Cooled Radiofrequency Ablation vs. Thermal Radiofrequency Ablation for Pain Management Procedures

Radiofrequency ablation (RFA) is a technique used to treat a variety of conditions including cancers and cardiac arrhythmias, and has become increasingly used in decreasing chronic pain in people with musculoskeletal disorders. When an area of the body becomes irritated and inflamed due to a condition such as osteoarthritis, a pain signal is transmitted to the brain through the nerve which supplies the affected area. If this signal can become disrupted by destroying the transmitting nerve, some of the pain perceived from the affected area can be decreased.  Commonly targeted nerves include the medial branches of the dorsal rami which innervated the facet joints in the spine, the S1-3 lateral nerves which innervate the SI joint and the geniculate nerves, which provide innervation to the knee. These nerves can be targeted under ultrasound or x-ray guidance, and destroyed by a process called radiofrequency ablation.

 

Radiofrequency ablation uses an alternating electrical current to deliver energy in the form of heat to a probe tip. Damage to the tissue first occurs to an area just beyond the tip through resistance heating. A difference in impedance between this small area of tissue and probe tip causes the small area of tissue to produce conductive heat. This transfers heat to adjacent tissue and expands the area of damaged tissue.  The temperature from the conductive heat is sensed by a device within the probe and allows the temperature at the tip to be monitored. Maximum tissue destruction occurs at temperatures between 60C and 70C.  However, when the temperature exceeds 100C (212F) steam and coagulation occur at the probe tip. To prevent this, most thermal radiofrequency devices automatically shut off when the probe reaches this temperature. If the device shuts off prematurely, however, this can result in an ineffective lesion. To keep the probe at an ideal temperature, a probe with a cooled tip may be used. In these cooled radiofrequency ablation systems saline is pumped through the probe tip, turns around within the tip and then returns to the pump. This mechanism allows for the ability to lengthen ablation times and to allow for larger lesions to be formed. As the nerves are not usually visualized directly when nerve ablation procedures are performed, a larger lesion theoretically would have a better chance at contacting and destroying more of the pain-transmitting nervous tissue.

 

Commonly targeted nerves for radiofrequency ablation are the medial branches of the dorsal rami which innervate the facet joints in the spine and contribute to some types of back pain. There have been several trials, including a recent randomized controlled trial, which have directly compared cooled and thermal RFA. In these trials there was no statistically significant difference in pain reduction between the two types of RFA.


Another commonly ablated nerve system is the geniculate nerves which provide sensation to the knee and transmit the pain signals from the knee joint.  Thermal RFA has been demonstrated lead to greater improvement in pain relief and function compared to sham RFA and also to decrease pain when compared to non-interventional therapy. The first study to employ cooled RFA was by Davis et al in 2018, and demonstrated improved pain relief and function when compared to intra-articular steroid injection. Based on the current literature, both thermal and cooled RFA are effective in patients who respond to lidocaine blocks of the geniculate nerves. However, more data are needed to determine if cooled RFA is more effective than thermal RFA in controlling pain and improving function. 

 

Both cooled and thermal radiofrequency ablation of the nerves which innervate the sacroiliac (SI) joint have been shown to be effective in reducing pain in patients with SI joint pain for up to a year. Cooled RFA has been compared directly to thermal RFA, in 2003 Cheng et al compared 30 patients who received thermal RFA and 58 who received cooled RFA. Both cooled and traditional RFA provided more than 50% pain reduction for 3-6 months in the majority of patients. However, there was no difference between cooled and thermal RFA in the duration of pain even after adjusting for potentially confounding variables.

 

Cooled and thermal radiofrequency ablation procedures are used to help control pain. They work by destroying nerve tissue which transmits pain signals from painful areas within the body. They are commonly used to help control certain types of back pain, SI joint pain and knee pain. Cooled radiofrequency ablation uses a fluid-cooled probe and allows for the formation of larger lesions at the probe tip. This increases the chance that the procedure destroys the target nerve tissue, and theoretically should allow for more successful procedures and decreased pain.  Currently, both cooled and thermal radiofrequency ablation techniques have been shown to decrease pain and increase function in most people who respond to initial nerve blocks. Data so far suggests that there are not significant differences in pain reduction between cooled and thermal RFA. However, there is not yet good high-quality data comparing the two types directly with respect to differences in patient pain or function.

 

References:

 

Ball R. The Science of Conventional and Water-Cooled Monopolar Lumbar Radiofrequency Rhizotomy: An Electrical Engineering Point of View. Pain Physician 2014; 17:E175-E211

 

Zachary L. McCormick, Marc Korn, Rajiv Reddy, Austin Marcolina, David Dayanim, Ryan Mattie, Daniel Cushman, Meghan Bhave, Robert J. McCarthy, Dost Khan, Geeta Nagpal, David R. Walega, Cooled Radiofrequency Ablation of the Genicular Nerves for Chronic Pain due to Knee Osteoarthritis: Six-Month Outcomes, Pain Medicine, Volume 18, Issue 9, September 2017, Pages 1631–1641

 

Lorentzen T. A cooled needle electrode for radiofrequency tissue ablation: thermodynamic aspects of improved performance compared with conventional needle design. Acad Radiol. 1996 Jul;3(7):556-63.

 

Dukewich, M et al. Comparative Effectiveness Review of Cooled Versus Pulsed Radiofrequency Ablation for the Treatment of Knee Osteoarthritis: A Systematic Review
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Mccormick, M et al. Randomized prospective trial of cooled versus traditional radiofrequency ablation of the medial branch nerves for the treatment of lumbar facet joint pain. Regional anesthesia and pain medicine. 2019 Mar;Vol.44(3), pp.389-397.

Pilcher T et al. Convective cooling effect on cooled-tip catheter compared to large-tip catheter radiofrequency ablation. Pacing Clin Electrophysiol. 2006 Dec;29(12):1368-74.

Jamison, D et al. Radiofrequency techniques to treat chronic knee pain: a comprehensive review of anatomy, effectiveness, treatment parameters, and patient selection. Journal of pain research, 2018;11, 1879–1888.

Choi W et al. Radiofrequency treatment relieves chronic knee osteoarthritis pain: a double-blind randomized controlled trial. Pain. 2011;152(3):481–487.

Sarı S et al.  Which one is more effective for the clinical treatment of chronic pain in knee osteoarthritis: radiofrequency neurotomy of the genicular nerves or intra-articular injection? Int J Rheum Dis. 2016 Aug 12.

Biswas B et al. Water-cooled radiofrequency neuroablation for sacroiliac joint dysfunctional pain. Journal of anaesthesiology, clinical pharmacology. 2016;32(4), 525–527.

 

Cheng J et al. Comparative outcomes of cooled versus traditional radiofrequency ablation of the lateral branches for sacroiliac joint pain. Clin J Pain. 2013;29:132–7

Laminectomy: Description, Indications and Post-Operative Care

Laminectomy is a surgery that creates space within the spinal canal by removing the lamina—the back part of your vertebra that covers your spinal canal. Laminectomy surgery is sometimes referred to “decompression surgery” as it also relieves pressure on the spinal cord and/or nerve roots. Usually the pressure is caused by bony overgrowths referred to as “bone spurs” secondary to arthritis within the spinal canal. Bone spurs will develop overtime with aging.

 

 

Once conservative treatment including but not limited to anti-inflammatory medications, neuropathic medications, physical therapy and/or corticosteroid injections have failed, a laminectomy may be recommended if severe symptoms persist or progress rapidly. Indications for the procedure include excessive back pain, numbness that may radiate down your arms or legs, muscle weakness making it difficult to stand or ambulate for a prolonged period of time or if you lose control of your bowel or bladder. In rare cases, a laminectomy may be more urgent to treat a herniated disc within the spinal canal.

 

For the most part, a laminectomy is a safe procedure that will require general anesthesia. The surgeon will typically make a small incision (depending on your body size) in your back and move certain muscles away to gain access to your spine. Depending on the condition, the surgeon may use a smaller incision (minimally-invasive) and a surgical microscope to perform the operation.

 

After the laminectomy, you are moved to a recovery room so that medical professionals can monitor you for complications after surgery and anesthesia. Potential complications include bleeding at the site of surgery (hematoma), infection, blood clots, additional nerve injury or cerebrospinal fluid leak. They will do a full neuromuscular physical exam and you may be able to go home the same day or have a short stay within the hospital. If the surgery includes a spinal fusion, your hospital length of stay is usually longer and you may be discharged to an acute rehabilitation unit prior to going home.

 

Post-operative care includes sitting upright to support your back for no more than 30 minutes at a time. You should lie on a firm mattress, and avoid soft couches or recliners. You may lie on your side, but not on your stomach. You should avoid bending, lifting anything greater than 10 pounds, pushing, twisting, stooping or straining for approximately 6 to 8 weeks until you are cleared for normal activity by your surgeon. These are typically referred to as spine precautions. You will also have to keep your surgical incision clean and dry, being careful when you bathe or shower as to not get the area wet, which can exacerbate infection risk. Lastly, you may require stronger prescription pain medication up to two weeks after the surgery, which is quite normal.  The staples or sutures that were placed to keep the incision closed are typically removed after 2 weeks. After a simple laminectomy, most people should expect a full recovery within 2-4 months.

References:

Pengel LH, Herbert RD, Maher CG, Refshauge KM. Acute low back pain: systematic review of its prognosis. BMJ 2003; 327:323.

Willems PC, Staal JB, Walenkamp GH, de Bie RA. Spinal fusion for chronic low back pain: systematic review on the accuracy of tests for patient selection. Spine J 2013; 13:99.

Trief PM, Grant W, Fredrickson B. A prospective study of psychological predictors of lumbar surgery outcome. Spine (Phila Pa 1976) 2000; 25:2616.

Brox JI, Reikerås O, Nygaard Ø, et al. Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: a prospective randomized controlled study. Pain 2006; 122:145.

Brox JI, Nygaard ØP, Holm I, et al. Four-year follow-up of surgical versus non-surgical therapy for chronic low back pain. Ann Rheum Dis 2010; 69:1643.

Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am 1991; 73:802.

Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical compared with nonoperative treatment for lumbar degenerative spondylolisthesis. four-year results in the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts. J Bone Joint Surg Am 2009; 91:1295.