DRG Stimulation Superior to Spinal Cord Stimulation for Lower Extremity Pain

The DRG has been shown to undergo pathophysiologic changes in animal models of chronic pain, and may be a viable target for neurostimulation.
The DRG has been shown to undergo pathophysiologic changes in animal models of chronic pain, and may be a viable target for neurostimulation.

Dorsal root ganglion (DRG) stimulation is more likely than spinal cord stimulation (SCS) to provide pain relief in patients with neuropathic pain affecting the lower extremities, according to the ACCURATE study published in Pain.1

Approximately 1.5% of the general population suffers from refractory neuropathic pain. SCS provides pain relief in less than 50% of patients with complex regional pain syndrome (CRPS) and other causes of chronic pain.2,3 In addition, SCS may be associated with unpleasant paresthesia and lead migration, and limitations in targeting may lead to reduced efficacy.

The DRG has been shown to undergo pathophysiologic changes in animal models of chronic pain, and thus may be a viable target for neurostimulation.4 Limited data suggest that DRG stimulation may have greater success rates in treating chronic pain than SCS.5

In the ACCURATE study (ClinicalTrials.gov Identifier: NCT01923285), researchers, led by Timothy R. Deer, MD, from the West Virginia University School of Medicine in Morgantown, compared the safety and efficacy of DRG stimulation vs SCS in patients with chronic intractable lower extremity pain due to CRPS or causalgia. The primary outcome was 3-month treatment success, defined as ≥50% decrease in the visual analog scale (VAS) score and the absence of stimulation-associated neurological deficits.

A total of 152 patients were randomly assigned in a 1:1 ratio to DRG stimulation (average age, 52.4; 51.3% women; lower limb pain duration, 7.5 years; 57.9% of patients with CRPS, 42.1% with causalgia) or SCS (average age, 52.5; 51.3% women;  lower limb pain duration, 6.8 years; 56.6% of patients with CRPS, 43.4% with causalgia) Study participants with CRPS all presented with sensory symptoms, either motor trophic (94.3%), vasomotor (65.5%), sudomotor, or edema (66.7%).

As neither DRG stimulation nor SCS was associated with neurologic deficits, a ≥50% reduction in VAS indicated treatment success.

DRG stimulation resulted in higher treatment success rates than SCS at 3 months (81.2% vs 55.7%; P <.0004). Similar rates of treatment success for DRG vs SCS were maintained at 12 months (74.2% vs 53.0%;  P <.0004), as well as within the subgroups of CRPS (82.5% vs 57.5%; P =.006) and causalgia (79.3% vs 53.3%; P =.014) at 3 months.In addition, postural variation (supine vs upright) was less likely to have an effect on paresthesia intensity in patients treated with DRG than in patients treated with SCS (P <.001). No differences in the rates of serious and/or device-related adverse effects. 

Summary and Clinical Applicability

Patients with refractory neuropathic pain make up an important patient population who suffer from chronic pain. However, SCS provides pain relief in less than half of patients in this population. In the ACCURATE study, Dr Deer and colleagues demonstrated that DRG stimulation produced greater rates of clinically meaningful pain relief than SCS.

“This [study] shows that the chance of getting a positive outcome with DRG spinal stimulation is the highest ever seen in the area of treatment for nerve injuries for the area from the waist to foot. Also, DRG spinal stimulation was superior to conventional treatment in all treatment groups,” he said.

Limitations and Disclosures

Withdrawal from the study was characterized as treatment failure. The absence of blinding may have played a role in such withdrawals, as patients randomly assigned to SCS may have been less motivated to remain in the trial

This study was funded by Spinal Modulation, LLC, part of St. Jude Medical.

 

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References

  1. Deer TR, Levy RM, Kramer J, et al. Dorsal root ganglion stimulation yielded higher treatment success rate for complex regional pain syndrome and causalgia at 3 and 12 months: a randomized comparative trial. Pain. 2017;158(4):669-681. doi: 10.1097/j.pain.0000000000000814
  2. Geurts JW, Smits H, Kemler MA, Brunner F, Kessels AG, van Kleef M. Spinal cord stimulation for complex regional pain syndrome type I: a prospective cohort study with long-term follow-up. Neuromodulation. 2013;16(6):523-529. doi: 10.1111/ner.12024
  3. Kemler MA, Barendse GA, van Kleef M, et al. Spinal cord stimulation in patients with chronic reflex sympathetic dystrophy. N Engl J Med. 2000;343(9):618-624. doi: 10.1056/NEJM200008313430904
  4. Koopmeiners AS, Mueller S, Kramer J, Hogan QH. Effect of electrical field stimulation on dorsal root ganglion neuronal function. Neuromodulation. 2013;16(4):304-311. doi: 10.1111/ner.12028 
  5. Van Buyten JP, Smet I, Liem L, Russo M, Huygen F. Stimulation of dorsal root ganglia for the management of complex regional pain syndrome: a prospective case series. Pain Pract. 2015;15(3):208-216. doi: 10.1111/papr.12170
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