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Disc disease is one of the most common causes of chronic back and neck pain, and is thought to account for approximately 10% of all cases of lower back pain. Disc disease refers to damage to the inter-vertebral discs which support and cushion the vertebral bones of the spine; it can occur acutely due to trauma and injury, or can develop over time due to age-related degeneration. Disc disease results in extension of disc material outside of its natural joint space, allowing it compress adjacent structures. When disc material compresses adjacent nerves, it can cause pain in the back, neck, and upper and lower extremities.
The initial management of back pain tends to be conservative, relying large on pain relieving medications either purchased over the counter, or prescribed. Conservative treatments can also include injections and physical therapy. Pain persisting beyond four weeks, however, is considered chronic and may reflect disc-related disease.
Many cases of chronic disc-related pain can be treated by a procedure known as disc denervation (DD), which may also be called radiofrequency ablation. DD involves the use of radio waves to generate heat adjacent to pain-transmitting nerve fibers, effectively silencing pain signals from reaching the brain. With the DD procedure, an interventional pain specialist can identify and target fibers causing pain due to discogenic disease (Kosharskyy & Rosen, 2007). The procedure tends to work well for patients experiencing disabling, chronic pain for which other conservative treatment options have failed.
The spinal column is composed of individual vertebral bones which, in conjunction with cartilaginous inter-vertebral discs between each vertebra, provide a flexible, supportive structure for the body while simultaneously providing protection for the spinal cord which lies in a central canal within the column. The spinal column is divided into cervical (neck), thoracic (upper back), lumbar (lower back), sacral and coccygeal (tailbone) segments. Each vertebra contains bony protrusions termed ‘processes’ which are directed upward and downward to form facet joints when connected with processes from adjacent vertebra above and below. These facet joints help keep the spine connected, and provide a flexible joint to allow motion within the spine.
The facet joints are highly innervated; that is, these joints receive many nerve fibers which allow for communication between the joint and the brain. Many of these fibers are sensory, in that they can relay signals, such as pain back to the brain when the joint is damaged or compressed by disease of nearby inter-vertebral discs.
The inter-vertebral discs are tough, gel-like structures composed of a fibrous outer layer, the annulus fibrosus, filled with a viscous inner layer, the nucleus pulposus. Either due to acute trauma or degeneration with age and time, these discs have a tendency to herniate, or extrude outside of their disc joint space, allowing disc material to compress nearby structures such as the highly innervated facet joints.
Diagnostic injections with a local anesthetic can help predict which patients may stand to benefit from a DD procedure; if the block to the nerves of the facet joint relieves pain, then the correct nerve has been identified and radiofrequency ablation of the nerve is likely to provide pain relief long-term (Levin, 2007).
Preparation for the DD procedure involves properly draping and positioning the patient on a procedural table, and preparing the injection site through which the radiofrequency needle will be guided to the source of pain. Preparation of the injection site involves proper sterilization to reduce the risk of infection, as well as administration of a local anesthetic (numbing agent) to reduce any discomfort associated with the procedure.
During the DD procedure itself, an interventional pain specialist will guide a radiofrequency needle under fluoroscopy, or real-time x-ray, to a location just adjacent to the nerves conveying pain signals to the brain. Once properly positioned, the needle is connected to an electrical generator which induces radio waves at the tip of the needle. The oscillation of the waves generates heat around the tip of the needle which destroys nervous tissue and effectively denervates the disc while sparing surrounding tissues. Following the procedure, the needle is removed and a bandage is placed over the injection site. The procedure typically lasts under an hour, and after a short observation period to monitor for potential adverse reactions, patients can return home.
DD is a minimally-invasive procedure that can provide relief of discogenic pain, while having many advantages over alternative therapies. Compared to traditional, open surgery, no hospitalization or general anesthesia is required as the procedure can be performed under local anesthesia on an outpatient basis. Recovery time is almost immediate, as there is little discomfort following the procedure and patients can quickly resume day-to-day activities. The procedure also spares significant amounts of tissue via quick, effective access to the source of pain with a needle as opposed to an incision. Finally, if pain relief is inadequate, the procedure can be repeated with no additional risk.
Complications associated with DD are very rare. One study found the incidence of complications to occur in only 1% of procedures, with all complications being relatively minor- such as mild pain at the procedure site for a few days following the procedure. As with any medical procedure, however, the risk nonetheless exists for potential complications such as bleeding, infection or possible inadvertent nerve damage.
Denervation with radiofrequency waves has an extensive, two decade history of successful use within the field of pain management. In a large 2007 study, 68.4% of patients treated with lumbar DD reported good-to-excellent pain relief which lasted from 6 to 24 months (Gofeld, et al., 2007). The study concluded that DD of the facet joints provided long-term pain relief for an outpatient procedure. Other studies have found that DD results not only in pain reduction, but also improves patient mobility and function with daily activities (van Cleef, et al., 1999).
Further research into DD continues, however it has become recognized as an effective treatment modality for the treatment of chronic, discogenic back and neck pain.
- Gofeld, M., et al. (2007). Radiofrequency denervation of the lumbar zygapophysial joints: 10-year prospective clinical audit. Pain Physician , 291-300.
- Kosharskyy, B., & Rosen, D. (2007). Lumbar discogenic pain. Disk degeneration and minimally invasive interventional therapies. Anasthesiol Intensivmed Notfallmed Schmerzther , 262-267.
- Levin, K. (2007). Nonsurgical Interventions for Spine Pain. Neurol Clin , 495-505.
- van Cleef, M., et al. (1999). Randomized trial of radiofrequency lumbar facet denervation for chronic low back pain. Spine , 1937-42.