How DRG Differs from SCS – The Idea of Pleasant Stimuli in CRPS
Written by Dr. Chu for the RSDSA blog.
As most patients suffering from Complex Regional Pain Syndrome know, long-term data regarding standard treatment for this oftentimes debilitating condition has been mediocre at best. In fact, most of the usual treatment available, until recently, have been extremely limited. Nerve-specific medications can have intolerable side effects and low responder rates. Injections such as sympathetic nerve blocks are typically short-lived. Even more advanced therapeutics such as Dorsal Column Stimulation (traditional SCS) have mixed results with patients reporting unwanted areas of stimulation or loss of pain relief over time.
The idea behind neuromodulation is simple, of course. Change the way our nervous system transmits pain signals by blocking it with low levels of electrical current delivered to the spinal cord via small implantable wires and replacing painful sensations with more pleasant ones, thereby giving patients relief. Traditional spinal cord stimulation has been used to treat a variety of chronic pain states. Originating back in, that late 1960s to treat refractory cancer pain, this technology has evolved to successfully help patients suffering from many different types of pain, including failed back surgery syndrome, chronic nerve pain, headaches, chronic pain that develops after trauma or surgery and many more, including CRPS.
I often tell my patients the simplest way to think about this it [is] to remember the last time you stubbed your toe. Between hopping on one leg and screaming at your furniture, you were probably also rubbing your toe. You instinctively do it because it makes your toe feel better. You are distracting your brain from the intense pain by introducing another type of sensation- the sensation of a nice massage.
But as I mentioned, traditional SCS is often not precise or targeted enough for patients with CRPS. Let’s say you suffer from complex regional pain syndrome of the foot that has been refractory to the usual conservative treatment. Spinal cord stimulation may be a reasonable option to treat the continuous pain in your foot, but you may also experience unwanted stimulation in other areas like your low back or thigh. Alternatively, doctors may be able to capture your painful areas with stimulation, but it may not provide durable pain relief.
Given these limitations with traditional SCS, pain physicians around the world have been so excited about Dorsal Root Ganglion Stimulation, a new, ground-breaking, novel treatment option for patients suffering from CRPS. Like traditional SCS, pain relief is achieved through an implantable medical device which delivers low levels of electricity. However, the primary difference is that physicians are now able to precisely place the stimulator leads to target specific areas of pain or damaged nerves, avoiding unwanted areas of stimulation. In addition, the therapy is “sub-threshold,” meaning pain relief is achieved without any paresthesia.
While this therapy has been available in other parts of the world for more than 5 years, the FDA only recently approve (Feb 2016) this treatment for the use in the US. Results from the U.S.-based ACCURATE study have recently been published. In comparing DRG stimulation to traditional SCS, the study found that after following CRPS patients for 12 months,
- More patients found pain relief with DRG stimulation (74%) when compared to SCS (53%)
- More patients reported better focused relief of their painful areas with DRG (95%) vs SCS (61%)
- More than 33% of patients in the study experienced 80% pain relief or better.
CRPS affects many patients in many different ways. More advanced treatments such as the ones discussed here may not be for everyone. However, if you or someone you know is suffering from CRPS, have undergone more conservative therapy without benefit, have significant functional limitations due to pain from CRPS, or continue to rely on high-doses of opiod therapy, DRG stimulation may be right for you.