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What is Radiofrequency Ablation?
Radiofrequency ablation explained by Denver, Golden, Aurora, Boulder, Broomfield, Jefferson, and Littleton Colorado’s top pain doctors
The radiofrequency ablation procedure uses radio waves to produce electricity, creating heat targeted to nerve regions for chronic pain treatment. This nonsurgical procedure uses targeted heat that, when applied to pain causing nervous tissues, disrupts the pains signals that are sent from the spinal cord and relayed to the brain. In this manner the pain pathway is blocked and the pain is relieved.
This procedure was developed in 1931 to treat trigeminal neuralgia. Trigeminal neuralgia causes sharp and intense facial pain. Radiofrequency ablation was used to target the pain causing trigeminal nerve and was successful. Over the past 15 years, radiofrequency ablation therapy has increased in popularity among both physicians and patients due to the mounting evidence of successful pain relief. Several scientific studies have reported that the particular type of interrupted nerve function elicited via radiofrequency ablation causes longer lasting and increased pain relief for pain that is related to the spine as compared to other conventional pain therapies. The evidence suggests that after radiofrequency ablation, continued pain relief occurs for a further six months to a year. Due to the many advantages of this procedure, including the fact that it can be done as an outpatient procedure, needle insertion precision, and the ability to have repetitive treatments if needed, it has become a treatment of choice.
Both methods of radiofrequency ablation treatment (continuous and pulsed radiofrequency) have been shown to be successful at inhibiting specific nerve’s pain signal transmission causing the elimination or reduction of chronic pain. In addition, evidence suggests that the neuronal damage caused by the heat that occurs during the radiofrequency ablation procedure has an important role in the pain relief observed. Interestingly, some studies implicate the role that the electric field has in pain relief due to the initiation of changes in the expression of genes in neurons that mediate pain pathway signals.
The most common use of radiofrequency ablation is the treatment of facet joint pain. Facet joints connect bones in the spinal column called vertebrae. If small nerves located in the facet joints become inflamed or damaged, pain signals are sent by them and received by the brain. This pain can often become chronic and the ablation treatment is used to destroy these tiny medial branch nerves that transmit the pain signals. This same procedure is also effectively applied for pain relief for pain in the cervical facets, pain of the lower back, and pain due to arthritis.
How is Radiofrequency Ablation Performed?
The procedure is usually performed with the patient lying on their stomach. However, if the areas of chronic pain to be treated are located, for example, in the neck, the patient will be asked to lie on their back. An intravenous (IV) line is then set up to deliver an anesthetic drug and, when needed, a gentle tranquilizer to reduce any possible discomfort. After the anesthetic takes effect, a needle is inserted in the spinal column area where the nerves causing the pain are positioned.
Imaging technology via X-ray or fluoroscopy is used to help direct the needle into the correct position. A microelectrode is then inserted into the needle and during electrode positioning an extremely low current of electricity is injected. This will yield tingling sensations in the nerves and the physician will ask the patient if they can sense the tingling, while also checking for motor stimulations (muscle twitch or contractions) in the patient to make sure the electrode has not been unintentionally placed in a motor neuron. The mild electrical current can sometimes cause minor muscle twitching and throbbing but it’s very crucial that the physician has the correct electron placement in the pain and not motor nerves to avoid motor nerve damage. When optimal needle and electron placement are confirmed, a numbing agent may be applied or steroids can be injected to the area targeted to reduce any inflammation already present or that that could develop due to the procedure. The current is then switched to a higher frequency creating heat that is transmitted via the electrode in either the affected nerve’s surrounding tissue or directly into the affected nerve itself.
The anesthetic and other agents applied (i.e. mild sedative, numbing agent, or steroids) should ensure that the heat created during the procedure does not cause discomfort or pain. However, the procedure may be painful for some patients and the physician will frequently ask the patient if pain is felt. If pain is experienced during the procedure the position of the needle can be adjusted or additional anesthetic may be administered. If patients start to feel pain during the radiofrequency ablation treatment, they should immediately tell the physician.
A generator is used to create the electrical current, which then passes via the electrode into the targeted nerves in the body, creating electro-thermal heat. The current then passes from the body to a grounding pad. This targeted application of electro-thermal heat causes the nerves to malfunction or become destroyed disrupting pain signaling.
After two to three weeks, if the pain relief target has not been experienced, the ablation treatment can be repeated. The nerves targeted by the procedure might regenerate after six to 18 months. However, the same pain level sensed before treatment may not return. Remaining active and participating in physical therapy will improve muscle strength and aid in the maintenance of minimal pain levels. The ablation procedure can be done again if the pain does return to pre-treatment levels.
Patients are treated with radiofrequency ablation on an outpatient basis and require only local anesthetics with some patients requiring a sedative to feel calmer. The majority of patients are able to return home after treatment within a few hours. The physician speaks to the patient before commencing the procedure to discuss any apprehensions and explain complications that might occur. During the ablation procedure, patients are asked to let the physician know of any pain or discomfort felt right away because this could indicate that nerve tissue that was not directed to be treated is being exposed to the electro-thermal heat.
When the ablation treatment is completed, patients are observed to see if any adverse side effects develop. These could include muscle weakness, motor problems, severe pain, or paralysis. Patients are discouraged from driving home and asked to practice caution when returning to everyday activities as, during recovery, mild soreness and pain can develop. Targeted nerves damaged during the procedure may not completely lose function until after one month and marginal pain might be felt during this time. In addition, for a month after treatment, patients may still experience some muscle weakness. In these cases, the physician may prescribe painkillers for the management of any pain or discomfort.
The following should be avoided after the treatment:
- Driving or running heavy machinery
- Any strenuous activity such as heavy lifting for 24 hours
- Baths and swimming pools for 48 hours
Showers can be taken as long as the bandage is secure before showering to keep the treated region dry.
Types of Radiofrequency Ablation
In 1931 continuous radiofrequency ablation was first used and pulsed radiofrequency was launched in 1974. In continuous radiofrequency ablation, the current frequency is gradually increased until the electrode temperature reaches 50-80°C (122-176°F). This temperature is maintained for 80-90 seconds as during this duration the heat causes nerve damage.
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Multiple sites on a nerve are usually subjected to the heat to increase the chance of causing the nerve to be entirely severed. The heat generated by the electrode disturbs the nerve’s capability to send pain signals. The radiofrequency ablation procedure can take approximately one to four hours depending on nerve location and number.
The pulsed radiofrequency ablation procedure is very similar to that of continuous radiofrequency ablation, instead using short 20 mseconds interludes of high voltage currents followed by 480 mseconds of resting periods between. These alternating currents produce temperatures between 40-42°C (104-108°F). This pulsing current pattern is continued for at minimum 120 seconds for a total of eight minutes contingent on nerve location and number.
The goal of pulsed radiofrequency ablation is nerve stunning in contrast to injuring via the continuous approach. The heat can dissipate during the rest periods between pulses and, as a result, the targeted nervous tissue remains below 42oC. As reported by clinical studies, brief heat bursts alternated with resting phases serves to weakens the cell membranes of directed nerves without destroying them. In this manner pulsed ablation induces a short-term inhibition in the capacity of the targeted nerves to send pain signals from the spinal nerves to the brain but does not produce severe nerve damage.
There are advantages of pulsed over continuous ablation procedures, including less nerve injury, less demand for anesthesia during the procedure, less scarring, and a reduced number of pain episodes after the procedure. In addition, the pulsed procedure can be used to treat different sites or pain conditions that would be unsuitable for treatment via the continuous treatment approach, for example, neuropathic pain caused by trigeminal neuralgia progresses. Performing continuous ablation treatment would cause further damage to those nerves. This could cause the symptoms to increase and, therefore, it is best to inhibit pain signals by paralyzing the nerve via pulsed ablation.
Continuous radiofrequency ablation yields longer lasting pain relief as compared to that of the pulsed approach. However, the pulsed ablation technique was developed to help reduce the incidence of side effects caused by the continuous ablation technique, such as damage to motor neurons that can cause motor discrepancies and pain in sensory neurons called deafferentation pain. Deafferentation pain occurs when sensory nerves that were not targeted unintentionally become damaged during the continuous ablation procedure. Studies have reported that patients do not experience as many adverse side effects from the pulsed ablation approach and it is more cost effective as compared to the continuous ablation technique.
Risk Factors Associated With Radiofrequency Ablation
The risks related to the radiofrequency ablation procedure include potential permanent damage to nerves and infection. In the case of an infection developing due to the ablation procedure, the dispensation of antibiotics via IV and surgery may be needed.
The radiofrequency ablation treatment is not recommended for patients with an ongoing infection, bleeding or blood clotting issues, or women who might be pregnant and weighing > 250 pounds. On the day of the treatment, insulin-dependent diabetics will need a physician to adjust their insulin dosage.
Patients on blood thinning medicines, for example daily baby aspirin, will need to obtain medical authorization from their doctor in order to discontinue the medicine for one week before the ablation procedure. Ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) will also need to be discontinued for preferably three days or at least 24 hours before the treatment. This is necessary because NSAIDs may affect blood clotting if these drugs are still in the body during the ablation therapy and serious bleeding can occur. The use of corticosteroids (e.g. cortisone, prednisone, or methylprednisolone) on a regular basis is not recommended as these drugs can exacerbate symptoms of nerve inflammation and cause further complications.
Side Effects Of Radiofrequency Ablation
Lesser side effects of the ablation procedure include slight bleeding at the needle insertion site, swelling, skin discoloration, bruising, and leg numbness. Most of these side effects will only last a few hours. If leg numbness occurs due to the use of anesthetics, it should last only a couple of hours and support can be given while the patient is moving or walking.
During the ablation procedure, a transient, but minor pain increase may occur that can extend into your legs or arms because the electrode placement is very close to targeted nerves. However, both the numbing agent and anesthetic delivered during the treatment are intended to reduce pain caused by the procedure itself. Motor nerves and blood vessels located around the targeted nerves have the potential risk of injury. In addition, there is a low risk of the electrode current to cause a burn, which is uncommon. Extremely rare but possibly dangerous side effects include bad responses to the anesthesia or tranquilizer administered during the procedure. Reactions such as these can lead to respiratory or cardiac problems and less likely seizures.
As the anesthetic wears off, slight back pain located at the site of injection may be felt. This can be treated with cold packs on treatment day. After two to three days, this back pain will normally subside and, if the pain has not diminished after this time, hot packs can be used for pain relief. Non-prescription pain medication can also be used for back pain relief.
One to two weeks after the procedure, in some cases, pain may be felt and might even increase slightly. This is because it may take a month for the treated nerves to finally die, and during this time, pain may somewhat increase. The pain should not be as great as that sensed before the continuous radiofrequency ablation procedure. Any symptoms experienced due to the procedure should be closely checked to be able to distinguish potential detrimental side effects.
Immediate medical attention is needed if any of the following occur: severe injection site pain along with swelling and leg frailty, paralysis, or fluid draining at the injection site as this may indicate the presence of an infection. For example, if a body temperature of 100.4 oF develops, this may indicate a serious infection and urgent medical attention should be sought.
Clinical reports provide evidence that the radiofrequency ablation procedure is well tolerated with minimal complications. Therefore, despite the side effects and risks associated with this procedure, the treatment has been shown to be both effective and safe for the treatment of chronic pain.
Methods For Diagnosis
A pain clinic doctor will help determine if radiofrequency ablation is the best method for you. Chronic pain sufferers whose symptoms are not relieved by the use of NSAIDs, physical therapy, or epidural or steroid injections, may require a somewhat more intrusive unconventional type of treatment. The physician should first assess the time duration that conventional pain treatment approaches were used before making a diagnosis. For example, if both painkillers and exercise did not relieve chronic pain after six weeks, the doctor will check the patient history to see if the patient had physical therapy or chiropractic treatment for at least four to six months before the pain clinic referral.
At the pain clinic, a patient suffering from chronic pain such as facet joint pain or lower back pain may be first treated with injections of steroid drugs for at least three months to ascertain whether this treatment type can provide pain relief. If steroid treatment injections do not solve the pain problem, diagnostic medial branch block procedures will be done to confirm the source of the back pain. If the patient then has pain relief after at least two diagnostic nerve blocks are done, then the ablation procedure can be recommended. A medial branch block is a type of nerve block induced when a needle is inserted in regions of the spinal column where affected pain nerve roots are found.
Imaging techniques such as fluoroscopy or X-rays are used to visualize correct needle insertion. Once there is confirmation of proper needle placement, a tube is inserted into the needle to deliver to the chronic pain causing nerve roots pain-relieving medication. The medication administered may include a combination of an anesthetic and steroid, or a drug that breaks down nervous tissue that serves to alleviate chronic pain by obstructing the pain signal transmission. The physician will observe whether a medial branch block is effective for pain relief and use this information to determine if radiofrequency ablation, which provides longer lasting pain relief as compared to a nerve block, will be also be successful. The greater the level of pain relief experienced by the patient, as a result of repeating the medial branch block procedure, increases the chance that the radiofrequency ablation procedure will be successful. Evidence from clinical trials suggest that the ablation treatment will provide relief from pain for six months to a year with documented patient cases experiencing pain relief for 22 months after treatment.
Before the physician can recommend radiofrequency ablation as the best method to treat chronic pain, the spine will need to be thoroughly examined to check for abnormalities. The spine assessment can be done using magnetic resonance imaging (MRI) scans or computed tomography (CT) scans. These scans are necessary because spinal abnormalities can make needle placement difficult or the ablation procedure may be determined to be an inappropriate treatment for some patients. Once the physician can rule out any spinal problems, they will perform a series of medial branch blocks to determine if the patient could benefit from radiofrequency ablation treatment.
Certain patients, before being referred to a pain clinic, may have already undergone open surgery. However, sometimes surgery does not successfully relieve chronic pain, and this is especially true in back pain patient cases. The radiofrequency ablation procedure may be recommended for these patients. The ablation treatment as compared to surgical procedures requires local anesthesia and, in some cases, only a mild sedative is needed. Open-surgery is also associated with a higher occurrence of complications due to the use of general anesthesia. Therefore, for all the reasons listed above, radiofrequency ablation therapy is usually preferred to repeating open surgical procedures.
Conditions Treated With Radiofrequency Ablation
The success and usefulness of radiofrequency ablation on lumbar facet joint pain, and for the removal and reduction of bone spurs and tumors was first showed by empirical studies. Ablation therapy has also been shown to be effective over the years for a number of other conditions including arthritis related pain, lumbar and cervical facet pain (neck region), dorsal root ganglion, herniated intervertebral discs, lower back pain caused by sacroiliac joint complex, trigeminal neuralgia, sphenopalatine ganglion (characterized by chronic headaches and atypical facial pain), and sympathetic ganglia.
Lumbar Facet Pain And Cervical Facet Pain
In patients with nerve damage or arthritis, conditions such as lumbar facet joint pain and cervical facet joint pain can commonly develop. Medial branch nerves mediate pain sensations felt in corresponding joints in the neck and back regions. A medial branch nerve block procedure is marginally invasive and offers a general idea of whether a pain region will successfully react to radiofrequency ablation treatment. Continuous ablation provides a span of relief for lumbar facet pain. Patients have reported relief of chronic pain lasting most commonly in the range of four to six months but have also had pain relief that lasted up to two years.
Within six months of treatment, patients have also reported significant improvements in the range of motion of affected joints and saw benefits in overall physical well-being. Furthermore, reports have indicated that continuous ablation provides relief of chronic pain for similar time intervals for pain related to cervical facets with pain relief lasting six to 18 months. Pulsed ablation, in comparison, for the treatment of both lumbar facet and cervical facet pain provides pain relief lasing approximately four months.
Dorsal Root Ganglion
Neuropathic spinal pain can be caused by dorsal root ganglia (DRG) inflammation and has been successfully treated using pulsed ablation at a temperature of 42o C (104 oF) over 120 seconds. Patients generally have significant or complete pain relief after a month, modest pain relief after three to six months, and minor pain relief after a year of the ablation treatment. The pulsed ablation approach is the best for DRG originated pain because it is usually due to nerve damage. Causing additional damage to DRG nerves via the continuous radiofrequency approach would most likely increase symptoms.
A herniated disc and unsuccessful prior back surgery are frequently causes of lower back pain, with pain in the lower limbs also being experienced. Clinical studies have revealed that pulsed ablation employed to the DRG causing lower back pain as well as the other ganglia accountable for the limb pain lead to considerable pain reprieve approximately one month after treatment. In the majority of the patients treated by this procedure, relief lasted for one year. Pressure increases on the nerves and subsequent unsuccessful back surgery can cause the development of pain originating from a herniated intervertebral disc due to nerves that were unintentionally injured. The continuous ablation approach would not be useful in these patient cases, as it would cause further nerve damage.
Low Back Pain
Evidence from clinical studies suggests that the radiofrequency ablation procedure for low back pain significantly reduces pain severity and this is sustained for one to two years in the majority of patients. In addition, the level of pain relief described by patients is greater and lasts longer compared to steroid injections. Furthermore, patients that had prior back surgery reported shorter recovery times, more wide-ranging pain relief, superior range of motion, decreased needs for painkillers, and improvements in their quality of life after undergoing radiofrequency ablation treatment.
Some patients who had back surgery before undergoing radiofrequency ablation did not achieve the same level of pain relief as did back pain patients without prior surgery. This suggests that previous surgery might have caused nerve tissue damage that could hinder radiofrequency ablation’s effectiveness. For example, deafferentation pain can occur due to unintentional nerve damage triggering the patient’s symptoms to worsen. If this occurs, back nerves responsible for the pain can be blocked or stunned via continuous radiofrequency and pulsed radiofrequency, respectively, but pain caused by the previous surgical procedure may not recover.
If the trigeminal nerve that mediates pain and touch sensations in the, eyes, nose, mouth, and the rest of the face becomes affected, trigeminal neuralgia can develop. The most common causes of this condition are thought to be nerve pressure from a distended blood vessel or tumor or underlying multiple sclerosis. Trigeminal neuralgia is typified by agonizing sharp pain that occurs during every day activities such as teeth brushing, shaving, applying makeup, chewing, drinking, or eating. Trigeminal neuralgia is commonly treated with medicines, injections of glycerol, or surgery. However, radiofrequency ablation treatment provides greater durations of pain relief as evidenced to date. Possible prescribed medications include muscle relaxants, antidepressants, and anti-seizure drugs. However, these treatments only reduce the pain occurrence and pain degree rather than permanently relieving symptoms. Glycerol injections stop pain signals by causing damage to the trigeminal nerve. However, patients report pain recurrence after this treatment along with facial tingling and numbness. In trigeminal neuralgia surgical treatment, the trigeminal nerve is severed or destroyed, but this risks possible motor deficits. Remarkably, many patients suffering trigeminal neuralgia treated with the pulsed ablation approach report symptom improvement lasting ten to 22 months.
Clinical studies specify that the pulsed radiofrequency approach is adequate to provide pain relief lasting approximately four months and damaging facial motor neurons might lead to severe complications. Therefore the ability of the pulsed approach to deliver lasting pain relief for trigeminal neuralgia patients makes pulsed radiofrequency ablation the best treatment choice as compared to the continuous approach.
A nerve network responsible for touch and pain sensations for the head and face regions is called sphenopalatine ganglia. If the sphenopalatine ganglia become irritated or inflamed, they may cause face muscle pain or headaches. Similarly to trigeminal nerves, damage to a sphenopalatine ganglioncan cause motor problems or paralysis. Therefore, in this condition, it is best to not have continuous ablation treatment. However, patients with atypical facial or chronic headaches report that up to one year of slight to modest pain relief, and in certain cases, even total pain relief can be achieved with pulsed radiofrequency ablation. Clinical studies indicate less need for opioid-based oral medications and the lack of complications such as swelling, numbness, bleeding, infection, and injection-site fluid retention. These studies provide strong evidence that pulsed radiofrequency ablation technique is effective and safe for the treatment of chronic nerve pain associated with sensitive areas including the face and head.
In general, the pain relief level experienced by patients who undertake radiofrequency ablation treatment is reliant upon multiple factors including the origin of the pain, where the pain is sensed, the cause of the pain, and the nerve number requiring treatment.
After a continuous ablation treatment is completed, patients achieve modest to total pain relief after nerve function is lost taking from two to four weeks. The overall pain relief from using this treatment type is usually sustained for six months to a year. The pulsed radiofrequency ablation procedure, as opposed to the continuous approach, upsets nerves by diminishing their cell membranes. Certain patients observe pain relief right away after the pulsed approach. Some patients are known to experience pain relief for even two years after undergoing radiofrequency ablation treatment.
The radiofrequency ablation procedure is regarded as one of the best minimally invasive and exact pain management therapies now available. The radiofrequency ablation approach uses a current that generates electro-thermal heat in the inflamed nerve region to temporarily destroy the nerves causing chronic pain. The heat induces lacerations along nerves leading to loss of function thereby inhibiting pain signals from the spine to the brain. Patients experience substantial pain reduction due to the after effects of the procedure.
This approach was initially used to treat pain in the lumbar facets and trigeminal neuralgia, yet it is now extensively used to treat many chronic pain conditions including pain relating to the lower back, cervical facets, and arthritis. With ablation treatment, as compared to conventional chronic pain therapies (i.e. steroid injections, physical therapy, or surgery), patients have reported shorter recovery times, improved motion range, reduced demand for pain medication, and improvements in their quality of life.
Continuous and pulsed radiofrequency are the two main ablation procedure types. Continuous ablation is more commonly used with lasting pain-relieving effects, in some cases, up to two years. The complication risk increases when nerves are uninterruptedly exposed to the electro-thermal heat generated. As a consequence of this, the pulsed ablation approach was developed as an alternate procedure to avoid the potential dangerous side effects or complications associated with the continuous approach (i.e. deafferenation pain, excessive scarring, and damage to motor nerves). The pulsed radiofrequency approach typically requires reduced anesthesia, is less intrusive as compared to the continuous ablation approach, and can be repeated more times as needed yielding pain relief lasting up to four months.
A physician will necessitate that a patient endure at least two successful medial branch block procedures to indicate how useful an ablation procedure might be before recommending it. During the medial branch block procedure, the position of the pain and nerves responsible will be evaluated to enable the physician to decide whether pulsed or continuous radiofrequency ablation is the best approach for that particular patient case.
Both pulsed and continuous radiofrequency ablation procedures are currently being optimized to the specific condition to be treated. As these procedures are improved upon further, physicians will be ready to treat a greater variety of conditions. Furthermore, the pain relief duration experienced by patients might increase and the number of side effects, as well as procedural complications, should be reduced.
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