What Is Radiofrequency Ablation?

Radiofrequency ablation explained by San Antonio, Austin, Houston, Dallas Texas top pain doctors

Radiofrequency ablation therapy is a minimally invasive procedure that utilizes radio waves to produce an electrical current that applies heat to targeted nerves, in an effort to relieve symptoms associated with chronic pain. The heat that is applied to the nerve tissues causes a semi-permanent disruption of the transmission of pain signals from the spine to the brain, by impairing or destroying the nerve tissue.

This treatment is a non-surgical option that was first discovered in 1931 as an effective option for relieving chronic pain associated with trigeminal neuralgia. Trigeminal neuralgia is a condition in which the facial nerves are affected, resulting in excruciating jolts of pain. Since its discovery, radiofrequency ablation has become increasingly popular among patients and physicians due to its documented pain relief benefits.

Multiple reports have explained that the disturbance of nerve function that results from radiofrequency ablation has led to greater decreases in spinal pain, compared to conventional treatment options. Furthermore, studies have shown that the pain relief experienced as the result of this therapy is maintained for six to 12 months after the procedure is performed. Additionally, radiofrequency ablation can be performed in an outpatient setting, allows for optimal needle insertion, and can be repeated if necessary. These factors make radiofrequency ablation an ideal treatment for many patients.

There are two primary methods of radiofrequency ablation: continuous radiofrequency and pulsed radiofrequency. Both of these methods have been found to be effective at disturbing the transmission of pain signals from specific nerves, which helps to reduce or eliminate chronic pain. Additionally, it has been thoroughly documented that the effectiveness of this treatment is due to the heat-induced nerve damage that occurs during this procedure. However, it has also been suggested that the pain relief benefits experienced after this procedure may be due to the impact that the electric field has on neuronal gene expression.

Presently, radiofrequency ablation is commonly used to treat pain that originates in the facet joints of the lumbar spine. Facet joints are located within the spinal column and connect the vertebrae to one another. Located within the facet joints are networks of medial branch nerves that are responsible for the transmission of pain signals to the brain when the nerves become inflamed or damaged. When the pain associated with inflammation or damage becomes chronic, radiofrequency ablation is often utilized to destroy the medial branch nerves, thereby reducing or eliminating the pain. In addition, radiofrequency ablation has been used to successfully treat other conditions such as low back pain, cervical facet joint pain, and arthritis pain.

Radiofrequency Ablation Procedure

Radiofrequency ablation procedures are relatively quick, lasting between one and two hours. Additionally, they are performed in an outpatient setting, with most patients being released within a few hours of the procedure. Prior to the procedure, the physician answers any questions that the patient may have, and also explains the complications that are associated with this procedure.

Usually this procedure is performed with the patient lying on their stomach; however, if the targeted nerves are located in the cervical region, the patient may lay on their back during the treatment. Prior to initiating a radiofrequency ablation procedure, the physician gives the patient an anesthetic, and sometimes a mild sedative, through an intravenous line in an effort to reduce any discomfort that may be experienced during the procedure.

After the anesthetic has taken effect, the physician inserts a needle into the spinal region where the affected nerves are located, using either X-ray or fluoroscopic guidance. Imaging technology is utilized to ensure accurate positioning of the needle. Once proper needle placement is confirmed, a microelectrode is inserted through the needle. While the electrode is being placed, a mild electric current is initiated that creates a tingling sensation. The physician observes the patient’s sensory and motor stimulation and asks the patient if they can feel the tingling. This helps to ensure that the microelectrode is positioned correctly. It is imperative that only the nerves responsible for the pain, as opposed to motor nerves, be treated during this procedure. Therefore, mild electrical current is used to ensure that large muscle groups are not being stimulated during the procedure. This mild current may cause sensations such as throbbing and twitching, but it is necessary as it provides the physician with information regarding the areas to avoid during treatment to prevent motor nerve damage.

Once the optimal needle and microelectrode placements are confirmed, a high frequency current is transmitted through the electrode into the affected nerve or into the tissues surrounding the affected nerve. Prior to sending the higher frequency current, the physician may use a numbing agent in the area of the targeted nerves. Steroids may also be injected into the area to help reduce inflammation that is present or that may develop following the procedure. Patients should not feel any discomfort or pain during the procedure as they are given an adequate amount of medication, including an anesthetic, mild sedative, and possibly corticosteroids to help manage their pain.

The high frequency current that is utilized during a radiofrequency ablation procedure disturbs normal nerve functioning by interfering with the nerve’s ability to transmit pain signals to the spinal cord, which would typically then send pain sensations to the brain. Specifically, the electrical current is transmitted from a generator into the electrode, and then moves from the electrode into the body and into a grounding pad. An electromagnetic field is created through this process that generates electro-thermal heat. The heat application to the targeted nerves causes them to become damaged or destroyed, and the disruption of their normal functioning for pain signal transmission leads to the relief of chronic pain symptoms.

A radiofrequency ablation procedure should not be painful; the physician will frequently ask the patient during the procedure if they have any discomfort. At times, changing the placement of the needle or an increase in anesthetic may be required. Patients are told to immediately notify the physician of any pain that they experience as it may signal that untargeted nerves are being stimulated during the procedure.

Upon completion of the ablation procedure, patients are monitored for side effects including motor deficits, muscle weakness, severe pain, and paralysis. Patients should have someone available to drive them home after the procedure and should cautiously return to normal activity levels. Mild pain and soreness may develop after the procedure and damaged nerves may take up to one month to completely lose their functioning, so pain can still be experienced during this time. Additionally, patients may experience muscle weakness during their recovery period. Physicians can prescribe pain medications to help a patient cope with their pain and discomfort during their recovery period following an ablation procedure.

If a patient does not experience satisfactory pain relief from the procedure, it can be performed again in two to three weeks. The nerves that are targeted during an ablation procedure may grow back after six to 18 months; however, this does not necessarily mean that the patient will experience the same level of chronic pain that they had prior to the procedure. Patients should be informed that by engaging in physical therapy treatment and remaining physically active, they would be helping to improve their muscle strength and minimize the pain that they experience. However, if their pain returns to a debilitating level, the ablation procedure can be repeated.

Following a radiofrequency ablation procedure, certain restrictions should be followed, including:

  • Avoid operating heavy machinery or driving for 24 hours after the procedure
  • Avoid strenuous exercise for at least 24 hours after the procedure
  • Avoid bathing for 24 to 48 hours after the procedure (showers may be taken but ensure that bandages are securely placed to avoid getting the injection site wet)
  • Avoid swimming for at least 48 hours after the procedure
  • Avoid getting the injection site wet (bandages may be removed at bed time, but should be replaced in the morning until the injection site is completely healed)

Types Of Radiofrequency Ablation

The two types of radiofrequency that are available for the treatment of chronic pain include continuous radiofrequency, which was developed in 1931, and pulsed radiofrequency, which was developed in the 19070s.

For continuous radiofrequency ablation procedures, the current frequency is gradually increased until the temperature of the electrode is between 50° and 80°C (122° and 176°F). This temperature is maintained for between 80 and 90 seconds, which is the approximate time that is required for heat to cause nerve damage. When a patient undergoes a continuous approach to radiofrequency ablation, multiple sites along a targeted nerve are exposed to the heat, increasing the likelihood that the nerve will be cut completely. This results in a disruption of the nerve’s ability to transmit signals of pain. The time that it takes to perform a radiofrequency ablation procedure ranges from one to two hours, depending on the location and number of nerves that need to be treated.

The pulsed procedure of radiofrequency ablation is similar to the continuous method except that brief, 20 millisecond intervals of high voltage currents, followed by longer, 480 millisecond intervals of silence are used during the procedure. The alternating electric currents produce temperatures that range from 40° to 42°C (104° to 107.8°F). The pulsing pattern of currents is maintained for a period of time, ranging from two to eight minutes, depending on the location and number of nerves to be treated.

During the silent intervals used in pulsed ablation, the heat dissipates and the targeted tissue remains below 42°C. Due to this fact, the degree of tissue damage that is achieved in the continuous method of radiofrequency ablation is not achieved using the pulsed method. The pulsed method essentially stuns the nerves as opposed to cutting or damaging them, which is what the continuous approach aims to do. According to clinical research, the alternating bursts of heat and silence weaken the membranes of the targeted tissues, but does not cause lesions. Pulsed radiofrequency therefore results in a temporary inhibition of the nerve’s ability to transmit pain signals from the spine to the brain, without causing significant nerve damage.

There are various other advantages of pulsed radiofrequency compared to continuous radiofrequency ablation, including a lower degree of nerve damage and a reduced need for local anesthetics during the procedure. Further, patients undergoing a pulsed radiofrequency ablation procedure are less likely to experience pain and scarring after the procedure. Additionally, pulsed radiofrequency ablation can be utilized at various sites and for a variety of conditions when the continuous approach is considered inappropriate. For instance, conditions such as trigeminal neuralgia should not be treated using a continuous approach as it develops as the results of nerve injury. Performing a continuous approach would result in further nerve damage, which potentially would result in an increase in pain symptoms. In these types of cases, utilizing a pulsed approach to radiofrequency ablation would be considered more appropriate.

The pain relief benefits of continuous radiofrequency ablation procedures is longer lasting than that which is achieved by a pulsed approach to treatment. The pulsed approach to radiofrequency was established in an effort to reduce the occurrence of side effects that can be seen with the continuous approach, including damage to motor nerves, which may result in motor deficits, and deafferentation pain. This type of pain develops when nerves that were not targeted become injured during treatment, causing unintentional damage and inflammation. Clinical research has shown that patients undergoing pulsed radiofrequency ablation procedures have not reported any adverse reactions from the procedure, and that this method is more cost-effective than the continuous approach.

Risk Factors Associated With Radiofrequency Ablation

The risks associated with radiofrequency ablation include possible permanent nerve damage and infection. When an infection results from an ablation procedure, the patient may need to be hospitalized to receive intravenous antibiotics. Further, surgery may be necessary.

Patients who have an active infection, such as a cold or sinus infection, should not undergo a radiofrequency ablation procedure. Furthermore, patients who have blood-clotting issues, women who may be pregnant, or individuals who weigh more than 250 pounds, are not suitable candidates for this procedure. Patients who have diabetes will need to have their insulin dose adjusted on the day of the ablation procedure.

It is important that individuals with poorly controlled diabetes and those who have heart conditions and are required to take blood thinning medication (i.e. aspirin) on a daily basis receive medical clearance from their physician to stop taking these medications for one week prior to the ablation procedure. Additionally, anti-inflammatory medications such as ibuprofen and other NSAIDs need to be discontinued for at least 24 hours before the procedure; however, most physicians prefer that patients discontinue these medications for 72 hours. NSAIDs can affect the body’s natural clotting process, therefore if they are not discontinued prior to the procedure, serious bleeding complications can occur. Furthermore, consuming steroid medications such as cortisone, methylprednisolone, or prednisone on a regular basis can aggravate or complicate symptoms that a patient is experiencing that is being caused by nerve inflammation.

Side Effects Of Radiofrequency Ablation

Minor side effects are associated with radiofrequency ablation, including bruising, swelling, bleeding, and skin discoloration. These side effects usually subside within a few days of the procedure. Other side effects that may occur include the potential risk of injury to the blood vessels and motor nerves surrounding the nerves to be treated. There is also the potential for an electrical burn to occur as the electric current passes through the electrode on the skin, however, this is uncommon. Leg numbness can be experienced by some patients, but this usually only lasts for a couple of hours and may be the result of the anesthetic used during the procedure as opposed to a side effect of the procedure itself. Patients that experience leg numbness should receive assistance with walking and moving around.

The electrode that is placed during an ablation procedure is positioned close to the targeted nerves. This can cause a temporary increase in pain that may extend into the lower or upper extremities. The anesthetic and numbing agents that are used during an ablation procedure are meant to help reduce the amount of pain experienced during the treatment.

Serious side effects that can occur during an ablation procedure include reactions to medications that are used during the procedure, including the anesthetic and sedative. These reactions can lead to cardiac issues, respiratory problems, or seizure. However, these types of side effects rarely occur.

After the anesthetic wears off, mild back pain may be felt at the injection site. This pain usually subsides within a few days and can be treated with over-the-counter pain remedies, as well as cold and hot packs until it subsides. In some patients, pain may be experienced or slightly worsened for a couple of weeks following the procedure, but this pain should gradually decrease. Continuous radiofrequency ablation procedures result in lesions on the nerves; however, it can take up to one month for the targeted nerves to lose function completely, so pain during this time may slightly increase. That being said, this pain should not be as severe as the pain experienced prior to the procedure.

Side effects that are experienced by patients following radiofrequency ablation should be monitored closely. Immediate medical attention is needed when there is pain at the injection site combined with redness, swelling, paralysis, or leg weakness, as these symptoms may be the result of bleeding or more serious complications. Patients who experience fluid drainage from the injection site or a fever over 100.4°F should also receive medical attention, as an infection may be developing.

Although there are various risks and side effects associated with radiofrequency ablation, it has been shown to be a safe and effective treatment option for pain control. Studies have also indicated that radiofrequency ablation is well tolerated by the majority of patients and that complications are rare.

Methods For Diagnosis

Patients who suffer from chronic pain that has been unresponsive to conservative treatment methods including non-steroidal anti-inflammatory drugs, steroid injections, epidural injections, and physical therapy may require more invasive treatment options to experience pain relief. Once a patient is referred to a pain clinic the physician will want to evaluate the length of time the patient was engaged in conservative treatment options before recommending radiofrequency ablation. For example, if the patient’s pain was not relieved by six weeks of medication and exercise, the physician will want to know if further treatments including physical therapy or chiropractic care were tried for at least four to six months before being referred to the pain clinic.

When a patient is referred to a pain clinic for chronic pain, such as low back pain or facet joint pain, they may be treated with a series of corticosteroid injections for a minimum of three months to determine if this type of treatment will provide pain relief. If the steroid injections fail to provide pain relief, the physician will perform medial branch blocks. If pain relief is experienced from this treatment, a minimum of two diagnostic medial branch blocks will be performed before recommending radiofrequency ablation.

Patients may have received steroid injections prior to being referred to a pain clinic and may have also undergone surgery. However, surgery is not always effective for the management of chronic pain, especially in patients suffering from chronic back pain. Radiofrequency ablation may be recommended to these patients. Ablation therapy only requires a local anesthetic, and in some patients, a mild sedative, therefore it is often preferred over repeating a surgical intervention. Additionally, surgical procedures are associated with a high incidence of complications due to open surgical procedures and general anesthesia.

Patients should receive imaging, such as computed tomography (CT) or magnetic resonance imaging (MRI), to assess their spine prior to undergoing a radiofrequency ablation procedure. If spinal abnormalities are seen on imaging, radiofrequency ablation may be inappropriate, as these deformities can make needle placement difficult. If no abnormalities are found on imaging, then the physician will begin with a series of medial branch blocks to assess the patient’s response in an effort to determine if radiofrequency will be beneficial for the patient.

A medial branch block is a type of nerve block whereby the needle is inserted into the spinal column in the region where the affected nerve roots are located. Fluoroscopy or X-ray guidance is utilized to ensure proper needle placement. Once proper needle placement is confirmed, a catheter is inserted through the needle to deliver pain medication directly to the nerves that are believed to be responsible for the patient’s pain. An anesthetic combined with a steroid, or a medication to disintegrate nerve tissue, is injected in order to reduce chronic pain. This treatment leads to prolonged pain relief by blocking pain signal transmission.

A patient’s response to a medial branch block provides an indication of how they will respond to radiofrequency ablation, which has a longer lasting effect than nerve block procedures. If a patient experiences increased pain relief with repeated medial branch blocks, they are more likely to experience positive results following a radiofrequency ablation procedure. According to reports, the pain relief experienced from an ablation procedure generally lasts between six and 12 months, and up to 22 months in some patients.

Conditions Related To Radiofrequency Ablation

Initially, studies showed that the benefits of radiofrequency ablation were focused on the treatment of lumbar facet joint pain, and the reduction and removal of tumors and bone spurs. However, throughout the years, radiofrequency ablation therapy has proven to be effective for various other conditions, including:

  • Lumbar facet pain
  • Cervical facet pain
  • Dorsal root ganglion pain resulting from herniated discs
  • Trigeminal ganglion pain
  • Sphenopalatine ganglion pain
  • Sympathetic ganglion pain
  • Arthritis type pain

Lumbar Facet Pain And Cervical Facet Pain

Pain originating in the lumbar facet joints or the cervical facets joints is fairly common and may result from arthritis or nerve damage. Within the facet joints is the medial branch nerve, which is responsible for pain sensation that is felt in the corresponding joints of the back and neck. When a non-invasive, diagnostic medial branch block provides pain relief for a patient with facet joint pain, it is likely that a radiofrequency ablation procedure will provide positive results. In regards to facet joint pain in the lumbar spine, continuous radiofrequency ablation provides a range of pain relief, with patients reporting pain relief lasting from four months to two years. However, most commonly, pain relief lasts for four to six months after the procedure.

In addition to pain relief after a radiofrequency procedure, patients have stated that their physical well-being, and their joint range of motion significantly improved approximately six months after treatment. Reports have shown that radiofrequency ablation provides similar pain relief benefits to patients experiencing cervical facet pain, with these patients typically reporting an improvement in symptoms for six to 18 months after the procedure. Conversely, both lumbar and cervical facet joint pain patients report pain relief lasting for approximately four months following a pulsed radiofrequency ablation procedure.

Dorsal Root Ganglion

Neuropathic spinal pain may be caused by inflammation of the dorsal root ganglia. This condition has been successfully treated with pulsed radiofrequency ablation at 42°C (104°F) for 120 seconds. Patients receiving this treatment report significant pain relief at one month after the procedure, moderate pain relief at three to six months after the procedure, and mild pain relief at 12 months after the procedure. The pulsed approach to radiofrequency ablation is more appropriate for these types of conditions as pain is usually the result of nerve damage, and the continuous approach to this procedure would result in more nerve damage and a worsening of pain symptoms.

Herniated intervertebral discs and failed spinal surgery are two common causes of low back pain. In some individuals with these conditions, lower extremity pain may also be experienced. Reports have indicated that pulsed radiofrequency ablation, applied to the dorsal root ganglia that is responsible for low back pain, as well as to the dorsal root ganglia that is responsible for lower extremity pain, leads to significant pain relief approximately one month after the treatment. In the majority of patients, the pain relief effects lasted for up to one year. Pain that results from intervertebral disc herniation or surgery is usually the result of increased pressure on the nerves of unintentional nerve damage. In these cases, continuous radiofrequency ablation would not be appropriate as it would cause further damage and potentially increase pain levels.

Low Back Pain

Studies have found that radiofrequency ablation provides low back pain patients with a significant reduction in the severity of their pain that is maintained for one to two years in the majority of patients who undergo this procedure. Moreover, the pain relief that is reported by patients is much more significant and longer lasting than corticosteroid injections. Patients who had undergone spinal surgery reported a greater range of motion, more extensive pain relief, an enhanced quality of life, a decreased need for pain medication, and a shorter recovery time after undergoing an ablation procedure.

Unfortunately, in some cases, patients who had undergone spinal surgery prior to undergoing radiofrequency ablation did not experience the same level of pain relief as those who had not previously undergone surgery. This finding indicates that spinal surgery may sometimes cause nerve damage that hinders the effectiveness of radiofrequency ablation. This may occur when nerves that were not targeted for treatment become damaged (e.g. motor nerves), resulting in deafferentation pain, causing a patient’s symptoms to become worse. If this occurs, even though spinal nerves that may be responsible for pain may be blocked using continuous radiofrequency, or stunned using pulsed radiofrequency, the pain that resulted from the spinal surgery will not improve.

Trigeminal Neuralgia

Trigeminal neuralgia is a pain condition that occurs when the trigeminal nerve, which is responsible for the perception of pain and touch in the eyes, face, nose, and mouth, is affected. Multiple sclerosis and pressure on the trigeminal nerve by a tumor or swollen blood vessel are believed to be the most common causes of this condition. Trigeminal neuralgia is characterized by severe pain that occurs with simple tasks such as chewing, drinking, brushing the teeth, shaving, eating, or putting on makeup.

Typically, trigeminal neuralgia is treated with medication, glycerol injections, or surgery. However, it appears that radiofrequency ablation provides the longest period of pain relief for patients suffering with this condition. Medications, including muscle relaxants, anti-seizure drugs, and antidepressants may be recommended for patients with trigeminal neuralgia. However, these types of treatments only reduce the occurrence and degree of pain that a patient experiences, as opposed to permanently relieving it. Glycerol injections block the transmission of pain signals by damaging the trigeminal nerve; however, patients have reported pain recurrence, as well as facial tingling and numbness after this form of treatment. Surgery for trigeminal neuralgia involves destroying a section of the trigeminal nerve; however, this poses the risk of resultant motor deficits. Remarkably, patients with this condition have been successfully treated with radiofrequency ablation, with symptom relief lasting between ten and 22 months.

The findings from these studies suggest that stunning the facial nerves and disrupting their membranes by using a pulsed approach to radiofrequency ablation is adequate for providing long-term pain relief. Typically, the pulsed method of radiofrequency ablation only provides four months of pain relief in patients suffering from lumbar or cervical facet pain, which is why the continuous method is preferred in these patients. However, if facial motor nerves are damaged it may lead to serious complications which is why the pulsed method is preferred in trigeminal neuralgia patients.

Sphenopalatine Ganglion

The sphenopalatine ganglia is a collection of nerves that provide touch and pain sensation to the head and face. When this collection of nerves is irritated or inflamed, a patient may experience facial muscle pain and chronic headaches. Damage to the nerves in this region can result in motor deficits or paralysis, which is why a pulsed approach to radiofrequency ablation is preferred in these patients.

Reports have indicated that utilizing pulsed radiofrequency ablation for patients with chronic headache and other conditions that may cause atypical facial pain can provide patients with up to one year of mild to moderate pain relief and complete relief for some patients. Additionally, patients have reported a reduced need for pain medications and the elimination of complications such as infection, bleeding, swelling, fluid retention around the injection site, and numbness. These findings suggest that a pulsed approach to radiofrequency ablation is safe and effective for the treatment of nerve pain in delicate areas such as the face and head.

Treatment Summary

The location and number of nerves to be treated during a radiofrequency ablation procedure determines the degree of pain relief that is typically experienced by patients undergoing this procedure. Moderate to complete pain relief is typically experienced by patients after the nerves have completely lost function, which can take between two weeks and a month, after undergoing a continuous radiofrequency ablation procedure. The pain relief effects of this procedure generally last between six and 12 months. Conversely, the pulsed approach to radiofrequency ablation stuns the targeted nerves and slightly weakens their membranes, which results in immediate pain relief in some patients that usually lasts for up to four months. Some patients receiving radiofrequency ablation report pain relief that lasts for up to two years after treatment.

Conclusion

Radiofrequency ablation is a non-surgical procedure that has been shown to be effective for the treatment of chronic pain. It involves the semi-permanent disturbance of nerves that are believed to be the source of chronic pain by utilizing heat created by an electrical current. The resulting heat causes lesions along the affected nerve, leading to a loss of nerve function and an interruption of the transmission of pain signals from the spinal cord to the brain. The result is a reduction in pain symptoms following the procedure.

Initially, radiofrequency ablation was found to be effective for the management of symptoms associated with trigeminal neuralgia and lumbar facet pain. However, it is now commonly used to treat arthritis pain, cervical facet pain, and lower back pain. In addition to pain relief, patients undergoing radiofrequency ablation typically report decreased recovery times, enhanced quality of life, increased range of motion, and a decreased need for analgesic medication when compared to other treatment options including surgery, corticosteroid injections, and physical therapy.

Continuous radiofrequency and pulsed radiofrequency are the two types of methods that are utilized in ablation procedures. Prior to undergoing a radiofrequency ablation procedure, patients will be required to undergo at least two diagnostic medial branch blocks, which will provide an indication of whether ablation will be successful. At the same time, the physician will determine what type of radiofrequency (continuous or pulsed) should be utilized for the procedure, depending on the location and number of nerves to be targeted during treatment.

At the present time, both the continuous and pulsed approaches to radiofrequency ablation are being optimized. The results of ongoing research may show that this treatment can be beneficial for a variety of other pain conditions that are unresponsive to conservative medical management.

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