the disc and that transmit pain. The heat also partially melts the annulus (the outer wall of the disc), which theoretically triggers the body to generate new proteins to attempt to strengthen the disc.

During recovery, the patient must rest for a few days and may need to wear a back support for several weeks. Pain relief is sometimes seen within a few days of the procedure, or may take several weeks to several months to be noticed. During this time, medications can be prescribed to reduce pain. Physical therapy is necessary to help reduce pain and increase flexibility and spinal strength. In addition, it will be several months before rigorous activity, heavy lifting or twisting can be resumed. In time, however, the pain is expected to decrease and the need for medications can be reduced or eliminated. Activity levels can then increase as well as a return to an active life.

 

Intradiscal Biacuplasty

Fig 1. Illustration demonstrating a band of radiofrequency current between 2 Transdiscal probes.
Fig. 2 Intra-operative x-ray of the final placement of two Transdiscal probes.

Intradiscal Biacuplasty utilizes a bipolar system that includes two cooled, radiofrequency electrodes placed on the posterolateral sides of the outer ring of the disc (annulus fibrosus). Cooled radiofrequency may increase the lesion size and facilitate ablation (neurotomy of the nerve fibres in the back of the disc) compared to standard RF electrodes.

Biacuplasty is still in its early stages of clinical research. Early results are very encouraging. This procedure offers the advantage of being a much simpler operative technique than its predecessor, IDET. At the same time, the early studies have shown positive results that may be superior to those of IDET.

Intradiscal Modulation in BC

Although both IDET and biacuplasty have been approved by Health Canada, neither is currently being performed in BC. The Royal College of Physicians and Surgeons of British Columbia is well aware of the potential benefits (demonstrated in early trials) of these procedures for patients with discogenic low back pain. However, the College of B.C. has recommended waiting until further supportive studies (Clinical Trials) have been performed, before offering such treatment to its residents. The Royal College of Physicians and Surgeons of BC considers the safety and well being of both its patients and physicians its top priority.

Currently, randomized controlled trials (high quality studies) are being performed in the U.S. and Canada. In the meantime, Dr. Helper is performing the necessary diagnostic work-ups for patients with discogenic low back pain. If patients are found to meet the strict qualification criteria for Intradiscal Modulation, they will have the option of being referred A) to a qualified practitioner who regularly performs the procedure, or B) to one of the academic study centres to participate in the ongoing clinical trial.

Chemical

Theoretically, if a drug or chemical compound could block nerve endings or stabilize the inflammatory process, it may potentially be beneficial in the treatment of discogenic low back pain. Some practitioners believe it is reasonable to use intradiscal injections (injections into the disc itself) for alleviating discogenic low back pain. Two compounds that have received considerable attention are:

Intradiscal Methylene Blue (MB)

Based upon the pathophysiology of disc degeneration, scientists hypothesized that if the nerve fibres and nerve endings growing into the disc along annular tears could be destroyed, discogenic pain would be alleviated. This is the basis for the recent investigation of methylene blue, a chemical capable of seeking and destroying nerve endings.

Early studies on the use of Methylene Blue in patients with IDDS (Internal Disc Disruption Syndrome) are very encouraging. One randomized controlled trial showed MB to be both safe and efficacious. Further studies are necessary to fully understand the benfits of Intradiscal Methylene Blue (MB) .

Intradiscal Corticosteroids

Basic scientific studies have identified enzymes and inflammatory mediators in degenerated disc tissue specimens. Thus, because of their anti-inflammatory properties, o]ne can rationalize the use of corticosteroids in the treatment of discogenic pain (Specifically, DDD),

Studies investigating the efficacy of intradiscal corticosteroid injections have yielded mixed results. A review of the literature shows that if you inject steroids into the disc of every patient with the diagnosis of discogenic low back pain, the outcomes are unimpressive. However, if you are choosy about which patients are offered intradiscal corticosteroids, the results are much more encouraging! It seems patients with moderately severe DDD with inflammatory endplate changes (seen on MRI) have a much better chance of obtaining sustained relief from the procedure. Thus, the selective use of intradiscal corticosteroid injections is a viable option in discogenic low back pain patients.

Biological

This category remains experimental. It refers to the Holy Grail of spine medicine. Scientific studies are ongoing for the development of medical compounds that actually "heal" disc degeneration/injury. While the problem remains unsolved, science is creeping closer everyday. In fact, a multi-centre randomized controlled trial (RCT) is currently being performed in the United States evaluating one of the most encouraging products in development (see Clinical Trials).

Conclusion: Intradiscal Modulation

Intradiscal modulation (thermal, chemical, biological) represents a very exciting step in the potential treatment of both IDDS and DDD. Remember, there are very strict criteria determine whether a patient is a candidate for Intradiscal Modulation. It is not an option for all patients with discogenic back pain. You should discuss the specific criteria with your specialist physician.