Complete Guide to Dorsal Root Ganglion (DRG) Stimulation Treatment For Complex Regional Pain Syndrome (CRPS)
Complex Regional Pain Syndrome (CRPS) is an extremely difficult neuropathic pain condition to treat or manage. In this article we deal with a fairly new available and innovative CRPS treatment; Dorsal Root Ganglion (DRG) Stimulation treatment for Complex Regional Pain Syndrome (CRPS).
DRG stimulation is a form of neuromodulation therapy, which works in the Dorsal Root Ganglion (DRG) area of the spine and it has been proven extremely effective for the treatment of CRPS (ACCURATE Study 2017).
DRG stimulation functions along the same idea as the traditional spinal cord stimulation or SCS. With the SCS you have a small device implanted along the spinal cord to produce electrical pulses to the nerves. It is these electrical pulses that stop your CRPS pain signals and swap them with a mild tingling feeling or sensation. Howeverwith DRG stimulation you’ll find will do mostly the same sort of thing as the SCS. However there is one critical and important difference, which is the target.
Many of those living with CRPS will have tried multiple treatments. Some may have been successful and others not so successful. Due to every person living with CRPS being an individual in terms of signs and symptoms and in turn treatment, people will find they have exhausted most of the standard treatments for their CRPS.
Some CRPS patients may have even tried Spinal Cord Stimulators which is an invasive treatment itself, but has no guarantee it will reduce the CRPS pain and symptoms significantly mainly due to the coverage the SCS can produce.
Dorsal Root Ganglion stimulation for both types of CRPS in the lower extremities was approved by the FDA in USA in February 2016. The Proclaim™ DRG Neurostimulation System for chronic neuropathic pain including CRPS was launched in Europe on 18th January 2017.
The Proclaim™ DRG is extremely up to date in terms of size, shape and technology. It uses both Bluetooth® wireless technology and also Apple iOS™ software proving how up to date the system actually is. Abbott, the system’s creator and manufacturer stated in their press release:
“Through the Proclaim platform’s Bluetooth® wireless technology and iOS™ software, the Proclaim DRG Neurostimulation System offers patients a more intuitive therapy experience, compared to current systems with traditional controllers that can be difficult to operate. This new system will improve the experience of how patients interact with their device, which may lead more patients to consider DRG stimulation for the treatment of chronic neuropathic pain.”
The DRG is not a cure for your CRPS but it is to help you manage your pain. It is also not seen as a replacement for the usual Spinal Cord Stimulator but instead it is an alternative.
Where and What Is The Dorsal Root Ganglion?
You can find the Dorsal Root Ganglion at the base of individual branching spinal nerves, very close to the spinal cord. It is adjacent to the dorsal nerve root, which exists as part of a pair of nerve roots exiting at each level of the spine. The ganglion forms a little bulge at the base of each spinal nerve.
Within the Dorsal Root Ganglion is a small bundle of nerves (neurons) that collect and transmit the sensory messages of touch and pain very quickly to the spinal cord rather than back to the brain. This shorter distance allows for a quicker response to painful stimulus. For example it is this that allows you to pull away your hand from a hot oven.
How Does The DRG Stimulation Work?
As we mentioned at the beginning, the Dorsal Root Ganglion or DRG stimulation is a neuromodulation therapy or treatment that is similar to traditional Spinal Cord Stimulation or SCS you may have heard of. The problem with the traditional SCS is that for approximately 50% of patients, over time the SCS will lose its effectiveness for pain relief. (Liem, L. 2014)
There is really one main difference between the SCS and DRG Stimulators which is the location. Instead of placing the electrodes over the rear aspect of the spinal cord as in SCS, the leads are implanted on the dorsal root ganglion. Tiny electrical impulses are sent through the implanted lead(s) onto the nerve attached to the DRG. You will either feel a comfortable tingling sensation in your CRPS area or you stop feeling any pain.
On the spinal column you will find a number of different Dorsal Root Ganglions and each one is associated with different parts of the body. It is because each DRG corresponds to particular and specific areas it means that if you stimulate the particular Dorsal Root Ganglion associated with the CRPS affected area, the result is much more targeted pain relief.
Ultimately instead of trying to get a wide coverage of pain relief with the SCS instead because of the specific targeting of the DRG stimulation there seems to be a better level of pain relief from the CRPS.
You would be able to change the location and intensity of the stimulation and there will usually be a trial period before the full implant just as in the SCS to ensure the DRG stimulator is suitable for you and your CRPS. This trial period is usually around 1 week in length and during the trial you will be fitted with a temporary DRG stimulator. Please click the Procedure Route to getting the DRG for CRPS section below.
What Is The Equipment Used For DRG Stimulation?
Currently there is one type of DRG stimulator for CRPS that is made by Abbott. The Proclaim™ stimulator is on the iOS™ platform and has Bluetooth® wireless technology.
Abbott stated in their New Release that the new Proclaim™:
“offers patients a more intuitive therapy experience, compared to current systems with traditional controllers that can be difficult to operate. ”
DRG stimulation has the same three (3) components as you would find with the traditional Spinal Cord Stimulator or SCS. It has:
- Generator and Battery: This is a small device that sends out mild electrical pulses to the DRG area. This is placed beneath the skin in the buttocks or abdomen, and can take you up to four leads. The battery is the approximate size of a large match box which is implanted either above your hip, either side of your stomach, near your belly button or on the upper part of one of your buttocks. The battery placement will depend on where is most comfortable for you and it will take into any physical issues may have such as being in a wheelchair. It has also been placed on your right or left side underneath either armpit.
- Leads: The leads are thin (approximately 1 mm in diameter) insulated wires that are attached to the generator and when activated send small electrical pulses from the generator to your dorsal root ganglia, to stop the pain signals. These are placed in your body in the area of the DRG. Up to 4 leads per battery can be added to help achieve sufficient and fuller coverage of your pain.
- Patient hand held controller: This handheld controller is effectively like a “remote control” that allows you to adjust the strength and location of stimulation or even turn stimulation off. However the new Proclaim™ has a hand controller that looks like an Apple iPod or Apple iPhone which is more discreet and not so obviously looking like a piece of medical equipment.
The company have said that the Proclaim™ DRG neurostimulator will provide:
“… patients with chronic neuropathic pain access to the company’s Proclaim platform, a magnetic resonance (MR)-conditional recharge-free system offering best-in-class programming, upgradeability and increased battery capacity. The Proclaim DRG Neurostimulation System also utilises an iPod touch mobile digital device patient controller that offers wireless communication via Bluetooth wireless technology.”
As we said above when the DRG stimulation is activated the DRG blocks the pain signals from being sent from that area to the brain. The stimulation will either stop the pain right away or create a low, background tingling sensation that you may not be able to feel. This is unlike the Spinal Cord Stimulators where you may feel a stronger sensation which for some people living with CRPS can be unpleasant, can even make the condition worsen or cause a flare up.
What are the advantages or benefits of the DRG stimulation?
One of the most important benefits to the Dorsal Root Ganglion (DRG) stimulation is that because it works directly in the area where the pain signals are coming from, it is able to target the harder-to-reach nerves that can be associated with peripheral intractable nerve pain, such as the CRPS pain in the legs and feet.
The DRG Stimulator works directly in the area where the pain signals are coming from. It is the only FDA-approved system specifically designed to stimulate the dorsal root ganglion (DRG), which has been clinically proven to provide superior pain relief over the conventional Spinal Cord Stimulators (SCS). According to van Bussell, C. et al (2015):
“Dorsal root ganglion (DRG) stimulation is an effective and safe stimulation technique..”
The most important and recent research study that has been done on the DRG stimulation for CRPS is the ACCURATE (2017) study and the results have been remarkable. It is the largest randomised neurostimulation clinical trial that compares the conventional SCS with DRG stimulation to treat CRPS and peripheral causalgia. The findings demonstrate that with DRG therapy, doctors are able to:
- Give patients more pain relief
- Deliver superior pain relief with larger coverage area – the normal SCS treatment has been used to help manage chronic intractable CRPS pain in the limbs or trunk. However for CRPS pain that is more focal or pain locations outside these areas the Spinal Cord Stimulation has been less successful.
- Provide a more stable and more long term relief to patients living with CRPS
What has been found is that by just stimulating the DRG, doctors are able to achieve sufficient coverage and pain relief in difficult-to-treat chronic pain conditions like Complex Regional Pain Syndrome (CRPS).
Research has shown that the DRG plays a crucial role in the management of chronic pain from CRPS. The DRG’s unique pathophysiological response to pain makes it a perfect target for pain management therapies like neurostimulation providing a greater chance that the person’s main area of pain is dealt with and they receive sufficient pain relief.
There have been other research studies undertaken apart from the Accurate Study, such as Deer et al.(2013), Liem, L. et al. (2014) and van Bussell, C. et al.(2015) In the Deer et al (2017) study they reported:
“… the successful use of DRG stimulation in 10 patients with chronic, intractable neuropathic pain of the trunk and/or limbs. These patients received DRG stimulation for 3–7 days. All patients experienced pain relief in the targeted anatomical regions, with reported improvement ranging from 17% to 100%.”
According to Abbott, DRG stimulation has been clinically proven superior to the standard SCS in treating lower limb pain associated with CRPS. Patients in the ACCURATE (2017) study reported focal chronic intractable pain in locations like the hip, groin, foot and knee.
At three (3) months, 81.2% of patients receiving DRG stimulation achieved effective pain relief and greater treatment success as compared to 55.7% of patients receiving traditional SCS stimulation. Durability of pain relief was seen after 12 months, with 74.2% of DRG stimulation patients achieving meaningful pain relief and greater treatment success when compared to 53% of patients receiving traditional SCS.
Other benefits of the DRG neurostimulator include:
- Better quality of life if pain relief of some degree is achieved
- Battery replacement has been improved with this DRG stimulator because unlike some SCS systems this DRG battery doesn’t have to be recharged as it uses a fraction of the energy that other systems use. You still have to change the battery every 5 years approximately but the replacement is an easier process. Due to the fact that the layer between the stimulator and the dorsal root ganglion cells is so narrow, the DRG stimulation uses approximately 10% of the energy required for the usual SCS
- It is reversible as it doesn’t cause any permanent damage or changes to the nerves. You will of course be left with scars if the DRG is removed at a later date, but would be smaller than the normal SCS scars
- Like the usual SCS you should be able to reduce the amount of oral medication you take which could mean less side effects from opioids or other medications
- Marginal risk of lead migration which is because the dorsal root ganglion is found in a very small space, which reduces the chances of lead migration. Stimulation leads reported less than a 1% migration rate in the ACCURATE Study. Traditional SCS reports a14% migration rate (Washburn, et al., Industry Wide Incidence Rate of SCS Related Complications, NANS 2010)
- The DRG isn’t just for CRPS but it can be used for other neuropathic pain conditions such as post amputation and phantom limb pain
In a recent research article regarding the Dorsal Root Ganglion stimulator and its use in patients who have had or need an amputation for CRPS by Goebel, A. et al (2017), they found that:
Dorsal Root Ganglion stimulation should be considered as a potentially effective treatment, even where conventional spinal cord stimulator treatment has failed to achieve reliable paraesthetic cover. Furthermore, this treatment may provide pain relief in those patients with CRPS recurrence in the stump after amputation.
What are the disadvantages of the DRG stimulation?
One main disadvantage for some people will be the cost of the DRG neurostimulator. There may be issues with the cost not only in the UK but around the world. However you are paying for the latest technology in CRPS treatment. Also as with any form of treatment there are disadvantages and potential adverse effects with the DRG stimulation. These include:
- Risks associated with any surgical procedure: bleeding from wound from surgery or where injections have been placed, local or systemic infection, swelling, inflammation, foreign body reaction etc.
- Risks associated with system placement procedures: pain at the implant site, swelling, infection, put in the wrong place etc.
- Risks associated with the use of the system: lead migration, allergic response or tissue reaction to the implanted system material, persistent pain at the INS and/or lead site, extension, or lead site, premature battery depletion, loss of pain relief over time, uncomfortable stimulation or ineffective pain control, changes in electrode position, inability to achieve the desired pain relief results, device failure, paralysis (very rare) etc.
- Additional risks as a result of the placement and stimulation of the lead in the area of the DRG, include pain due to setting the stimulation parameters too high
What Are The Guidelines For The Dorsal Root Ganglion (DRG) Stimulation?
The National Institute for Health and Care Excellence (NICE) in the UK is the organisation responsible for recommending which medicines and treatments are used by the NHS. The guidelines for the DRG are the same as for the Spinal Cord Stimulator or SCS. NICE recommends spinal cord stimulation for severe prolonged pain that has responded to a trial of stimulation in failed back surgery syndrome, Complex Regional Pain Syndrome and neuropathic pain.
The NICE recommendations for the SCS are as follows:
Spinal cord stimulation is recommended as a possible treatment for adults with chronic pain of neuropathic origin if they:
- Continue to experience chronic pain (measuring at least 50 mm on a 0–100 mm visual analogue scale) for at least 6 months despite standard treatments, and have had a successful trial of spinal cord stimulation as part of an assessment by a specialist team
- Treatment with spinal cord stimulation should only be given after the person has been assessed by a specialist team experienced in assessing and managing people receiving treatment with spinal cord stimulation.
What Is The Route To Getting A DRG For CRPS?
There are only certain clinics in the UK who offer the Dorsal Root Ganglion stimulators. To see which clinics offer the DRG please read below. However there are a few things that you will have to have before full implant is considered:
- You will need to see and be assessed by either a pain specialist or neuromodulation team to discuss all options open to you
- You will see a psychologist to determine your suitability for the DRG and will look at the impact of chronic pain / CRPS on your activities, mood, relationships and sleep. At either or both of the pain specialist assessment or psychologist assessment they may ask you about your expectations of the DRG and how you would feel if it doesn’t work for you and your CRPS
- Before you go for full implant of the DRG you will usually have a trial period of between 5 – 10 days but usually 1 week, but this depends on each pain clinic or neuromodulation clinic. During this time you would be fitted with a temporary DRG system which is to determine whether it is effective for your CRPS pain or not. If it is not effective then the temporary system will be removed and there won’t be any permanent damage to your nerves. The trial is normally just a day case surgery but may be overnight depending on your medications
- If your trial period goes well and is successful then you go to the full or permanent implant
What is the approximate cost?
The approximate cost is £15,000. However if you are on the NHS system in the UK then you won’t pay anything. It is available under Private Treatment here in the UK.
Some people have allergic reactions to different materials. Unfortunately this may mean that if you have allergies to some of the materials that the DRG is made of, you may not be able to have the implant.
According to the Proclaim™ DRG Clinicians Manual the following materials are intended to come into contact with tissue:
- Silicone Rubber
- Epoxy Resin
- Polybutylene terephthalate
- Polyether ether ketone
- Cobalt nickel chromium molybdenum alloy
The manual also says that the above components are not made with natural rubber latex.
If you have any allergies against any form of material, then it is crucial that you mention those allergies and the reaction you get if exposed with your specialist or the implanter.
There are some contraindications for the Proclaim™ DRG according to the
Proclaim™ DRG Clinicians Manual which are:
- Unable to operate the system
- Poor surgical risks
- Under the age of 18
How Is The Trial DRG Stimulation Implant Procedure Carried Out?
The procedure for implanting a DRG stimulation device is similar to the procedure for implanting an SCS or Spinal Cord Stimulator.
- You will be admitted to either as a day case, general ward or neurosciences ward which will either be on the day of your trial DRG implant or the day before. Most people will be in hospital for between 1 day up to 8 days depending on either the length of your trial period if you are staying in hospital for it or if you have had your trial period at home and you are returning for the full implant. This all depends on your hospital
- The DRG procedure will take place in the operating theatre and you will lie down on your front. You will most likely be given some sedation medication to make you drowsy but not asleep. You will have a local anaesthetic injection in your back where the electrodes will be placed
- To place the electrodes into your spine your surgeon will use a hollow epidural needle and to check whether the electrodes are giving you the tingling feeling in the correct area of your pain they will test them at this point while you are awake
- If the surgeon has got the correct point many people have commented that they have instant relief or will shout out that the pain has decreased. If the test is successful the electrode wire will be placed under your skin on your buttock or stomach through a small cut which is approximately 3cm in length. After this, the battery will be implanted and the wires will all be connected up
- However if the trial wasn’t as successful with your pain or wasn’t conclusive, they would secure the wire outside your body with medical tape and connect it to an external device to trial the DRG stimulation
(DRG for CRPS Leaflet, Oxford)
What Happens After The Trial DRG?
The trial will either take place in hospital or at home and this is dependent on each hospital. After the operation fitting the trial, your stimulator will be set up for you to achieve pain relief from it. You will most likely be assessed regularly by your specialists to make sure you are getting pain relief from the DRG and to assess the level of pain relief you are having. If you are receiving sufficient pain relief from the DRG stimulator then you will need a further procedure to go from trial DRG implant to full DRG implant.
In this 2nd stage procedure the leads will need to be connected under your skin to the battery which will be usually placed in your buttock or on your belly.
You would go home with a patient controller so you can adjust your settings, but the settings will usually be a lot lower than those of the SCS settings. The stimulation device can be programmed externally to emit electrical pulses at appropriate intervals.
For patients who have the Proclaim™ DRG implanted you will be able to access the Proclaim platform and use the iPod touch mobile digital device patient controller that features wireless communication via Bluetooth, which as we mentioned earlier on in the blog, is far more discreet than the traditional SCS controllers people are used to.
Here is a brief video from SpinalCordStim.com entitled ‘Axium DRG Stimulation Overview’