Approaches to neuropathic amputation-related pain: narrative review of surgical, interventional, and medical treatments.

BACKGROUND/IMPORTANCE: Neuropathic amputation-related pain can consist of phantom limb pain (PLP), residual limb pain (RLP), or a combination of both pathologies. Estimated of lifetime prevalence of pain and after amputation ranges between 8% and 72%. OBJECTIVE: This narrative review aims to summarize the surgical and non-surgical treatment options for amputation-related neuropathic pain to aid in developing optimized multidisciplinary and multimodal treatment plans that leverage multidisciplinary care. EVIDENCE REVIEW: A search of the English literature using the following keywords was performed: PLP, amputation pain, RLP. Abstract and full-text articles were evaluated for surgical treatments, medical management, regional anesthesia, peripheral block, neuromodulation, spinal cord stimulation, dorsal root ganglia, and peripheral nerve stimulation. FINDINGS: The evidence supporting most if not all interventions for PLP are inconclusive and lack high certainty. Targeted muscle reinnervation and regional peripheral nerve interface are the leading surgical treatment options for reducing neuroma formation and reducing PLP. Non-surgical options include pharmaceutical therapy, regional interventional techniques and behavioral therapies that can benefit certain patients. There is a growing evidence that neuromodulation at the spinal cord or the dorsal root ganglia and/or peripheral nerves can be an adjuvant therapy for PLP. CONCLUSIONS: Multimodal approaches combining pharmacotherapy, surgery and invasive neuromodulation procedures would appear to be the most promising strategy for preventive and treating PLP and RLP. Future efforts should focus on cross-disciplinary education to increase awareness of treatment options exploring best practices for preventing pain at the time of amputation and enhancing treatment of chronic postamputation pain.

A Pharmacological Evaluation of the Analgesic Effect and Hippocampal Protein Modulation of the Ketamine Metabolite (2R,6R)-Hydroxynorketamine in Murine Pain Models.

BACKGROUND: The ketamine metabolite (2R,6R)-hydroxynorketamine ([2R,6R]-HNK) has analgesic efficacy in murine models of acute, neuropathic, and chronic pain. The purpose of this study was to evaluate the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) dependence of (2R,6R)-HNK analgesia and protein changes in the hippocampus in murine pain models administered (2R,6R)-HNK or saline. METHODS: All mice were CD-1 IGS outbred mice. Male and female mice underwent plantar incision (PI) (n = 60), spared nerve injury (SNI) (n = 64), or tibial fracture (TF) (n = 40) surgery on the left hind limb. Mechanical allodynia was assessed using calibrated von Frey filaments. Mice were randomized to receive saline, naloxone, or the brain-penetrating AMPA blocker (1,2,3,4-Tetrahydro-6-nitro-2,3-dioxobenzo [f]quinoxaline-7-sulfonamide [NBQX]) before (2R,6R)-HNK 10 mg/kg, and this was repeated for 3 consecutive days. The area under the paw withdrawal threshold by time curve for days 0 to 3 (AUC 0-3d ) was calculated using trapezoidal integration. The AUC 0-3d was converted to percent antiallodynic effect using the baseline and pretreatment values as 0% and 100%. In separate experiments, a single dose of (2R,6R)-HNK 10 mg/kg or saline was administered to naive mice (n = 20) and 2 doses to PI (n = 40), SNI injury (n = 40), or TF (n = 40) mice. Naive mice were tested for ambulation, rearing, and motor strength. Immunoblot studies of the right hippocampal tissue were performed to evaluate the ratios of glutamate ionotropic receptor (AMPA) type subunit 1 (GluA1), glutamate ionotropic receptor (AMPA) type subunit 2 (GluA2), phosphorylated voltage-gated potassium channel 2.1 (p-Kv2.1), phosphorylated-calcium/calmodulin-dependent protein kinase II (p-CaMKII), brain-derived neurotrophic factor (BDNF), phosphorylated protein kinase B (p-AKT), phosphorylated extracellular signal-regulated kinase (p-ERK), CXC chemokine receptor 4 (CXCR4), phosphorylated eukaryotic translation initiation factor 2 subunit 1 (p-EIF2SI), and phosphorylated eukaryotic translation initiation factor 4E (p-EIF4E) to glyceraldehyde 3-phosphate dehydrogenase (GAPDH). RESULTS: No model-specific gender difference in antiallodynic responses before (2R,6R)-HNK administration was observed. The antiallodynic AUC 0-3d of (2R,6R)-HNK was decreased by NBQX but not with pretreatment with naloxone or saline. The adjusted mean (95% confidence interval [CI]) antiallodynic effect of (2R,6R)-HNK in the PI, SNI, and TF models was 40.7% (34.1%-47.3%), 55.1% (48.7%-61.5%), and 54.7% (46.5%-63.0%), greater in the SNI, difference 14.3% (95% CI, 3.1-25.6; P = .007) and TF, difference 13.9% (95% CI, 1.9-26.0; P = .019) compared to the PI model. No effect of (2R,6R)-HNK on ambulation, rearing, or motor coordination was observed. Administration of (2R,6R)-HNK was associated with increased GluA1, GluA2, p-Kv2.1, and p-CaMKII and decreased BDNF ratios in the hippocampus, with model-specific variations in proteins involved in other pain pathways. CONCLUSIONS: (2R,6R)-HNK analgesia is AMPA-dependent, and (2R,6R)-HNK affected glutamate, potassium, calcium, and BDNF pathways in the hippocampus. At 10 mg/kg, (2R,6R)-HNK demonstrated a greater antiallodynic effect in models of chronic compared with acute pain. Protein analysis in the hippocampus suggests that AMPA-dependent alterations in BDNF-TrkB and Kv2.1 pathways may be involved in the antiallodynic effect of (2R,6R)-HNK.

Selective Inhibition of NaV1.8 with VX-548 for Acute Pain.

BACKGROUND: The NaV1.8 voltage-gated sodium channel, expressed in peripheral nociceptive neurons, plays a role in transmitting nociceptive signals. The effect of VX-548, an oral, highly selective inhibitor of NaV1.8, on control of acute pain is being studied. METHODS: After establishing the selectivity of VX-548 for NaV1.8 inhibition in vitro, we conducted two phase 2 trials involving participants with acute pain after abdominoplasty or bunionectomy. In the abdominoplasty trial, participants were randomly assigned in a 1:1:1:1 ratio to receive one of the following over a 48-hour period: a 100-mg oral loading dose of VX-548, followed by a 50-mg maintenance dose every 12 hours (the high-dose group); a 60-mg loading dose of VX-548, followed by a 30-mg maintenance dose every 12 hours (the middle-dose group); hydrocodone bitartrate-acetaminophen (5 mg of hydrocodone bitartrate and 325 mg of acetaminophen every 6 hours); or oral placebo every 6 hours. In the bunionectomy trial, participants were randomly assigned in a 2:2:1:2:2 ratio to receive one of the following over a 48-hour treatment period: oral high-dose VX-548; middle-dose VX-548; low-dose VX-548 (a 20-mg loading dose, followed by a 10-mg maintenance dose every 12 hours); oral hydrocodone bitartrate-acetaminophen (5 mg of hydrocodone bitartrate and 325 mg of acetaminophen every 6 hours); or oral placebo every 6 hours. The primary end point was the time-weighted sum of the pain-intensity difference (SPID) over the 48-hour period (SPID48), a measure derived from the score on the Numeric Pain Rating Scale (range, 0 to 10; higher scores indicate greater pain) at 19 time points after the first dose of VX-548 or placebo. The main analysis compared each dose of VX-548 with placebo. RESULTS: A total of 303 participants were enrolled in the abdominoplasty trial and 274 in the bunionectomy trial. The least-squares mean difference between the high-dose VX-548 and placebo groups in the time-weighted SPID48 was 37.8 (95% confidence interval [CI], 9.2 to 66.4) after abdominoplasty and 36.8 (95% CI, 4.6 to 69.0) after bunionectomy. In both trials, participants who received lower doses of VX-548 had results similar to those with placebo. Headache and constipation were common adverse events with VX-548. CONCLUSIONS: As compared with placebo, VX-548 at the highest dose, but not at lower doses, reduced acute pain over a period of 48 hours after abdominoplasty or bunionectomy. VX-548 was associated with adverse events that were mild to moderate in severity. (Funded by Vertex Pharmaceuticals; VX21-548-101 and VX21-548-102 ClinicalTrials.gov numbers, NCT04977336 and NCT05034952.).

Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures.

ABSTRACT: Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention. Biomarkers are used to diagnose, track, and treat other diseases, but no validated clinical biomarkers exist yet for chronic pain. To address this problem, the National Institutes of Health Common Fund launched the Acute to Chronic Pain Signatures (A2CPS) program to evaluate candidate biomarkers, develop them into biosignatures, and discover novel biomarkers for chronification of pain after surgery. This article discusses candidate biomarkers identified by A2CPS for evaluation, including genomic, proteomic, metabolomic, lipidomic, neuroimaging, psychophysical, psychological, and behavioral measures. Acute to Chronic Pain Signatures will provide the most comprehensive investigation of biomarkers for the transition to chronic postsurgical pain undertaken to date. Data and analytic resources generatedby A2CPS will be shared with the scientific community in hopes that other investigators will extract valuable insights beyond A2CPS's initial findings. This article will review the identified biomarkers and rationale for including them, the current state of the science on biomarkers of the transition from acute to chronic pain, gaps in the literature, and how A2CPS will address these gaps.

Multiorganizational consensus to define guiding principles for perioperative pain management in patients with chronic pain, preoperative opioid tolerance, or substance use disorder.

Significant knowledge gaps exist in the perioperative pain management of patients with a history of chronic pain, substance use disorder, and/or opioid tolerance as highlighted in the US Health and Human Services Pain Management Best Practices Inter-Agency Task Force 2019 report. The report emphasized the challenges of caring for these populations and the need for multidisciplinary care and a comprehensive approach. Such care requires stakeholder alignment across multiple specialties and care settings. With the intention of codifying this alignment into a reliable and efficient processes, a consortium of 15 professional healthcare societies was convened in a year-long modified Delphi consensus process and summit. This process produced seven guiding principles for the perioperative care of patients with chronic pain, substance use disorder, and/or preoperative opioid tolerance. These principles provide a framework and direction for future improvement in the optimization and care of 'complex' patients as they undergo surgical procedures.

Analgesic Effectiveness and Dorsal Root Ganglia Protein Modulation of a Peripheral Adenosine Monophosphate Kinase Alpha Activator (O304) Following Lumbar Disk Puncture in the Mouse.

BACKGROUND: Disk herniation is a primary cause of radicular back pain. The purpose of this study was to evaluate the antiallodynic effective dose in 50% of the sample (ED 50 ) and dorsal root ganglion (DRG) protein modulation of a peripheral direct adenosine monophosphate kinase alpha (AMPKα) activator (O304) in a murine model of lumbar disk puncture. METHODS: Male (n = 28) and female (n = 28) mice (C57BL6/J) were assessed for hind paw withdrawal threshold (PWT) and burrowing. Abdominal surgery was performed on all mice, and 48 received a lumbar disk puncture (27-G needle), with 8 serving as nondisk puncture controls. Assessments were repeated at day 7, and mice were then randomized into 5 groups of equal numbers of males and females: O304 at 100 mg/kg (n = 10), 150 mg/kg (n = 10), 200 mg/kg (n = 10), and 250 mg/kg (n = 10) or drug vehicle (n = 8). Starting on day 7, mice received daily gavages of O304 or vehicle for 7 days. On days 14 and 21 PWT and on day 14 burrowing were assessed. The area under the PWT by time curve (AUC) from day 7 to 21 was determined by trapezoidal integration. DRG protein modulation was evaluated in male (n = 10) and female (n = 10) mice (C57BL6/J). Following disk puncture, mice were randomized to receive O304 200 mg/kg or vehicle for 7 days starting on day 7. On day 14, mice were euthanized; the DRG harvested and immunoblot performed for mammalian target of rapamycin (mTOR), transient receptor potential ankyrin 1 (TRPA1), phosphorylated adenosine monophosphate kinase (p-AMPK), phosphorylated extracellular signal-regulated kinase (p-ERK), phosphorylated eukaryotic translation initiation factor 2 subunit 1 (p-EIF2S1), phosphorylated eukaryotic translation initiation factor 4e (p-EIF4E), and glyceraldehyde 3-phosphate dehydrogenase (GADPH). RESULTS: Disk puncture decreased PWT greater in female mice compared with male mice and decreased burrowing at 7 days. PWTs were increased with increasing doses of O304 from 150 to 250 mg/g on day 14 and sustained through day 21. The ED 50 (95% confidence interval [CI]) for reducing mechanical allodynia was 140 (118-164) mg/kg. Burrowing was not increased at day 14 compared to day 7 by O304 administration. Compared to vehicle-treated animals, O304 increased (95% CI) the p-AMPK/GADPH ratio, difference 0.27 (0.08-0.45; P = . 004) and decreased (95% CI) the ratios of p-TRPA1, p-ERK1/2, pEIF4E, and p-EIF2S1 to GADPH by -0.49 (-0.61 to -0.37; P < . 001), -0.53 (-0.76 to -0.29; P < . 001), -0.27 (-0.42 to 0.11; P = . 001), and -0.21 (-0.32 to -0.08; P = . 003) in the DRG, respectively. CONCLUSIONS: The direct peripheral AMPK activator O304 reduced allodynia in a dose-dependent manner, and immunoblot studies of the DRG showed that O304 increased p-AMPK and decreased TRPA1, p-ERK1/2, as well as translation factors involved in neuroplasticity. Our findings confirm the role of peripheral AMPKα activation in modulating nociceptive pain.

Multi-Site Observational Study to Assess Biomarkers for Susceptibility or Resilience to Chronic Pain: The Acute to Chronic Pain Signatures (A2CPS) Study Protocol.

Chronic pain has become a global health problem contributing to years lived with disability and reduced quality of life. Advances in the clinical management of chronic pain have been limited due to incomplete understanding of the multiple risk factors and molecular mechanisms that contribute to the development of chronic pain. The Acute to Chronic Pain Signatures (A2CPS) Program aims to characterize the predictive nature of biomarkers (brain imaging, high-throughput molecular screening techniques, or "omics," quantitative sensory testing, patient-reported outcome assessments and functional assessments) to identify individuals who will develop chronic pain following surgical intervention. The A2CPS is a multisite observational study investigating biomarkers and collective biosignatures (a combination of several individual biomarkers) that predict susceptibility or resilience to the development of chronic pain following knee arthroplasty and thoracic surgery. This manuscript provides an overview of data collection methods and procedures designed to standardize data collection across multiple clinical sites and institutions. Pain-related biomarkers are evaluated before surgery and up to 3 months after surgery for use as predictors of patient reported outcomes 6 months after surgery. The dataset from this prospective observational study will be available for researchers internal and external to the A2CPS Consortium to advance understanding of the transition from acute to chronic postsurgical pain.

The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations for Surgical Technique for Spinal Cord Stimulation.

INTRODUCTION: The field of neurostimulation for the treatment of chronic pain is a rapidly developing area of medicine. Although neurostimulation therapies have advanced significantly as a result of technologic improvements, surgical planning, device placement, and postoperative care are of equal importance to optimize outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for these often-overlooked areas of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based on their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from the last NACC publication in 2017 to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on evidence strength and consensus when evidence was scant. RESULTS: This NACC project provides guidance on preoperative assessment, intraoperative techniques, and postoperative management in the form of consensus points with supportive evidence. These results are based on grade of evidence, strength of consensus, and expert opinion. CONCLUSIONS: The NACC has given guidance for a surgical plan that encompasses the patient journey from the planning stage through the surgical experience and postoperative care. The overall recommendations are designed to improve efficacy and the safety of patients undergoing these neuromodulation procedures and are intended to apply throughout the international community.

The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations on Best Practices for Cervical Neurostimulation.

INTRODUCTION: The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on the use of neurostimulation in the cervical region to improve outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for an often-overlooked area of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based upon their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when NACC last published guidelines) to the present. Identified studies were graded using the US Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence was scant. RESULTS: The NACC examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process. CONCLUSIONS: The NACC recommends best practices regarding the use of cervical neuromodulation to improve safety and efficacy. The evidence- and consensus-based recommendations should be utilized as a guide to assist decision making when clinically appropriate.

A multisociety organizational consensus process to define guiding principles for acute perioperative pain management.

The US Health and Human Services Pain Management Best Practices Inter-Agency Task Force initiated a public-private partnership which led to the publication of its report in 2019. The report emphasized the need for individualized, multimodal, and multidisciplinary approaches to pain management that decrease the over-reliance on opioids, increase access to care, and promote widespread education on pain and substance use disorders. The Task Force specifically called on specialty organizations to work together to develop evidence-based guidelines. In response to this report's recommendations, a consortium of 14 professional healthcare societies committed to a 2-year project to advance pain management for the surgical patient and improve opioid safety. The modified Delphi process included two rounds of electronic voting and culminated in a live virtual event in February 2021, during which seven common guiding principles were established for acute perioperative pain management. These principles should help to inform local action and future development of clinical practice recommendations.

Trajectories of opioid consumption from day of surgery to 28 days postoperatively: a prospective cohort study in patients undergoing abdominal, joint, or spine surgery.

INTRODUCTION: Descriptions of opioid use trajectories and their association with postsurgical pain and opioid consumption are limited. We hypothesized that trajectories of opioid consumption in the first 28 days following surgery would be associated with unique patterns of pain and duration of opioid use. METHODS: A prospective longitudinal cohort of patients undergoing elective inpatient abdominal, joint, or spine surgery between June 2016 and June 2019 was studied. At hospital discharge and every 7 days for 28 days, patients were assessed for pain, analgesic use, pain interference, satisfaction, and side effects. Duration of opioid use was determined for 6 months. The primary analysis used latent class group modeling to identify trajectories of opioid use. RESULTS: Decreasing, high, and persistent opioid trajectories were identified following joint and spine surgery and a decreasing and persistent trajectory following abdominal surgery. Reported pain was greater in the high and persistent trajectories compared with the decreasing use trajectories. Compared with the decreasing opioid trajectory, the median duration of opioid use was increased by 4.5 (95% CI 1 to 22, p<0.01) weeks in persistent opioid use abdominal and by 6 (95% CI 0 to 6, p<0.01) weeks in the high or persistent use joint and spine groups. The odds (95% CI) of opioid use at 6 months in the high or persistent opioid use trajectory was 24.3 (2.9 to 203.4) for abdominal and 3.7 (1.9 to 7.0) for joint or spine surgery compared with the decreasing use trajectory. Morphine milliequivalent per 24 hours of hospitalization was the primary independent predictor of opioid use trajectories. CONCLUSIONS: We observed distinct opioid use trajectories following abdominal and joint or spine surgery that were associated with different patterns of pain and duration of opioid use postoperatively. Prediction of postoperative opioid use trajectory groups may be clinically important for identifying risk of prolonged opioid use.

Complex Regional Pain Syndrome: A Comprehensive Qualitative Research Study on Unmet Needs in the "Patient Journey".

PURPOSE: This qualitative research study aimed to characterize the "patient journey" for patients with complex regional pain syndrome (CRPS) and identify the unmet needs related to the management and treatment of the condition for healthcare providers (HCPs), patients, and their caregivers. MATERIALS AND METHODS: Multifaceted, dynamic methodology, iteratively gathering cognitive, emotional and social insights, was used to support and conduct in-depth, immersion interviews across the USA with 59 HCPs in-office and in roundtable discussions, and 20 patient-support partner dyads in-home. RESULTS: Patients were aged >18 years, primarily female, and all were diagnosed with CRPS (limited to type 1 in this patient cohort). Results show that the current state of CRPS treatment may fall short in multiple key areas. In some cases, poor awareness of CRPS causes delayed diagnoses impacting the opportunity for early treatment, resulting in long-term poor health outcomes. Consequently, the CRPS "patient journey" may be characterized by clinical frustration of physicians and disappointment for some patients. The poor treatment experiences and outcomes for some patients and HCPs may build the perception of a non-collaborative relationship. HCPs and patients agree that an effective treatment would be one that addresses CRPS rather than its symptoms, and the availability of such an option would transform the treatment experience. CONCLUSION: CRPS leads to cognitive, social and emotional burdens for patients and their caregivers. There is an unmet need for improved CRPS disease awareness and successful therapeutic options to aid in earlier diagnoses, effective treatment and better outcomes for HCPs, patients, and their caregivers.

Multimodal Analgesic Management for Lumbar Decompression Surgery in the Ambulatory Setting: Clinical Case Series and Review of the Literature.

BACKGROUND: Effective pain control is vital for successful surgery in the ambulatory setting. Our study aims to characterize a case series of patients who underwent lumbar decompression (LD) in the ambulatory surgical center (ASC) with the use of a multimodal analgesic (MMA) protocol. METHODS: A prospective surgical registry was retrospectively assessed for patients who underwent single or multilevel LD in an ASC using MMA from 2013 to 2019. Observation in excess of 23 hours was not permitted at the ASC, and patients were required to be discharged the same day. Length of stay, patient-reported visual analog scale pain scores before discharge, and the quantity of narcotic medications administered to patients before discharge were recorded. Quantity of narcotic medications were converted into units of oral morphine equivalents and summed across all types of narcotic medications prescribed. RESULTS: A total of 499 patients were included. In total, 86.0% (429) of the patients underwent a single-level decompression procedure, 13.8% (69) of patients underwent a 2-level, and 0.2% (1) of the patients underwent a 3-level procedure; 83.6% (417) of the patients in this study underwent a primary LD, and 14.0% (70) underwent a revision decompression. CONCLUSIONS: This is the largest clinical case series focused on LD procedures within an ASC requiring no planned 23-hour observation. This study demonstrates the feasibility of performing LD surgery in an ASC with proper patient selection, surgical technique, and MMA protocol. All patients were discharged from the surgical center on the same day of surgery.

Multimodal Analgesic Management for Cervical Spine Surgery in the Ambulatory Setting.

BACKGROUND: Patient selection and analgesic techniques, such as the multimodal analgesic (MMA) protocol, aid in ambulatory surgical center (ASC) cervical spine surgery. The purpose of this case series is to characterize patients undergoing anterior cervical discectomy and fusion (ACDF) and total cervical disc replacement (CDR) in an ASC with an enhanced MMA protocol. METHODS: A prospectively maintained registry was retrospectively reviewed for cervical surgeries between May 2013 and August 2019. Inclusion criteria included ASC patients who underwent single-level or multilevel CDR or ACDF using an MMA protocol. Baseline, intraoperative, and postoperative characteristics were recorded, including length of stay, visual analog scale pain scores, neck disability index, complications, and narcotics administered. RESULTS: A total of 178 patients met inclusion criteria with 125 single-level, 52 two-level, and 1 three-level procedure. Of those patients, 127 underwent ACDF and 51 underwent CDR. The longest procedure was 95 minutes and the mean length of stay was 6.1 hours, with 2 patients requiring hospital admission. All other patients were discharged within 10 hours. One of the admitted patients experienced a postoperative seizure that was later determined to be secondary to drug use and serotonin syndrome. The second patient developed an anterior cervical hematoma 5 hours postoperatively, which was immediately evacuated. The patient was admitted for observation and discharged the next day. CONCLUSION: In our study, patients experienced considerable improvement in disability scores, with a low likelihood of postoperative complications. A safe and effective MMA protocol may help facilitate anterior cervical surgery in the outpatient setting. LEVEL OF EVIDENCE: 3. CLINICAL RELEVANCE: Transitioning anterior cervical discectomy and fusions to the ASC requires an appropriate MMA protocol. Our findings reveal that an enhanced MMA protocol will help improve disability scores while keeping the likelihood of postoperative complications low. This supports the ASC setting for cervical spine procedures in appropriate patient populations.

Radiation safety and knowledge: an international survey of 708 interventional pain physicians.

INTRODUCTION: Interventional pain procedures have increased in complexity, often requiring longer radiation exposure times and subsequently higher doses. The practicing physician requires an in-depth knowledge and evidence-based knowledge of radiation safety to limit the health risks to themselves, patients and healthcare staff. The objective of this study was to examine current radiation safety practices and knowledge among interventional pain physicians and compare them to evidence-based recommendations. MATERIALS AND METHODS: A 49-question survey was developed based on an extensive review of national and international guidelines on radiation safety. The survey was web-based and distributed through the following professional organizations: Association of Pain Program Directors, American Academy of Pain Medicine, American Society of Regional Anesthesia and Pain Medicine, European Society of Regional Anesthesia and Pain Therapy, International Neuromodulation Society, and North American Neuromodulation Society. Responses to radiation safety practices and knowledge questions were evaluated and compared with evidence-based recommendations. An exploratory data analysis examined associations with radiation safety training/education, geographical location, practice type, self-perceived understanding, and fellowship experience. RESULTS: Of 708 responding physicians, 93% reported concern over the health effects of radiation, while only 63% had ever received radiation safety training/education. Overall, ≥80% physician compliance with evidence-based radiation safety practice recommendations was demonstrated for only 2/15 survey questions. Physician knowledge of radiation safety principles was low, with 0/10 survey questions having correct response rates ≥80%. CONCLUSION: We have identified deficiencies in the implementation of evidence-based practices and knowledge gaps in radiation safety. Further education and training are warranted for both fellowship training and postgraduate medical practice. The substantial gaps identified should be addressed to better protect physicians, staff and patients from unnecessary exposure to ionizing radiation during interventional pain procedures.

Enhanced Recovery After Surgery Pathway for Single-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion Decreases Length of Stay and Opioid Consumption.

BACKGROUND: Opioid requirements in the perioperative period in patients undergoing lumbar spine fusion surgery remain problematic. Although minimally invasive surgery (MIS) techniques have been developed, there still remain substantial challenges to reducing length of hospital stay (LOS) because of postoperative opioid requirements. OBJECTIVE: To study the effect of implementing an enhanced recovery after surgery (ERAS) pathway in patients undergoing a 1-level MIS transforaminal lumbar interbody fusion (MIS TLIF) at our institution. METHODS: We implemented an ERAS pathway in patients undergoing an elective single-level MIS TLIF for degenerative changes at a single institution. Consecutive patients were enrolled over a 20-mo period and compared with a pre-ERAS group prior to the implementation of the ERAS protocol. The primary outcome was LOS. Secondary outcomes included reduction in morphine milligram equivalent units (MME), pain scores, postoperative urinary retention (POUR), and incidence of postoperative delirium. Patients were compared using the chi-square and Welch's 2-sample t-tests. RESULTS: A total of 299 patients were evaluated in this study: 87 in the ERAS group and 212 in the pre-ERAS group. In the ERAS group, there was a significant reduction in LOS (3.13 ± 1.53 vs 3.71 ± 2.07 d, P = .019), total admission MME (252.74 ± 317.38 vs 455.91 ± 498.78 MME, P = .001), and the number of patients with POUR (48.3% vs 65.6%, P = .008). There were no differences in pain scores. CONCLUSION: This is the largest ERAS MIS fusion cohort published to date evaluating a single cohort of patients in a generalizable manner. This ERAS pathway has shown a substantial decrease in LOS and opioid requirements in the immediate perioperative and postoperative period. There is further work to be done to evaluate patients undergoing other complex spine surgical interventions.

Preoperative cognitive-behavioral therapy for reducing pain catastrophizing and improving pain outcomes after total knee replacement: a randomized clinical trial.

INTRODUCTION: Cognitive-behavioral therapy (CBT) can reduce preoperative pain catastrophizing and may improve postsurgical pain outcomes. We hypothesized that CBT would reduce pain catastrophizing more than no-CBT controls and result in improved pain outcomes. METHODS: The study was a randomized controlled trial of patients undergoing elective total knee arthroplasty between January 2013 and March 2020. In phase 1, the change in pain catastrophizing scores (PCS) among 4-week or 8-week telehealth, 4-week in person and no-CBT sessions was compared in 80 patients with a PCS >16. In phase 2, the proportion of subjects that achieved a 3-month decrease in Western Ontario and McMaster Universities Osteoarthritis (WOMAC) pain subscale >4 following 4-week telehealth CBT with no-CBT controls were compared in 80 subjects. RESULTS: In phase 1, 4-week telehealth CBT had the highest completion rate 17/20 (85%), demonstrated an adjusted median reduction in PCS of -9 (95% CI -1 to -14, p<0.01) compared with no-CBT and was non-inferior to 8-week telehealth CBT at a margin of 2 (p=0.02). In phase 2, 29 of 35 (83%) in the 4-week telehealth CBT and 26 of 33 (79%) subjects in the no-CBT demonstrated a decrease in the WOMAC pain subscale >4 at 3 months, difference 4% (95% CI -18% to 26%, p=0.48), despite a median decrease in the PCS for the 4-week CBT and no-CBT group of -6 (-10 to -2, p=0.02). CONCLUSIONS: Our findings demonstrate that CBT interventions delivered prior to surgery in person or via telehealth can reduced PCS scores; however, this reduction did not lead to improved 3-month pain outcomes. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT01772329, registration date 21 January 2013).

Does aerobic exercise training alter responses to opioid analgesics in individuals with chronic low back pain? A randomized controlled trial.

ABSTRACT: We tested whether aerobic exercise training altered morphine analgesic responses or reduced morphine dosages necessary for adequate analgesia. Patients with chronic back pain were randomized to an 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 45). Before and after the intervention, participants underwent 3 laboratory sessions (double-blinded, crossover) to assess effects of saline placebo, i.v. morphine (0.09 mg/kg), and i.v. naloxone (12 mg) on low back pain and evoked heat pain responses. Differences in evoked and back pain measures between the placebo and morphine conditions indexed morphine analgesia, with pre-post intervention changes the primary outcome. Endogenous opioid analgesia was indexed by differences in evoked and low back pain measures between the naloxone and placebo conditions. A Sex X Intervention interaction on the analgesic effects of morphine on visual analogue scale back pain intensity was observed (P = 0.046), with a similar trend for evoked pain threshold (P = 0.093). Male exercisers showed reduced morphine analgesia pre-post intervention, whereas male controls showed increased analgesia (with no differences in females). Of clinical significance were findings that relative to the control group, aerobic exercise produced analgesia more similar to that observed after receiving ≈7 mg morphine preintervention (P < 0.045). Greater pre-post intervention increases in endogenous opioid function (from any source) were significantly associated with larger pre-post intervention decreases in morphine analgesia (P < 0.046). The overall pattern of findings suggests that regular aerobic exercise has limited direct effects on morphine responsiveness, reducing morphine analgesia in males only.