The dorsal root ganglion (DRG) is a group of cells, found along some of your nerves, as they connect to your spinal cord. Pain signals from your body are sent and processed in the DRG before they move further to the spinal cord and brain.
Therapeutic electrical pulses that are applied to the DRG can treat chronic pain. The therapy is known as “DRG stimulation” or “DRG neuro-stimulation”. This new treatment is now available in the United States. It has been successfully used for chronic leg pain, such as complex regional pain syndrome (CRPS). However, it has also treated chronic foot, knee, groin, abdomen, and pelvic pain.
Pain specialists perform implants with DRG stimulators. A DRG stimulator (device) is placed in your back, close to a certain DRG. The DRG stimulator “turns off” your pain by acting on a targeted DRG. This may be a new treatment option for you if you suffer from chronic pain in a focused area.
The DRG – a control center for pain
A DRG lies on either side of your spinal cord, at several levels spanning the length of your back. Each DRG brings in pain signals from a certain body part such as the arms, legs, back, abdomen, and others. It sends the information further, to the spinal cord and brain.
For example, if you step on a hot surface, pain signals travel up your leg nerve(s), to a certain DRG. That DRG increases the pain signals and sends them to the spinal cord or it completely blocks them. Thus, the DRG works like a control center for pain.
The central nervous system then releases chemical or electrical messages, telling your body how to react. You may quickly withdraw your foot from the hot surface (a reflex). You may become aware of the injury because you have inflammation and pain in your foot.
The DRG – a target for treatment
For many years, scientists thought that the spinal cord and the brain are solely responsible for pain sensations. However, recent findings suggest that the DRG is an important pain-sensing organ.
The DRG plays a part in the appearance of allodynia, an unpleasant chronic pain sensation that starts even after a minor trigger. For example, a light touch or the mere brush of your clothes on your skin cause excruciating pain.
Several characteristics make the DRG a good target for chronic pain treatments:
- The DRG is easily reached due to its unique location along either side of the spinal cord. Your pain specialist can use an epidural approach. (Epidurals are injections commonly used to control pain during labor and various surgeries).
- The DRG has a role in both normal and in abnormal pain (pain outlasting the expected healing time).
- There is no CSF (fluid that bathes the spinal cord) around the DRG. The CSF can act as an energy sink and skew the effects of stimulation.
- DRG stimulation provides a focused treatment. This helps when you are having pain in a specific area such as the foot, groin, or abdomen (among others).
The ACCURATE study
Treatments focused on the DRG were first approved in Europe and Australia, before reaching the United States. However, in a recent study, a large group of U.S. doctors used DRG stimulation to treat patients with CRPS leg pain. The results were published in the ACCURATE Study.
CRPS is a chronic pain disorder that affects mostly the arms and legs. Symptoms include extreme pain, swelling, limited ability to move the limb, and skin changes. It may initially affect one limb and then spread to the other side of the body.
The results of the ACCURATE study were impressive:
- Three months after receiving a DRG stimulator, 70% of CRPS patients had over 80% pain relief. CRPS patients with DRG stimulators had better pain relief than patients who received a spinal cord stimulator. (Spinal cord stimulators are another treatment option for chronic pain.)
- At one year after the implant, 67.3 % of DRG stimulation patients continued to have over 80% percent pain relief. Only 52% of patients with spinal cord stimulators had over 80% pain relief after one year in the study.
The U.S. Food and Drug Administration approved DRG stimulation in 2016, based on the Accurate Study.
Is DRG stimulation right for you?
Pain specialists generally offer stimulation to patients with CRPS who have not improved with conservative treatments.
DRG therapy may be an option if you have:
- Chronic pain for six months or more.
- Isolated chronic pain in a lower part of the body, such as the foot, knee, hip or groin. A past injury or surgery may have caused this pain.
- Little or no relief from physical therapy, medications, sympathetic nerve blocks, or traditional (spinal cord) stimulation.
Conditions treated with DRG stimulation
According to existing studies, the following pain conditions improved after treatment with DRG stimulation:
- Low back pain due to herniated discs and shooting pains in the leg.
- Peripheral neuropathy (foot numbness, tingling, and shooting pains).
- Knee pain that persists after a surgery.
- Postherpetic neuralgia (chest or back pain after a breakout of herpes zoster).
- Neuropathic chest pain (chronic pain that can start after a surgery).
- Diabetic peripheral neuropathy (foot pain and numbness in diabetics).
How DRG stimulators work
A DRG stimulator device is made up of parts that are designed to work together to help manage your pain:
- Generator. This small box-like device sends out electrical pulses. It contains a battery and it is placed under your skin.
- Leads. Thin insulated wires carry the electrical pulses from the generator to your DRG (or several DRGs). The wires are placed in specific areas of your back, depending on the desired level of treatment.
- Patient controller. A handheld “remote control” allows you to adjust the strength of stimulation or even to turn it off.
A DRG stimulator implant involves four steps:
- Patient Evaluation. Your pain specialist finds the source of your pain based on your medical history, neurological exam, and imaging studies. Your doctor will trace your pain to specific DRGs.
- Trial. Your pain specialist places a temporary DRG stimulator device at the dorsal root ganglion where your pain stems from. This procedure can be done under sedation (twilight anesthesia).
- Device Evaluation. The device remains in place over a period of several days-weeks. This should give you enough time to see if your pain improves. Your input helps your pain specialist decide if the device is likely to help you in the long term. (Even though the device is placed in your back, it can treat pain in areas other than your back – legs, abdomen, groin and pelvic area).
- Implant. You will have a minor surgical procedure in order to receive your permanent device. It is performed in a hospital or surgery center. You may go home the same day or stay overnight.
We understand the debilitating effects of living with chronic pain. Our doctors at National Spine and Pain Centers, are available to offer you the latest treatments for chronic pain. Click here for an appointment.