Diagnostic lumbar discography is a valuable and essential tool for studying the intervertebral discs. A significant portion of patients with chronic low back pain will have degenerative discs. MRI studies can clearly define the morphology but the most important consideration is the fact that not all degenerative discs are painful. Discography is the only technique that can identify both a degenerative disc and one that is a potential pain generator.
The annulus of the disc has nerve fibers, whereas no nerves have been demonstrated in the nucleus of the disc. The pain of provocative discography may be due to mechanical stimulation of pain fibers situated in the concentric layers of the annulus, which is the typical location of degenerative or traumatic changes.
Diagnostic lumbar discography must always be performed with a manometer that can measure both static and dynamic pressures within the disc. The provocation of concordant back pain at a variety of intradiscal pressures can reveal much about the structure of the disc.
Treatment options following diagnostic discography include IDET (intradiscal electrothermal therapy), nucleoplasty (percutaneous disc decompression). Information about these procedures can be found elsewhere on this website.
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Intradiscal Electrothermal Therapy (IDET)
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IDET (Intradiscal Electro-thermal Therapy) is a new, relatively non-invasive method for treating chronic back pain caused by intervertebral disc disease. Most Americans suffer back pain at one time or another. For the majority, the problem is short-lived and resolves with conservative therapy, such as rest, anti-inflammatory medications and physical therapy.
However, the pain may persist for more than six months in some patients and can cause significant discomfort, such that sitting in a chair or car seat is unbearable. For most of these patients, the intervertebral disc is the site of the pain.
Until the development of IDET, treatment options were greatly limited. Conservative care was disappointing in many patients. Surgical treatment included lumbar fusion, which typically is a costly and lengthy procedure requiring general anesthesia. Fusion of the spine is accomplished using bone graft or metal rods. Rehabilitation is demanding and good results are sometimes difficult to obtain, especially in patients with two or more degenerative discs.
Initial results from IDET are very encouraging. As of August of 2001 more than 45,000 patients have been treated with IDET in the United States. Results indicate in well-selected patients that at least 65-80% will obtain good to excellent results, and completely avoid the need for surgery. Complications have been very rare, and well below the rate occurring with operative techniques.
Development of the Technique
Several years ago, physicians at Stanford University Medical Center developed a flexible catheter that could be placed into the lumbar intervertebral disc. The catheter is heated to approximately 80-95 degrees Celsius for a defined period of time. Several theories have been suggested for how pain is relieved. Heating of the disc reorders and contracts the collagen fibers. The tightening of the fibrous structure of the annular tissue may also enhance the structure integrity of the damaged disc, while reducing the overall volume. Another postulated mechanism is denervation of nociceptive (painful) nerve fibers.
How are Disc Problems Diagnosed?
The best way to diagnose lumbar intervertebral disc disease is by careful history and physical examination. Many patients will complain of difficulty sitting and bending forward. Pain may radiate into the legs, but rarely goes further than the knees. MRI studies may indicate disc degeneration or annular tears. All patients who are considered good candidates for IDET undergo diagnostic pressure-controlled discography. During this procedure, contrast is injected into the lumbar discs to identify the source of the pain. A control disc must also be injected so that the results from the other discs are considered valid.
What to Expect During the Procedure
IDET is performed on an outpatient basis. Patients will have an IV started for administration of antibiotics and other medications. An anesthesiologist is usually present to ensure adequate sedation and pain control. Local anesthesia at the catheter insertion sites is used to further reduce pain.
After the appropriate level has been identified by fluoroscopy, a special needle is placed into the disc. Following this, an Oratec catheter is slowly advanced into the disc under fluoroscopic guidance. After the catheter is properly placed, it is heated using a well-defined protocol to 80-90 degrees Celsius. The patient is then observed for one hour in the recovery area and discharged.
Post-Procedural Rehabilitation
This could represent the most important part of the entire treatment protocol. Heating of the disc with IDET may cause an initial weakening of the structure. Therefore, it is very important that the patient wear a lumbar support for two months following the procedure. If the patient is doing well, then a gentle physical therapy program is initiated at week 8 to 9. Rehabilitation with careful supervision is continued for several months.
Summary
IDET is a very promising technique for treatment of painful lumbar spine problems that formerly were treated with expensive and invasive spine surgery. Initial results indicate that 65-80% of patients will obtain good to excellent pain relief, with minimal complications and at a considerable savings when compared to surgery.
Patient Selection Criteria for IDET:
* Pain greater than 6 months.
* Mostly low back pain.
* Pain worse with sitting.
* Minimal neurologic symptoms.
* No nerve root impingement.
* Negative neurologic exam.
* Concordant lumbar discography.
* Disc height no less than 50%.
* Negative response to injection and conservative therapies.
* Psycho-social issues are non-contributory.
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Nucleoplasty is a minimally invasive procedure for disc decompression, a principle used in the treatment of herniated discs for over 30 years and in over 500,000 patients. The difference between Nucleoplasty and earlier procedures is the unique Coblation¨ technology, which enables tissue removal with thermal treatment to achieve disc decompression quickly and efficiently. Coblation technology has been used successfully in over 1 million procedures since its introduction in arthroscopic surgery in 1995.
Disc decompression has been shown to treat symptomatic patients with contained herniated discs. By combining tissue removal with thermal treatment, disc decompression can be achieved simply and efficiently.
Nucleoplasty utilizes patented Coblation technology for ablating and coagulating soft tissue, combining both approaches for partial disc removal. Coblation ablates tissue via a low-temperature, molecular dissociation process to create small channels within the disc. On withdrawal, the channels are thermally treated, producing a zone of thermal coagulation.
The Nucleoplasty procedure is performed under local anesthesia and fluoroscopic guidance with the patient in a lateral or prone position. While monitoring the patient, a series of channels are created by advancing the Wand into the disc while ablating tissue. After stopping at a pre-determined depth, the Perc-D Wand is slowly withdrawn, while coagulating, to the starting position. The Wand is then rotated clockwise, and another channel is created. Approximately six channels are created, depending on the desired amount of tissue reduction.
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