Spinal Cord Stimulation Lead Research Articles

Post Dural Puncture Headache After Spinal Cord Stimulator Lead Insertion Successfully Treated with Occipital Nerve Blocks

Post Dural Puncture Headache After Spinal Cord Stimulator Lead Insertion Successfully Treated with Occipital Nerve Blocks

Spinal Cord Stimulation with Implantation of Surgical Leads is a Sufficient Salvage Therapy for Patients Suffering from Persistent Spinal Pain Syndrome—A Retrospective Single-center Experience

ObjectivePersistent spinal pain syndrome (PSPS) poses a significant medical challenge, often leading to diminished quality of life for affected individuals. In response to this clinical dilemma, Spinal Cord Stimulation (SCS) has emerged as a promising intervention aimed at improving the functional outcomes and overall well-being of patients suffering from these debilitating syndrome. In case a therapy with percutaneous lead fails, e.g. due to a dislocation, surgical lead can be used as a stable alternative. This is resulting in a more invasive procedure and does not allow for intraoperative monitoring. The aim of the study is to investigate the efficacy and safety of the use of surgical leads, as there have been only a few case series published so far. MethodsWe included PSPS patients that gave consent to a SCS therapy and were treated with Surgical Leads. Outcome scores concerning the quality of life (SF-36), pain related disability (Oswestry disability index [ODI]), sleeping quality (Pittsburgh Sleep Quality Index [PSQI]), and pain intensity (NRS) were obtained prior surgery and at outpatient visits after permanent implantation. ResultsIn this study, 36 patients were implanted with a Surgical Lead SCS system. One patient developed a new neurological deficit characterized by left-sided leg paresis attributable to postoperative hemorrhage, and another patient experienced a wound infection. These complications contributed to an overall morbidity rate of 5.6%. In overall 5 patients (20.8%) the electrodes were explanted within the first month. Follow-up data of 24 subjects with a median time of 21 [15-47] months were available. The mean pain intensity at rest and in motion was reduced. Further pain depending disability improved from a median ODIpreop=38 [30-57]% to ODIfollow-up =21 [9-35]% (p<0.01). Additionally the Sleeping Quality and the Quality of Life improved concerning the physical (Median PCS preop=22.5 [20.4-30.4] vs. PCSfollow-up = 41.8 [35.2-47.0], p < 0.01).) and mental (Median MCSpreop=45.4 [31.1-55.5] vs. MCSfollow-up=58.1 [47.6-59.8], p=0.018). component. ConclusionSCS with surgical leads is a safe secondary technique to treat PSPS, where treatment with percutaneous leads fail. The results show a promising long-term effect concerning pain intensity and functional outcome.

Cardiac sensing at a spinal cord stimulation lead: a promising on-device potential biomarker for pain and wellbeing.

Introduction: In the search for objective measures of therapeutic outcomes for patients with spinal cord stimulation (SCS) devices, various metrics of cardiac performance have been linked to pain as well as overall health. To track such measures at home, recent studies have incorporated wearables to monitor cardiac activity over months or years. The drawbacks to wearables, such as patient compliance, would be obviated by on-device sensing that incorporates the SCS lead. This study sought to evaluate the feasibility of using SCS leads to record cardiac electrograms. Methods: The quality of signals sensed by externalized, percutaneous leads in the thoracic spine of 10 subjects at the end of their SCS trial were characterized across various electrode configurations and postures by detecting R-peaks and calculating signal-to-noise ratio (SNR). In a subset of 5 subjects, cardiac metrics were then compared to those measured simultaneously with a wearable. Results: The average signal quality was acceptable for R-peak detection (i.e., SNR > 5) for all configurations and positions across all 10 subjects, with higher signal quality achieved when recording in resting positions. Notably, the spinal lead recordings enabled more reliable beat detection compared to the wearable (n = 29 recording pairs; p < 0.001). When excluding wearable recordings with over 35% missed beats, the inter-beat intervals across devices were highly correlated (n = 22 recording pairs; Pearson correlation: R = 0.99, p < 0.001). Further comparisons in these aligned wearable and corresponding spinal-lead recordings revealed significant differences in the frequency domain metrics (i.e., absolute and normalized high and low frequency HRV power, p < 0.05), but not in time domain HRV parameters. Discussion: The ability of an implanted SCS system to record electrocardiograms, as demonstrated here, could provide the basis of automated SCS therapy by tracking potential biomarkers of the patient's overall health state without the need for additional external devices.

Boosting Confidence: Enhancing Spinal Cord Stimulator Needle and Lead Placement Through Simulation Training.

Background This pilot study aims to examine the effectiveness of a spinal cord stimulator (SCS) simulator training system in improving theconfidence of pain fellows in SCS placement. Methodology Five Ukrainian physicians (neurologists, neurosurgeons, and an anesthesiologist) completed a 10-item survey regarding their confidence in various aspects of SCS placement and their opinions on how effective SCS models were for educational purposes. After placing SCS leads using the SCS simulator, the physicians took the same survey again. The Mann-Whitney U test was used to determine if there was a significant difference in total scores pre and post-simulator training.The software PAST (PAleontological STatistics) was used for statistical analysis. Results Overall, five participants had a 38% statistically significant increase in survey scores before and after the intervention (mean: 4.2 vs. 6.2, p = 0.0055). With regards to each item of the survey, participants had a significantly increased confidence in driving leads (2.6 vs. 5.2, p = 0.008) and in overall technical skills for the SCS procedure after the training (2.8 vs. 5.2, p = 0.0188). Although the other eight survey items were not statistically significant (p > 0.05), participants had a 28% increase in confidence when inserting epidural needles, a 20% increase in interpreting simulated X-rays, a 32% increase in navigating challenging anatomical variations, a 12% increase in identifying key anatomical landmarks, a 20% increase in ensuring the correct placement of the lead, or a 53% increase in preparedness for performing an SCS procedure in a real clinical setting. The participant's perspective on how valuable the stimulator training was for enhancing procedural skills increased by 38% and how well the simulator replicated real-life SCS procedure increased by 52%, although both were statistically insignificant (p > 0.05). Conclusions This pilot study shows that the utilization of simulated neuromodulation training is a viable means of augmenting neuromodulation education by increasing physician's confidence in aspects of the SCS placement procedure. The extent to which simulator training improves procedural skills in a real-life SCS placement needs to be investigated further.

Difficult Single-Lead Spinal Cord Stimulator Trial for Failed Back Surgery Syndrome Salvages Treatment

BACKGROUND: Spinal cord stimulation (SCS) is a minimally invasive neuromodulation treatment modality primarily used for failed back surgery syndrome (FBSS), complex regional pain syndrome, and diabetic neuropathy. Specifically, when utilized for the treatment of FBSS, placement can be complicated by the excessive scarring, adhesions, and altered anatomy limiting the access to the epidural space and advancement of the leads. CASE REPORT: Our patient is a 58-year-old woman with a history of scoliosis and severe lumbar spinal stenosis who presented for trial of an SCS for FBSS. Given the refractory nature to medical and minimally invasive management, an SCS trial was performed. Unfortunately, due to the extensive fibrosis and adhesions in her epidural space, only a single lead could be placed but experienced pain relief. During the permanent SCS, 2 leads were successfully placed with the patient ultimately receiving &gt; 50% pain relief. CONCLUSIONS: Here, we present a case of FBSS refractory to medical and minimally invasive management where a single SCS lead was placed during the trial, due to scarring and adhesions, and 2 leads during the permanent SCS procedure. Our case report suggests considering even the trial of a single-lead placement during an SCS trial in patients with an otherwise difficult anatomy, as the placement of the permanent lead offers greater access to the epidural space potentially allowing for the placement of a second lead and potentially salvaging the entire therapy. KEY WORDS: Spinal cord stimulator, spinal stenosis, single lead, failed back surgery syndrome

Neuronavigation-Guided Implantation of a Surgical Spinal Cord Stimulation Lead in a Patient With Chronic Pain With Scoliosis and Severe Spinal Cord Rotation: A Technical Note

Neuronavigation-Guided Implantation of a Surgical Spinal Cord Stimulation Lead in a Patient With Chronic Pain With Scoliosis and Severe Spinal Cord Rotation: A Technical Note

Biplane fluoroscopy-guided percutaneous spinal cord stimulation

ObjectiveFluoroscopy is useful for spinal cord stimulation (SCS) lead placement. We employed biplane fluoroscopy for SCS lead placement. In this study, we sought to confirm the validity of using biplane fluoroscopy for SCS lead placement and to establish whether biplane fluoroscopy safely reduces the duration of surgery. MethodsClinical data were retrospectively collected from the medical records of patients who underwent SCS lead placement under local anesthesia from 2015 to 2022. The duration of the surgical phase and the total radiation exposure time per case were recorded. ResultsForty-six patients underwent percutaneous SCS lead implantation. Recording was completed in 41 cases: one lead was placed in 13 cases and two leads were placed in 28 cases. Monoplane and biplane fluoroscopy was used in 15 and 26 patients, respectively. Although the type of fluoroscopy did not significantly affect the mean duration of the surgical phase in patients in which one lead was placed, biplane fluoroscopy was associated with a significant reduction in the mean duration of the surgical phase in patients that underwent placement of two leads (P=0.002). No significant differences in the total radiation exposure time were observed between patients in the monoplane and biplane fluoroscopy groups that were implanted with one (P=0.21) or two leads (P=0.62). ConclusionsThe use of biplane fluoroscopy reduced the duration of surgery necessary for the placement of two SCS leads. Biplane fluoroscopy represents a practical and safe adjustment to the current practice of SCS lead implantation.

Paddle Lead Spinal Cord Stimulation in the Morbidly Obese Patient Population: Outcomes and Complications in a Single-Surgeon Cohort

Paddle lead spinal cord stimulation (SCS) is used to treat refractory chronic pain. Morbidly-obese patients seek SCS to reduce chronic pain. However, these patients face worse surgical outcomes, and the SCS literature has not evaluated safety and efficacy in this patient population. This study is the largest single-surgeon case series to date on morbidly obese patients with paddle lead SCS implantations. The primary objective is to report post-operative complication rates in morbidly-obese patients receiving SCS implants. The secondary objective is to report patient-reported pain scores and PROMIS Pain Interference and Physical Function scores in these patients. A retrospective chart review was conducted. The patient charts were reviewed from the day of procedure consent to 6 months post-op. Demographic information, pain scores, PROMIS scores, neurological complications, infections, and wound complications were documented. 67 patients were included. The mean pre-operative BMI was 44.47±4.02 kg/m2. The mean age was 58.9±11.4 years old. There were no neurological complications. 3/67 (4%) developed culture-positive infections. 9/67 (13%) patients developed superficial wound dehiscence without underlying infection. The mean post-op PROMIS PF score was 31.6±6.2 (n=16) and the mean post-op PROMIS PI score was 64.0±6.4 (n=16). There was a reduction in pain scores, from 7.9±1.7 pre-op to 5.7±2.5 post-op (n=22, p=0.004). Paddle lead SCS implantation is safe for morbidly-obese patients. The only minimal-risk complications present were post-operative infections and wound dehiscence. Surgical care can be modified to further reduce the rates of infection and dehiscence.

ID: 213534 Early Outcomes With the Medtronic Closed-Loop Spinal Cord Stimulation Study

Spinal cord stimulation (SCS) is a therapy for the treatment of chronic pain that relies on the application of mild electrical stimulation delivered to the dorsal column fibers of the spinal cord via lead(s) implanted in the epidural space. Most of the current SCS systems do not adjust the stimulation to reflect changes in distance between the SCS lead and the cord during activities of daily living. Hence, the net energy delivered varies dynamically resulting in inconsistent therapy delivery i.e., open-loop (OL) SCS.1 Closed-Loop SCS (CL SCS), where the therapy is titrated by the physiologic response of the spinal cord to stimulation – known as evoked compound action potential (ECAPs),2 can be used to address this limitation of OL SCS systems. The objective of this study is to evaluate patient experience and therapy durability with CL SCS. Primary study objective is to demonstrate the reduction in overstimulation sensation with the CL feature in subjects implanted with the CL SCS system. Secondary objectives include characterizing therapy efficacy in reducing overall, back or leg pain as measured by the proportion of subjects with ≥50% reduction in pain score, at the time of the 3-month visit. Consistency of dosing and long-term durability of therapy will also be characterized.

ID: 205124 Paddle Lead Spinal Cord Stimulation in Patients With Morbid Obesity – Outcomes and Complications

Prior studies have shown morbidly obese patients face worse post-operative outcomes. This retrospective case series aims to report outcomes of morbidly obese patients following paddle lead spinal cord stimulation (SCS) implantation by a single surgeon.

ID: 222778 Spinal ECAP Morphology: Decoding the Spinal Cord With an Indicator of Lead Position

The spinal evoked compound action potential (ECAP) is a biopotential originating from the synchronous activation of dorsal column fibers in response to spinal cord stimulation (SCS). However, the factors contributing to the unique morphology of the ECAP waveform in humans have not been well elucidated. We examine whether the ECAP morphology is related to the medial-to-lateral placement of the SCS lead. Morphometry of the spinal cord, as well as recent studies in sheep,2 indicates that the superficial dorsal columns in humans have largest fiber types located more laterally3. We hypothesize, that laterally placed contacts may be associated with shorter ECAP latency.

ID: 214925 Early Experience With Closed-Loop SCS During In-Clinic Testing

Therapeutic outcomes with spinal cord stimulation (SCS) have continued to improve with the introduction of new waveforms.1 However, regardless of the waveform in use, the therapy dose delivered to the cord will vary dynamically due to the movement of the cord within the spinal canal, relative to the SCS lead. This leads to the activation of different volumes of tissue and inconsistent therapy delivery. Patients typically respond by adjusting the therapy amplitude up or down, which could result in less-than-optimal pain relief.2 Closed-Loop SCS, titrated by the physiologic response of the spinal cord to stimulation – known as evoked compound action potential (ECAPs), can be used to effectively mitigate this issue and maintain a consistent therapeutic dose.3 The objective of this study is to optimize a workflow to efficiently program Closed-Loop SCS with contemporary waveforms (e.g., Differential Target Multiplexed (DTM) SCS), with an investigational external neurostimulator (ENS), capable of stimulating and recording ECAPs, in Medtronic SCS trial participants.

Novel Evoked Synaptic Activity Potentials (ESAPs) Elicited by Spinal Cord Stimulation.

Spinal cord stimulation (SCS) evokes fast epidural evoked compound action potential (ECAP) that represent activity of dorsal column axons, but not necessarily a spinal circuit response. Using a multimodal approach, we identified and characterized a delayed and slower potential evoked by SCS that reflects synaptic activity within the spinal cord. Anesthetized female Sprague Dawley rats were implanted with an epidural SCS lead, epidural motor cortex stimulation electrodes, an epidural spinal cord recording lead, an intraspinal penetrating recording electrode array, and intramuscular electromyography (EMG) electrodes in the hindlimb and trunk. We stimulated the motor cortex or the epidural spinal cord and recorded epidural, intraspinal, and EMG responses. SCS pulses produced characteristic propagating ECAPs (composed of P1, N1, and P2 waves with latencies <2 ms) and an additional wave ("S1") starting after the N2. We verified the S1-wave was not a stimulation artifact and was not a reflection of hindlimb/trunk EMG. The S1-wave has a distinct stimulation-intensity dose response and spatial profile compared with ECAPs. 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX; a selective competitive antagonist of AMPA receptors (AMPARs)] significantly diminished the S1-wave, but not ECAPs. Furthermore, cortical stimulation, which did not evoke ECAPs, produced epidurally detectable and CNQX-sensitive responses at the same spinal sites, confirming epidural recording of an evoked synaptic response. Finally, applying 50-Hz SCS resulted in dampening of S1-wave but not ECAPs. Therefore, we hypothesize that the S1-wave is synaptic in origin, and we term the S1-wave type responses: evoked synaptic activity potentials (ESAPs). The identification and characterization of epidurally recorded ESAPs from the dorsal horn may elucidate SCS mechanisms.

Resolution of Celiac Artery Compression Syndrome Following Spinal Cord Stimulation: A Case Report

BACKGROUND: Celiac artery compression syndrome is characterized by postprandial epigastric pain, weight loss, and occasional epigastric bruit, and can be difficult to treat because there are no definitive guidelines. We present a case of a 47-year-old man who had postprandial pain, weight loss, and chronic diarrhea for 5 years, which was resolved with spinal cord stimulation (SCS). CASE REPORT: After extensive workup, a diagnosis of celiac artery compression syndrome was confirmed. Due to previous treatment failures, repeat celiac plexus blocks becoming less efficacious, and surgical unsuitability, the patient underwent an SCS trial. They continued having pain relief, so a permanent spinal cord stimulator lead was implanted. CONCLUSION: We highlight complete resolution of celiac artery compression syndrome using SCS. KEY WORDS: Case report, celiac artery compression syndrome, celiac plexus block, median arcuate ligament syndrome, spinal cord stimulation

Paddle-Lead Spinal-Cord Stimulation Surgeries for Chronic Neuropathic Pain: A Single Surgeon Case-Series Outcome Analysis in Indian Population.

Background Spinal-cord stimulation (SCS) for relief of chronic neuropathic pain is well established. Objective The inherent limitations with conventional percutaneous lead SCS are lead migration, positional variations in stimulation, as well as possible nonreplication of benefits after permanent SCS implantation, which were experienced during a positive trial period. To circumvent these limitations, we analyzed five consecutive cases of chronic intractable neuropathic pain who underwent direct SCS paddle lead placement during the trial period for pain relief. In addition, during the process of placing a permanent paddle lead, the impediment created by prior epidural scarring in such chronic patients can be obviated mechanically thereby increasing the efficacy of the procedure. Material and Methods The demographic details, diagnosis, preoperative visual analogue scale score (VAS), and follow-up VAS were recorded. Surgical procedure consisted of a standard dorsal laminotomy followed by placement of permanent paddle leads. Results All patients reported significant improvement in their VAS scores. Mean duration of follow-up was 23.6 months (9-35 months). Mean preoperative VAS was 9.4 and 1.4 at the last follow-up. No major complications were found. Conclusion With careful patient selection and appropriate surgical strategy, it was possible to implant permanent paddle leads during SCS trial itself in our five patients thereby replicating and sustaining the trial period pain relief. We argue that this can be a new cost-effective and reliable technique for the placement of SCS leads achieving excellent and sustained pain relief.

GABAergic Signaling during Spinal Cord Stimulation Reduces Cardiac Arrhythmias in a Porcine Model.

Neuraxial modulation, including spinal cord stimulation, reduces cardiac sympathoexcitation and ventricular arrhythmogenesis. There is an incomplete understanding of the molecular mechanisms through which spinal cord stimulation modulates cardiospinal neural pathways. The authors hypothesize that spinal cord stimulation reduces myocardial ischemia-reperfusion-induced sympathetic excitation and ventricular arrhythmias through γ-aminobutyric acid (GABA)-mediated pathways in the thoracic spinal cord. Yorkshire pigs were randomized to control (n = 11), ischemia-reperfusion (n = 16), ischemia-reperfusion plus spinal cord stimulation (n = 17), ischemia-reperfusion plus spinal cord stimulation plus γ-aminobutyric acid type A (GABAA) or γ-aminobutyric acid type B (GABAB) receptor antagonist (GABAA, n = 8; GABAB, n = 8), and ischemia-reperfusion plus GABA transaminase inhibitor (GABAculine, n = 8). A four-pole spinal cord stimulation lead was placed epidurally (T1 to T4). GABA modulating pharmacologic agents were administered intrathecally. Spinal cord stimulation at 50 Hz was applied 30 min before ischemia. A 56-electrode epicardial mesh was used for high-resolution electrophysiologic recordings, including activation recovery intervals and ventricular arrhythmia scores. Immunohistochemistry and Western blots were performed to measure GABA receptor expression in the thoracic spinal cord. Cardiac ischemia led to myocardial sympathoexcitation with reduction in activation recovery interval (mean ± SD, -42 ± 11%), which was attenuated by spinal cord stimulation (-21 ± 17%, P = 0.001). GABAA and GABAB receptor antagonists abolished spinal cord stimulation attenuation of sympathoexcitation (GABAA, -9.7 ± 9.7%, P = 0.043 vs. ischemia-reperfusion plus spinal cord stimulation; GABAB, -13 ± 14%, P = 0.012 vs. ischemia-reperfusion plus spinal cord stimulation), while GABAculine alone caused a therapeutic effect similar to spinal cord stimulation (-4.1 ± 3.7%, P = 0.038 vs. ischemia-reperfusion). The ventricular arrhythmia score supported these findings. Spinal cord stimulation during ischemia-reperfusion increased GABAA receptor expression with no change in GABAB receptor expression. Thoracic spinal cord stimulation reduces ischemia-reperfusion-induced sympathoexcitation and ventricular arrhythmias through activation of GABA signaling pathways. These data support the hypothesis that spinal cord stimulation-induced release of GABA activates inhibitory interneurons to decrease primary afferent signaling from superficial dorsal horn to sympathetic output neurons in the intermediolateral nucleus.

Cerebrospinal Fluid Leak Following Explantation of Percutaneous Spinal Cord Stimulator Device: A Case Report

BACKGROUND: While spinal cord stimulation (SCS) is a safe and effective treatment for chronic pain, some patients require explantation of their devices due to complications or inadequate pain control. The rate of SCS implantation has steadily increased over the years; however, the complications of percutaneous lead extraction have not been well-documented in the scientific literature. CASE REPORT: We present an 86-year-old patient at our institution who developed an intraoperative cerebrospinal fluid (CSF) leak during SCS explantation. The leak was conservatively managed with tight surgical closure and placement of an abdominal binder. The patient tolerated the procedure well and only developed a minor headache which self-resolved. CONCLUSION: Although rare, SCS lead extraction can cause CSF leakage from unintentional intraoperative dural tear. While most CSF leaks can be managed conservatively and do not require surgical repair, pain physicians need to be well-informed on how to manage CSF leaks that occur during SCS explantation. KEY WORDS: Case report, cerebrospinal fluid leak, chronic pain, explantation, spinal cord stimulation

Abstract 11617: Chronic Spinal Cord Stimulation Mitigates Cardiac Sympathoexcitation and Reduces Ventricular Arrhythmias Induced by Myocardial Infarction

Introduction: Spinal cord stimulation (SCS) is effective neuromodulation therapy for pain, but little is known about the effectiveness of SCS for arrhythmia prevention in chronic myocardial infarction (MI). Hypothesis: Chronic SCS reduces MI-induced cardiac sympathoexcitation and reduces ventricular arrhythmias. Methods: Yorkshire pigs were randomized to chronic left circumflex coronary artery MI alone (n=11) or MI + chronic SCS (n=9). Epidural SCS lead was placed percutaneously T1-T4 of the spinal cord and reactive SCS was performed at 10 kHz, 0.03ms, and 2.5mA after MI. Holter ECG was recorded for heart rate variability (HRV) analysis, performed throughout 4-5 weeks post-MI. To create acute stress in chronic MI, epicardial extraventricular programmed stimulus (S1/S2 pacing), and acute left anterior descending coronary artery (LAD) ischemia(1h)+reperfusion(2h) (I/R) injury were conducted during terminal experiment. SCS was continued throughout terminal experiment. Cardiac electrophysiological data (activation recovery interval (ARI) and dispersion of repolarization (DOR)), as well as ventricular arrhythmia quantification were measured by placing a 56-electrode mesh sock over the heart . Data is shown as mean±SEM. Results: 1 week after MI, 30min HRV showed a higher high-frequency band and lower very-low and low-frequency band with SCS (%HF: MI 25±4 vs SCS 51±4, p=0.0028. %VLF: 50±4 vs 30±3, p=0.0015. %LF: 22±2 vs 14±2, p=0.047). In the terminal experiment, SCS reduced the maximum slope (Smax) of the electrical restitution curve described by S1/S2 pacing (Smax: MI 0.6±0.03 vs SCS 0.4±0.05, p=0.023). After acute LAD ischemia, SCS reduced global %ARI change (MI -19±3% vs SCS -11±1%, p=0.019), specifically in the ischemic region (MI -31±4% vs SCS -16±3%, p=0.008), and global %DOR (MI 1513±288% vs SCS 595±144%, p=0.011). Chronic SCS also reduced ventricular tachycardia and ventricular fibrillation during acute I/R (MI 15±3 vs SCS 5±0.8, p=0.014). Conclusions: Reactive SCS therapy mitigates cardiac autonomic imbalance in chronic MI and protects from new acute ischemia induced cardiac sympathoexcitation and ventricular arrhythmias.

Combining Awake Anesthesia with Minimal Invasive Surgery Optimizes Intraoperative Surgical Spinal Cord Stimulation Lead Placement.

Spinal cord stimulation (SCS) is an effective and validated treatment to address chronic refractory neuropathic pain in persistent spinal pain syndrome-type 2 (PSPS-T2) patients. Surgical SCS lead placement is traditionally performed under general anesthesia due to its invasiveness. In parallel, recent works have suggested that awake anesthesia (AA), consisting of target controlled intra-venous anesthesia (TCIVA), could be an interesting tool to optimize lead anatomical placement using patient intra-operative feedback. We hypothesized that combining AA with minimal invasive surgery (MIS) could improve SCS outcomes. The goal of this study was to evaluate SCS lead performance (defined by the area of pain adequately covered by paraesthesia generated via SCS), using an intraoperative objective quantitative mapping tool, and secondarily, to assess pain relief, functional improvement and change in quality of life with a composite score. We analyzed data from a prospective multicenter study (ESTIMET) to compare the outcomes of 115 patients implanted with MIS under AA (MISAA group) or general anesthesia (MISGA group), or by laminectomy under general anesthesia (LGA group). All in all, awake surgery appears to show significantly better performance than general anesthesia in terms of patient pain coverage (65% vs. 34–62%), pain surface (50–76% vs. 50–61%) and pain intensity (65% vs. 35–40%), as well as improved secondary outcomes (quality of life, functional disability and depression). One step further, our results suggest that MISAA combined with intra-operative hypnosis could potentialize patient intraoperative cooperation and could be proposed as a personalized package offered to PSPS-T2 patients eligible for SCS implantation in highly dedicated neuromodulation centers.

Bioheat Model of Spinal Column Heating During High-Density Spinal Cord Stimulation

IntroductionHigh-density (HD) spinal cord stimulation (SCS) delivers higher charge per time by increasing frequency and/or pulse duration, thus increasing stimulation energy. Previously, through phantom studies and computational modeling, we demonstrated that stimulation energy drives spinal tissue heating during kHz SCS. In this study, we predicted temperature increases in the spinal cord by HD SCS, the first step in considering the potential impact of heating on clinical outcomes. Materials and MethodsWe adapted a high-resolution computer-aided design–derived spinal cord model, both with and without a lead encapsulation layer, and applied bioheat transfer finite element method multiphysics to predict temperature increases during SCS. We simulated HD SCS using a commercial SCS lead (eight contacts) with clinically relevant intensities (voltage-controlled: 0.5–7 Vrms) and electrode configuration (proximal bipolar, distal bipolar, guarded tripolar [+−+], and guarded quadripolar [+−−+]). Results were compared with the conventional and 10-kHz SCS (current-controlled). ResultsHD SCS waveform energy (reflecting charge per second) governs joule heating in the spinal tissues, increasing temperature supralinearly with stimulation root mean square. Electrode configuration and tissue properties (an encapsulation layer) influence peak tissue temperature increase—but in a manner distinct for voltage-controlled (HD SCS) compared with current-controlled (conventional/10-kHz SCS) stimulation. Therefore, depending on conditions, HD SCS could produce heating greater than that of 10-kHz SCS. For example, with an encapsulation layer, using guarded tripolar configuration (500-Hz, 250-μs pulse width, 5-Vpeak HD SCS), the peak temperature increases were 0.36 °C at the spinal cord and 1.78 °C in the epidural space. ConclusionsAs a direct consequence of the higher charge, HD SCS increases tissue heating; voltage-controlled stimulation introduces special dependencies on electrode configuration and lead encapsulation (reflected in impedance). If validated with an in vivo measurement as a possible mechanism of action of SCS, bioheat models of HD SCS serve as tools for programming optimization.