Dorsal Root Ganglion Stimulation
Devices to stimulate the dorsal root ganglion (DRG) became available in the mid-2010s for treating chronic pain, particularly in areas that were hard to treat with traditional spinal cord stimulation, such as the hand, chest, abdomen, foot, knee or groin. (1)
The DRG is an easily accessible structure in the spine that plays a key role in the development and management of chronic neuropathic pain. It is a bundle of sensory nerve cell bodies within the epidural space. Each nerve root communicates to the dorsal root ganglion in a way that allows sensory messages from a defined area of the body. Therefore, applying stimulation to the DRG can permit focused therapy to a specific focal area.
DRG stimulator components consist of electrical leads, an optional extension, and an implantable pulse generator. The electrical leads are threaded into the epidural space and from there, into the intervertebral foramen, in which the DRG lies. Each lead is tipped by four electrode contacts that are placed over the DRG. A non-rechargeable pulse generator is implanted in a pocket either in the upper buttock/low back or, with an extension, into the abdominal wall. In the period after surgery the leads can be programmed to give stimulation based on the pain pattern. Patients go home with a small hand-held controller that switches between stimulation settings.
In addition to focusing stimulation, DRG neuromodulation has a few other distinguishing aspects. At 12 months, patients who responded to the therapy were reported to have both less discomfort, and also improved mood scores. (2) The pain-relieving stimulation can be flexibly programmed so that if a patient prefers, the therapy can create a tingling sensation of paresthesia. In many patients relief occurs without parasthesia. In addition, any perception of paresthesia is less subject to positional change as compared to conventional SCS, since the cerebrospinal fluid near the DRG is relatively thin. (3)
References:
1. (2015), International Neuromodulation Society 12th World Congress Neuromodulation: Medicine Evolving Through Technology June 6–11, 2015 Montreal, Canada. Neuromodulation: Technology at the Neural Interface, 18: e107–e399. doi: 10.1111/ner.12333.
2. One-year outcomes of spinal cord stimulation of the dorsal root ganglion in the treatment of chronic neuropathic pain. Liem L, Russo M, Huygen FJ, Van Buyten JP, Smet I, Verrills P, Cousins M, Brooker C, Levy R, Deer T, Kramer J. Neuromodulation. 2015 Jan;18(1):41-8; discussion 48-9. doi: 10.1111/ner.12228. Epub 2014 Aug 21. PMID: 2514546.
3. Kramer, J., Liem, L., Russo, M., Smet, I., Van Buyten, J.-P. and Huygen, F. (2015), Lack of Body Positional Effects on Paresthesias When Stimulating the Dorsal Root Ganglion (DRG) in the Treatment of Chronic Pain. Neuromodulation: Technology at the Neural Interface, 18: 50–57. doi: 10.1111/ner.12217.
Reviewed May 3, 2016
Timothy Deer, MD, FIPP
President, International Neuromodulation Society, 2015-2018
Clinical Professor of Anesthesiology, West Virginia University School of Medicine, Charleston, WV, USA.
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