Faculty Bibliography

BACKGROUND:Complex Regional Pain Syndrome (CRPS) is a challenging and often disabling condition marked by persistent pain, most commonly in a limb following injury or surgery. It presents with a wide array of symptoms, including intense pain, swelling, alterations in skin color and temperature, motor dysfunction, and trophic changes such as skin and tissue atrophy. While the precise cause of CRPS is not fully understood, it is thought to stem from abnormal nervous system activity, leading to heightened pain sensitivity and inflammatory responses. A thorough understanding of CRPS is essential for accurate diagnosis, effective treatment, and enhancing patients' quality of life.Although attempts have been made to distinguish between acute and chronic CRPS, there are currently no established diagnostic criteria specific to chronic CRPS in medical literature. OBJECTIVE:This ASIPP guidance document offers updated, evidence-based recommendations for the diagnosis and management of Chronic Complex Regional Pain Syndrome (CRPS), with a primary focus on introducing novel, time-based diagnostic criteria specific to the chronic phase. These proposed criteria address significant gaps in the current literature, where existing standards, such as the Budapest Criteria, do not sufficiently differentiate between the acute and chronic stages of the condition. METHODS:An expert panel convened by the American Society of Interventional Pain Physicians (ASIPP) conducted a comprehensive literature review and employed a structured consensus process to develop recommendations. Acknowledging that the clinical and pathological characteristics of CRPS change significantly beyond 12 months, the panel proposed chronic-specific diagnostic criteria based on disease duration, clinical history, physical examination findings, and optional diagnostic tests. These draft criteria were refined through multidisciplinary input and expert consensus. RESULTS:The diagnostic framework for chronic CRPS consists of four key components:General Criteria - Require fulfillment of the Budapest Criteria for at least 12 months, continued recognition of CRPS as a diagnosis of exclusion, and differentiation from generalized nociplastic pain syndromes.History-Based Criteria - Mandate the presence of at least three out of five specific historical features.Physical Examination Criteria - Include asymmetric limb findings, sensory disturbances, and musculoskeletal changes.Optional Diagnostic Testing - May involve assessments such as intraepidermal nerve fiber density (IENFD) and imaging evidence of regional bone demineralization.This framework builds upon the Budapest Criteria by incorporating time-dependent features of chronic CRPS, including musculoskeletal dystrophy, neurogenic inflammation, and sympathetic dysfunction. Emerging objective tools-such as quantitative sensory testing (QST), skin biopsy for IENFD, functional MRI, and serum biomarkers of neuroinflammation-may further support diagnosis in complex or uncertain cases.Treatment recommendations highlight a multimodal strategy that integrates physical rehabilitation, pharmacologic management of neuropathic pain, sympathetic nerve blocks, and advanced neuromodulation. Emphasis is placed on individualized care pathways tailored to disease stage and patient-specific characteristics. CONCLUSIONS:This article presents the first structured, time-sensitive diagnostic criteria for chronic CRPS, aimed at improving diagnostic accuracy and informing treatment strategies. Adoption of these criteria may enhance clinical outcomes and promote further research into the natural history and pathophysiology of CRPS progression.

OBJECTIVE:The CDC recommends initiating opioids for pain treatment at the lowest effective dose and duration. We examine how interactions between dose, duration, and other medication factors (e.g., drug type) influence opioid use disorder (OUD) risk-a gap not considered by CDC guidelines. SUBJECTS/METHODS:Using Medicaid claims data (2016-2019) from 25 states, we analyzed opioid-naïve adults, newly diagnosed with musculoskeletal pain who initiated opioids within three months of diagnosis. A 6-month washout confirmed no prior opioid exposure or musculoskeletal diagnosis. METHODS:Initial opioids were categorized by "dose-days supplied" (low [>0-20 mg MME] to very high [>90 mg MME] dose, and short [1-7 days] to moderate [>7-30 days] supply), and by opioid type; physical therapy (PT) sessions were also recorded. Using Poisson regression models, we estimated the OUD risk associated with dose-days categories, adjusting for baseline demographics, clinical characteristics, and medications. We separately examined opioid dose-days and PT, and assessed PT's moderating effect on dose-days' impact. RESULTS:Among 30,536 patients, half initiated opioids at 20-50 MME for 1-7 days, and 20% received PT. OUD risk was 2-3 times higher for opioids initiated for >7-30 days compared to 1-7 days across doses, and 5.5 times higher for opioids initiated for >7-30 days at > 90 MME versus 1-7 days at < 20 MME. PT alone, neither affected OUD risk nor mitigated the increased risk from longer or higher-dose opioids. CONCLUSIONS:Our findings support the need for careful opioid prescribing and alternative pain management strategies, as the observed associations between initial prescription characteristics and OUD were not mitigated by adjunctive PT. PERSPECTIVE/CONCLUSIONS:This study demonstrated that initial opioid prescriptions of 7-30 days, especially above 90 MME/day, increased OUD risk in opioid-naïve patients with musculoskeletal pain; physical therapy did not mitigate the risk. Different opioids posed varied risks, even at the same dose and duration. Careful prescribing and alternative pain management are essential.

Widespread hyperalgesia, characterized by pain sensitivity beyond the primary pain site, is a common yet under-characterized feature across chronic pain conditions, including chronic pancreatitis (CP). In this exploratory study, we identified a candidate neural biosignature of widespread hyperalgesia using high-density electroencephalography (EEG) in patients with chronic low back pain (cLBP). Specifically, stimulus-evoked delta, theta, and alpha oscillatory activity in the bilateral medial orbitofrontal cortex (mOFC) differentiated cLBP patients with widespread hyperalgesia from healthy controls. To examine cross-condition generalizability and advance predictive biomarker development for CP, we applied this mOFC-derived EEG biosignature to an independent cohort of patients with CP. The biosignature distinguished CP patients with widespread hyperalgesia and predicted individual treatment responses to peripherally targeted endoscopic therapy. These preliminary findings provide early support for a shared cortical signature of central sensitization across pain conditions and offer translational potential for developing EEG-based predictive tools for treatment response in CP.

SUMMARY OF BACKGROUND DATA/UNASSIGNED:Facet joint degeneration is a known source of chronic axial low back pain, and intra-articular steroid injections (IASI) have been used as a treatment. OBJECTIVES/UNASSIGNED:To systematically review the evidence of the effectiveness of fluoroscopically guided lumbar IASI for the treatment of lumbar facet joint pain. METHODS/UNASSIGNED:The primary outcome was ≥50 % pain reduction at ≥ 1 month, measured by Visual Analog Scale and/or Numeric Rating Scale. Secondary outcomes included ≥30 % functional improvement on a validated functional scale. Studies including group mean improvements in pain/function without categorical reporting were also considered. Two reviewers independently screened Embase, Cochrane, PubMed Medline, Ovid Medline, Web of Knowledge, and Google Scholar. The risk of bias was assessed using the Cochrane Risk of Bias Tool, and evidence quality was evaluated using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE). RESULTS/UNASSIGNED:Of the 701 publications screened, 21 met the inclusion criteria. Success rates for clinically significant pain reduction (≥50 % pain relief) ranged from 13 to 74 %, and functional improvement (≥30 % improvement) was 29 % at ≥ 1 month, based on only one study. Overall, mean improvement ranged from 11 to 59 % for pain relief and 8-58 % for function at ≥ 1 month. In the seven studies selecting patients with facet or medial branch blocks, success rates for clinically significant pain reduction (≥50 % pain relief) are reported as 13-74 % at ≥ 1 month. In this subgroup, mean pain improvement rates ranged from 23 to 67 % and functional improvement from 15 to 58 % at ≥ 1 month. According to GRADE, the overall quality of the evidence is very low due to the high risk of bias, study heterogeneity, and inconsistent methodologies. DISCUSSION/CONCLUSION/UNASSIGNED:Pragmatic and observational studies suggest IASI may reduce pain and disability, while sham-controlled trials have not demonstrated efficacy. Given the very low quality of evidence, the true effect of IASI is highly uncertain. Further high-quality, placebo-controlled studies using standardized diagnostic criteria are needed.

We estimated the extent to which different pain management practices, considered together as well as individually, mediated the relationship between chronic pain or physical disability and new-onset opioid use disorder (OUD) in a large cohort of adult Medicaid patients. Considering the plausibility of the assumptions required to identify different mediational estimands, we estimated natural indirect effects when considering mediation through the group of mediators together and estimated interventional indirect effects when considering mediation through each pain management practice individually. We estimated each effect using a nonparametric one-step estimator. The pain management variables we examined mediated all of the total effect of chronic pain on OUD risk and nearly half of the total effect of physical disability on OUD risk. High-dose, long-duration opioid prescribing and co-prescription of opioids with benzodiazepines, gabapentinoids, and muscle relaxants each contributed substantially to the increased risk of OUD due to chronic pain (contributing to 10-37% of the overall effect) and more moderately to the increased risk of OUD due to physical disability (contributing to 3-19% of the overall effect). Antidepressant or anti-inflammatory prescribing and physical therapy generally did not contribute to increased OUD risk, and, in some cases, even contributed to small reductions in risk.

INTRODUCTION/UNASSIGNED:This study aims to investigate the interregional functional connectivity in chronic back pain patients with widespread hyperalgesia, patients with localized back pain, and pain-free controls using stimulus-evoked high-density EEG recordings. METHODS/UNASSIGNED:We conducted high-density EEG recordings to compare the functional connectivity and betweenness centrality between these groups. RESULTS/UNASSIGNED:Compared with controls, chronic pain patients showed altered functional connectivity between regions that process cognitive information and regions that process sensory or affective information. Widespread hyperalgesia, however, is further differentiated from localized pain by decreased inter-hemispheric connectivity of sensory and affective areas and increased intra-hemispheric connectivity between sensory and cognitive cortices. Graph-theoretic analysis showed that whereas chronic pain is associated with decreased centrality of prefrontal, orbitofrontal, and cingulate areas, widespread hyperalgesia is distinguished by increased centrality of prefrontal and insular areas. DISCUSSION/UNASSIGNED:Together, our results show that although widespread hyperalgesia shares certain features with localized pain, it is further characterized by distinct cortical mechanisms.

BACKGROUND/UNASSIGNED:The informed consent process has traditionally taken place in person. The introduction of electronic consent (eConsent) has made remote consenting processes possible. Use of eConsent has increased since the COVID-19 pandemic. It has streamlined the process of consenting patients and has been shown to benefit the research study team and participants. ECONSENT IN THE KETAMINE ANALGESIA FOR LONG-LASTING PAIN RELIEF AFTER SURGERY KALPAS STUDY/UNASSIGNED:The KALPAS study is a multicenter, double-blind, randomized controlled study investigating the effectiveness of ketamine in reducing chronic post-mastectomy pain in women undergoing mastectomy for oncologic indication. The study uses a two-part consent form consisting of a master consent with information applicable to all sites and site-specific information. All potential participants receive the full two-part consent form for review. When signing the eConsent, however, all potential participants are provided with a concise summary of the informed consent document, an approach not widely used by multicenter studies. eConsent has been noted to be beneficial to research staff when trying to gather informed consent from participants who live far away from the hospital, want to include their family and friends, and for researchers who can approach patients outside of their clinical appointments. CONCLUSION/UNASSIGNED:The ability to consent patients remotely has allowed for a flexible workflow within sites and a more patient-centric process that focuses on including loved ones in the discussion and scheduling time to speak to a principal investigator. Demand for eConsent will likely continue in the post-COVID era, and use of a concise summary can allow for a more efficient consenting process.

INTRODUCTION/BACKGROUND:People with chronic pain are at increased risk of opioid misuse. Less is known about the unique risk conferred by each pain management treatment, as treatments are typically implemented together, confounding their independent effects. This study estimated the extent to which pain management treatments were associated with risk of opioid use disorder (OUD) for those with chronic pain, controlling for baseline demographic and clinical confounding variables and holding other pain management treatments at their observed levels. METHODS:Data were analyzed in 2024 from 2 chronic pain subgroups within a cohort of non-pregnant Medicaid patients aged 35-64 years, 2016-2019, from 25 states: those with (1) chronic pain and physical disability (CPPD) (N=6,133) or (2) chronic pain without disability (CP) (N=67,438). Nine pain management treatments were considered: prescription opioid (1) dose and (2) duration; (3) number of opioid prescribers; opioid co-prescription with (4) benzo- diazepines, (5) muscle relaxants, and (6) gabapentinoids; (7) nonopioid pain prescription, (8) physical therapy, and (9) other pain treatment modality. The outcome was OUD risk. RESULTS:Having opioids co-prescribed with gabapentin or benzodiazepine was statistically significantly associated with a 37-45% increased OUD risk for the CP subgroup. Opioid dose and duration also were significantly associated with increased OUD risk in this subgroup. Physical therapy was significantly associated with an 18% decreased risk of OUD in the CP subgroup. DISCUSSION/CONCLUSIONS:Coprescription of opioids with either gabapentin or benzodiazepines may substantially increase OUD risk. More positively, physical therapy may be a relatively accessible and safe pain management strategy.

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.