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Clinical reports indicate that, for patients having lower back and leg pain, pulsed radiofrequency therapy directed at the dorsal root ganglia can offer analgesia without causing nerve damage that can occur with conventional radiofrequency therapy, according to a meta-analysis.

Michael Verdolin, MD, director of the Pain Specialists of San Diego in La Mesa, California, and Melanie Goodman Keiser, PhD, of devicemaker Medtronic, reviewed multiple sources from the medical literature, focusing on six papers that included 225 patients treated with pulsed radiofrequency.

In some of the studies, lumbar radiculopathy pain was relieved at levels rated at 20 to 80 mm on a 100-mm visual analog scale, according to the pair's poster presentation at the .

"Clinical studies have shown a progression of technological advancement in pulsed radiofrequency of the dorsal root ganglion, including changing parameters and polarity," Verdolin and Keiser reported. "Comparative studies have shown significant reductions in pain scores with these advances."

Overall, the investigators found that pulsed radiofrequency of the dorsal root ganglion is a safe and effective treatment for chronic lumbosacral radicular pain. Verdolin said that literal review also indicated that the cause of the pain may be due to C-fiber activation and neuroinflammatory mediators. The pulsed treatment appears to reduce this activity, and hence the pain, Verdolin told 番茄社区.

"Lumbar radiculopathy is back pain that radiates down into the lower extremities due to the compression or irritation of the nerve roots," he explained. "Pulsed radiofrequency stimulation of the dorsal root ganglion has been used as an early treatment for this." Medtronic's Accurian RF platform is currently marketed for ablation of nerve tissue and is capable of pulsed treatment.

In reviewing the presentation, Yili Huang, DO, director of the Pain Management Center at Northwell Health's Phelps Hospital in Sleepy Hollow, New York, told 番茄社区, "Conventional radiofrequency ablation neurotomy is a nonsurgical technique that uses radiofrequency to generate heat (up to 80°C) that can temporarily destroy portions of a nerve that is causing a painful signal. The cut nerves often grow back so the relief is temporary, but the improvement can often last up to a year. This can be safely performed for chronic pain caused by arthritis of the lower back, neck, knee, hip, and shoulders."

However, Huang said, "because conventional radiofrequency ablation denatures portions of the nerve, treatment is often limited to smaller and less significant nerves. Lumbar radiculopathy is one of the most common causes of back and leg pain and will affect 60%-90% of people during their lifetime. It is caused when a group of larger nerves that transmit feeling (sensory nerves) are impacted by disc herniation or spinal stenosis as they exit the spinal cord. Traditional interventional nonsurgical treatment includes epidural steroid injections to decrease inflammation around the nerves, but the frequency and efficacy are limited by cumulative side effects of steroid treatments."

While conventional radiofrequency therapy can treat smaller nerves, it is contraindicated in the nerves controlling the motor nerve, Huang said. That opens the door for the newer treatment of pulsed radiofrequency ablation.

"It differs from conventional radiofrequency ablation in that pulsed temperatures do not exceed 42°C and it is given at 20-ms pulses every 0.5 seconds as compared to up to 90°C for [one and a half] sustained minutes with conventional treatment."

"Although not well understood, it is believed that pulsed radiofrequency ablation works by changing the way nerves fire by exposing it to the electrostatic field from the radiofrequency. At the lower temperatures, pulsed radiofrequency does not damage or denature the nerves," Huang said.

"Given the growing evidence that pulsed radiofrequency ablation at the dorsal root ganglion can safely and effectively treat lumbar radiculopathy and the relative dearth of effective treatment options for this very common and often debilitating disease, further evaluation of this treatment is definitely warranted," he said.

"I would like to see expanded trials evaluating efficacy, as well as long-term safety -- especially evaluation of any potential consequences of repeated treatment of the dorsal root ganglion with pulsed radiofrequency ablation," Huang said.