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Ablation therapies involve the manipulation of energy to destroy any abnormal tissue that may be causing pain or disease, and is used for the treatment of a wide variety of medical conditions1. The manipulation of energy used in ablation (destruction) can take the form of heat (thermal), cold (cryo), lasers, chemicals and electrical pulses created by radio waves (radiofrequency). Radiofrequency ablation (RFA) is a minimally invasive surgical technique in which electricity is pulsed to generate an electrical field that can interfere with impulse transmission in specific nerves that carry pain signals, or generate heat with which abnormal tissue can be destroyed2, 3, 7. RFA is the most common ablation technique for a variety of tissues, including those of the bone, kidney, liver and heart, and was initially indicated for the treatment of conditions that were inoperable or in which surgery would be too traumatic7. With advances in technology and the understanding of many diseases, the indications for RFA as a medical treatment have expanded. RFA’s widespread adoption today is largely due both to its broad array of uses, and the safety of the energy source7.
During RFA treatment, radio frequencies are delivered to tissue via an electrode connected to a voltage generator. The electrical energy generated causes movement in the molecular components of cells, leading to friction and the generation of heat7. Tissue is then ablated as temperatures exceed 60° C. RFA is easily targeted, and since it causes heat in the cells themselves as opposed to the electrode, damage is minimized to adjacent tissues and complications are minor and rare.
RFA can be applied in two ways; (1) as a continuous stream of energy, which tends to generate very high temperatures and thermally destroy targeted tissue, or (2) as pulses of energy which generate lower temperatures and less tissue destruction, and can be utilized to create stronger electrical fields and disrupt the electrical transmission of nerve signals5. Continuous RFA can be delivered at low frequencies to reduce heat generation for more sensitive tissues, or can be cooled with simultaneous injection of saline9. In continuous RFA, the goal is the destroy portions of nervous tissue with heat, and has the broadest effective applicability of the two applications5, 6. Pulsed RFA generally isn’t as effective as continuous due to lower temperatures, but it’s associated with fewer side effects5.
The spinal column consists of several bones, called vertebrae, which are stacked atop one another from the pelvis to the base of the skull, forming a protective channel for the spinal cord24. There are 33 of these vertebrae divided into five regions: (1) cervical, which are found in the neck closest to the skull (identified as C1-C7), (2) thoracic, found along the upper back (identified as T1-T12), (3) lumbar, found along the lower back (identified as L1-L5), (4) sacral, which are contiguous with the pelvis or hip (identified as S1-S5), and (5) coccygeal, which are fused as the tailbone.
Vertebrae are connected to one another by two facet, or zygapophysial, joints located on either side of the bone. Facet joints connect the superior articular process, or upward-directed portion of one vertebra with the inferior articular process, or downward directed portion of the vertebral bone above it24. When combined, these two vertebrae, along with the inter-vertebral disc cushioning in between the bones, form a spinal segment. Facet joints assist with spinal weight bearing, prevent the sliding of vertebral bones on top of one another, and limit spinal extension and rotation6. The facet joint is a common joint associated with chronic pain that is amenable to RFA treatment2, 3, 4. Cervical facet joints may refer pain to the head, neck and shoulders, thoracic facet joints may radiate pain to the upper back, middle back, and chest wall and lumbar facet joints may refer pain to the back, buttocks, and thighs4.
RFA is often used in the management of spinal and neuropathic conditions, which can manifest as chronic headaches, or pain of the lower back and neck3. In most cases, back and neck pain resolve with time and conservative treatment, however some patients may develop chronic pain2, 4. The rationale for RFA in the treatment of these conditions is to damage and deactivate nerves that carry painful stimuli to the brain3. RFA has been indicated for the treatment of the following chronic conditions2, 3, 5
Sacroiliac (SI) Joint Pain
The SI joint connects the spine and the pelvis at the base of the back. Improper function of this joint can cause pain in the lower back, buttocks, groin, thighs and legs, which can lead to difficulty sitting, standing, walking, lying, bending and lifting8. This dysfunction can occur as a result of injury, with potential causes including motor vehicle accidents, sports injuries, work injuries, leg length imbalance, arthritis, joint infection, gout, pregnancy and more8, 9. For SI joint pain refractory to conservative treatments, RFA offers the possibility to destroy the nerves responsible for transmitting pain from the SI joint8, 9.
A meta-analysis of multiple research studies concluded that RFA was an effective treatment for SI joint pain, with continued relief demonstrated for half of study participants 6 months following the procedure9. Pain relief may diminish over time, however, due to normal nerve regeneration.
Trigeminal neuralgia (TN)
TN is a common cause of facial pain, particularly in the elderly, that manifests as intermittent attacks of intense, sharp or stabbing pain distributed along branches of the trigeminal nerve which carries sensory stimuli from several regions of the face13. For patients who fail to receive adequate pain relief from pharmacologic therapy, RFA may be a reasonable alternative. The target for RFA is the trigeminal ganglion (cluster of nerve cell bodies) or root located just inside the skull13. Continuous RFA offers best chance for complete pain relief compared to other surgical interventions, including pulsed RFA5.
Cervicogenic headache refers to any headache that accompanies, or originates from, any primary neck disorder14. With cervicogenic headaches, the first three cervical spinal nerves can refer pain to the head due to pathology of vertebral joints, particularly facet joints. A diagnostic nerve block that provides symptomatic relief may be an indication for RFA as an appropriate treatment depending on the location. RFA is only recommended for the treatment of referred pain stemming from the facet joints between vertebrae C2 and C314.
Cluster headaches occur periodically and can cause immense pain for afflicted patients. RFA of the sphenopalatine ganglion in the head has also shown promise for the treatment of episodic cluster headache
Low back pain
It’s been estimated that as many as 5% of the population are experiencing low back pain at any given time, and that up to 60-90% of individuals will experience low back pain at some point in their lifetime10. While most instances of low back pain will resolve in a few weeks on their own or with conservative treatment, such as rest and anti-inflammatory medications, some cases persist as chronic low back pain.
Two common sources of chronic low back pain are indicated for treatment with RFA; (1) lumbar radicular pain of the low back and legs stemming from compressed nerves, and (2) pain from lumbar facet (zygapophysial) joints5, 10. The cause of pain at the facet joints is unclear, but could involve direct innervations, mechanical or vascular changes to the joint10.
Studies of RFA for the treatment of lumbar radicular pain have been promising, suggesting that RFA is viable for short-term relief of pain until nerve regeneration occurs- at which time the procedure can be repeated or alternative treatments can be investigated6. Additionally, no serious complications have been reported as a result of this procedure.
RFA for the treatment of lumbar facet joint pain focuses on ablating the medial branches of the dorsal rami, located near the affected facet joint10. One review reported 90% patient satisfaction following RFA for facet joint-related low back pain one year following the procedure10. The same review referenced another series of studies reported procedure success rates ranging from 50-98% within one month following RFA, and 50-92% six months following RFA.
Radicular pain can also stem from compressed nerves near cervical vertebrae, which can manifest as pain in the neck, shoulder and upper extremities2, 3, 5. Pulsed RFA applied to medial branch nerves, has been shown to be effective in reducing cervical radicular pain and improving patient function2, 4.
RFA is also recommended for a variety of other painful conditions that are not specific to the musculoskeletal system or spine:
Varicose veins and venous insufficiency
Varicose veins are veins that become twisted and engorged with blood, which can subsequently cause pain and cosmetic deformity. When the deformity compromises the ability of venous blood to flow toward the heart, a patient is termed to have venous insufficiency. RFA is a minimally invasive treatment available to ablate insufficient (or incompetent) veins21. In the UK, RFA has been approved for the treatment of varicose veins, and has been associated with fewer complications and faster recovery times than more traditional surgical techniques11.
Obstructive sleep apnea (OSA)
OSA occurs when breathing stops for short periods during sleep as the result of airway narrowing or blockage, and is associated with many medical disorders. A common symptom of OSA is snoring, which can cause social discomfort and interfere with sleep12. RFA of the soft palate can reduce the amount of tissue around the airway, widening the space for airflow. RFA treatment on the soft palate has shown promise in reducing snoring and potential progression to OSA12.
A cardiac arrhythmia refers to a problem with the rate, or rhythm of a heart beat; it can beat too fast, too slow, or irregularly15. Certain cells of the heart automatically stimulate the organ to beat at a certain rhythm and rate, even without input from the central nervous system. If these cells become abnormal or pathologic, they can disrupt the normal beating of the heart. The treatment of choice for this condition is to destroy, or ablate these dysfunctional cells. Today, RFA is the energy source of choice for catheter ablation of cardiac tissue in the case of arrhythmias, particularly those responsible for increasing heart rate16.
Barrett’s esophagus refers to abnormal changes to the cells the line the esophagus, often as the result of gastric esophageal reflux disease17. Barrett’s esophagus has clinical significance in that these abnormal changes are strongly associated with further progression to esophageal adenocarcinoma, which can be a lethal cancer. Many studies suggest that RFA is very effective at removing these abnormal cells to prevent possible cancerous progression, and provides a better alternative to more traditional treatment methods which involved surgical removal of affected portions of the esophagus17.
RFA has been shown to be effective in reducing the tumor burden of both primary cancers (the original cancer local to affected tissue) and metastases (spreading of a primary cancer to other tissues and organs) 7. In fact, RFA is largely considered superior to other ablative techniques in cancer treatment, likely because cancer cells are more susceptible to heat which is generated by continuous radiofrequency stimulation.
Bone tumors can cause pain and swelling, and predispose patients to increased fracture risk from trauma22. The bone is also a popular location for the spread of cancer from other tissues and organs (metastases), such as breast, kidney, lung, prostate and thyroid cancers. RFA is used to treat a wide variety of primary and metastatic bone tumors7.
Surgical resection of lung tumors requires an invasive procedure which can take a large toll on cancer patients. RFA has shown potential as a minimally-invasive treatment of patients with primary non-small cell lung cancer and metastases from adjacent lung tissue and other organs, for patients who are not candidates for traditional surgical resection18.
Hepatocellular carcinoma is an aggressive, primary cancer of the liver. Local ablation is the treatment of choice for patients with smaller tumors that are not amenable to surgical resection, and for patients that do not qualify for, or are waiting for, a liver transplant19. Studies have shown RFA to be more effective than other ablation or injection alternatives for the treatment of small liver tumors.
Renal cell carcinomas represent 80-85% of all kidney cancers20. The treatment of choice for removing renal cell tumors is surgical resection. Although the long-term effectiveness of RFA for destroying tumors in renal cell carcinoma hasn’t been established, it may provide a minimally invasive alternative to conventional surgical resection20
Pancreatic cancer is deadly, and improving long-term survival is difficult and reliant upon major surgical resection (cutting out) of the organ25. Although more research is needed, RFA is emerging as a feasible, and well tolerated, treatment option for pancreatic cancer when performed by experienced providers.
Diagnosis of anatomical problems leading to chronic pain in the back and neck can be very difficult, as most pathology can’t be seen with radiologic imaging6. In many cases, the only method for determining an exact causal location is for a physician to elucidate likely locations via characteristics of the pain, and perform an injection to chemically inactivate the nerve as an initial trial for pain relief. The diagnosis is confirmed if this nerve ‘test block’ relieves the chronic pain10.
Once a diagnosis is made for which RFA is an indicated treatment, the procedure is scheduled. During the procedure, the patient will be positioned and draped in such a manner as allows for easy access to any tissue targeted for RFA, and the skin through which radiofrequency needles will be inserted is sterilized7. Depending upon the tissue, a patient is then completely sedated or injected with anesthetic to numb the area and avoid any discomfort from the procedure. A small incision is made with the scalpel though the skin, and an appropriately sized electrode (depending on the amount of ablation needed) is selected and guided to the target tissue using ultrasound, or more commonly, fluoroscopy (a real-time x-ray), so that the inserted needles can be guided in real-time to a precise destination7. For bone cancers, drilling may be necessary to gain access to the target tissue.
Once the electrode is placed, it is connected with an external generator which is grounded to the patient’s skin7. Activation of the generator delivers radiofrequency stimulus to the tissue. To avoid potential complications, a small stimulus may be applied before ablation to ensure that no motor fibers are affected6. Once ablation is complete, the electrode can be kept active as it’s removed to cauterize tissue, and in the case of tumor ablation, prevent spreading of any invasive cells7. After the procedure, a type of cement can be injected through the incision and soft tissue channel to stabilize bony tissue (especially if weight bearing), and anesthetic can be injected to provide for immediate pain relief6, 7.
Even though RFA is minimally invasive compared with many alternative surgical procedures; it still carries certain risks of side effects and complications3. Potential side effects following an RFA procedure can include4:
- Abnormal skin sensation in areas innervated by the ablated nerve
- Increased skin sensitivity to stimulation in areas innervated by the ablated nerve
- A temporary increase in pain from inflammation of nervous tissue near the ablation site
- In the treatment of TGN, a loss of sensation in the face while the original pain remains; also known as anesthesia dolorosa
- Collapsing of the lung when treating lung tumors
- An increase in pain caused by disconnection of an ablated nerve from the central nervous system
- Unintentional damage of motor nerves which are involved in motion rather than sensation
Other possible side effects of RFA, although which have yet to be specifically reported in research studies, include4:
- Reflex of involuntary portions of the nervous system that can temporarily induce dizziness or fainting spells
- Skin burns from the radiofrequency electrode
- Allergic reactions to chemicals and instruments used during the procedure
- Unintentional damage of nearby vessels, nerves and tissues adjacent to the site targeted for ablation
Infection and bleeding are also risks during any surgical procedure. It should be noted, however, that complication rates for RFA are approximately 1% on average, and of those complications, the vast majority are relatively minor4.
Musculoskeletal and spinal problems, particularly low back pain, are common causes of disability. RFA is increasingly being used in the treatment of chronic pain that may not respond to other, more conventional treatments3. While RFA has shown promise as a long-term solution for many etiologies of chronic pain, it may not represent a permanent solution; reductions in pain can fade with time, however repeated procedures have been shown to be successful in these cases6.
RFA is a treatment with wide utility in medicine, particularly for the management of chronic pain. Experience and new technology has expanded the usefulness of RFA and improved treatment outcomes in recent years7. Treatment of chronic pain using RFA is a relatively new field, however, and more investigation is warranted to expand the effectiveness of RFA, and explore new indications for treatment which may yield improvements in patient quality of life.
Mayo Clinic. Ablation therapy. Retrieved from: http://www.mayoclinic.org/ablation/types.html. Accessed March 15, 2012.
Niemisto L, Jousimaa J, Hurri H, Kalso EA, Malmivaara A. Radiofrequency denervation for chronic neck pain (Protocol). Cochrane Database of Systematic Reviews 2010, Issue 7. Art. No.: CD008573. DOI: 10.1002/14651858.CD008573.
Niemisto L, Jousimaa J, Hurri H, Kalso EA, Malmivaara A. Radiofrequency denervation for chronic low-back pain (Protocol). Cochrane Database of Systematic Reviews 2010, Issue 7. Art. No.: CD008572. DOI: 10.1002/14651858.CD008572.
Boswell, M.; et al. (2007) A Systematic Review of Therapeutic Facet Joint Interventions in Chronic Spinal Pain. Pain Physician. Vol. 10, 229-253.
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ExitCare. (2011). Sacroiliac joint dysfunction. MD Consult Web site, Patient Education.
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Shepherd, A.C.; et al. (2010) Randomized clinical trial of VNUS ClosureFAST radiofrequency ablation versus laser for varicose veins. Brit J Surg. 97(6). 810-818.
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National Heart Lung and Blood Institute. What is an Arryhthmia?. Retrieved from: http://www.nhlbi.nih.gov/health/health-topics/topics/arr/. Accessed March 17, 2012.
Ganz, L. (2011). Catheter ablation of cardiac arrhythmias: Overview and technical aspects. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
Bergman, J. (2012). Radiofrequency ablation for Barrett’s esophagus. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
Dupuy, D. (2010). Radiofrequency ablation of lung tumors. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
Curley, S.; et al. (2012). Nonsurgical therapies for localized hepatocellular carcinoma: Radiofrequency ablation, percutaneous ethanol injection, thermal ablation, and cryoablation. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
Atkins, M.; Choueiri, T. (2011). Epidemiology, pathology, and pathogenesis of renal cell carcinoma. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
Scovell, S. (2011). Radiofrequency ablation for the treatment of lower extremity chronic venous disease. In: UpToDate, Basow, DS (Ed), UpToDate, Waltham, MA.
A.D.A.M. Bone tumors. Retrieved from: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002210/. Accessed March 18, 2012
Narouze, S.; et al. (2008) Sp[henopalatine Ganglion Radiofrequency Ablationfor the Management of Chronic Cluster Headache. Headache. 49(4) 571-577.
Hansen, J. (2010). Back. Hansen: Netter’s Clinical Anatomy, 2nd Ed. MD Consult Web site, Core Collection.
Girelli, R.; et al. (2010) Feasibility and safety of radiofrequency ablation for locally advanced pancreatic cancer. Brit J Surg. 97(2). 220-225.