Dorsal Root Ganglion (DRG) Stimulation Versus A Traditional Spinal Cord Stimulator

Treating Chronic Pain In Lower Extremities: DRG Stimulation vs SCS

Dorsal root ganglion (DRG) stimulation is an outpatient neuromodulation therapy, similar to traditional spinal cord (SCS) stimulation. Rather than placing the electrode leads within the lower part of the spinal cord as in SCS, DRG leads are implanted on the dorsal root ganglion, a cluster of neurons mid-spine, in the rear root of the spinal nerves.

According to the Cleveland Clinic’s Department of Pain Management, “The dorsal root ganglion represents the sensory gate of the spinal cord. Every sensory perception entering the spinal cord must pass through the dorsal root ganglion.” Therefore, the DRG neurons are capable of influencing all nerve sensations before sending on to the spinal cord for processing on to other areas of the body. This makes DRG stimulation a particularly effective therapeutic approach for patients with stubborn chronic pain, failed hip and failed knee surgeries.

Components of DRG Stim

A DRG stimulation implant features two components that are surgically implanted:

1) A pulse generator, which is placed beneath the skin in the buttocks or abdomen. This can have up to four leads. 2) The generator leads, which are positioned near the target treatment area. When the generator is activated, the leads send small electrical impulses to the dorsal root ganglion, blocking the pain stimulant.

Similar to SCS, patients must first undergo a one week trial implant to determine if the therapy is effective. Following a successful trial, the DRG is permanently implanted under the skin, much like a pacemaker.

What Are the Advantages: DRG v SCS

There are several advantages of targeting the dorsal root ganglion for pain relief:

  • Directed anatomical targeting – DRG stimulation offers a highly-directed field to limit extraneous paresthesia in the painful area. So, in a DRG stimulation clinical trial for chronic lower limb pain, 94.5 percent of patients who received targeted stimulation in the area of pain did not experience extraneous paresthesia, This is compared to 61.2 percent of patients in an SCS control group.

  • Low energy requirements – The dorsal root ganglion is surrounded by a very thin layer of spinal fluid. Because the layer between the stimulator and the dorsal root ganglion is so narrow, DRG stimulation uses only about 10 percent of the energy required for a traditional SCS. This means the batteries lasts longer.

  • Marginal risk of lead migration – The dorsal root ganglion is tucked in this small space, which reduces the chances of lead migration. In studies, lead migration was reported less than a 1 percent of cases. Traditional SCS lead migration is reported in 14 percent of cases. (Washburn, et al., Industry Wide Incidence Rate of SCS Related Complications, NANS 2010.)

  • Minimal postural effects – Because the dorsal root ganglion is located in such a small space, and the cerebral spinal fluid in between does not vary with the position of the patient’s body, the stimulation pattern for DRG is constant regardless of changes in position. The patient receives the same stimulation –and pain relief – lying down, standing, sitting or walking. The pattern and strength of stimulation can vary with body positioning in SCS patients.

According to one doctor who oversaw a recent DRG versus SCS study, “The minute we turned on the DRG stimulation, her pain was 100 percent gone. We could touch and squeeze her foot with absolutely no pain.” The patient received the implant one week after her trial and has remained pain-free ever since. She’s back to her normal life – wearing shoes, walking and working.”

The FDA has approved DRG stimulation for lower extremity CRPS, which could include neuropathic pain conditions and chronic pain following foot, knee, hip, groin and other surgeries. DRG stimulation is not a replacement for SCS, but rather an alternative to it. Because certain areas are tough to capture with spinal cord stimulation – the foot, the front of the knee, the groin, — using DRG stimulation is a new treatment option for these conditions inadequately managed with a conventional SCS.

Dr. Mekhail says one of the best future indications for DRG stimulation is diabetic neuropathy. Over time, high blood sugar can damage the peripheral nerves, particularly in the legs and feet. Patient pain is often managed with medication, which can be costly and may cause multiple side effects. “Using DRG stimulation at the L5 ganglia, we can target both feet and relieve the intractable pain of diabetic neuropathy,” he says.

This is also a treatment option for patients with CRPS who have had limited to no success with conservative treatments for their pain — physical therapy, medications and sympathetic nerve blocks. DRG stimulation can provide relief while saving in healthcare costs for ineffective procedures.

DRG Stimulation Study Results

Several promising results from the safety and effectiveness trial of DRG stimulation:

  • Three months after the implant, 70 percent of participants who received DRG stimulation had greater than 80 percent pain relief. This is compared to 52 percent of the control group who underwent SCS.

  • One year after the implant, 67.3 percent of DRG subjects had greater than 80 percent pain relief. This is compared to 54 percent of SCS subjects.

  • 5 percent of DRG subjects received targeted stimulation in the area of pain without extraneous paresthesia. This is compared to 61.2 percent of SCS subjects.

Dr. Rock can be reached at 312-697-7102.

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