Neurostimulation Devices for the Treatment of Neurologic Disorders

Rapid advancements in neurostimulation technologies are providing relief to an unprecedented number of patients affected by debilitating neurologic and psychiatric disorders. Neurostimulation therapies include invasive and noninvasive approaches that involve the application of electrical stimulation to drive neural function within a circuit. This review focuses on established invasive electrical stimulation systems used clinically to induce therapeutic neuromodulation of dysfunctional neural circuitry. These implantable neurostimulation systems target specific deep subcortical, cortical, spinal, cranial, and peripheral nerve structures to modulate neuronal activity, providing therapeutic effects for a myriad of neuropsychiatric disorders. Recent advances in neurotechnologies and neuroimaging, along with an increased understanding of neurocircuitry, are factors contributing to the rapid rise in the use of neurostimulation therapies to treat an increasingly wide range of neurologic and psychiatric disorders. Electrical stimulation technologies are evolving after remaining fairly stagnant for the past 30 years, moving toward potential closed-loop therapeutic control systems with the ability to deliver stimulation with higher spatial resolution to provide continuous customized neuromodulation for optimal clinical outcomes. Even so, there is still much to be learned about disease pathogenesis of these neurodegenerative and psychiatric disorders and the latent mechanisms of neurostimulation that provide therapeutic relief. This review provides an overview of the increasingly common stimulation systems, their clinical indications, and enabling technologies.

Impact of the National Institute for Health and Care Excellence (NICE) guidance on medical technology uptake: analysis of the uptake of spinal cord stimulation in England 2008-2012

BACKGROUND

The National Institute for Health and Care Excellence (NICE) Technology Appraisal Guidance on spinal cord stimulation (SCS) was published in 2008 and updated in 2012 with no change. This guidance recommends SCS as a cost-effective treatment for patients with neuropathic pain.

OBJECTIVE

To assess the impact of NICE guidance by comparing SCS uptake in England pre-NICE (2008-2009) and post-NICE (2009-2012) guidance. We also compared the English SCS uptake rate with that of Belgium, the Netherlands, France and Germany.

DESIGN

SCS implant data for England was obtained from the Hospital Episode Statistics (HES) database and compared with other European countries where comparable data were available.

RESULTS

The HES data showed small increases in SCS implantation and replacement/revision procedures, and a large increase in SCS trials between 2008 and 2012. The increase in the total number of SCS procedures per million of population in England is driven primarily by revision/replacements and increased trial activity. Marked variability in SCS uptake at both health regions and primary care trust level was observed.

CONCLUSIONS

Despite the positive NICE recommendation for the routine use of SCS, we found no evidence of a significant impact on SCS uptake in England. Rates of SCS implantation in England are lower than many other European countries.

Evaluating the Readability, Quality, and Reliability of Online Patient Education Materials on Spinal Cord Stimulation

AIM

To obtain health-related information internet usage is rapidly increasing. However, there are concerns about the comprehensibility and reliability of internet-accessed health-related information. The aim of this research was to investigate the reliability, quality, and readability of patient education materials (PEMs) about spinal cord stimulation (SCS) on the internet.

MATERIAL AND METHODS

A total of 114 websites suitable for the study were identified after a search on Google for the term "spinal cord stimulation." Gunning Fog (GFOG), Flesch-Kincaid Grade Level (FKGL), Flesch Reading Ease Score (FRES), and Simple Measure of Gobbledygook (SMOG) were used to determine the readability of sites. The credibility of the websites was assessed using the Journal of the American Medical Association (JAMA) score. Quality was assessed using the global quality score (GQS), the DISCERN score, and the Health on the Net Foundation code of conduct (HONcode).

RESULTS

Evaluating the text sections, the mean SMOG and FKGL were 10.92 ± 1.61 and 11.62 ± 2.11 years, respectively, and the mean FRES and GFOG were 45.32 ± 10.71 and 14.62 ± 2.24 (both very difficult), respectively. Of all the websites, 10.5% were found to be of high quality, 13.2% were found to be of high reliability, and only 6.1% had a HONcode. A significant difference was found between the typologies of the websites and the reliability and quality scores (p < 0.05).

CONCLUSION

The internet-based PEMs about SCS were found to have a readability level that exceeded the Grade 6 level recommended by the National Health Institute. However, the materials demonstrated low reliability and poor quality. It is advisable that websites addressing Spinal Cord Stimulation (SCS), a specific neuromodulation technique among various interventional strategies for chronic pain management, maintain readability standards in line with established indexes and provide content that is reliable and tailored to the general public's educational level.

The Neurostimulation Appropriateness Consensus Committee (NACC)®: Recommendations for Spinal Cord Stimulation Long-Term Outcome Optimization and Salvage Therapy

INTRODUCTION

The International Neuromodulation Society (INS) has recognized a need to establish best practices for optimizing implantable devices and salvage when ideal outcomes are not realized. This group has established the Neurostimulation Appropriateness Consensus Committee (NACC)® to offer guidance on matters needed for both our members and the broader community of those affected by neuromodulation devices.

MATERIALS AND METHODS

The executive committee of the INS nominated faculty for this NACC® publication on the basis of expertise, publications, and career work on the issue. In addition, the faculty was chosen in consideration of diversity and inclusion of different career paths and demographic categories. Once chosen, the faculty was asked to grade current evidence and along with expert opinion create consensus recommendations to address the lapses in information on this topic.

RESULTS

The NACC® group established informative and authoritative recommendations on the salvage and optimization of care for those with indwelling devices. The recommendations are based on evidence and expert opinion and will be expected to evolve as new data are generated for each topic.

CONCLUSIONS

NACC® guidance should be considered for any patient with less-than-optimal outcomes with a stimulation device implanted for treating chronic pain. Consideration should be given to these consensus points to salvage a potentially failed device before explant.

Catastrophizing as a Predictor for Pain Perception and Disability Among Patients Undergoing Spinal Cord Stimulation

Background and Objectives: The International Society for Modulation defines persistent spinal pain syndrome type 2 (PSPS-type 2), formerly known as failed back surgery syndrome, as a condition where patients continue to experience pain or develop new pain following spinal surgery intended to alleviate back or lower-limb discomfort. PSPS-type 2 is characterized by pain and significant disability, affecting quality of life. Spinal cord stimulation has proven effective in treating this syndrome, although the role of psychological factors, such as pain catastrophizing and central sensitization, remain unclear. This study seeks to examine the potential connection between psychosocial responses and both functionality and pain perception in patients with persistent spinal pain syndrome type 2 who have undergone spinal cord stimulation treatment. Materials and Methods: A single-site, cross-sectional study was conducted on individuals diagnosed with persistent spinal pain syndrome type 2 who were receiving spinal cord stimulation. Study participants were required to meet specific eligibility criteria and were assessed for disability, pain perception, fear of movement, pain catastrophizing, and central sensitization. The spinal cord stimulation procedure involved the placement of electrodes at vertebral levels T8-T11 for precise pain control, with a particular focus on targeting the dorsal root ganglion to alleviate chronic pain. Results: Thirty-seven patients with persistent spinal pain syndrome type 2 have undergone spinal cord stimulation treatment for 4.68 ± 5.25 years. Clinical assessments indicated a pain perception score of 5.6 ± 1.96, Central Sensitization Inventory score of 42.08 ± 18.39, disability score of 37.62 ± 16.13, fear of movement score of 33.11 ± 8.76, and pain catastrophizing score of 28.43 ± 13.14. Finally, pain catastrophizing was significantly associated with pain perception (β = 0.075 and p = 0.008) and disability (β = 0.90 and p < 0.01). Conclusions: Catastrophizing plays a crucial role in pain perception and disability among patients with persistent spinal pain syndrome type 2 receiving spinal cord stimulation. Integrating psychological interventions may improve clinical outcomes for these patients.

Effects of an extended MRI approval of an implantable spinal cord stimulation device on compliance with manufacturer's recommendations

OBJECTIVE

The current approval for all available spinal cord stimulation (SCS) devices set several limitations for magnetic resonance imaging (MRI). As a result, most of the necessary examinations are not possible within the scope of the restrictive approvals and, if legally permitted, must be carried out off-label. This retrospective subgroup analysis investigates if the currently extended MRI approval of one specific device allows more MRI scans to be conducted within the manufacturer's recommendations.

MATERIALS AND METHODS

Technical MRI data (saved in the DICOM headers) and medical treatment data for all MRI examinations on patients with Proclaim® implantable pulse generators (IPG; Proclaim® spinal cord stimulation systems, Abbott Laboratories, Plano, TX, USA) were examined. Due to a major change in our standard operating procedures for MRI scans in 2019, the two time periods (before and after 2019) were separately analyzed.

RESULTS

We identified 62 MRI scans with the IPG. The entire implanted system was approved for MRI examinations in just over 50% of the cases, regardless of old and new approval. Options for lead placement were expanded in the new approval; however, this did not significantly improve the number of MR conditional devices. By contrast, for a higher specific absorption rate, significantly more scans within the recommendations are possible in Period 2 (p = 0.011). However, the number of possible scans did not reach statistical significance in Period 1 (p = 0.078). No device-related adverse events were noted.

CONCLUSION

The new MRI approval is suitable for performing more scans within the manufacturer's specifications. Cervical leads remain problematic because longer leads are required, and the lower impedances inhibit the MRI mode.

10 kHz High-Frequency Spinal Cord Stimulation for Chronic Thoracic Pain: A Multicenter Case Series and a Guide for Optimal Anatomic Lead Placement

BACKGROUND

Surgical options for thoracic pain are limited and carry significant risk and morbidity. Spinal cord stimulation has the potential to be used for treatment of thoracic pain, as it has been useful for treating multiple types of chronic pain. Conventional tonic stimulation is limited in the treatment of thoracic pain, as it can produce paresthesia that is difficult to localize. Conversely, high-frequency spinal cord stimulation (HF-SCS) does not activate dorsal column A Beta fibers and does not produce paresthesia, and thus may be more beneficial in treating thoracic back pain not manageable with tonic stimulation.

OBJECTIVES

To evaluate (1) the efficacy of 10 kHz HF-SCS for patients with chronic thoracic pain; and (2) appropriate paresthesia-free lead placement and programming targets for 10 kHz HF-SCS for patients with chronic thoracic pain.

STUDY DESIGN

Retrospective case series.

SETTING

Multisite academic medical center or pain clinic.

METHODS

A retrospective chart review was performed on 19 patients with thoracic back pain who underwent HF-SCS implantation. These patients had lead placement and stimulation between the T1-T6 vertebral levels. Outcome measures collected include location of device implant, stimulation settings, and pain scores at baseline, end of trial, and 1, 6, and 12 months postimplant. Follow-up phone calls collected information on if the patient reported functional improvement, improved sleep, or decreased pain medication usage. A Wilcoxon signed-rank test compared differences in mean pain scores across time points.

RESULTS

Significantly decreased Visual Analog Scale scores were observed with 17/19 (89.5%) patients demonstrating response to therapy (> 50% reduction in pain scores). These results were sustained relative to baseline at 1, 6, and 12 months postimplant, depending on length of follow-up. Many patients also reported functional improvement (17/19), improved sleep (14/19), and reduction in use of pain medications after implantation (9/19). A total of 15/19 patients reported best relief when contacts over T1 or T2 vertebrae were used for stimulation.

LIMITATIONS

This study is limited by its retrospective design. Additionally, including documentation from multiple sites may be prone to selection and abstraction bias. Data were also not available for all patients at all time points.

CONCLUSIONS

HF-SCS may be a viable option for significant, long-lasting pain relief for thoracic back pain. There may also be evidence for anatomically based lead placement and programming for thoracic back pain. Randomized, controlled trials with extended follow-up are needed to further evaluate this therapy.

KEY WORDS

Thoracic pain, back pain, spinal cord stimulation, high frequency, 10 kHz.