Abstract
Dorsal root ganglion (DRG) stimulation is a novel therapeutic option that is being increasingly utilized for patients with neuropathic pain. The potential complications during the placement of this device remain unknown. We describe a potential complication during DRG stimulator placement not previously reported in the literature. A 50-year-old male presented to the ED with lower back pain and right lower extremity radicular pain following placement of DRG stimulator at outside facility. A fragment of an introducer catheter was retained in the spinal canal and L2-L3 neural foramen. Patient underwent L2-L3 laminectomy for removal of the catheter without any complications. DRG stimulation is an effective option for intractable neuropathic pain, but the safety of the procedure and its long-term complications need to be further investigated.
Keywords: Dorsal root ganglion, stimulation, neuropathic, pain, catheter, complication
Introduction
Treatment of refractory neuropathic pain remains difficult, but advances in technologies such as spinal cord stimulation has been shown to have efficacy of 40–70%.1 The dorsal root ganglion (DRG) contains pseudounipolar neurons that allow transmission of impulses from the periphery to the central nervous system. As such, the DRG is an important therapeutic target because the excitability of the DRG neurons may result in increased nociceptive signalling causing neuropathic pain.2 Neurostimulation of the DRG may have upstream and downstream effects by reducing the hyperexcitability of the neurons to relieve neuropathic pain.3 The ACCURATE trial demonstrated that DRG stimulation provided more targeted pain relief in more patients compared to spinal cord stimulation.4 Although DRG stimulators have been used in Europe for years and were approved by the Food and Drug Administration (FDA) in February 2016 in the United States for complex regional pain syndrome (CRPS), the complications associated with the use of the device remains to be evaluated.
Case report
History and examination
A 50-year-old male with a past medical history of chronic pain syndrome and lumbar post-laminectomy syndrome presented to the Emergency Department (ED) at University Hospital in Newark, New Jersey, 5 days after undergoing DRG stimulation trial at an outside facility. The patient complained of 8 out of 10 back pain and right leg numbness. During the procedure, there was shearing of the introducer catheter with a retained fragment in the spinal canal and right L2-L3 neural foramen. The patient was notified of the retained catheter after placement of the DRG stimulator. The patient started to experience the symptoms 1 day after the procedure. One day prior to the ED visit, the patient had the trial stimulator removed at the outside facility and was instructed to visit the ED for the symptoms and removal of the catheter. Since the stimulator was placed at an outside facility, the exact circumstances under which the shearing of the catheter occurred could not be obtained. Physical examination did not reveal any motor deficit and no other sensory deficits asides from right leg numbness. At baseline, patient uses a cane to ambulate. He has a history of multiple surgeries in the past including spinal fusion, bilateral hip replacement, right knee replacement and bilateral shoulder surgeries. Computed tomography (CT) of the lumbar spine showed a hyperdensity in the right L2 foramen (Figure 1). The patient was then scheduled for an L2-L3 laminectomy for retrieval of the catheter.
Figure 1.
CT of lumbar spine showing a hyperdensity in the right L2 foramen.
Procedure
The patient was taken to the operating room for removal of the catheter, after informed consent was obtained. Under general anaesthesia, the patient was positioned in a prone position and his back was prepped and draped. Perioperative cefazolin 1000 mg was given. Fluoroscopy was used to mark a 4-cm incision over the L2 spinous process and inject 1% lidocaine with epinephrine. Incision was made to expose the L2 and L3 lamina including the L2-L3 interlaminar space. The L2 spinous process was removed and the L2 lamina and the superior aspect of the L3 lamina were drilled with a high-speed drill. The catheter was identified and removed while the ligamentum flavum was carefully dissected off. The fascia and skin were closed in standard fashion and the patient was transferred to the recovery room in stable condition without any intraoperative complications.
Post-operative course
Postoperatively, our patient experienced 8 out of 10 back pain the day after the procedure, but was able to ambulate independently. The patient refused to participate in occupational therapy and was discharged.
Discussion
The complications of spinal cord stimulators are well documented, such as electrode migration, infections, electrode fracture and hardware failure, but recommendations are also available to avoid these complications.5 DRG stimulation is a novel therapy for neuropathic pain and the complications of this therapeutic option remain to be evaluated. We describe a rare complication of a retained catheter occurring after DRG lead placement, which required subsequent surgical removal. Placement of the DRG stimulator lead requires the lead to be placed inside a delivery sheath, which is curved at the end to direct the lead into the neural foramen. The sheath containing the lead is inserted into the tuohy needle and advanced in the epidural space to access the DRG. After confirmation of correct lead placement, the sheath is retracted over the needle, which can potentially lead to shearing of the sheath or damage to the lead. Vancamp et al.6 recommended that the injection port should not be more than 90o away from the mark on the needle as the sheath is being retracted to avoid damage to the sheath.
In a prospective study with 10 patients, Deer et al.7 noticed 17 safety events in seven patients including 3 with transient increased pain after the procedure, 7 with device inactivation, 1 lead migration and 1 reaction to antibiotics concluding that the device was safe for implantation. Liem et al. also confirmed the safety of the procedure, but reported 70 events in 24 subjects including infection, CSF leak, inflammation, inadequate pain relief, flu-like symptoms and temporary motor stimulation.8 In the ACCURATE trial, DRG stimulator procedure related complications were significantly higher than SCS procedure related complications with pain at incision site being the most common for both.4 Liem et al. also examined the safety of DRG stimulator 1 year after the procedure and found temporary motor stimulation, cerebrospinal fluid leak with headache, and infection to be the most common complications. Four lead revisions were done due to either high impedance, lead migration or lead fracture. Seven explantations were performed secondary to infection, noncompliance or lack of efficacy.8
Device-related complications may be reduced over time as physicians become more experienced with the procedure and its techniques and reduce the procedure time. Before implanting DRG stimulators, it is important that physicians complete the necessary courses, practice on models or cadavers and initially place the stimulators under the guidance of more experienced physicians. However, complications from the procedure can be inherent to the placement technique and equipment itself. As the frequency of DRG stimulator placement increases, physicians should continue to implement techniques to reduce complications and evaluate patient outcomes at their institutions.
Conclusion
We describe a potential procedure-related complication from placement of DRG stimulator. Various studies have shown the effectiveness of DRG stimulation and its advantages over spinal cord stimulation. It is a novel therapeutic option for neuropathic pain having gained FDA approval in 2016 for CRPS. The literature examining the procedure-related complications and long-term outcomes is limited. Further studies are needed to recommend techniques to increase the safety of the procedure.
Acknowledgments
The guarantor (A.M.) is the person willing to take full responsibility for the article, including for the accuracy and appropriateness of the reference list. This will often be the most senior member of the research group and is commonly also the author for correspondence. G.K. wrote the first draft of the manuscript. All the authors reviewed and edited the manuscript and approved the final version of the manuscript.
Footnotes
Conflict of interest: The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship and/or publication of this article.
Ethical approval: New Jersey Medical School does not require ethical approval for reporting individual cases.
Informed consent: Written informed consent was obtained from a legally authorized representative for anonymized patient information to be published in this article.
Guarantor: AM
Contributorship: GK wrote the first draft of the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript.
References
- 1. Forget P, Boyer T, Steyaert A, et al. Clinical evidence for dorsal root ganglion stimulation in the treatment of chronic neuropathic pain. A review. Acta Anaesthesiol Belg 2015; 66(2): 37–41. [PubMed] [Google Scholar]
- 2. Sapunar D, Kostic S, Banozic A, et al. Dorsal root ganglion – a potential new therapeutic target for neuropathic pain. J Pain Res 2012; 5: 31–38. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Krames ES. The dorsal root ganglion in chronic pain and as a target for neuromodulation: a review. Neuromodulation 2015; 18(1): 24–32. [DOI] [PubMed] [Google Scholar]
- 4. 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] [PMC free article] [PubMed] [Google Scholar]
- 5. Bendersky D, Yampolsky C. Is spinal cord stimulation safe? A review of its complications. World Neurosurg 2014; 82(6): 1359–1368. [DOI] [PubMed] [Google Scholar]
- 6. Vancamp T, Levy RM, Peña I, et al. Relevant anatomy, morphology, and implantation techniques of the dorsal root Ganglia at the lumbar levels. Neuromodulation 2017; 20(7): 690–702. [DOI] [PubMed] [Google Scholar]
- 7. Deer TR, Grigsby E, Weiner RL, et al. A prospective study of dorsal root ganglion stimulation for the relief of chronic pain. Neuromodulation 2013; 16(1): 67–71. [DOI] [PubMed] [Google Scholar]
- 8. Liem L, Russo M, Huygen FJ, et al. One-year outcomes of spinal cord stimulation of the dorsal root ganglion in the treatment of chronic neuropathic pain. Neuromodulation 2015; 18(1): 41–48. [DOI] [PubMed] [Google Scholar]