Long-term safety of spinal cord stimulation systems in a prospective, global registry of patients with chronic pain.

Aim: The availability of long-term (>2 years) safety outcomes of spinal cord stimulation (SCS) remains limited. We evaluated safety in a global SCS registry for chronic pain. Methods: Participants were prospectively enrolled globally at 79 implanting centers and followed out to 3 years after device implantation. Results: Of 1881 participants enrolled, 1289 received a permanent SCS implant (1776 completed trial). The annualized rate of device explant was 3.5% (all causes), and 1.1% due to inadequate pain relief. Total incidence of device explantation >3 years was 7.6% (n = 98). Of these, 32 subjects (2.5%) indicated inadequate pain relief as cause for removal. Implant site infection (11 events) was the most common device-related serious adverse event (<1%). Conclusion: This prospective, global, real-world study demonstrates a high-level of safety for SCS with low rate of explant/serious adverse events. Clinical Trial Registration: NCT01719055 (ClinicalTrials.gov).

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.

Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). The primary end point was a composite of safety and efficacy at 3 months, and subjects were assessed through 12 months for long-term outcomes and adverse events. The predefined primary composite end point of treatment success was met for subjects with a permanent implant who reported 50% or greater decrease in visual analog scale score from preimplant baseline and who did not report any stimulation-related neurological deficits. No subjects reported stimulation-related neurological deficits. The percentage of subjects receiving ≥50% pain relief and treatment success was greater in the DRG arm (81.2%) than in the SCS arm (55.7%, P < 0.001) at 3 months. Device-related and serious adverse events were not different between the 2 groups. Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS.

Spinal cord stimulation: the types of neurostimulation devices currently being used, and what radiologists need to know when evaluating their appearance on imaging.

Neural stimulation is increasingly used as a treatment for chronic pain. Common indications for spinal cord stimulation include chronic neuropathic and oncological pain, intractable angina, or chronic pain secondary to vascular disease. It is estimated that up to 4 million patients may be candidates for the therapy. Therefore, it is likely that an increasing number of patients will have spinal neurostimulation devices implanted over the coming years. Because radiography and computed tomography are the primary imaging modalities used to evaluate the proper positioning of these devices, radiologists should be familiar with their appearance. The purpose of this article is to discuss the types of neurostimulation devices currently being used and to demonstrate their respective imaging appearances.

Occipital neuromodulation: ultrasound guidance for peripheral nerve stimulator implantation.

We report a case of chronic left-sided occipital neuralgia in a 21-year old female patient. The patient in question suffered from chronic greater occipital neuralgia for a duration of many years, which had been refractory to other conservative medical management strategies. Blockade of the greater occipital nerve with local anesthetic was consistently useful in attenuating the patient's pain, though the effects were always short lived. Consequently, a successful trial of greater occipital nerve stimulation was undertaken. Compared with spinal cord stimulation, peripheral nerve stimulation devices are often more difficult to precisely place given limited ability to visualize soft tissues with traditional fluoroscopic guidance. Additionally, there are anatomic subtleties relevant to the greater occipital nerve that potentially complicate stimulator lead placement, both from the standpoint of optimal neuromodulation efficacy and maximum safety. Ultrasound technology is a maturing imaging modality that allows soft tissue visualization and is consequently useful in addressing each of these aforementioned concerns. The specific use of high-frequency ultrasound guidance for this procedure simplified the initial device placement and allowed proper visualization of soft tissue structures, which facilitates precise device deployment. Additionally, the ability to identify relevant vascular structures may further increase the safety of stimulator lead placement. The potential advantages of ultrasound-augmented procedural techniques, specifically as they pertain to occipital stimulator lead placement, are discussed with particular emphasis on potentially decreasing intraoperative and postoperative complications while optimizing stimulation efficacy.

Feasibility of ultrasound-guided percutaneous placement of peripheral nerve stimulation electrodes in a cadaver model: part one, lower extremity.

BACKGROUND AND OBJECTIVES: Peripheral nerve stimulation (PNS) is analgesic for some lower extremity neuropathic pain syndromes. PNS currently involves open surgical placement of electrode(s). Increasingly, ultrasound guidance is used for perioperative neural block. Minimally invasive placement of PNS electrodes for lower extremity targets using ultrasound guidance has not been reported. We hypothesized that ultrasound-guided placement of PNS electrodes was feasible. METHODS: Four cadaver mid-thigh transected fresh frozen specimens were studied. Specimens were scanned utilizing a 14 to 7 MHz linear probe and electrodes were placed proximal to the tibial, peroneal, and sciatic nerves at various locations. Anatomical dissection was performed to check placement accuracy and evaluate for grossly visible neural injuries. RESULTS: Acceptable locations for ultrasound-guided electrode placement were: (1) tibial nerve, approximately 8 to 14 cm superior to the medial malleolus above the tarsal tunnel, or at the upper popliteal fossa; (2) peroneal nerve, approximately 2 to 4 cm inferior to the lateral fibular head or at the upper popliteal fossa; (3) sciatic nerve immediately superior to the bifurcation (high popliteal area); and (4) lateral sural nerve at the lower popliteal fossa. No grossly visible neural injuries were seen. Electrode placements appeared to be in satisfactory locations for stimulation. CONCLUSIONS: Ultrasound imaging to facilitate peripheral nerve electrode placement is feasible. This new minimally invasive approach to lead placement requires further study to determine trial implantation criteria, optimal locations, anchoring techniques, and best clinical practice.

Introduction of infection control measures to reduce infection associated with implantable pain therapy devices.

INTRODUCTION: Implantable pain therapy devices for chronic pain include spinal cord stimulators (SCS) and intrathecal drug delivery systems (IDDS). A number of different complications can occur after implantation of these devices, but among the most serious is infection. Based on Centers for Disease Control and Prevention guidelines for prevention of surgical site infection, published literature on infection risk with implantable pain therapy devices, and recommendations from groups within our own our institution, we introduced infection control measures for all patients receiving either SCS or IDDS. METHODS: After approval from the Institutional Review Board, we performed a retrospective review of patients undergoing primary implantation of SCS or IDDS before and after introduction at our institution of safety measures designed to reduce device-related infection. We compared infection incidence and compliance to infection precautions before and after introduction of these measures. RESULTS: Thirty-four SCS or IDDS were implanted before implementation of the infection control measures and 58 were placed after. Five device-related infections occurred. Adherence to most infection precautions improved during the study period, but 100% compliance was seen only with venue used for implantation. Infection incidence declined after introduction of the safety measures, but the reduction was not statistically significant. CONCLUSIONS: Introduction of infection control measures for implantable pain therapy devices improved adherence to most infection precautions in our practice. Lack of specific documentation could have hindered practice surveillance within our group. A tool to document performance of infection control measures would be useful not only as a marker of compliance but could also serve as a reminder to perform certain safety measures.

The use of spinal cord stimulation in refractory abdominal visceral pain: case reports and literature review.

Patients will commonly seek medical attention for refractory abdominal pain. The many causes of abdominal pain include pathologies of the gastrointestinal, genitourinary, musculoskeletal, and nervous systems. Unfortunately, a large number of patients will develop chronic abdominal pain that is recalcitrant to definitive therapies and nonspecific treatments such as cognitive-behavioral, physical, and pharmacologic therapies. Although spinal cord stimulation is classically used for neuropathic and ischemic conditions, a growing number of reports describe its efficacy in visceral disease. We describe our experience with spinal cord stimulation in two patients with refractory abdominal pain. Although the exact etiology in these complex patients is not defined, it is theorized that visceral hypersensitivity is at least one component. Finally, we will summarize the applicable literature in order to explain a possible mechanism of analgesia in visceral disease.

Cardiovascular collapse during elective orthopedic surgery: massive intraoperative pulmonary thromboembolism treated with emergent cardiopulmonary bypass.

Successful management strategies for pulmonary thromboembolism-primarily published as case reports-include a spectrum ranging from medical treatment with cardiovascular support and anticoagulation to more invasive interventions such as pulmonary embolectomy. We present a case of massive intraoperative pulmonary embolism that was managed with emergent pulmonary embolectomy. Unlike previously reported cases, this aggressive management strategy was unsuccessful, due in part perhaps to lack of discernible clot during embolectomy.