Early Experience With a Novel Miniaturized Spinal Cord Stimulation System for the Management of Chronic Intractable Pain of the Back and Legs

Emotional and psychosocial function after dorsal column spinal cord stimulator implantation: a systematic review and meta-analysis

BACKGROUND

The efficacy of spinal cord stimulation (SCS) in chronic pain studies is traditionally assessed by pain scores, which do not reflect the multidimensional nature of pain perception. Despite the evidence of SCS's influence on emotional functioning comprehensive assessments of its effect remain lacking.

OBJECTIVE

To assess changes in emotional and psychosocial functioning in patients who underwent SCS implantation for chronic pain.

EVIDENCE REVIEW

Ovid MEDLINE, EMBASE, PsychINFO, Cochrane CENTRAL and Scopus databases were searched for original peer-reviewed publications reporting emotional functioning after SCS. The primary outcomes were a pooled mean difference (MD) in anxiety, depression, global functioning, mental well-being and pain catastrophizing at 12 months. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to determine the quality of evidence.

FINDINGS

Thirty-two studies were included in the primary analysis. Statistically significant improvements were observed in anxiety (MD -2.16; 95% CI -2.84 to -1.49; p<0.001), depression (MD -4.66; 95% CI -6.26 to -3.06; p<0.001), global functioning (MD 20.30; 95% CI 14.69 to 25.90; p<0.001), mental well-being (MD 4.95; 95% CI 3.60 to 6.31; p<0.001), and pain catastrophizing (MD -12.09; 95% CI -14.94 to -9.23; p<0.001). Subgroup analyses revealed differences in Global Assessment of Functioning and mental well-being based on study design and in depression based on waveform paradigm.

CONCLUSION

The results highlight the statistically and clinically significant improvements in emotional and psychosocial outcomes in patients with chronic pain undergoing SCS therapy. However, these results need to be interpreted with caution due to the very low certainty of evidence per the GRADE criteria.

PROSPERO REGISTRATION

CRD42023446326.

Pocket pain following spinal cord stimulator generator implantation: A narrative review of this under-reported risk

INTRODUCTION

Spinal cord stimulation (SCS) is a well-established treatment option for chronic pain. Pain over the implantable pulse generator, or pocket pain, is an incompletely understood risk of SCS implantation which may limit the efficacy of treatment and patient quality of life. The goal of this narrative review is to analyze the literature to gain a more thorough understanding of the incidence and risk factors for the development of pocket pain to help guide treatment options and minimize its occurrence in the future.

METHODS

A literature review was conducted investigating the development of pocket pain in patients with SCS for the management of a variety of pain conditions.

RESULTS

In total, 305 articles were included in the original database search and 50 met the criteria for inclusion. The highest level of evidence for papers that specifically investigated pocket pain was level III. Four retrospective, observational analyses included pocket pain as a primary outcome. The remainder of the included studies listed pocket pain as an adverse event of SCS implantation.

CONCLUSIONS

There is a relative dearth of primary literature that examines the incidence, characteristics, and health economic implications of pocket pain in patients with SCS. This highlights the need for large-scale, high-quality prospective or randomized controlled trials examining pocket pain. This may ultimately help prevent and reduce pocket pain leading to improved efficacy of treatment and greater patient quality of life.

Wireless Battery-free and Fully Implantable Organ Interfaces

Advances in soft materials, miniaturized electronics, sensors, stimulators, radios, and battery-free power supplies are resulting in a new generation of fully implantable organ interfaces that leverage volumetric reduction and soft mechanics by eliminating electrochemical power storage. This device class offers the ability to provide high-fidelity readouts of physiological processes, enables stimulation, and allows control over organs to realize new therapeutic and diagnostic paradigms. Driven by seamless integration with connected infrastructure, these devices enable personalized digital medicine. Key to advances are carefully designed material, electrophysical, electrochemical, and electromagnetic systems that form implantables with mechanical properties closely matched to the target organ to deliver functionality that supports high-fidelity sensors and stimulators. The elimination of electrochemical power supplies enables control over device operation, anywhere from acute, to lifetimes matching the target subject with physical dimensions that supports imperceptible operation. This review provides a comprehensive overview of the basic building blocks of battery-free organ interfaces and related topics such as implantation, delivery, sterilization, and user acceptance. State of the art examples categorized by organ system and an outlook of interconnection and advanced strategies for computation leveraging the consistent power influx to elevate functionality of this device class over current battery-powered strategies is highlighted.

Treating Chronic, Intractable Pain with a Miniaturized Spinal Cord Stimulation System: 1-Year Outcomes from the AUS-nPower Study During the COVID-19 Pandemic

Purpose

Spinal cord stimulation (SCS) is a highly effective treatment for chronic neuropathic pain. Despite recent advances in technology, treatment gaps remain. A small SCS system with a miniaturized implantable pulse generator (micro-IPG; <1.5 cm3 in volume) and an externally worn power source may be preferred by patients who do not want a large, implanted battery. We report here the long-term outcomes from the first-in-human study evaluating the safety and performance of a new neurostimulation system.

Patients and Methods

This was a prospective, multi-center, open-label, single-arm study to evaluate this SCS system, in the treatment of chronic, intractable leg and low-back pain. Consented subjects who passed screening continued on to the long-term phase of the study. One-year, patient-reported outcomes (PRO's) such as pain (Numeric Rating Scale, NRS), functional disability, quality of life, and mood were captured.

Results

Twenty-six (26) evaluable subjects with permanent implants were included in this analysis. The average leg pain NRS score decreased from 6.8 ± 1.2 at baseline to 1.1 ± 1.2 at the end of the study (p < 0.001), while the average low-back pain NRS score decreased from 6.8 ± 1.2 to 1.5 ± 1.2 (p < 0.001). The responder rate (proportion with ≥50% pain relief) was 91% in the leg(s) and 82% in the low back. There were significant improvements in functional disability (Oswestry Disability Index) and in mood (Beck Depression Inventory), demonstrating a 46% and 62% improvement, respectively (p < 0.001). Eleven-point Likert scales demonstrated the wearable to be very comfortable and very easy to use.

Conclusion

There were considerable challenges conducting a clinical study during the COVID-19 pandemic, such as missed study programming visits. Nevertheless, subjects had significant PRO improvements through 1-year. The small size of the implanted device, along with a proprietary waveform, may allow for improved SCS outcomes and a drop in incidence of IPG-pocket pain.