CRPS Awareness Day 28: Neuromodulation and DRG
By Dr. Timothy Deer
CRPS/RSD is a debilitating painful condition affecting thousands of patients. Chronic pain as a result of CRPS not only impacts the patient, but the patient’s family and loved ones as well. Many are forced to give up work or other meaningful life and family activities due to the ongoing persistent pain. Many CRPS patients continue to suffer extreme pain and limited function in spite of receiving the correct diagnosis and appropriate care.
Treatment guidelines for CRPS exist and have been widely published and accepted in the national and international medical community. Those guidelines start with conservative care including physical therapy, nerve-pain medications, supportive counseling, and in some cases nerve blocks. For patients not responding to those treatments, neuromodulation therapies are considered. Neuromodulation is the application of electrical signals to the nervous system to control chronic pain. The first studies to demonstrate neuromodulation’s favorable impact on severe CRPS are now over a decade old. A new neuromodulation technique called Dorsal Root Ganglion (DRG) stimulation has been evaluated and found effective specifically in the treatment of CRPS.
The ACCURATE clinical study is the largest randomized, controlled neurostimulation trial conducted in patients with complex regional pain syndrome (CRPS) and peripheral causalgia, to assess the safety and efficacy of dorsal root ganglion or DRG stimulation in the treatment of chronic, intractable pain (defined as difficult-to-treat pain that has been present for a minimum of six months). There were 152 subjects with chronic, intractable pain of the lower limbs enrolled and randomized in the ACCURATE clinical study. They were randomized to a DRG stimulation group or a control group (using a traditional neurostimulation device) across 22 investigational sites. The ACCURATE clinical study was designed to measure whether a new type of neurostimulation, called DRG therapy, can help more patients with difficult-to-treat isolated pain caused by CRPS of the lower limbs. This kind of pain may be focused in a lower extremity (foot, knee, hip or groin); it is believed to be a problem in the nervous system affecting the way pain signals are sent between the brain and the rest of the body. But for patients with CRPS, traditional pain management methods— including traditional neurostimulation— often don’t work. All 152 patients enrolled and randomized in the ACCURATE clinical study experienced chronic pain in a lower extremity. The pain typically began after an injury, surgery, or other medical intervention and continued for six or more months. The goal of the ACCURATE clinical study was to demonstrate safety and efficacy of DRG stimulation as compared to traditional neurostimulation. What were the results of the ACCURATE study? 86% of DRG patients had persistent pain relief at 12 months, vs 70% in the control group. DRG patients had an average of 81.4% reduction in their pain at 12 months and 94.5% of DRG patients did not experience stimulation outside the area of pain at 12 months.
When a patient is felt to be a DRG stimulation candidate, a trial procedure is scheduled. This is done on an outpatient basis, where the stimulating lead or wire is carefully placed near the DRG structure at the appropriate location for that patient’s CRPS pain. This temporary lead is kept in place for about one week to determine the patient’s response to therapy, and to decide whether to implant the long-term DRG stimulation device (which is similar to a pacemaker, see figure X). This trial period is an important feature of DRG stimulation allowing the patient the opportunity to evaluate the effectiveness of the therapy before making a decision on implant in collaboration with their physician.
Follow up information at one year suggest the patient has a better than 80% chance of reducing or eliminating their opioids. This is done most effectively when DRG is used as part of a multimodal treatment plan using physical medicine, counseling and other modalities.