Longevity and Utilization Cost of Rechargeable and Non-Rechargeable Spinal Cord Stimulation Implants: A Comparative Study.

INTRODUCTION: Despite major advancements in features and capabilities of the implantable pulse generator (IPG), real-life longevity and cost-effectiveness studies to guide pain specialists to make the appropriate choice between rechargeable and non-rechargeable IPG are limited. Our study aimed to compare the longevity and cost effectiveness of rechargeable vs. non-rechargeable IPG and SCS systems. METHODS: Data were collected for all SCS implantations performed between 1994 and 2018. The primary goal was to determine IPG longevity, defined as the time interval between IPG implantation and elective replacement due to IPG end of life (EOL). On the other hand, SCS system longevity was defined as the time between SCS implantation and its removal or revision for any reason other than IPG EOL. Kaplan-Meier and log-rank tests were used to assess IPG and SCS system longevities. Cost analysis was performed for cost effectiveness. RESULTS: The median IPG longevity was significantly higher for rechargeable SCS devices than for non-rechargeable SCS devices (7.20 years and 3.68 years, respectively). The median cost per day was similar for both IPGs, $13.90 and $13.81 for non-rechargeable and rechargeable, respectively. The median cost for SCS systems was higher for the rechargeable group ($60.70) compared with the non-rechargeable group ($31.38). CONCLUSIONS: Rechargeable IPG had increased longevity compared to their non-rechargeable counterparts, yet there was no significant difference in the actual longevity due to premature revisions or explantations between both SCS systems. Furthermore, non-rechargeable SCS systems were found to be the more cost-effective option when compared with rechargeable SCS systems.

Assessment of axonal recruitment using model-guided preclinical spinal cord stimulation in the ex vivo adult mouse spinal cord.

Spinal cord stimulation (SCS) is used clinically to limit chronic pain, but fundamental questions remain on the identity of axonal populations recruited. We developed an ex vivo adult mouse spinal cord preparation to assess recruitment following delivery of clinically analogous stimuli determined by downscaling a finite element model of clinical SCS. Analogous electric field distributions were generated with 300-µm × 300-µm electrodes positioned 200 µm above the dorsal column (DC) with stimulation between 50 and 200 µA. We compared axonal recruitment using electrodes of comparable size and stimulus amplitudes when contacting the caudal thoracic DC and at 200 or 600 µm above. Antidromic responses recorded distally from the DC, the adjacent Lissauer tract (LT), and in dorsal roots (DRs) were found to be amplitude and site dependent. Responses in the DC included a unique component not seen in DRs, having the lowest SCS recruitment amplitude and fastest conduction velocity. At 200 µm above, mean cathodic SCS recruitment threshold for axons in DRs and LT were 2.6 and 4.4 times higher, respectively, than DC threshold. SCS recruited primary afferents in all (up to 8) caudal segments sampled. Whereas A and C fibers could be recruited at nearby segments, only A fiber recruitment and synaptically mediated dorsal root reflexes were observed in more distant (lumbar) segments. In sum, clinically analogous SCS led to multisegmental recruitment of several somatosensory-encoding axonal populations. Most striking is the possibility that the lowest threshold recruitment of a nonprimary afferent population in the DC are postsynaptic dorsal column tract cells (PSDCs) projecting to gracile nuclei.NEW & NOTEWORTHY Spinal cord stimulation (SCS) is used clinically to control pain. To identify axonal populations recruited, finite element modeling identified scaling parameters to deliver clinically analogous SCS in an ex vivo adult mouse spinal cord preparation. Results showed that SCS first recruited an axonal population in the dorsal column at a threshold severalfold lower than primary afferents. These putative postsynaptic dorsal column tract cells may represent a previously unconsidered population responsible for SCS-induced paresthesias necessary for analgesia.

Multicenter Retrospective Study of Neurostimulation With Exit of Therapy by Explant.

INTRODUCTION: Spinal cord stimulation (SCS) devices are cost effective and improve function as well as quality of life. Despite the demonstrated benefits of SCS, some patients have the device explanted. We are interested in exploring the patient characteristics of those explanted. METHODS: This is a retrospective chart review of neurostimulation patients who underwent explantation at 18 centers across the United States within the previous five years. RESULTS: Data from 352 patients were collected and compiled. Failed Back Surgery syndrome was the most common diagnosis (38.9%; n = 136/350) and over half of the patients reported numerical rating scale (NRS) scores ≥8 prior to implant (64.3%; n = 207/322). All patients reported changes in NRS scores across time, with an initial decrease after implant followed by a pre-explant increase (F (2, 961) = 121.7, p < 0.001). The most common reason for device explant was lack or loss of efficacy (43.9%; 152/346) followed by complications (20.2%; 70/346). Eighteen percent (18%; 62/343) of patients were explanted by a different physician than the implanting one. Rechargeable devices were explanted at a median of 15 months, whereas primary cell device explants occurred at a median of 36 months (CI 01.434, 2.373; median endpoint time ratio = 2.40). DISCUSSION: Loss or lack of efficacy and complications with therapy represent the most frequent reasons for neurostimulation explantation. Of the devices that were explanted, therapy was terminated earlier when devices were rechargeable, when complications occurred, or when pain relief was not achieved or maintained. Furthermore, in nearly 20% of the cases, a different provider than the implanting physician performed device removal. CONCLUSIONS: SCS is largely a safe and efficacious strategy for treating select chronic refractory pain syndromes. Further prospective data and innovation are needed to improve patient selection, maintain SCS therapeutic efficacy and reduce the reasons that lead to device explant.

The Incidence of Spinal Cord Injury in Implantation of Percutaneous and Paddle Electrodes for Spinal Cord Stimulation.

OBJECTIVE: Spinal cord stimulation (SCS) has been proven effective for multiple chronic pain syndromes. Over the past 40 years of use, the complication rates of SCS have been well defined in the literature; however, the incidence of one of the most devastating complications, spinal cord injury (SCI), remains largely unknown. The goal of the study was to quantify the incidence of SCI in both percutaneous and paddle electrode implantation. METHODS: We conducted a retrospective review of the Thomson Reuter's MarketScan database of all patients that underwent percutaneous or paddle SCS implantation from 2000 to 2009. The main outcome measures of the study were the incidence of SCI and spinal hematoma within 30 days following operation. RESULTS: Overall 8326 patients met inclusion criteria for the study (percutaneous: 5458 vs. paddle: 2868). The overall incidence of SCI was 177 (2.13%) (percutaneous: 128 (2.35%) vs. paddle: 49 (1.71%), p = 0.0556). The overall incidence of spinal hematoma was 59 (0.71%) (percutaneous: 41 (0.75%) vs. paddle: 18 (0.63%), p = 0.5230). CONCLUSION: Our study shows that the overall incidence of SCI in SCS is low (2.13%), supporting that SCS is a safe procedure. No significant difference was found in the rates of SCI or spinal hematoma between the percutaneous and paddle groups. Further studies are needed to characterize the mechanisms of SCI in SCS and long-term outcomes in these patients.

Visions on the future of medical devices in spinal cord stimulation: what medical device is needed?

Recently burst stimulation and 10 kHz stimulation have been developed as novel stimulation designs. Both appear to be superior to classical tonic stimulation in the amount of responders and the amount of pain suppression and have as an extra advantage that they are paresthesia-free. This evolution is very important as it shifts the focus of research from better targeting by developing new lead configurations to better communication with the nervous system. It can be envisioned that this is only the start of a new trend in spinal cord, brain, and peripheral nerve stimulation and that more new stimulation designs will be developed in the near future such as pseudorandom burst stimulation, pleasure stimulation, noise stimulation and reconditioning stimulation. This evolution mandates a new approach in the development of internal pulse generators, and the most obvious approach is to develop an upgradable stimulator, on which new stimulation designs can be downloaded, analogous to the apps people download on their smartphones. This will create a shift from hardware driven products to software driven stimulators.

International neuromodulation society critical assessment: guideline review of implantable neurostimulation devices.

INTRODUCTION: Spinal cord stimulation (SCS) is well accepted for the treatment of chronic pain since its beginning in 1967. As its use continues to enter into the chronic pain treatment algorithm earlier, conscience patient selection and durability of the therapy are clearly clinically relevant. To improve treatment efficacy, consensus statements and guidelines were developed. OBJECTIVE: The purpose of this work is to review the relevant guideline statements for implantable neurostimulation therapies to treat chronic pain and to identify guideline gaps and future directions for recommendation platforms. MATERIALS AND METHODS: A systematic literature search through EMBASE, Medline, Cochrane data base, as well as peer-reviewed, nonindexed journals and materials presented at national and international meetings was performed to chronologically identify consensus statements or guideline statements for use of neurostimulation therapies to treat chronic neuropathic pain limited to the English language. RESULTS: From 1998 to 2013, 22 guideline statements were identified. Thirteen of the 22 guidelines were society-sponsored guideline statements from ten societies. Two guideline statements were from research foundations, two were government supported, and one statement was published as a position statement. CONCLUSIONS: The current available guideline statements have clear deficiencies in either scope of coverage, evidence synthesis, or lack of transparency of funding. Improved evidence and best practice/guideline assessment may improve patient outcomes and accessibility to these important modalities. Further prospective comparator randomized data are required to not only provide data of clinical and cost-effectiveness in other indications but also to better describe the position of neurostimulation application within the disease management pathway. Therein cases where there appears to be sufficient evidence and consensus, every effort should be made to secure access to these effective therapies. Importantly, each guideline only has a useful clinical half-life, if not updated. This should be acknowledged by both clinicians and third-party payers. Based on these deficiencies, the International Neuromodulation Society recommended the creation of a consensus conference to examine the appropriate use of neurostimulation for pain and ischemic disease.

New devices in heart failure: an European Heart Rhythm Association report: developed by the European Heart Rhythm Association; endorsed by the Heart Failure Association.

Several new devices for the treatment of heart failure (HF) patients have been introduced and are increasingly used in clinical practice or are under clinical evaluation in either observational and/or randomized clinical trials. These devices include cardiac contractility modulation, spinal cord stimulation, carotid sinus nerve stimulation, cervical vagal stimulation, intracardiac atrioventricular nodal vagal stimulation, and implantable hemodynamic monitoring devices. This task force believes that an overview on these technologies is important. Special focus is given to patients with HF New York Heart Association Classes III and IV and narrow QRS complex, who represent the largest group in HF compared with patients with wide QRS complex. An overview on potential device options in addition to optimal medical therapy will be helpful for all physicians treating HF patients.

Predictors of implantable pulse generator placement after sacral neuromodulation: who does better?

OBJECTIVES: Numerous studies have documented a relationship between provider variables, including surgeon volume and specialty, and outcomes for surgical procedures. In this study we analyzed claims data from a Medicare database to analyze outcomes of sacral neuromodulation (SNM) with respect to both provider and patient factors. MATERIALS AND METHODS: A 5% random sample of Medicare beneficiaries from 1997 to 2007 was the data source. Data retrieved included demographic information, ICD-9 diagnosis codes, and CPT procedure codes. Multivariate analysis was performed to identify predictors of progression to implantable pulse generator (IPG) implantation. RESULTS: After stage I testing, urologists were more likely than gynecologists to proceed to IPG placement (Center for Medicare and Medicaid Services: 49% vs. 43%, p < 0.0001). After percutaneous testing, gynecologists were more likely than urologists to proceed to battery placement (63% vs.44%, p = 0.005). Among the patient variables analyzed, women were more likely than men to progress to battery placement. Patients treated by high-volume providers had higher rates of IPG placement after formal stage I trials (71% vs. 33%, p < 0.0001). CONCLUSIONS: The rate of IPG implantation after SNM was greater among high-volume providers. Women had better outcomes than men. Further research may better define the relationship between outcomes of sacral neuromodulation and specific etiology of voiding dysfunction.

Assessment of economic effectiveness in treatment of neuropathic pain and refractory angina pectoris using spinal cord stimulation.

BACKGROUND: The implementation of new diagnostic and therapeutic technologies is related to expanding financial needs. The escalation of expenses for health protection and simultaneous economic problems has resulted in an interest in the subject of economic assessment. Decision makers in the health sector should have reasonable tools that will allow them to make complex evaluations of the economic suitability of health technologies. Economic analysis should also prove that launching new procedures can save money. Numerous studies indicate that chronic pain and psycho-sociological variables lead to a worse quality of life. Chronic pain issues are a major public health problem, by virtue of the difficulties in efficient therapy and the social costs reflected in incapability of work and disability. Spinal cord stimulation is the most efficacious procedure in the treatment of chronic pain. OBJECTIVES: The aim of the study was to estimate the costs of treatment of 37 patients suffering from refractory angina pectoris and neuropathic pain who underwent SCS surgery between 2002 and 2008 in the Neurosurgery Clinic of the 10th Military Hospital in Bydgoszcz in the period of two years before and two years after spinal cord stimulation. The authors also assessed quality of life, using the SF 36 questionnaire, and degree of pain using VAS. MATERIAL AND METHODS: The issue was examined with a cost-benefit analysis. Cost was understood as the expenses made two years before and two years after the SCS procedure. The benefits were health care expenses saved by implementation of the SCS procedure. All the costs included in both alternative treatment techniques in a period of 5 years underwent a discounting procedure. The authors also included the price of the neurostimulator under a sensitivity analysis. To assess the quality of life before and after the SCS procedure, a SF 36 questionnaire was used, and to assess the level of pain before and after the SCS procedure, the VAS scale. RESULTS: The costs of treatment of refractory angina pectoris and neuropathic pain are lower when using spinal cord stimulation. In the case of refractory angina pectoris, savings reached 46% whereas in the case of neuropathic pain, 13.2%. The costs of the purchase of the device returned in three years for angina pectoris and seven years for neuropathic pain. SCS in both cases brought a reduction of the level of pain and an improvement to quality of life. CONCLUSIONS: SCS in both neuropathic pain and refractory angina pectoris is a procedure that brings benefits in the form of savings. After using SCS in both cases, the quality of life improved and the level of pain was reduced.