Implantable Stimulator Research Articles

Relationship between number of prior lumbar spine surgeries and outcomes following spinal cord stimulator implantation: A multisite, retrospective pooled analysis.

Lumbar spine surgery is a common procedure for treating disabling spine-related pain. In recent decades, both the number and cost of spine surgeries have increased despite technological advances and modification in surgical technique. For those patients that have continued uncontrolled back and/or lower extremity pain following lumbar spine surgery, spinal cord stimulation (SCS) has emerged as a viable treatment option. However, the impact of lumbar spine surgical history remains largely unstudied. Specifically, the current study considers the impact of number of prior lumbar spine surgeries on pain relief outcomes following SCS implantation. We queried the electronic medical record of five separate pain practices for all patients who have undergone a SCS implant between January 1, 2017, and March 1, 2020. Inclusion criteria consisted of any patients with an SCS implant who underwent a prior lumbar spine surgery. The primary outcome was the mean calculated percentage pain relief in patients based on number of prior lumbar spine surgeries. There was a total of 1974 total SCS implant cases identified across five separate pain clinics. There was no difference in mean calculated pain relief in patients with one prior spine surgery versus those with two or more prior spine surgeries (28.2% vs. 25.8%, adjusted β-coefficient -3.1, 95% CI -8.9 to 2.7, p = 0.290). Similarly, when analyzing number of spine surgeries as a continuous variable, there was no association between number of spine surgeries and calculated pain relief (adjusted β-coefficient -1.5, 95% CI -4.0 to 1.1, p = 0.257). Additionally, after patients were stratified based on waveform, there was no association between number of prior lumbar spine surgeries (analyzed both as a categorical and continuous variable) and calculated percentage pain relief. This multicentered retrospective study found that there was no significant difference in pain scores in individuals who received SCS following one or more lumbar spine surgeries. Additionally, the waveform of the SCS device had no statistically significant impact on post-operative pain scores following one or more lumbar spine surgeries.

The effect of COVID-19 on pain control in patients with a neurostimulator in situ- a retrospective study.

De-novo chronic neuropathic pain following COVID-19 is widely recognised. However, there are currently no published studies investigating the effect of SARS-CoV-2 infection on patients with pre-existing neuropathic pain who have required spinal cord stimulator (SCS) implantation. Here, the authors aimed to analyse outcomes in their institution's patients who had spinal cord stimulator (SCS) implantation or revision procedures to the system over a 5-year period. Specifically, the short-term and long-term outcomes of patients who contracted COVID-19 during the follow-up period were compared to the control group of patients who did not. Patients included in this study had spinal cord stimulator implantation (de-novo and revision procedures) between 1 January 2017 and 31 January 2022, for neuropathic pain of any aetiology. Patients deemed eligible for the study were invited to participate in a telephone survey through which clinical outcome data were collected. Pain scores were assessed with a modified form of the Brief Pain Inventory (BPI). Of 91 patients, 48 (52.7%) had contracted COVID-19 by the time of the survey. Patients who contracted COVID-19 had significantly worse BPI scores in the 'Least pain' domain following their infection and at time of the survey, when compared to their score 6 months after the operation. 22.9% (n = 11) of the patients who contracted COVID-19 experienced a change in their symptoms following their infection. Within this sub-group, there was a statistically significant deterioration in BPI scores in 10/11 domains following their infection and in 2/11 domains at time of the survey. Worsening severity of COVID-19 symptoms was not associated with worse BPI scores. Infection with SARS-CoV-2, in a significant proportion of patients with an SCS in situ, causes at least a transient deterioration in pain control. Further prospective multicentre studies are indicated to establish the prevalence of this phenomenon.

Potential Roles of Specific Subclasses of Premotor Interneurons in Spinal Cord Function Recovery after Traumatic Spinal Cord Injury in Adults.

The differential expression of transcription factors during embryonic development has been selected as the main feature to define the specific subclasses of spinal interneurons. However, recent studies based on single-cell RNA sequencing and transcriptomic experiments suggest that this approach might not be appropriate in the adult spinal cord, where interneurons show overlapping expression profiles, especially in the ventral region. This constitutes a major challenge for the identification and direct targeting of specific populations that could be involved in locomotor recovery after a traumatic spinal cord injury in adults. Current experimental therapies, including electrical stimulation, training, pharmacological treatments, or cell implantation, that have resulted in improvements in locomotor behavior rely on the modulation of the activity and connectivity of interneurons located in the surroundings of the lesion core for the formation of detour circuits. However, very few publications clarify the specific identity of these cells. In this work, we review the studies where premotor interneurons were able to create new intraspinal circuits after different kinds of traumatic spinal cord injury, highlighting the difficulties encountered by researchers, to classify these populations.

349 Brain Functional Imaging of Pain States Using Resting-State fMRI and Multi-Delay PCASL in Chronic Low-Back Pain Patients Implanted With Thoracic Spinal Cord Stimulation

INTRODUCTION: A treatment of chronic low-back pain is implantation of a thoracic spinal cord stimulator (tSCS), which has been shown to reduce pain. The functional changes in pain processing regions of the brain as assessed by resting-state fMRI and multi-delay pseudocontinuous arterial spin labeling (PCASL) have never been studied. METHODS: PCASL data based on 5 post-label delays (0.5–2.5s) as well as rsfMRI were acquired in five patients (1F) post-tSCS with cLBP and five healthy subjects (2F). Patient MRI scans were taken post-implantation with the SCS device turned off. Three PCASL measures and four rsfMRI measures were derived and normalized into MNI space and smoothed. Averaged values for each measure from the pain ROI atlas were extracted and compared between patients and controls. Statistics were conducted following Box-Cox transformation of data. RESULTS: Arterial transit time derived from PCASL showed a significant difference in the OFC, SMA, and PSG of patients, but other ASL measures showed no effect. Several regions across the rs-fMRI measures showed significant differences, including those involved in cognition (DLPFC, PCC), and pain processing (PSG) and sensation (S2). CONCLUSIONS: Functional imaging showed that cLBP patients treated with SCS display differences in resting-state function and brain perfusion across several pain regions of the brain. These areas are mainly part of the cognitive and behavioral components of the pain circuitry.

Consensus Guidelines of Irreversible Electroporation for Pancreatic Tumors: Protocol Standardization Using the Modified Delphi Technique.

Since no uniform treatment protocol for pancreatic irreversible electroporation (IRE) exists, the heterogeneity throughout literature complicates the comparison of results. To reach agreement among experts, a consensus study was performed. Eleven experts, recruited according to predefined criteria regarding previous IRE publications, participated anonymously in three rounds of questionnaires according to a modified Delphi technique. Consensus was defined as having reached ≥80% agreement. Response rates were 100, 64, and 64% in rounds 1 to 3, respectively; consensus was reached in 93%. Pancreatic IRE should be considered for stage III pancreatic cancer and inoperable recurrent disease after previous local treatment. Absolute contraindications are ventricular arrhythmias, implantable stimulation devices, congestive heart failure NYHA class 4, and severe ascites. The inter-electrode distance should be 10 to 20 mm and the exposure length should be 15 mm. After 10 test pulses, 90 treatment pulses of 1,500 V/cm should be delivered continuously, with a 90-µs pulse length. The first postprocedural contrast-enhanced computed tomography should take place 1 month post-IRE, and then every 3 months. This article provides expert recommendations regarding patient selection, procedure, and follow-up for IRE treatment in pancreatic malignancies through a modified Delphi consensus study. Future studies should define the maximum tumor diameter, response evaluation criteria, and the optimal number of preoperative FOLFIRINOX cycles.

Intraoperative EABR Testing Predicts Strength of Cochlear Implant Stimulation Optimized After Long-Term Use in Pediatric Malformation Ears.

This study focused on the intensities of cochlear implant (CI) stimulation in pediatric CI users with inner ear malformation or cochlear nerve deficiency (CND). In this population, CI programming is difficult because a large intensity of CI stimulation is required to achieve sufficient hearing, but the excess CI stimuli often induce facial nerve stimulation. We aimed to assess whether the results of intraoperative electrically evoked auditory brainstem responses (EABRs) testing predict maximum current levels of CI stimuli (cC levels) optimized by a behavioral-based method after long-term CI use. A retrospective case review. A tertiary referral CI center. A total of 116 ears with malformations (malformation group) and 63 control ears (control group) from patients younger than 18 years who received CI. The malformation group comprised 23 ears with a common cavity (CC), 26 with incomplete partition type 1 (IP-1), 26 with incomplete partition type 2 (IP-2), and 41 with CND. Diagnostic. Correlation between intraoperative EABR results and cC levels determined by the behavioral-based CI programming after long-term CI use. The CC, IP-1, and CND ears required significantly larger cC levels than the IP-2 ears and control groups. However, the cC levels increased to reach the plateau 1 year after surgery in all groups. Among the malformation group, 79 ears underwent intraoperative EABR testing. Greater than 80% of the CC, IP-1, and IP-2 ears and 54.8% of the CND ears exhibited evoked wave V (eV) and were included in the eV-positive category. Myogenic responses but no eV were observed in 18.2, 15.0, and 35.5% of the CC, IP-1, and CND ears, defined as the myogenic category. No eV or myogenic response was elicited in 9.7% of the CND ears. We focused on minimum current levels that elicited eV (eV levels) in the eV-positive category and maximum current levels that did not elicit any myogenic responses (myogenic levels) in the myogenic category. A significant relationship was detected between the eV levels and the cC levels. When analyzed in each malformation type, the eV levels significantly correlate with the cC levels in the CC and CND ears but not in the IP-1 and IP-2 ears, probably because of slight variation within the IP-1 group and the small number of the IP-2 group. The myogenic category did not show a significant relationship between the myogenic levels and cC levels, but the cC levels were similar to or smaller than the myogenic levels in most ears. This study confirmed that intraoperative EABR testing helps predict the optimal cC levels in malformation ears. EABR-based CI programming immediately after cochlear implantation, followed by behavioral-based CI programming, may allow us to achieve early postoperative optimization of CI maps even in young children with severe malformations.

Anticoagulation Management During a Spinal Cord Stimulator Trial on a Patient With ST-Elevation Myocardial Infarction

BACKGROUND: Spinal cord stimulators (SCSs) are indicated for the treatment of many pain syndromes. They are often trialed prior to placement of a permanent implant. Patients on anticoagulation therapy are instructed to follow the American Society of Regional Anesthesia and Pain Medicine guidelines during this process. CASE REPORT: Here we describe a unique case of a patient who had an SCS trial, followed by an ST-elevation myocardial infarction (STEMI) on day 4 postimplantation. After coronary revascularization, the patient started dual antiplatelet therapy, which posed significant for epidural hematoma with recent stimulator implantation. CONCLUSIONS: The patient was bridged with intravenous antiplatelet agents prior to SCS trial removal and monitored closely. Our discussion will focus on all anticoagulation management of patients with a recent STEMI who had undergone a trial SCS implantation. KEY WORDS: Spinal cord stimulation, neuromodulation, chronic pain, anticoagulation

MOSFET Characteristics and Related Biological Devices Analysis

With the development of modern electronic information technology, portable, fast, and high-performance electronic information products have brought great changes to people's life and health. People pay more and more attention to electronic information products. Not only in the civil aspect, high-end precision electronics industry, such as artificial intelligence, the new generation of electronic communication technology, medical devices, aerospace, and defense fields are based on various chips, to establish a complete national industrial system. This article describes MOSFET basic introduction, working principle and structure, etc., which plays an important role in the modern electronic information industry, including its application in implantable medical devices-current stimulator. The conclusion of this article is that with more and more capital and talent investment, the future of the chip industry with MOSEF as the basic component is very optimistic. The significance of this paper is to introduce the existing MOSFET technology and put forward views for future development.

Precision Rehabilitation After Neurostimulation Implantation for Multifidus Dysfunction in Nociceptive Mechanical Chronic Low Back Pain

Chronic low back pain (CLBP) is a debilitating, painful, and costly condition. Implantable neuromuscular electrical stimulation targeting the multifidus musculature is growing as a non-pharmacologic option for patients with recalcitrant nociceptive mechanical CLBP who have failed conservative treatments (including medications and physical therapy) and for whom surgery is not indicated. Properly selecting patients who meet specific criteria (based on historical results from randomized controlled trials), who diligently adhere to implant usage and precisely implement neuromuscular rehabilitation, improve success of significant functional recovery, as well as pain medication reductions. Patients with nociceptive mechanical CLBP who underwent implanted multifidus neurostimulation have been treated by physicians and rehabilitation specialists who have honed their experience working with multifidus neurostimulation. They have collaborated on consensus and evidence-driven guidelines to improve quality outcomes and to assist providers when encountering patients with this device. Physicians and physical therapists together provide precision patient-centric medical management with quality neuromuscular rehabilitation to encourage patients to be experts of both their implants and quality spine motion to help override long-standing multifidus dysfunction related to their CLBP.

Irregularity of instantaneous gamma frequency in the motor control network characterize visuomotor and proprioceptive information processing

Objective. The study aims to characterize movements with different sensory goals, by contrasting the neural activity involved in processing proprioceptive and visuo-motor information. To accomplish this, we have developed a new methodology that utilizes the irregularity of the instantaneous gamma frequency parameter for characterization. Approach. In this study, eight essential tremor patients undergoing an awake deep brain stimulation implantation surgery repetitively touched the clinician’s finger (forward visually-guided/FV movement) and then one’s own chin (backward proprioceptively-guided/BP movement). Neural electrocorticographic recordings from the motor (M1), somatosensory (S1), and posterior parietal cortex (PPC) were obtained and band-pass filtered in the gamma range (30–80 Hz). The irregularity of the inter-event intervals (IEI; inverse of instantaneous gamma frequency) were examined as: (1) auto-information of the IEI time series and (2) correlation between the amplitude and its proceeding IEI. We further explored the network connectivity after segmenting the FV and BP movements by periods of accelerating and decelerating forces, and applying the IEI parameter to transfer entropy methods. Main results. Conceptualizing that the irregularity in IEI reflects active new information processing, we found the highest irregularity in M1 during BP movement, highest in PPC during FV movement, and the lowest during rest at all sites. Also, connectivity was the strongest from S1 to M1 and from S1 to PPC during FV movement with accelerating force and weakest during rest. Significance. We introduce a novel methodology that utilize the instantaneous gamma frequency (i.e. IEI) parameter in characterizing goal-oriented movements with different sensory goals, and demonstrate its use to inform the directional connectivity within the motor cortical network. This method successfully characterizes different movement types, while providing interpretations to the sensory-motor integration processes.

Defining the Shape of the Mylohyoid Muscle: A Morphometric Imaging Study.

Implantable hypoglossal nerve stimulation (HNS) therapy is an evolving therapeutic alternative for patients with refractory obstructive sleep apnea (OSA). The muscular anatomy of this region has implications for surgical access through this zone as well as positioning and anchoring of hardware in this area. The purpose of this study was to radiologically describe the topography of the mylohyoid muscle and adjacent structures across a wide age spectrum. We retrospectively evaluated computed tomography scans of the neck in 102 patients who were imaged for reasons unrelated to the floor of mouth or submental space. Patients with prior surgery or pathology in the area of interest were excluded. Fourteen relevant muscle measurements were made on a midline sagittal image and a coronal image positioned at the midpoint between the hyoid bone and the mandible. We included 49 men and 53 women with an average age of 44 years (range 19-70). The average mylohyoid length was 42 mm; the average distance between the anterior digastric bellies was 17 mm. The average angle of the central mylohyoid was 174° in the sagittal plane and 164° in the coronal plane. Several measurements were significantly correlated with patient age, including the angle measurements and the distance between the digastric muscles. Aberrant digastric anatomy was common. The mylohyoid muscle has multiple radiologically distinct segments with predictable curvatures. An understanding of submental muscular anatomy, along with its variability between patients, may be beneficial to the development of bilateral implantable neurostimulation technology for the treatment of refractory OSA. N/A Laryngoscope, 134:2970-2975, 2024.

Spinal cord electrical stimulation with neurophysiological monitoring for treatment of high-risk diabetic foot

To evaluate the clinical efficacy of a single-session implantation of spinal cord electrical stimulation with neurophysiological monitoring a spinal cord electrical stimulator under general anesthesia with neurophysiological monitoring for the treatment of high-risk diabetic foot. The clinical data of seven patients with high-risk diabetic foot who underwent spinal cord electrical stimulation in neurosurgery ward nine of Tianjin Huanhu Hospital from May 2022 to May 2023 were collected. The operation was performed under general anesthesia with the "C" arm X ray machine guidance and neurophysiological monitoring. The arterial diameter and peak flow rate of lower extremity, lower extremity skin temperature (calf skin temperature, foot skin temperature), visual analog scale (VAS), continuous distance of movement, blood glucose level and toe wound were compared between patients before and after surgery. A total of seven patients with high-risk diabetic foot were included. The diameters and peak flow rates of femoral artery, popliteal artery, anterior tibial artery, posterior tibial artery and dorsal foot artery in both lower limbs were significantly improved after surgery. All patients had different degrees of lower limb pain before operation. After operation, VAS score decreased significantly (1.1±0.9 vs. 6.8±3.4), the pain was significantly relieved, and the calf skin temperature and foot skin temperature were significantly higher than those before surgery [calf skin temperature (centigrade): 33.3±0.9 vs. 30.9±0.7, foot skin temperature (centigrade): 31.4±0.8 vs. 29.1±0.6], fasting blood glucose and postprandial blood glucose were significantly lower than those before surgery [fasting blood glucose (mmol/L): 7.6±1.4 vs. 10.5±1.2, postprandial blood glucose (mmol/L): 9.3±2.3 vs. 13.5±1.1], the differences were statistically significant (all P < 0.01). The lower limb movement of all seven patients was significantly improved after surgery, including one patient who needed wheelchair travel before surgery, and one patient who had intermittent claudication before surgery. Among them, one patient needed wheelchair travel and one patient had intermittent claudication before surgery. All patients could walk normally at 2 weeks after operation. Among the seven patients, two patients had the diabetic foot wound ulceration before surgery, which could not heal for a long time. One month after surgery, blood flow around the foot wound recovered and the healing was accelerated. The wound was dry and crusted around the wound, and the wound healed well. For diabetic high-risk foot patients who are intolerant to diabetic peripheral neuralgia and local anesthesia spinal cord electrical stimulation test, one-time implantation of spinal cord electrical stimulator under general anesthesia under neurophysiological monitoring can effectively alleviate peripheral neuralgia and other diabetic foot related symptoms, improve lower limb blood supply, and reduce the risk of toe amputation. Clinical practice has proved the effectiveness of this technique, especially for the early treatment of diabetic high-risk foot patients.

Knee Joint Preservation in Tactical Athletes: A Comprehensive Approach Based upon Lesion Location and Restoration of the Osteochondral Unit.

The unique physical demands of tactical athletes put immense stress on the knee joint, making these individuals susceptible to injury. In order to ensure operational readiness, management options must restore and preserve the native architecture and minimize downtime, while optimizing functionality. Osteochondral lesions (OCL) of the knee have long been acknowledged as significant sources of knee pain and functional deficits. The management of OCL is predicated on certain injury characteristics, including lesion location and the extent of subchondral disease. Techniques such as marrow stimulation, allograft and autologous chondrocyte implantation are examined in detail, with a focus on their application and suitability in tactical athlete populations. Moreover, the restoration of the osteochondral unit (OCU) is highlighted as a central aspect of knee joint preservation. The discussion encompasses the biomechanical considerations and outcomes associated with various cartilage restoration techniques. Factors influencing procedure selection, including lesion size, location, and patient-specific variables, are thoroughly examined. Additionally, the review underscores the critical role of post-operative rehabilitation and conditioning programs in optimizing outcomes. Strengthening the surrounding musculature, enhancing joint stability, and refining movement patterns are paramount in facilitating the successful integration of preservation procedures. This narrative review aims to provide a comprehensive resource for surgeons, engineers, and sports medicine practitioners engaged in the care of tactical athletes and the field of cartilage restoration. The integration of advanced preservation techniques and tailored rehabilitation protocols offers a promising avenue for sustaining knee joint health and function in this demanding population.

Shifts in patient preference of third-line overactive bladder therapy after introduction of the implantable tibial nerve stimulator.

Third-line therapies for overactive bladder (OAB) that are currently recommended include intravesical Onabotulinumtoxin-A injections (BTX-A), percutaneous tibial nerve stimulation (PTNS), and sacral neuromodulation (SNM). The implantable tibial nerve stimulator (ITNS) is a novel therapy that is now available to patients with OAB. The objective of this study was to analyze shifts in patient preference of third-line therapies for OAB after introducing ITNS as an option amongthe previously established therapies for non-neurogenic OAB. A survey was designed and distributed via SurveyMonkey to the platform's audience of U.S. adults of age 18 and older. Screening questions were asked to include only subjectswho reported symptoms of OAB. Descriptions of current AUA/SUFU guideline-approved third-line therapies (BTX-A, PTNS, and SNM) were provided, and participants were asked to rank these therapies in order of preference (stage A). Subsequently, ITNS was introduced with a description, and participants were then asked to rank their preferences amongst current guideline-approved therapies and ITNS (stage B). Absolute and relative changes in therapy preferences between stage A and stage B were calculated. Associations between ultimate therapy choice in stage B and participant characteristics were analyzed. A total of 485 participants completed the survey (62.5% female). The mean age was 49.1 ± 36.5 years (SD). The most common OAB symptoms reported were urgency urinary incontinence (UUI) (73.0%) and urinary urgency (68.0%). 29.2% of patients had tried medication for OAB in the past, and 8.0%-10.3% of patients were previously treated with a third-line therapy for OAB. In stage A, participants ranked their first choice of third-line therapy as follows: 28% BTX-A, 27% PTNS, and 13.8% SNM. 26.6% of participants chose no therapy, and 4.5% chose all three equally. In stage B, participants ranked their first choice as follows: 27.6% BTX-A, 19.2% PTNS, 7.8% SNM, and 19.2% ITNS. 21.9% of participants chose no therapy and 4.3% chose all four equally as their first choice. There were both absolute and relative declines in proportions of patients interested in BTX-A, SNM, and PTNS as their first choice of third-line therapy with the introduction of ITNS. Patients originally interested in PTNS in stage A had the greatest absolute change after the introduction of ITNS with 7.8% of participants opting for ITNS in stage B. Those interested in SNM in stage A had the largest relative change in interest, with 43.5% of those originally interested in SNM opting for ITNS in stage B. Finally, with the introduction of ITNS, the number of participants initially not interested in any third-line therapy declined by an absolute change of 4.7% and relative change of 17.6%. Participants experiencing concurrent stress urinary incontinence (SUI) symptomswere more likely to choose a current guideline-approved third-line therapy than ITNS or no therapy at all (p = 0.047). Those who had prior experience with third-line therapies were more likely to choose a third-line therapy other than ITNS as their ultimate choice of therapy in stage B. Of those who had chosen a guideline-approvedthird-line therapy in stage B (not ITNS), 13.6% had prior experience with BTX-A, 14.7% with PTNS, and 32 (11.2%) with SNM (p < 0.001, p < 0.001, p = 0.009, respectively). From our study, it appears that ITNS may attract a subset of patients who would not have otherwise pursued current guideline-approved third-line therapies for OAB. When patients are provided with descriptions of third-line OAB therapies including ITNS as an option, ITNS appears to compete with SNM and PTNS. It is possible that ITNS will provide patients with a different phenotype of neuromodulation therapy that can appeal to a niche OAB population. Given that ITNS devices have been introduced relativelyrecently to the market, their application will largely depend on cost and payer coverage, provider bias, and patient comorbidities. Further study is needed to understand how these factors interact with and influence patient preference of advanced OAB therapy to understand which patients will most benefit from this treatment modality.

A mm-sized acoustic wireless implantable neural stimulator based on a piezoelectric micromachined ultrasound transducer

Implantable medical devices are increasingly being used to perform electrophysiological stimulation, thus calling for wireless implantable neural stimulators for which wireless power transfer is needed. Compared with radio frequency and inductive coupling wireless power transfer methods, acoustic wireless power transfer features lower attenuation, a smaller size and a higher safe power threshold. This paper demonstrates the design, fabrication, assembly and characterization of a mm-sized acoustic wireless implantable neural stimulator based on a piezoelectric micromachined ultrasound transducer. Ex vivo experiments in water are conducted to characterize the power transfer link, showing improvement of the power transfer efficiency by more than two times with a matching circuit. Following FDA guidelines, the wireless implantable neural stimulator achieves a 3.24 μW output power in tissue. The feasibility for rat sciatic nerve stimulation is successfully demonstrated in vivo by the implantable prototype with a size of 5 × 5.5 × 2.5 mm3. The proposed solution has the potential to shrink the entire implanted system to a monolithic transducer-IC chip, paving the way toward an acoustic wireless implantable neural stimulator with higher levels of biocompatibility, integration and miniaturization.

An electrode-impedance-aware neurostimulator IC that achieves low-power consumption and fast charge balance

Implantable neural stimulation is becoming increasingly popular for treating neurologically impaired patients, restoring neural functions which would otherwise be lost due to diseases or injuries. The charge balance of the stimulus pulses is of paramount importance for the long-term safety of the electrode-tissue interface. This paper presents a novel neurostimulator integrated circuit in which two novel charge balancing schemes are proposed. One is based on acquiring the access resistance part (RS) of the inter-electrode impedance. Thanks to its adaptive anodic phase, the RS-based charge balance circuit does not require an additional discharge phase, achieving faster charge balance than most existing stimulator ICs. The other scheme is based on acquiring the double-layer capacitance part (CDL) of the inter-electrode impedance and the entire charge balancing process (inc. monitoring, computation and compensation) is performed in the analog domain. This is in sharp contrast to the existing electrode-impedance-aware charge balancing schemes which require ADCs and compute the net charge in the digital domain. Hence the new impedance-aware charge-balancing scheme is faster and more power friendly. The impedance-aware stimulator ASIC has been implemented using X-FAB’s 180-nm CMOS process. The post-layout simulation results suggest a good charge balance is achieved as the voltage deviation from the electrode offset voltage on the electrode after the charge compensation reduces to 2.64 mV and –1.39 mV under the RS-based and CDL-based charge balancing schemes, respectively. The additional power overhead due to the proposed CDL-based charge balancer circuit is 2.46 μW at a stimulation rate of 400 Hz.

Rehabilitation exercise-driven symbiotic electrical stimulation system accelerating bone regeneration.

Electrical stimulation can effectively accelerate bone healing. However, the substantial size and weight of electrical stimulation devices result in reduced patient benefits and compliance. It remains a challenge to establish a flexible and lightweight implantable microelectronic stimulator for bone regeneration. Here, we use self-powered technology to develop an electric pulse stimulator without circuits and batteries, which removes the problems of weight, volume, and necessary rigid packaging. The fully implantable bone defect electrical stimulation (BD-ES) system combines a hybrid tribo/piezoelectric nanogenerator to provide biphasic electric pulses in response to rehabilitation exercise with a conductive bioactive hydrogel. BD-ES can enhance multiple osteogenesis-related biological processes, including calcium ion import and osteogenic differentiation. In a rat model of critical-sized femoral defects, the bone defect was reversed by electrical stimulation therapy with BD-ES and subsequent bone mineralization, and the femur completely healed within 6 weeks. This work is expected to advance the development of symbiotic electrical stimulation therapy devices without batteries and circuits.

Retrospective Evaluation of Bipolar Peripheral Nerve Stimulation for Nociceptive and Neuropathic Pain: A Pilot Study.

This retrospective review evaluates pain and patient-defined functional goal improvement utilizing bipolar peripheral nerve stimulation (PNS) in chronic neuropathic and nociceptive pain states. Our dataset includes 24 patients who underwent implantation of a permanent peripheral nerve stimulator from January 2018 through December 2022. A total of 29 leads were implanted amongst 24 patients, with 5 patients having leads at 2 different dermatomes. Fifteen leads were placed for primarily neuropathic pain, and 14 leads were placed for nociceptive pain. Inclusion criteria were the following: pain duration greater than 6 months, documented peri-procedural Numerical Pain Rating Scale (NPRS) and greater than 60 days follow-up post implant. Data was collected and analyzed showing that 89.6% of implants at 6 months follow-up and 70% at 12 months follow-up achieved 50% or greater pain relief. A significant reduction in NPRS scores when comparingpre-procedure pain scores (Median = 7, n = 29) to 6-month follow-up data (Median = 2, n = 29), p<0.001 with a large effect size, r =0.61.Ninety-three percent of patients reported achieving their personal functional goal. Twelve of the fourteen (86%) leads implanted for primary nociceptive pain and fourteen of the fifteen (93%) leads implanted for neuropathic pain achieved ≥50% relief at 6 months. At twelve months, seven leads in each group provided ≥50% sustained pain relief. Of the 14 patients that were on opioids, 6 discontinued, while another 2 had a reduction in oral morphine milligram equivalents (MME) at the 12-month follow-up. This retrospective review demonstrates the potential clinical application of PNS in both nociceptive and neuropathic pain states. Further prospective studies are warranted to validate the effectiveness of PNS in the treatment of refractory nociceptive and neuropathic pain states.

Mapping of Capsular Side Effects by using Intraoperative Motor-Evoked Potentials during Asleep Deep Brain Stimulation Surgery of the Subthalamic Nucleus for Parkinson’s Disease

Introduction: The aim of this study was to present a novel technique for subthalamic nucleus (STN) deep brain stimulation (DBS) implantation under general anesthesia by using intraoperative motor-evoked potentials (MEPs) through direct lead stimulation and determining their correlation to the thresholds of postoperative stimulation-induced side effects. Methods: This study included 22 consecutive patients with advanced Parkinson’s disease who underwent surgery in our institution between January 2021 and September 2023. All patients underwent bilateral implantation in the STN (44 leads) under general anesthesia without microelectrode recordings (MERs) by using MEPs with electrostimulation directly through the DBS lead. No cortical stimulation was performed during this process. Intraoperative fluoroscopic guidance and immediate postoperative computed tomography were used to verify the electrode’s position. The lowest MEP thresholds were recorded and were correlated to the postoperative stimulation-induced side-effect threshold. The predictive values of the MEPs were analyzed. Five DBS leads were repositioned intraoperatively due to the MEP results. Results: A moderately strong positive correlation was found between the MEP threshold and the capsular side-effect threshold (RS = 0.425, 95% CI, 0.17–0.67, p = 0.004). The highest sensitivity and specificity for predicting a side-effect threshold of 5 mA were found to be at 2.4 mA MEP threshold (sensitivity 97%, specificity 87.5%, positive predictive value 97%, and negative predictive value 87.5%). We also found high sensitivity and specificity (100%) at 1.15 mA MEP threshold and 3 mA side-effect threshold. Out of the total 44 leads, 5 (11.3%) leads were repositioned intraoperatively due to MEP thresholds lower than 1 mA (4 leads) or higher than 5 mA (1 lead). The mean accuracy on postoperative CT was 1.05 mm, and there were no postoperative side-effects under 2.8 mA. Conclusion: Intraoperative MEPs with electrostimulation directly through the contacts of the DBS lead correlate with the stimulation-induced capsular side effects. The lead reposition based on intraoperative MEP may enlarge the therapeutic window of DBS stimulation.

An Energy-Efficient Wireless Power Receiver With One-Step Adiabatic-Bipolar-Supply Generating for Implantable Electrical Stimulation Applications.

This paper presents an energy-efficient wireless power receiver for implantable electrical stimulation applications, which can achieve one-step adiabatic bipolar-supply that is generated by a hybrid single-stage dual-output regulating (SSDOR) rectifiers. The structure using only four switches overcomes the disadvantages that the two output voltage values in the traditional dual-output rectifiers are close to each other. A constant-current (CC) controlled adiabatic dynamic voltage scaling (DVS) technique is proposed to minimize the voltage headroom of the stimulating drivers and improve the stimulation efficiency significantly. In addition, the receiver adopts only one general constant on-time (COT) low-frequency control to adjust the stimulation current, reducing both the power consumption and the complexity of the control circuits. The proposed receiver has been fabricated in a 0.18 μm BCD process with ±6 V voltage compliance and 2.5 mA maximum stimulating current. With a current range from ±1.5 mA to ±2.5 mA, the measured maximum average headroom voltage is only 80 mV and the peak total efficiency of the receiver is 85.6 %. The functionalities of the proposed receiver have been successfully verified through in vitro experiments.