The sex-dependent impact of adipose tissue and inflammation on chronic pain - A cross-sectional study from the all of us research program

Emerging evidence suggests an association between chronic pain and elevated body fat. We sought to determine if individuals with higher body fat, measured by hip circumference (HC) and waist circumference (WC), are at risk for chronic pain when they demonstrate higher expression of inflammatory markers. We investigated the incidence and severity of pain in patients with varying WC/HC and inflammatory markers (C-Reactive Protein, IL-6, leptin) using the NIH-sponsored All of Us Database. For each inflammatory marker and sex, participants were divided into four groups based on combinations of normal/high marker levels and small/large WC/HC. We used statistical analysis to compare WC/HC and pain severity (mean NRS pain score) between groups of the same sex. In females, but not males, combinations of elevated CRP with large WC/HC exerted additive effects on the incidence of chronic pain (p < 0.01) and severe pain (p < 0.001), as well as on the severity of pain evaluated by the mean NRS pain score (p < 0.01). This relationship held true for females with high IL-6 or leptin and large WC or HC (p < 0.001 for chronic pain and severe pain incidence, and p < 0.05 for pain severity). Neither IL-6 nor leptin showed any significant impact on pain in males. Obesity status and CRP exert additive prognostic effects for chronic pain in females, but not in males. The concomitant evaluation of other inflammatory factors, such as IL-6 or leptin in females, may further augment the prediction of chronic pain. PERSPECTIVE: This article investigates the relationship between chronic pain, obesity, and inflammatory markers. It could help elucidating sex difference in pain mechanisms, as well as the risk factors for chronic pain, potentially improving patient diagnosis, follow-up and treatment.

A scoping review of mechanisms of auricular acupuncture for treatment of pain

OBJECTIVES

Auricular acupuncture (AA) is becoming increasingly common in primary care clinics, emergency departments and peri-operatively for pain relief. Over the last decade, since the last comprehensive reviews were published, the literature has expanded. In this scoping review, we seek to document the efficacy of AA in treating both acute and chronic pain, describe the mechanism of action of AA in treating pain, and discuss how AA has been integrated into Western medicine to date.

METHODS

The authors performed a MEDLINE search inclusive of articles from 1966 to June 2023 including articles written in English identifying literature. We included human studies when more than 3 patients were included. Three hundred and fourteen unique articles were identified and 152 were selected by title screen. After abstract review, 117 were chosen for full-text review. Following full-text review, 33 articles were excluded and 21 added from references, totaling 105 articles included in our scoping review.

RESULTS

AA reduces pain severity in patients with both acute and chronic pain. The best studies in the acute settings have occurred in the peri-operative setting where sham AA is employed, multiple sessions of AA are given, and medication dosing is carefully monitored. In these cases, AA reduced pain and post-operative medications. In patients with chronic pain, multiple sessions of AA resulted not only in pain relief but also in improvements in function and disability. Literature suggests that AA works through multiple mechanisms with the most compelling data coupled to the autonomic nervous system and neuroendocrine system. Curriculums designed to teach AA and aid in implementation have been published.

CONCLUSION

AA is an accessible, effective means of pain relief. AA is relatively straightforward to learn, and protocols and curriculums exist to teach healthcare professionals this valuable skill. Overcoming implementation barriers, including patient education, are essential next steps.

The Evolution of Surgical Technique in Spinal Cord Stimulation: A Scoping Review

Since the advent of spinal cord stimulation (SCS), its operative technique has consistently advanced. We performed a scoping review of the literature regarding SCS operative techniques to highlight key advancements. To review, summarize, and highlight key changes in SCS implantation techniques since their inception. The authors performed a MEDLINE search inclusive of articles from 1967 to June 2023 including human and modeling studies written in English examining the role of trialing, intraoperative neuromonitoring, and surgical adaptations. Using the Rayyan platform, two reviewers performed a blinded title screen. Of the 960 articles, 197 were included in the title screen, 107 were included in the abstract review, and ultimately 69 articles met inclusion criteria. We examined the utility of trialing and found that historical controls showed significant efficacy, whereas recent results are more equivocal. We discuss the significant improvement in outcomes with intraoperative neuromonitoring for asleep SCS placement. We highlight technique improvements that led to significant reductions in infection, lead migration, and inadequate pain relief. Physicians implanting SCS systems for chronic pain management must continually refine their surgical techniques to keep up with this rapidly evolving therapy. In addition, through collaborative efforts of neuromodulators and industry, SCS is safer and more effective for patients suffering from chronic pain.

Incidence and Prevalence of Pain Medication Prescriptions in Pathologies with a Potential for Chronic Pain

BACKGROUND

Heightened risks of dependence, addiction, anxiolytic effects, or prescription overdose death due to long-term use of pain medication have increased awareness about extended pain medication use in chronic pain populations. The goal of this study was to evaluate the incidence and prevalence of pain medication prescriptions from 2012 to 2022 in common pathologies with a potential for chronic pain.

METHODS

A retrospective cohort study was conducted using electronic health records from TriNetX (Cambridge, Massachusetts) Global Collaborative Network. For 10 distinct cohorts (total n = 9,357,584 patients), pain medication prescriptions were extracted for five classes, namely nonsteroidal anti-inflammatory drug (NSAIDs) and acetaminophen, opioids, gabapentinoids, neuropathic mood agents, and muscle relaxants. Annual incidence and prevalence of each class of medication were evaluated for the past 11 yr.

RESULTS

From 2012 to 2022, there was a significant increase in prescriptions of NSAIDs, except for patients with fibromyalgia, and persistent spinal pain syndrome (PSPS) type 2. Interestingly, over time, prescriptions of opioids in patients with complex regional pain syndrome, endometriosis, osteoarthritis, and PSPS type 2 increased, as did prescriptions of muscle relaxants for all cohorts except those with fibromyalgia. Incidence of prescriptions of neuropathic mood agents is high for patients with complex regional pain syndrome (both types) and PSPS type 2. Only for benzodiazepines did there seem to be a decline over the years, with a significantly decreased time trend in patients with complex regional pain syndrome type 1, fibromyalgia, and PSPS type 2.

CONCLUSIONS

During the last 11 yr, an increase in incidence of NSAIDs and acetaminophen, opioids, neuropathic agents, and muscle relaxants was observed. Only prescriptions of benzodiazepines significantly decreased over time in specific cohorts. Overall, patients with PSPS type 2 and complex regional pain syndrome (both types) consume a broad variety of pain medication classes.

EDITOR’S PERSPECTIVE

Sacral Tarlov perineurial cysts: a systematic review of treatment options

Tarlov perineurial spinal cysts (TCs) are an underrecognized cause of spinal neuropathic symptoms. TCs form within the sensory nerve root sleeves, where CSF extends distally and can accumulate pathologically. Typically, they develop at the sacral dermatomes where the nerve roots are under the highest hydrostatic pressure and lack enclosing vertebral foramina. In total, 90% of patients are women, and genetic disorders that weaken connective tissues, e.g., Ehlers-Danlos syndrome, convey considerable risk. Most small TCs are asymptomatic and do not require treatment, but even incidental visualizations should be documented in case symptoms develop later. Symptomatic TCs most commonly cause sacropelvic dermatomal neuropathic pain, as well as bladder, bowel, and sexual dysfunction. Large cysts routinely cause muscle atrophy and weakness by compressing the ventral motor roots, and multiple cysts or multiroot compression by one large cyst can cause even greater cauda equina syndromes. Rarely, giant cysts erode the sacrum or extend as intrapelvic masses. Disabling TCs require consideration for surgical intervention. The authors' systematic review of treatment analyzed 31 case series of interventional percutaneous procedures and open surgical procedures. The surgical series were smaller and reported somewhat better outcomes with longer term follow-up but slightly higher risks. When data were lacking, authorial expertise and case reports informed details of the specific interventional and surgical techniques, as well as medical, physical, and psychological management. Cyst-wrapping surgery appeared to offer the best long-term outcomes by permanently reducing cyst size and reconstructing the nerve root sleeves. This curtails ongoing injury to the axons and neuronal death, and may also promote axonal regeneration to improve somatic and autonomic sacral nerve function.

Experience with a hybrid recruitment approach of patient-facing web portal screening and subsequent phone and medical record review for a neurosurgical intervention trial for chronic ischemic stroke disability (PISCES III)

BACKGROUND

Recruitment of participants is the greatest risk to completion of most clinical trials, with 20-40% of trials failing to reach the targeted enrollment. This is particularly true of trials of central nervous system (CNS) therapies such as intervention for chronic stroke. The PISCES III trial was an invasive trial of stereotactically guided intracerebral injection of CTX0E03, a fetal derived neural stem cell line, in patients with chronic disability due to ischemic stroke. We report on the experience using a novel hybrid recruitment approach of a patient-facing portal to self-identify and perform an initial screen for general trial eligibility (tier 1), followed by phone screening and medical records review (tier 2) prior to a final in-person visit to confirm eligibility and consent.

METHODS

Two tiers of screening were established: an initial screen of general eligibility using a patient-facing web portal (tier 1), followed by a more detailed screen that included phone survey and medical record review (tier 2). If potential participants passed the tier 2 screen, they were referred directly to visit 1 at a study site, where final in-person screening and consent were performed. Rates of screening were tracked during the period of trial recruitment and sources of referrals were noted.

RESULTS

The approach to screening and recruitment resulted in 6125 tier 1 screens, leading to 1121 referrals to tier 2. The tier 2 screening resulted in 224 medical record requests and identification of 86 qualifying participants for referral to sites. The study attained a viable recruitment rate of 6 enrolled per month prior to being disrupted by COVID 19.

CONCLUSIONS

A tiered approach to eligibility screening using a hybrid of web-based portals to self-identify and screen for general eligibility followed by a more detailed phone and medical record review allowed the study to use fewer sites and reduce cost. Despite the difficult and narrow population of patients suffering moderate chronic disability from stroke, this strategy produced a viable recruitment rate for this invasive study of intracranially injected neural stem cells.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03629275.

Improved Selectivity in Eliciting Evoked Electromyography Responses With High-Resolution Spinal Cord Stimulation

BACKGROUND AND OBJECTIVES

As spinal cord stimulation (SCS) offers a therapy for increasing numbers of patients with chronic pain and spinal cord injury, it becomes increasingly important to better understand its somatotopy. In this prospective study, we investigate whether high-resolution SCS (HR-SCS) offers improved selectivity assessed through elicitation of evoked electromyography (EMG) responses as compared with commercial paddle leads.

METHODS

Vertical tripole configurations were used to elicit EMG responses in both types of paddles placed for standard-of-care indications between T6 and T10. In HR-SCS, evoked EMG responses in lower extremity/abdominal muscle groups were monitored at 6 to 8 mediolateral sites. All commercial paddle columns were tested. Percentage change in the maximum root mean square value was calculated at a group level. Heat maps were generated to identify responders for each muscle group. Responders were considered patients who had a >50% change in root mean square over baseline.

RESULTS

We demonstrated significantly greater motor responses across medial and lateral contacts and greater responder rates consistently at the T6 and T9 levels with HR-SCS as compared with commercial paddles in 18 patients. Distal muscle groups (gastrocnemius and tibialis anterior) and proximal muscle groups (biceps femoris and quadriceps) were selectively activated at both levels.

CONCLUSION

We demonstrate that HR-SCS has greater selectivity in eliciting evoked EMG responses in an intraoperative setting. HR-SCS offers recruitment of muscle groups at lateral contacts concurrently with medial contacts. We provide data that HR-SCS may provide higher spatial resolution, which has the potential to allow for personalization of care and treatment of pain syndromes/symptoms which to date have not been effectively treated.

Evolution of Deep Brain Stimulation Techniques for Complication Mitigation

Complication mitigation in deep brain stimulation has been a topic matter of much discussion in the literature. In this article, we examine how neurosurgeons as individuals and as a field generated and adapted techniques to prevent infection, lead fracture/lead migration, and suboptimal outcomes in both the acute period and longitudinally. The authors performed a MEDLINE search inclusive of articles from 1987 to June 2023 including human studies written in English. Using the Rayyan platform, two reviewers (J.P. and R.M.) performed a title screen. Of the 776 articles, 252 were selected by title screen and 172 from abstract review for full-text evaluation. Ultimately, 124 publications were evaluated. We describe the initial complications and inefficiencies at the advent of deep brain stimulation and detail changes instituted by surgeons that reduced them. Furthermore, we discuss the trend in both undesired short-term and long-term outcomes with emphasis on how surgeons recognized and modified their practice to provide safer and better procedures. This scoping review adds to the literature as a guide to both new neurosurgeons and seasoned neurosurgeons alike to understand better what innovations have been trialed over time as we embark on novel targets and neuromodulatory technologies.

The level of agreement between the numerical rating scale and visual analogue scale for assessing pain intensity in adults with chronic pain

The numerical rating scale and visual analogue scale are used to quantify pain intensity. However, it has not yet been explored whether these scores are interchangeable in adults with chronic pain. Data from the prospective multicentre cross-sectional INTERVAL study were used to evaluate the one-dimensionality and agreement between numerical rating scale scores and visual analogue scale scores in adults with chronic pain. Pain intensity scores using the numerical rating scale and visual analogue scale were provided by 366 patients with chronic pain for current, average, minimal and maximal pain. To evaluate whether pain intensity scales are completed in accordance with each other, the proportion of patients who satisfied the following condition was calculated: minimal pain intensity ≤ maximal pain intensity. A factor analysis confirmed the one-dimensionality of the pain measures. A significant difference was found between numerical rating scale and visual analogue scale scores for average, current, minimum and maximum pain. Intra-class correlation coefficient estimates ranged from 0.739 to 0.858 and all measures failed to show sufficient and acceptable agreement at the 95% level. The strength of agreement between pain severity categories was classified as 'moderate' for average and minimal pain and 'substantial' for current and maximal pain. The proportion of patients who scored minimal pain ≤ maximal pain was 97.5% for the numerical rating scale and 89.5% for the visual analogue scale. This study failed to show an acceptable agreement between the numerical rating scale and visual analogue scale when pain intensity was rated by adults with chronic pain, despite showing both scales measure the same information.

Gut dysbiosis in patients with chronic pain: a systematic review and meta-analysis

Introduction

Recent evidence supports the contribution of gut microbiota dysbiosis to the pathophysiology of rheumatic diseases, neuropathic pain, and neurodegenerative disorders. The bidirectional gut-brain communication network and the occurrence of chronic pain both involve contributions of the autonomic nervous system and the hypothalamic pituitary adrenal axis. Nevertheless, the current understanding of the association between gut microbiota and chronic pain is still not clear. Therefore, the aim of this study is to systematically evaluate the existing knowledge about gut microbiota alterations in chronic pain conditions.

Methods

Four databases were consulted for this systematic literature review: PubMed, Web of Science, Scopus, and Embase. The Newcastle-Ottawa Scale was used to assess the risk of bias. The study protocol was prospectively registered at the International prospective register of systematic reviews (PROSPERO, CRD42023430115). Alpha-diversity, β-diversity, and relative abundance at different taxonomic levels were summarized qualitatively, and quantitatively if possible.

Results

The initial database search identified a total of 3544 unique studies, of which 21 studies were eventually included in the systematic review and 11 in the meta-analysis. Decreases in alpha-diversity were revealed in chronic pain patients compared to controls for several metrics: observed species (SMD= -0.201, 95% CI from -0.04 to -0.36, p=0.01), Shannon index (SMD= -0.27, 95% CI from -0.11 to -0.43, p<0.001), and faith phylogenetic diversity (SMD -0.35, 95% CI from -0.08 to -0.61, p=0.01). Inconsistent results were revealed for beta-diversity. A decrease in the relative abundance of the Lachnospiraceae family, genus Faecalibacterium and Roseburia, and species of Faecalibacterium prausnitzii and Odoribacter splanchnicus, as well as an increase in Eggerthella spp., was revealed in chronic pain patients compared to controls.

Discussion

Indications for gut microbiota dysbiosis were revealed in chronic pain patients, with non-specific disease alterations of microbes.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023430115.

Predictors of Skip Laminotomy for Placement of Paddle Leads for Spinal Cord Stimulation

OBJECTIVES

Placement of a standard paddle lead for spinal cord stimulation (SCS) requires a laminotomy for positioning of the lead within the epidural space. During initial placement, an additional laminotomy or laminectomy, termed a "skip" laminotomy, may be necessary at a higher level to pass the lead to the appropriate midline position. Patient and radiographic factors that predict the need for a skip laminotomy have yet to be identified.

MATERIALS AND METHODS

Participants who underwent SCS paddle placement at Albany Medical Center between 2016 and 2017 were identified. Operative reports were reviewed to identify the paddle type, level of initial laminotomy, target level, and skip laminotomy level. Preoperative thoracic magnetic resonance images (MRIs) were reviewed, and spinal canal diameter, interpedicular distance, and dorsal cerebral spinal fluid thickness were measured for each participant when available.

RESULTS

A total of 106 participants underwent thoracic SCS placement. Of these, 97 had thoracic MRIs available for review. Thirty-eight participants required a skip laminotomy for placement of the paddle compared with 68 participants who did not. There was no significant difference in demographic features including age, sex, body mass index, and surgical history. Univariate analyses that suggested trends were selected for further analysis using binary logistic regression. Level of initial laminotomy (odds ratio [OR] = 1.51, p = 0.028), spinal canal diameter (OR = 0.71, p = 0.015), and dorsal cerebrospinal fluid thickness (OR = 0.61, p = 0.011) were correlated with skip laminotomy. Target level (OR = 1.27, p = 0.138) and time from trial (1.01, p = 0.117) suggested potential association. The multivariate regression was statistically significant, X2(10) = 28.02, p = 0.002. The model explained 38.3% of the variance (Nagelkerke R2) and predicted skip laminectomy correctly in 73.3% of cases. However, for the multivariate regression, only a decrease in spinal canal diameter (OR = 0.59, p = 0.041) was associated with a greater odds of skip laminotomy.

CONCLUSIONS

This study aims to characterize the patient and radiographic factors that may predict the need to perform a skip laminotomy during the initial placement of SCS paddles. Here, we show that radiographic and anatomic variables, primarily spinal canal diameter, play an important role in predicting the need for a skip laminotomy. Furthermore, we suggest that target level for placement and level of initial laminotomy also may contribute. Further investigation of the predictive factors for performing a skip laminotomy would help optimize surgical planning and preoperative patient selection and counseling.

Perceptions of pain in aging females undergoing spinal cord stimulation

Aim: Effects of age and sex on chronic pain outcomes following spinal cord stimulation (SCS) have not yet been assessed. Methods: We retrospectively reviewed 1 year outcomes from a database of patients receiving thoracic SCS. Subjects were divided into four cohorts: pre-menopausal and post-menopausal females, and aged-matched males. Improvement using the numerical rating scale, Oswestry Disability Index (ODI), Beck's Depression Inventory (BDI), McGill Pain Questionnaire and Pain Catastrophizing Scale (PCS) was assessed. Results: Older females were notably different from males and females under 60 as they had greater improvements in ODI, BDI and PCS. Further, females ≥60 had greater improvement in PCS compared with males ≥60. Conclusion: Our findings suggest greater improvement with 1 year SCS treatment in post-menopausal females, compared with age-matched males.

An assessment of the long-term impacts of the coronavirus disease 2019 pandemic on academic neurosurgery

OBJECTIVE

The goal of this study was to survey residents, fellows, and residency program leadership to assess the long-term impacts of the coronavirus disease 2019 (COVID-19) on residency training by using a structured survey methodology.

METHODS

A survey was distributed to US neurosurgical residents and fellows (n = 2085) as well as program directors (PDs) and chairs (n = 216) in early 2022. Bivariate analysis was performed to identify factors associated with a decreased likelihood of pursuing a career in academic neurosurgery because of the pandemic, a perception that surgical skills preparation was negatively impacted, personal financial concerns, and a preference for remote education. Significant differences in the bivariate analysis underwent further multivariate logistic regression analysis to evaluate for predictors of these outcomes.

RESULTS

An analysis of complete surveys from 264 residents and fellows (12.7%) and 38 PDs and chairs (17.6%) was performed. Over half of the residents and fellows (50.8%) believed that their surgical skills preparation was negatively impacted by the pandemic, and a notable proportion believed that they were less likely to go into academics because of the pandemic's impact on their professional (20.8%) and personal (28.8%) life. Those less likely to pursue academics were more likely to report that work-life balance did not improve (p = 0.049), personal financial concerns increased (p = 0.01), and comradery among residents (p = 0.002) and with faculty (p = 0.001) did not improve. Residents who indicated they were less likely to go into academics were also more likely to have been redeployed (p = 0.038). A large majority of PDs and chairs indicated that the pandemic resulted in financial setbacks for their departments (71.1%) and institutions (84.2%), with 52.6% reporting reduced faculty compensation. Financial setbacks at the institutional level were associated with a worsened opinion of hospital leadership (p = 0.019) and reports of a reduced quality of care for non-COVID-19 patients (p = 0.005) but not from faculty member losses (p = 0.515). A plurality of trainees (45.5%) reported a preference for a remote format for educational conferences compared to 37.1% who disagreed.

CONCLUSIONS

This study provides a cross-section of the pandemic's impact on academic neurosurgery, highlighting the importance of continued efforts to assess and address the long-term consequences of the COVID-19 pandemic for US academic neurosurgery.

Incidence of Infections, Explantations, and Displacements/Mechanical Complications of Spinal Cord Stimulation During the Past Eight Years

OBJECTIVES

The overall awareness and potential of real-world data have drastically increased in the medical field, with potential implications for postmarket medical device surveillance. The goal of this study was to evaluate real-world data on incidence of infections, explantations, and displacements/mechanical complications of spinal cord stimulation (SCS) during the past eight years and to forecast point estimates for the upcoming three years on the basis of the identified patterns.

MATERIALS AND METHODS

Based on electronic health records from 80 healthcare organizations within the TriNetX data base in the USA, data of 11,934 patients who received SCS as treatment for persistent spinal pain syndrome type 2 (PSPS T2) were extracted. Events of interest were explantations and displacements/mechanical complications of both the lead and implanted pulse generator (IPG), in addition to infection rates from 2015 to 2022. Mann-Kendall tests were performed to detect monotonic trends in the time series. Forecasts were conducted for the upcoming three years for every event of interest.

RESULTS

Statistically significant increasing time trends were revealed for the annual incidence of IPG and lead displacements/mechanical complications in patients with PSPS T2 over the past eight years. These time trends were visible in both male and female patients and in smokers and nonsmokers. For annual incidence of explantations and infections, no significant time effect was observed. In 2025, the incidence of displacements/mechanical complications of the lead (3.07%) is predicted to be the highest, followed by explantations of the IPG (2.67%) and lead (2.02%).

CONCLUSIONS

Based on real world data, device explantation was the most frequent event of interest, with negative peaks in the time series in 2016 and 2020, presumably due to the introduction of rechargeable pulse generators and to the COVID-19 pandemic, respectively.

MR thermometry imaging for low intensity focused ultrasound modulation of spinal nervous tissue

OBJECTIVES

Previously in rodent and swine models, we have shown that external low intensity focused ultrasound (liFUS) can be used to modulate pain responses. To ensure no adverse heating events occur with liFUS modulation in a non-invasive manner, we perform initial work in swine to show that magnetic resonance thermometry imaging (MRTI) is capable of measuring <2.0 °C changes at the L5 DRG. Further, we show that our device can be constructed in an MR-compatible fashion to minimize artifact.

METHODS

Three MRTI techniques (referenceless, corrected proton resonance frequency shift (PRFS), and PRFS) were applied to assess accuracy of detecting thermal changes at the L5 DRG in unheated euthanized swine. A region of interest (ROI) that includes the L5 DRG was delineated, within which MRTI temperature changes were spatially averaged (ground truth 0 °C). In separate experiments with phantoms, B0 field-inhomogeneity, RF transmit (B1+) and fast gradient echo (fSPGR) magnitude images were acquired to downselect liFUS device materials that produce the least MRI artifacts.

RESULTS

Referenceless, corrected PRFS, and PRFS MRTI resulted in temperature measurements of 0.8 ± 1.1 °C, 1.1 ± 1.3 °C and 5.2 ± 5 °C, respectively. Both materials caused B0 perturbation but minimal B1+ and MRTI artifacts. The presence of imaging artifacts did not preclude thermal imaging of the region.

SIGNIFICANCE

We provide preliminary data suggesting that referenceless MRTI can adequately detect small thermal changes at the DRG that may occur with neuromodulation, which is one of the first steps in creating a table of safe parameters for liFUS therapy in humans.

Investigation of the intraoperative cortical responses to spinal motor mapping in a patient with chronic pain

Intraoperative neurophysiological monitoring (IONM) in spinal cord stimulation (SCS) surgery for chronic pain is shown to provide effective guidance during device placement. Electromyography (EMG) is used to determine the laterality of the paddle. In some SCS cases, laterality cannot be obtained via EMG due to patient physiology. Electroencephalography (EEG) is already used in IONM to monitor cortical responses. Here, we show proof-of-concept of assessing the responses of epidurally evoked EMGs simultaneously with EEGs to determine laterality during IONM using a high-resolution (HR) SCS paddle. An 8-column HR-SCS paddle was acutely placed at T9-T10 interspace in patients with failed back surgery syndrome. EMG signals from 18 muscle groups were recorded simultaneously with 60-channel EEG signals at various stimulation amplitudes (0-10 mA). Particular attention was paid to regions associated with pain including the somatosensory cortex (S1), prefrontal cortex (PFC), and motor cortex (M1). When left and right lateral contacts were stimulated at low amplitudes (1-2 mA), significant changes were seen in θ, α, and β powers in the contralateral PFC but not in M1 or S1. There was a significant correlation between M1 and contralateral contacts in α power. At higher currents (7-8 mA), right-sided contacts resulted in α power change. We found significant differences in α, θ, and β powers in PFC for contralateral stimulation of the lateral SCS contacts at low amplitudes and in α power at higher amplitudes. The changes in PFC suggest the potential of EEG for understanding a cortical mechanism of action of SCS and provide insight into the pathophysiology of chronic pain.NEW & NOTEWORTHY Here, we present proof of concept of assessing the responses of epidurally evoked electromyography simultaneously with scalp electroencephalography to determine whether both laterality and insights into pain mechanisms can be elucidated. With stimulation, significant changes were seen in θ, α, and β band power in the contralateral prefrontal cortex and in α power in the motor cortex. We provide insight into the mechanism of action of SCS in preventing pain in this patient.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Occipital Nerve Stimulation for the Treatment of Patients With Medically Refractory Occipital Neuralgia: Update

BACKGROUND

The Guidelines Task Force conducted a systematic review of the relevant literature on occipital nerve stimulation (ONS) for occipital neuralgia (ON) to update the original 2015 guidelines to ensure timeliness and accuracy for clinical practice.

OBJECTIVE

To conduct a systematic review of the literature and update the evidence-based guidelines on ONS for ON.

METHODS

The Guidelines Task Force conducted another systematic review of the relevant literature, using the same search terms and strategies used to search PubMed and Embase for relevant literature. The updated search included studies published between 1966 and January 2023. The same inclusion/exclusion criteria as the original guideline were also applied. Abstracts were reviewed, and relevant full text articles were retrieved and graded. Of 307 articles, 18 were retrieved for full-text review and analysis. Recommendations were updated according to new evidence yielded by this update .

RESULTS

Nine studies were included in the original guideline, reporting the use of ONS as an effective treatment option for patients with medically refractory ON. An additional 6 studies were included in this update. All studies in the original guideline and this current update provide Class III evidence.

CONCLUSION

Based on the availability of new literature, the current article is a minor update only that does not result in modification of the prior recommendations: Clinicians may use ONS as a treatment option for patients with medically refractory ON.

Machine Learning in Spinal Cord Stimulation for Chronic Pain

Spinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. The success of SCS is dependent on candidate selection, response to trialing, and programming optimization. Owing to the subjective nature of these variables, machine learning (ML) offers a powerful tool to augment these processes. Here we explore what work has been done using data analytics and applications of ML in SCS. In addition, we discuss aspects of SCS which have narrowly been influenced by ML and propose the need for further exploration. ML has demonstrated a potential to complement SCS to an extent ranging from assistance with candidate selection to replacing invasive and costly aspects of the surgery. The clinical application of ML in SCS shows promise for improving patient outcomes, reducing costs of treatment, limiting invasiveness, and resulting in a better quality of life for the patient.

Assessing the Location, Relative Expression and Subclass of Dopamine Receptors in the Cerebellum of Hemi-Parkinsonian Rats

Parkinson's Disease (PD) is a neurodegenerative disease with loss of dopaminergic neurons in the nigrostriatal pathway resulting in basal ganglia (BG) dysfunction. This is largely why much of the preclinical and clinical research has focused on pathophysiological changes in these brain areas in PD. The cerebellum is another motor area of the brain. Yet, if and how this brain area responds to PD therapy and contributes to maintaining motor function fidelity in the face of diminished BG function remains largely unanswered. Limited research suggests that dopaminergic signaling exists in the cerebellum with functional dopamine receptors, tyrosine hydroxylase (TH) and dopamine transporters (DATs); however, much of this information is largely derived from healthy animals and humans. Here, we identified the location and relative expression of dopamine 1 receptors (D1R) and dopamine 2 receptors (D2R) in the cerebellum of a hemi-parkinsonian male rat model of PD. D1R expression was higher in PD animals compared to sham animals in both hemispheres in the purkinje cell layer (PCL) and granule cell layer (GCL) of the cerebellar cortex. Interestingly, D2R expression was higher in PD animals than sham animals mostly in the posterior lobe of the PCL, but no discernible pattern of D2R expression was seen in the GCL between PD and sham animals. To our knowledge, we are the first to report these findings, which may lay the foundation for further interrogation of the role of the cerebellum in PD therapy and/or pathophysiology.

Role of Integrative Health on Neuropathic Pain

PURPOSE OF REVIEW

Patients diagnosed with neuropathic pain experience continuous or intermittent spontaneous pain throughout their lives. Pharmacological treatments often provide limited relief; therefore, a multidisciplinary approach should be utilized to manage neuropathic pain. This review examines the current literature on integrative health modalities (anti-inflammatory diets, functional movement, acupuncture, meditation, and transcutaneous therapy) for treating patients with neuropathic pain.

RECENT FINDINGS

The use of an anti-inflammatory diet, functional movement, acupuncture, meditation, and transcutaneous therapy in treating neuropathic pain has been investigated in prior literature with positive outcomes. However, there remains a large void in evidence-based knowledge and clinical applicability for these interventions. Overall, integrative health offers a cost-efficient and harmless way of creating a multidisciplinary approach to managing neuropathic pain. There are many complementary approaches to treating neuropathic pain as part of an integrative medicine approach. Research is needed to explore other herbs and spices not yet reported in the peer-review literature. Additionally, follow-on research is needed to understand the clinical applicability of the proposed interventions as well as the dose and timing of the interventions to predict response and duration.

The Use of Salvage Procedures for Wound Complications in Neuromodulation

OBJECTIVE

Wound complications are a prevalent concern for neuromodulation procedures. While removal of the device was recommended, attempts to salvage expensive hardware have become commonplace. We examine our management in wound issues to aid in providing guidance for these situations.

METHODS

We identified 40 patients over an 8-year period in a large neuromodulation practice, who underwent washout or partial salvage of hardware. We examined the efficacy of washout and partial explants on the ability to salvage the implants. Covariates including age, sex, body mass index, smoking status, anticoagulation, and device type were considered.

RESULTS

There were 29 washouts and 10 partial hardware removal cases. Washouts were successful in 15/29 cases (51.7%), partial hardware removal was successful in 2/10 cases (20%), and removal with replacement was not successful (0 of 1). Washouts tended to be more successful than partial removal procedures (P = 0.08). In cases of successful washout, the average duration between infectious symptoms and washout was 7.27 ± 2.19 days. None of the demographic variables were associated with increased likelihood of washout failure.

CONCLUSIONS

Our results demonstrate a higher rate of washout failure in those who underwent partial device removal and in the presence of purulence at the surgical site. Further investigation must be conducted to determine the instances in which hardware removal is indicated to prevent failure or removal due to infection. Identification of these parameters will optimize therapeutic benefit and long-term financial impact.

Long-term safety of spinal cord stimulation systems in a prospective, global registry of patients with chronic pain

Aim: The availability of long-term (>2 years) safety outcomes of spinal cord stimulation (SCS) remains limited. We evaluated safety in a global SCS registry for chronic pain. Methods: Participants were prospectively enrolled globally at 79 implanting centers and followed out to 3 years after device implantation. Results: Of 1881 participants enrolled, 1289 received a permanent SCS implant (1776 completed trial). The annualized rate of device explant was 3.5% (all causes), and 1.1% due to inadequate pain relief. Total incidence of device explantation >3 years was 7.6% (n = 98). Of these, 32 subjects (2.5%) indicated inadequate pain relief as cause for removal. Implant site infection (11 events) was the most common device-related serious adverse event (<1%). Conclusion: This prospective, global, real-world study demonstrates a high-level of safety for SCS with low rate of explant/serious adverse events. Clinical Trial Registration: NCT01719055 (ClinicalTrials.gov).

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation

BACKGROUND

Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity.

AIM

The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response".

DISCUSSION

Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

Clinical Longevity of 106,462 Rechargeable and Primary Cell Spinal Cord Stimulators: Real World Study in the Medicare Population

INTRODUCTION

Spinal cord stimulators (SCS) are available with either primary cell (PC) or rechargeable cell (RC) batteries. Although RC systems are proposed to have a battery longevity upward of nine years, in comparison with four years for PC systems, there are few studies of longevity of SCS in the real world.

MATERIALS AND METHODS

This was an observational, nonrandomized, retrospective study of Medicare beneficiaries who received neurostimulator implants in the outpatient hospital. This study used Medicare fee-for-service claims data from 2013 to 2020. The clinical longevity of the implantable pulse generator (IPG), defined as the duration from implant until removal for any reason, was compared between PC and RC devices. Life distribution analysis was used to approximate device lifespan. The secondary analysis separated removals into explant or replacements. The statistics were adjusted for relevant clinical covariates.

RESULTS

A total of 25,856 PC and 79,606 RC systems were included in the study. At seven years after implant, 53.8% of PC IPGs and 55.0% of RC IPGs remained in use. The life distribution modeling analysis projected a median lifespan of 8.2 years for PC and 9.0 years for RC devices. The rate of explant was lower for PC devices (19.2%) than for RC devices (22.0%, hazard ratio (HR) = 0.96, p = 0.082), whereas the rate of replacements was higher for PC devices (33.7%) than for RC devices (29.5%, HR = 1.31, p < 0.001). An analysis of the battery type used in device replacements showed an increasing adoption of PC devices over time.

CONCLUSIONS

This large, retrospective, real-world analysis of Medicare claims data demonstrated that the clinical longevity of neurostimulator devices is similar for PC and RC batteries. In the past, clinicians may have defaulted to RC devices based on the assumption that they provided extended battery life. Considering this longevity data, clinicians should now consider the choice between PC and RC devices based on other individual factors pertinent to the patient experience and not on purported longevity claims.

Establishing Minimal Clinically Important Difference in Sleep Outcomes after Spinal Cord Stimulation in Patients with Chronic Pain Disorders

INTRODUCTION

As one of the most common medical conditions for which patients seek medical care, chronic pain can be debilitating. The relationship between chronic pain and sleep is thought to be bidirectional, suggesting that treatment of one can be beneficial to the other. There is mounting evidence that spinal cord stimulation (SCS) improves aspects of sleep. How meaningful that is to patients' lives has not been ascertained.

OBJECTIVE

The aim of the current study was to further elucidate the effect of SCS on sleep by examining the relationship between pain outcome measures with the insomnia severity index (ISI) and to establish the minimally clinical important difference (MCID), which is defined as the smallest noticeable change that an individual perceives as clinically significant.

MATERIALS AND METHODS

We prospectively collected ISI, Epworth sleepiness scale (ESS), Numerical Rating Scale, McGill Pain Questionnaire-Short Form, Oswestry Disability Index, Beck Depression Inventory, and Pain Catastrophizing Scale data both pre- and postoperatively for chronic pain patients who underwent SCS placement and had long-term outcomes. The ISI is a well-studied questionnaire used to assess an individual's level of insomnia.

RESULTS

We correlated the ESS and ISI with pain outcome measures in sixty-four patients at a mean follow-up of 9.8 ± 2.9 months. The ISI showed correlations with disability as measured through the Oswestry Disability Index (p = 0.014) and depression as measured through the Beck Depression Inventory (p = 0.024). MCID values for the ISI were calculated using both anchor- and distribution-based methods. The minimal detectable change method resulted in an MCID of 2.4 points, standard error of measurement resulted in an MCID of 2.6 points, and the change difference resulted in an MCID of 2.45. The receiver operating characteristic method yielded an MCID of 0.5-point change with an area under the curve of 0.61.

CONCLUSION

This study successfully established MCID ranges for the ISI outcome measure to help gauge improvement in insomnia after SCS. The ISI has ample evidence of its validity in assessment of insomnia, and MCID values of 2.4-2.6 correlate with improvement in disability and depression in our patients.

Artifacts Can Be Deceiving: The Actual Location of Deep Brain Stimulation Electrodes Differs from the Artifact Seen on Magnetic Resonance Images

INTRODUCTION

Deep brain stimulation (DBS) is a common treatment for a variety of neurological and psychiatric disorders. Recent studies have highlighted the role of neuroimaging in localizing the position of electrode contacts relative to target brain areas in order to optimize DBS programming. Among different imaging methods, postoperative magnetic resonance imaging (MRI) has been widely used for DBS electrode localization; however, the geometrical distortion induced by the lead limits its accuracy. In this work, we investigated to what degree the difference between the actual location of the lead's tip and the location of the tip estimated from the MRI artifact varies depending on the MRI sequence parameters such as acquisition plane and phase encoding direction, as well as the lead's extracranial configuration. Accordingly, an imaging technique to increase the accuracy of lead localization was devised and discussed.

METHODS

We designed and constructed an anthropomorphic phantom with an implanted DBS system following 18 clinically relevant configurations. The phantom was scanned at a Siemens 1.5 Tesla Aera scanner using a T1MPRAGE sequence optimized for clinical use and a T1TSE sequence optimized for research purposes. We varied slice acquisition plane and phase encoding direction and calculated the distance between the caudal tip of the DBS lead MRI artifact and the actual tip of the lead, as estimated from MRI reference markers.

RESULTS

Imaging parameters and lead configuration substantially altered the difference in the depth of the lead within its MRI artifact on the scale of several millimeters - with a difference as large as 4.99 mm. The actual tip of the DBS lead was found to be consistently more rostral than the tip estimated from the MR image artifact. The smallest difference between the tip of the DBS lead and the tip of the MRI artifact using the clinically relevant sequence (i.e., T1MPRAGE) was found with the sagittal acquisition plane and anterior-posterior phase encoding direction.

DISCUSSION/CONCLUSION

The actual tip of an implanted DBS lead is located up to several millimeters rostral to the tip of the lead's artifact on postoperative MR images. This distance depends on the MRI sequence parameters and the DBS system's extracranial trajectory. MRI parameters may be altered to improve this localization.

A Pilot Study Comparing Algorithmic Adaptive Conventional Stimulation with High-Dose Stimulation in Chronic Pain Patients

INTRODUCTION

Spinal cord stimulation is an effective method of treatment for chronic pain. We previously showed that programming using accelerometry was advantageous for paresthesia-based stimulation. However, programming can be labor intensive.

OBJECTIVE

Here we focus on standardized programming for both accelerometer-based paresthesia-induced programming (termed "shuffle") and high-dose (HD) subthreshold programming with stimulation delivered over the T9-10 interspace.

METHODS

In this prospective cross-over study, patients received 4 weeks of shuffle programming and 4 weeks of HD programming in a randomized order. In both intervals, contacts overlying T9-10 were programmed. Pain scales with measurements of activity and sleep were collected at the end of each study arm and compared with preoperative baseline scores.

RESULTS

Twelve patients were enrolled, with 10 patients completing this study. Compared with baseline, during the HD study period, significant improvements were seen in worst pain of week (P = 0.03) and current pain (P = 0.04) as rated on Numeric Rating Scale scores and walking on the Activity Test (P = 0.012). No difference was seen from baseline compared with shuffle stimulation or in shuffle stimulation compared with HD stimulation.

CONCLUSION

In this pilot study, we demonstrated that HD stimulation at T9-10 is superior to algorithmic programming of paresthesia-based stimulation. These results compared with our previous work with shuffle suggest that paresthesia-based stimulation may necessitate stimulation of additional contact locations and additional programming to optimize. This algorithmic programming of paresthesia-based stimulation continues to warrant exploration.

Speaker Gender Representation at the North American Neuromodulation Society Annual Meeting (2017-2021): Have We Made Progress in Closing the Gender Gap?

Background

Speaker gender representation at medical conferences is a significant site of gender disparity. Our primary objective was to quantify the proportion of female speakers and compare plenary session opportunities by gender at the North American Neuromodulation Society (NANS) Annual Conference.

Methods

Data from the 2017-2021 NANS Annual Conference presentations were abstracted. Primary outcomes included gender composition of speaker slots, gender composition of individual speakers, and comparison of plenary speaker slots by gender. Secondary outcomes included comparisons of session size, age, professional degree, and number of presentations per speaker based on gender.

Results

Gender composition of annual speaker slots was (% slots presented by women): 2017:14.6%; 2018:20.5%; 2019:23.5%; 2020:21.0%; 2021:41.4%. Annual gender composition of individual speakers was (% women): 2017:18.7%; 2018:20.6%; 2019:24.6%; 2020:24.9%; 2021:33.8%. Of all speaker slots, the percentage of plenary slots did not differ based on gender, with 11.4% presented by female speakers versus 11.2% presented by male speakers (OR 1.0, 95% CI 0.7-1.5, P=0.893). Compared to male speaker slots, there was an association of lower age (43.9±5.6 vs 50.8±8.9, P<0.001), lower odds of holding a single doctorate degree (OR 0.3, 95% CI 0.2-0.5, P<0.001), and lower odds of holding a dual MD/PhD or DO/PhD degree (OR 0.3, 95% CI 0.1-0.5, P<0.001) in female speaker slots. Compared to male speakers, there was an association of higher number of presentations per female speaker at the 2021 NANS Annual Meeting (2.48±1.60 vs 1.79±1.30, P=0.008).

Conclusion

Although the volume of female speaker slots and individual speakers trailed behind their male counterparts, female speaker representation steadily increased at each subsequent annual NANS meeting. We identified no difference in plenary session slots based on gender.

The effects of low intensity focused ultrasound on neuronal activity in pain processing regions in a rodent model of common peroneal nerve injury

BACKGROUND

Non-invasive, external low intensity focused ultrasound (liFUS) offers promise for treating neuropathic pain when applied to the dorsal root ganglion (DRG).

OBJECTIVE

We examine how external liFUS treatment applied to the L5 DRG affects neuronal changes in single-unit activity from the primary somatosensory cortex (SI) and anterior cingulate cortex (ACC) in a common peroneal nerve injury (CPNI) rodent model.

METHODS

Male Sprague Dawley rats were divided into two cohorts: CPNI liFUS and CPNI sham liFUS. Baseline single-unit activity (SUA) recordings were taken 20 min prior to treatment and for 4 h post treatment in 20 min intervals, then analyzed for frequency and compared to baseline. Recordings from the SI and ACC were separated into pyramidal and interneurons based on waveform and principal component analysis.

RESULTS

Following CPNI surgery, all rats (n = 30) displayed a significant increase in mechanical sensitivity. In CPNI liFUS rats, there was a significant increase in pyramidal neuron spike frequency in the SI region compared to the CPNI sham liFUS animals beginning at 120 min following liFUS treatment (p < 0.05). In the ACC, liFUS significantly attenuated interneuron firing beginning at 80 min after liFUS treatment (p < 0.05).

CONCLUSION

We demonstrate that liFUS changed neuronal spiking in the SI and ACC regions 80 and 120 min after treatment, respectively, which may in part correlate with improved sensory thresholds. This may represent a mechanism of action how liFUS attenuates neuropathic pain. Understanding the impact of liFUS on pain circuits will help advance the use of liFUS as a non-invasive neuromodulation option.

High-Resolution Spinal Motor Mapping Using Thoracic Spinal Cord Stimulation in Patients With Chronic Pain

BACKGROUND

High-resolution spinal cord stimulation (HR-SCS) paddle can stimulate medial-dorsal columns and extend stimulation coverage to the laterally positioned spinal targets.

OBJECTIVE

To investigate the medio-lateral selectivity of an HR-SCS paddle in patients with chronic pain.

METHODS

During standard-of-care spinal cord stimulation (SCS) placement, epidurally evoked electromyography and antidromic dorsal column-evoked potentials were recorded in 12 subjects using an HR-SCS paddle with 8 medio-lateral sites spanning the full epidural width at thoracic T9-12 and a commercial paddle consecutively.

RESULTS

Recruitment maps were aligned with respect to physiological midline which was overlapping with anatomic midline in 10 of 11 cases. Overlapping contacts between the HR-SCS and commercial paddles exhibited similar patterns while HR-SCS demonstrated higher precision targeting of certain dermatomes. Spinal motor maps showed that the lateral contacts triggered stronger responses in medial gastrocnemius, adductor magnus, and tibialis anterior while the medial contacts triggered stronger responses in gluteus maximus and adductor hallucis. The time-locked popliteal fossa responses indicated ipsilateral activation by HR-SCS at the lateral contacts and bilateral activation at the medial contacts with stronger ipsilateral responses.

CONCLUSION

This study is the first to perform high-resolution medio-lateral SCS mapping in patients with chronic pain. These results show promise that HR-SCS may provide additional ipsilateral recruitment within the extremities which improve targeting of focal pain in the lower extremities. Furthermore, this study supports the functional use of intraoperative neuromonitoring as a decision tool to determine physiological midline in thoracic SCS surgeries and provides a full methodological framework.

Botulinum Toxin as an Effective Treatment for Trigeminal Neuralgia in Surgical Practices

BACKGROUND

Trigeminal neuralgia (TN) is a common cause of craniofacial pain with many medical and surgical therapies, all of which are imperfect. We examine the use of botulinum toxin type-A (BTX-A) as an intermediary approach in surgical practices.

METHODS

We retrospectively identified TN patients seen by both pain neurology and neurosurgery at our center. Demographics were collected. Pain intensity was assessed using the numerical rating scale (NRS) and compared from baseline to after BTX-A treatment via paired t test. Responder status was assessed, and success of BTX-A was determined for each cohort. Doses of common medications were compared between baseline visit and the most recent BTX-A administration visit.

RESULTS

Thirty-one patients underwent BTX-A therapy for TN, 24 (77%) female and 7 (23%) male. Mean age was 62.5 ± 3.1 years and 29 (94%) identified as white. When divided into cohorts according to indication, 11 (35%) failed prior TN surgery, 9 (29%) either declined surgery or were poor surgical candidates, 4 (13%) had multiple sclerosis, 4 (13%) had trigeminal neuropathic pain, and 3 (10%) had atypical TN with pain in additional dermatomes outside the trigeminal distribution. Significant reductions in NRS from baseline to following initial BTX-A treatment were seen in the declined/high risk for surgery (p = 0.004) and those who failed prior TN surgery (p = 0.035) groups. No significant variation in demographics was found between any two groups (p > 0.05 for all). Finally, there was no significant reduction in total daily dose of gabapentin, carbamazepine, oxcarbazepine, baclofen, or lamotrigine in BTX-A responders (p > 0.05 for all).

DISCUSSION

Indication is an important predictor for BTX-A, with classical TN patients exhibiting the highest response rates. This research highlights the viability of BTX-A as an important tool in the arsenal of providers seeking to treat TN in a minimally invasive manner.

Mindfulness Meditation in the Treatment of Chronic Pain

Chronic pain is a leading cause of disability in the United States. Limited efficacy associated with pharmacologic management and surgical interventions in refractory patients has led to further exploration of cognitive and behavioral interventions as both an adjunctive and primary therapeutic modality. Mindfulness-based meditation has shown to be effective in reducing pain in randomized studies of chronic pain patients as well as models of experimentally induced pain in healthy participants. These studies have revealed specific neural mechanisms which may explain both short-term and sustained pain relief associated with mindfulness-based interventions.

Developing a fast-track discharge protocol for patients with cerebral aneurysms treated via neuroendovascular techniques

INTRODUCTION

As we emerge from the current pandemic, hospitals, staff, and resources will need to continue to adjust to meet ongoing healthcare demands. Lessons learned during past shortages can be used to optimize peri-procedural protocols to safely improve the utilization of hospital resources.

METHODS

Retrospective review of patients who underwent elective endovascular intracranial aneurysm treatment was performed. Multivariable logistic regression was used to identify factors associated with patients who were able to be discharged within 24 h of elective procedures. Rates of complications (particularly readmission) were determined.

RESULTS

330 patients underwent elective endovascular aneurysm treatment with 86 (26.1%) discharged within 24 h. Factors associated with earlier discharge included procedure years (2019-2021) and male sex. Patients were more likely to be discharged later (after 24 h) if they underwent stent-coil embolization or flow-diversion. There was no association between discharge timing and likelihood of readmission.

DISCUSSION

Our review highlights the safety of earlier discharge and allowed us to prepare a fast-track protocol for same-day discharge in these patients. This protocol will be studied prospectively in the next phase of this study. As we gain more comfort with emerging, minimally invasive endovascular therapies, we hope to safely achieve same-day discharge on a protocolized and routine basis, reducing the demand of elective aneurysm treatments on our healthcare system.

CONCLUSION

We retrospectively demonstrate that early discharge following elective aneurysm treatment is safe in our cohort and provide a fast-track pathway based on these findings for other centers developing similar protocols.

Low Intensity Focused Ultrasound Increases Duration of Anti-Nociceptive Responses in Female Common Peroneal Nerve Injury Rats

OBJECTIVE

Chronic pain affects 7%-10% of Americans, occurs more frequently and severely in females, and available treatments have been shown to have less efficacy in female patients. Preclinical models addressing sex-specific treatment differences in the treatment of chronic pain have been limited. Here we examine the sex-specific effects of low intensity focused ultrasound (liFUS) in a modified sciatic nerve injury (SNI) model.

MATERIALS AND METHODS

A modified SNI performed by ligating the common peroneal nerve (CPN) was used to measure sensory, behavioral pain responses, and nerve conduction studies in female and male rats, following liFUS of the L5 dorsal root ganglion.

RESULTS

Using the same dose of liFUS in females and males of the same weight, CPN latency immediately after treatment was increased for 50 min in females compared to 25 min in males (p < 0.001). Improvements in mechanical pain thresholds after liFUS lasted significantly longer in females (seven days; p < 0.05) compared to males (three days; p < 0.05). In females, there was a significant improvement in depression-like behavior as a result of liFUS (N = 5; p < 0.01); however, because males never developed depression-like behavior there was no change after liFUS treatment.

CONCLUSIONS

Neuromodulation with liFUS has a greater effect in female rats on CPN latency, mechanical allodynia duration, and depression-like behavior. In order to customize neuromodulatory techniques for different patient phenotypes, it is essential to understand how they may alter sex-specific pathophysiologies.

Efficacy of 10 kHz spinal cord stimulation in complex regional pain syndrome: A retrospective analysis

INTRODUCTION

We examine the clinical efficacy of High Frequency 10 kHz (HF10) spinal cord stimulation (SCS) CRPS patients.

MATERIALS AND METHODS

This is a retrospective cohort study of SCS-naïve patients with CRPS treated with HF10-SCS after a successful trial. Patients were evaluated at 2 weeks, 6 weeks, 3 months, and 6 months post-operatively. Outcomes included mean numeric pain rating scale (NRS), mean NRS reduction, NRS percentage improvement (PI), patient reported subjective pain PI (Pain PI), and patients reporting > 50% benefit in symptoms. Pre and post-operative NRS were compared by ordinal regression analysis accounting for the patient's response to the SCS trial.

RESULTS

20 patients met inclusion criteria. 75% were female. Mean age 51 years. Baseline mean NRS was 6.1 for the cohort (1.7). Post-operatively, mean NRS decreased to 4.5 at 2 weeks (p = 0.077), 3.8 at 6 weeks (p = 0.034), 3.7 at 3 months (p = 0.307), and 4.4 at 6 months (p = 0.832). Mean NRS reduction and NRS PI is reported within. Pain PI was 25% at 2 weeks, 55% at 6 weeks, 54% at 3 months, and 53% at 6 months. Greater than 50% reduction in symptoms was reported in 25% of patients at 2 weeks, 85% at 6 weeks, 87% at 3 months, and 64% at 6 months.

CONCLUSIONS

HF10 SCS may represent an effective treatment option for reducing objective and subjective symptoms in CRPS that warrants further study.

Development of Machine Learning-Based Models to Predict Treatment Response to Spinal Cord Stimulation

BACKGROUND

Despite spinal cord stimulation's (SCS) proven efficacy, failure rates are high with no clear understanding of which patients benefit long term. Currently, patient selection for SCS is based on the subjective experience of the implanting physician.

OBJECTIVE

To develop machine learning (ML)-based predictive models of long-term SCS response.

METHODS

A combined unsupervised (clustering) and supervised (classification) ML technique was applied on a prospectively collected cohort of 151 patients, which included 31 features. Clusters identified using unsupervised K-means clustering were fitted with individualized predictive models of logistic regression, random forest, and XGBoost.

RESULTS

Two distinct clusters were found, and patients in the cohorts significantly differed in age, duration of chronic pain, preoperative numeric rating scale, and preoperative pain catastrophizing scale scores. Using the 10 most influential features, logistic regression predictive models with a nested cross-validation demonstrated the highest overall performance with the area under the curve of 0.757 and 0.708 for each respective cluster.

CONCLUSION

This combined unsupervised-supervised learning approach yielded high predictive performance, suggesting that advanced ML-derived approaches have potential to be used as a functional clinical tool to improve long-term SCS outcomes. Further studies are needed for optimization and external validation of these models.

The Impact of Multidisciplinary Conferences on Healthcare Utilization in Chronic Pain Patients

Approximately 100 million adults in the United States have chronic pain, though only a subset utilizes the vast majority of healthcare resources. Multidisciplinary care has been shown to improve outcomes in a variety of clinical conditions. There is concern that multidisciplinary care of chronic pain patients may overwhelm existing resources and increase healthcare utilization due to the volume of patients and the complexity of care. We report our findings on the use of multidisciplinary conferences (MDC) to facilitate care for the most complex patients seen at our tertiary center. Thirty-two of nearly 2,000 patients seen per year were discussed at the MDC, making up the top 2% of complex patients in our practice. We evaluated patients' numeric rating score (NRS) of pain, medication use, hospitalizations, emergency department visits, and visits to pain specialists prior to their enrollment in MDC and 1 year later. Matched samples were compared using Wilcoxon's signed rank test. Patients' NRS scores significantly decreased from 7.64 to 5.54 after inclusion in MDC (p < 0.001). A significant decrease in clinic visits (p < 0.001) and healthcare utilization (p < 0.05) was also observed. Opioid and non-opioid prescriptions did not change significantly (p = 0.43). 83% of providers agreed that MDC improved patient care. While previous studies have shown the effect of multi-disciplinary care, we show notable improvements with a team established around a once-a-month MDC.

Spinal Cord Stimulation as Treatment for Cancer and Chemotherapy-Induced Pain

Neuropathic pain is a rampant disease exacting a significant toll on patients, providers, and health care systems around the globe. Neuromodulation has been successfully employed to treat many indications including failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), phantom limb pain (PLP), radiculopathies, and intractable pelvic pain, among many others. Recent studies have also demonstrated efficacy for cancer-related pain and chemotherapy induced neuropathy with these techniques. Spinal cord stimulation (SCS) is the most commonly employed technique and involves implantation of percutaneous or paddle leads targeting the dorsal columns of the spinal cord with the goal of disrupting the pain signals traveling to the brain. Tonic, high frequency, and burst waveforms have all been shown to reduce pain and disability in chronic pain patients. Closed-loop SCS systems that automatically adjust stimulation parameters based on feedback (such as evoked compound action potentials) are becoming increasingly used to help ease the burden placed on patients to adjust their programming to their pain and position. Additionally, dorsal root ganglion stimulation (DRGS) is a newer technique that allows for dermatomal coverage especially in patients with pain in up to two dermatomes. Regardless of the technique chosen, neuromodulation has been shown to be cost-effective and efficacious and should be given full consideration in patients with chronic pain conditions.