Opioids should not be prescribed for chronic pain after spinal cord injury

Relationships of self-reported opioid and benzodiazepine use with health-related quality of life among adults with spinal cord injury

BACKGROUND

There is limited understanding of the relationships between prescription opioid and benzodiazepine use and indices of health-related quality of life (HRQOL) among those with spinal cord injuries (SCI).

OBJECTIVE

To identify the relationships between self-reported prescription opioid and benzodiazepine use and two indicators of HRQOL, number of days in poor physical health and poor mental health in the past 30 days among adults with SCI.

METHODS

A cross-sectional cohort study of 918 adults with chronic (>1 year), traumatic SCI living in the Southeastern United States was conducted. Participants completed a self-report assessment (SRA).

RESULTS

In the preliminary model, both opioid and benzodiazepine use were associated with a greater number of days in poor physical health and poor mental health in the past month. After controlling for health conditions (pain intensity, spasticity, anxiety and perceived sleep insufficiency), opioid use was associated with 2.04 (CI = 0.69; 3.39) additional poor physical health days in the past 30 days, and benzodiazepine use was associated with 2.18 (CI = 0.70; 3.64) additional days of poor mental health. Age was associated with greater number of poor physical health days and fewer poor mental health days. Lower income was associated with poor mental health days. Most of the health conditions were significantly related to the number of past month poor physical and mental health days.

CONCLUSIONS

Opioid and benzodiazepine use are associated with poor physical and mental HRQOL, even after controlling for health conditions. Treatment strategies should consider potential unanticipated negative consequences of pharmacological interventions.

Unraveling the physiological and psychosocial signatures of pain by machine learning

BACKGROUND

Pain is a complex subjective experience, strongly impacting health and quality of life. Despite many attempts to find effective solutions, present treatments are generic, often unsuccessful, and present significant side effects. Designing individualized therapies requires understanding of multidimensional pain experience, considering physical and emotional aspects. Current clinical pain assessments, relying on subjective one-dimensional numeric self-reports, fail to capture this complexity.

METHODS

To this aim, we exploited machine learning to disentangle physiological and psychosocial components shaping the pain experience. Clinical, psychosocial, and physiological data were collected from 118 chronic pain and healthy participants undergoing 40 pain trials (4,697 trials).

FINDINGS

To understand the objective response to nociception, we classified pain from the physiological signals (accuracy >0.87), extracting the most important biomarkers. Then, using multilevel mixed-effects models, we predicted the reported pain, quantifying the mismatch between subjective level and measured physiological response. From these models, we introduced two metrics: TIP (subjective index of pain) and Φ (physiological index). These represent possible added value in the clinical process, capturing psychosocial and physiological pain dimensions, respectively. Patients with high TIP are characterized by frequent sick leave from work and increased clinical depression and anxiety, factors associated with long-term disability and poor recovery, and are indicated for alternative treatments, such as psychological ones. By contrast, patients with high Φ show strong nociceptive pain components and could benefit more from pharmacotherapy.

CONCLUSIONS

TIP and Φ, explaining the multidimensionality of pain, might provide a new tool potentially leading to targeted treatments, thereby reducing the costs of inefficient generic therapies.

FUNDING

RESC-PainSense, SNSF-MOVE-IT197271.

Neuropathic Pain Induced by Spinal Cord Injury from the Glia Perspective and Its Treatment

Regional neuropathic pain syndromes above, at, or below the site of spinal damage arise after spinal cord injury (SCI) and are believed to entail distinct pathways; nevertheless, they may share shared defective glial systems. Neuropathic pain after SCI is caused by glial cells, ectopic firing of neurons endings and their intra- and extracellular signaling mechanisms. One such mechanism occurs when stimuli that were previously non-noxious become so after the injury. This will exhibit a symptom of allodynia. Another mechanism is the release of substances by glia, which keeps the sensitivity of dorsal horn neurons even in regions distant from the site of injury. Here, we review, the models and identifications of SCI-induced neuropathic pain (SCI-NP), the mechanisms of SCI-NP related to glia, and the treatments of SCI-NP.

Substance use during the COVID-19 pandemic among persons with traumatic spinal cord injury: A cross-sectional perspective

STUDY DESIGN

Analysis of data from two cohorts of Spinal Cord Injury Model Systems Database (SCIMS) participants, pre-pandemic (2017-2019, n = 6368) and during pandemic (2020, n = 1889).

OBJECTIVES

To examine differences in substance use during the pandemic compared to the years prior to the pandemic.

SETTING

19 SCIMS Centers.

METHODS

Participant characteristics, wellness (depression, life satisfaction, resilience), participation, and substance use between the two cohorts were compared. Multiple logistic regression examined the association of the pandemic with substance use after accounting for other factors.

RESULTS

Characteristics of the two cohorts were similar. Cannabis and sedative uses were not greatly different (28.8% vs 25.1%, and 8.3% vs 6.6%) but did reach statistical significance. Non-prescribed opioid use was double for the pandemic group (6.6% vs 3.3%). Alcohol use patterns were similar across the two cohorts. Measures of wellness were similar, while the pandemic group reported lower participation. The odds of use of cannabis, sedatives, and opioids were 1.3, 1.3, and 2.2 times greater, respectively, for the pandemic cohort after accounting for demographics, wellness, and participation. Greater use of non-prescribed opioids was reported during the pandemic in the South compared to prior to the pandemic (13.8% vs 6.1%).

CONCLUSIONS

The pandemic may have been associated with increased use of non-prescribed substances in the traumatic spinal cord injury population. Efforts to pursue longitudinal investigations would be warranted for definitive analysis of trends. The provision of demonstrably effective substance use treatment resources delivered via accessible methods will likely be needed in this population, particularly opioid treatment.

The efficacy, safety, and satisfaction of telehealth-delivered hypnotic cognitive therapy for chronic pain in spinal cord injury: A pilot study with historical controls

CONTEXT/OBJECTIVE

In-person hypnotic cognitive therapy (HYP-CT) is a promising treatment for chronic spinal cord injury-related pain. We describe the effects of HYP-CT delivered via Zoom (Z-HYP-CT) and compare the effects to historical controls who received hypnosis, cognitive therapy, or HYP-CT in-person.

DESIGN

Open pilot trial of HYP-CT versus historical controls.

SETTING

Telehealth study that recruited people with chronic SCI.

PARTICIPANTS

Adults with moderate to severe chronic SCI-related pain.

INTERVENTIONS

Four weekly sessions of HYP-CT delivered via Zoom.

OUTCOME MEASURES

The primary outcome was average pain intensity on a 0-10 numerical rating scale measured at end of treatment (4 weeks) and 12 weeks. Secondary outcomes included pain interference, depression, sleep, pain catastrophizing, and pain self-efficacy.

RESULTS

23 individuals with SCI-related pain participated in the open trial and were compared to 21 historical controls. Average age was 54 years, 70% were male, and the majority were White. The participants were 11.6-13.1 years post-SCI and average pain intensity was 4.8-5.4/10. After Z-HYP-CT mixed-effects linear regressions showed that pain intensity was significantly less at 4 weeks (-1.28, P < .0001) and 12 weeks (-1.50, P < .0001) relative to baseline. Pain interference, depression, and pain catastrophizing also decreased significantly at both time points. There were no significant differences between the effects of Z-HYP-CT versus historical controls on any outcome variable.

CONCLUSION

HYP-CT delivered via telehealth was associated with reduced pain intensity and other benefits that were comparable to the effect achieved by in-person historical controls. The effects of Z-HYP-CT should be evaluated using a randomized controlled design.

Polypharmacy in spinal cord injury: Matched cohort analysis comparing drug classes, medical complications, and healthcare utilization metrics with 24-month follow-up

OBJECTIVE

Polypharmacy in spinal cord injury (SCI) is common and predisposes patients to increased risk of adverse events. Evaluation of long-term health consequences and economic burden of polypharmacy in patients with SCI is explored.

DESIGN

Retrospective cohort.

METHODS

The IBM Marketscan Research Databases claims-based dataset was queried to search for adult patients with SCI with a 2-year follow-up.

PARTICIPANTS

Two matched cohorts were analyzed: those with and without polypharmacy, analyzing index hospitalization, readmissions, payments, and health outcomes.

RESULTS

A total of 11 569 individuals with SCI were included, of which 7235 (63%) were in the polypharmacy group who took a median of 11 separate drugs over two years. Opioid analgesics were the most common medication, present in 57% of patients with SCI meeting the criteria of polypharmacy, followed by antidepressant medications (46%) and muscle relaxants (40%). Risk of pneumonia was increased for the polypharmacy group (58%) compared to the non-polypharmacy group (45%), as were urinary tract infection (79% versus 63%), wound infection (30% versus 21%), depression (76% versus 57%), and adverse drug events (24% versus 15%) at 2 years. Combined median healthcare payments were higher in polypharmacy at 2 years ($44 333 vs. $10 937, P < .0001).

CONCLUSION

Majority of individuals with SCI met the criteria for polypharmacy with nearly 60% of those prescribed opioids and taking drugs from high-risk side effect profiles. Polypharmacy in SCI was associated with a greater risk of pneumonia, depression, urinary tract infections, adverse drug events, and emergency room visits over two years with four times higher overall healthcare payments at 1-year post-injury.

Perspectives of people with spinal cord injury on a pain education resource

Introduction

Spinal cord injury (SCI) often leads to neuropathic pain that negatively affects quality of life. Several qualitative research studies in individuals with SCI who experience neuropathic pain indicate the lack of adequate information about pain. We previously developed an educational resource, the SeePain, based on scientific literature and a series of qualitative interviews of people with SCI, their significant others/family members, and SCI healthcare providers.

Methods

However, to quantitatively evaluate the utility of this educational resource in a larger sample, we examined the agreement and usefulness ratings of statements regarding clarity/comprehensibility, content, and format of the SeePain, derived from the thematic analysis of our previous qualitative interviews. Participants completed a survey that provided a digital version of the SeePain and then rated their agreement/usefulness with the statements using numerical rating scales.

Results

There were overall high perceived agreement and usefulness ratings regarding the SeePain's clarity, content, and format. A factor analysis reduced the agreement and usefulness ratings into 4 components (content, clarity, format, and delivery medium). Group comparisons showed that individuals with higher education were more likely to endorse electronic and website formats, and the usefulness of a shorter version of the SeePain; females and younger individuals showed greater endorsement for clarity. Finally, higher pain intensity ratings were associated with greater agreement and usefulness of the content of the SeePain.

Discussion

Overall, these results support the utility of the SeePain as a source of information regarding pain that may facilitate communication about pain and its management following SCI.

Treatments perceived to be helpful for neuropathic pain after traumatic spinal cord injury: A multicenter cross-sectional survey study

DESIGN

Cross-sectional survey.

OBJECTIVE

To evaluate the perceived helpfulness of pharmacological and non-pharmacological interventions and their combinations for neuropathic pain (NeuP) and subcategories of NeuP after spinal cord injury (SCI).

SETTING

Six Spinal Cord Injury Model System Centers.

METHODS

Three hundred ninety one individuals at least one year post traumatic SCI were enrolled. A telephone survey was conducted to determine the pharmacologic and non-pharmacologic treatments used in the last 12 months for each participant's three worst pains, whether these treatments were "helpful", and if currently used, each treatments' effectiveness.

RESULTS

Two hundred twenty participants (56%) reported 354 distinct NeuPs. Pharmacological treatments rated helpful for NeuP were non-tramadol opioids (opioids were helpful for 86% of opioid treated NeuPs), cannabinoids (83%), and anti-epileptics (79%). Non-pharmacological treatments rated helpful for NeuP were massage (76%), body position adjustment (74%), and relaxation therapy (70%). Those who used both opioids and exercise reported greater NeuP treatment helpfulness compared to participants using opioids without exercise (P = 0.03).

CONCLUSIONS

Opioids, cannabinoids, and massage were reported more commonly as helpful than treatments recommended as first-line therapies by current clinical practice guidelines (CPGs) for NeuP after SCI (antiepileptics and antidepressants). Individuals with SCI likely value the modulating effects of pharmacological and non-pharmacological treatments on the affective components of pain in addition to the sensory components of pain when appraising treatment helpfulness.

Indicators of publicly funded prescription opioid use among persons with traumatic spinal cord injury in Ontario, Canada

OBJECTIVE

To describe the proportion and identify predictors of community-dwelling individuals with traumatic spinal cord injury (TSCI) who were dispensed ≥1 publicly funded opioid in the year after injury using a retrospective cohort study.

SETTING

Ontario, Canada.

PARTICIPANTS, INTERVENTIONS, OUTCOME MEASURES

We used administrative data to identify predictors of receiving publicly funded prescription opioids during the year after injury for individuals who were injured between April 2004 and March 2015. Our outcome was modeled using robust Poisson multivariable regression and we reported adjusted relative risks (aRR) with 95% confidence intervals.

RESULTS

In our retrospective cohort of 934 individuals with TSCI who were eligible for the provincial drug program, 510 (55%) received ≥1 prescription opioid in the year after their injury. Most individuals were male (71%) and the median age was 63 years (interquartile range: 42-72). Being male (aRR 1.15, 95% confidence interval [CI] 1.01-1.31), having chronic obstructive pulmonary disease (aRR 1.25, 95% CI 1.05-1.50), and using prescription opioids before injury (aRR 1.46, 95% CI 1.29-1.66) were significantly associated with receiving opioids in the year after TSCI. Short durations of hospital stay after injury were also identified as being a significant risk factor of outpatient opioid use (aRR = 1.28, 95% CI = 1.08-1.51) when compared to longer hospital stays.

CONCLUSION

This study presented evidence showing that most individuals eligible for Ontario's public drug program who experienced a TSCI used opioids in the year following their injury. Due to the paucity of research on this population and their potential for elevated risks of adverse events, it is important for additional studies to be conducted on opioid use in this population to understand short-term and long-term risks and benefits.

Spinal cord injury and prescribed opioids for pain: a scoping review

OBJECTIVE

Spinal cord injury (SCI) is a life-altering neurological condition affecting physical and psycho-social functioning and associated high rates of pain. Thus, individuals with SCI may be more likely to be exposed to prescription opioids. A scoping review was conducted to synthesize published research findings on post-acute SCI and prescription opioid use for pain, identify literature gaps, and propose recommendations for future research.

METHODS

We searched 6 electronic bibliographic databases (PubMed [MEDLINE], Ovid [MEDLINE], EMBASE, Cochrane Library, CINAHL, PsychNET) for articles published from 2014 through 2021. Terms for "spinal cord injury" and "prescription opioid use" were used. Included articles were in English and peer reviewed. Data were extracted using an electronic database by 2 independent reviewers. Opioid use risk factors for chronic SCI were identified and a gap analysis was performed.

RESULTS

Of the 16 articles included in the scoping review, a majority were conducted in the United States (n = 9). Most articles lacked information on income (87.5%), ethnicity (87.5%), and race (75%). Prescription opioid use ranged from 35% to 64% in articles reporting this information (n = 7 articles, n = 3675 participants). Identified risk factors for opioid use included middle age, lower income, osteoarthritis diagnosis, prior opioid use, and lower-level spinal injury. Limited reporting of diversity in study populations, absence of risk of polypharmacy, and limited high quality methodology were identified gaps.

CONCLUSIONS

Future research should report data on prescription opioid use in SCI populations, with additional demographics such as race, ethnicity, and income, given their importance to risk outcomes.

Assessment of high-risk opioid use metrics among individuals with spinal cord injury: A brief report

OBJECTIVE

To examine high-risk opioid prescription metrics among individuals with chronic spinal cord injury (SCI) living in South Carolina.

DESIGN

Cohort Study.

SETTING

Two statewide population-based databases, an SCI Surveillance Registry and state prescription drug monitoring program (PDMP).

PARTICIPANTS

Linked data was obtained for 503 individuals with chronic (>1year-post injury) SCI who were injured in 2013 or 2014 and who survived at least 3 years post-injury.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE(S)

Opioid prescription metrics were obtained from the PDMP. Fill data during the period between January 1, 2014 and December 31, 2017 were analyzed to assess high-risk opioid use. Outcomes included: percentage of individuals prescribed chronic opioids, high-dose chronic opioid therapy (daily morphine milligram equivalents (MME) ≥50 and ≥90), and chronic concurrent opioids and benzodiazepines, sedatives, or hypnotics (BSH).

RESULTS

Over half (53%) of the individuals filled an opioid in years 2-3 after injury. Of those, 38% had a concurrent BSH fill during the study period, 76% of which were for benzodiazepines. In any given quarter over the two-year timeframe, over half of the opioid prescriptions were for 60 days or more (chronic opioid prescriptions). Of those, roughly 40% of the individuals had high-dose chronic opioid prescriptions ≥50 MME/d and 25% were ≥90 MME/d. Over 33% had a concurrent BSH prescription for ≥60 days.

CONCLUSIONS

While the number of individuals receiving high-risk opioid prescriptions may not be large, it is a concerning number of prescriptions. The findings suggest a need for more cautious opioid prescribing and monitoring of high-risk use in adults with chronic SCI.

Opioid Dependence and Associated Health Care Utilization and Cost in Traumatic Spinal Cord Injury Population: Analysis Using Marketscan Database

Background

Postinjury pain is a well-known debilitating complication of spinal cord injury (SCI), often resulting in long-term, high-dose opioid use with the potential for dependence. There is a gap in knowledge about the risk of opioid dependence and the associated health care utilization and cost in SCI.

Objectives

To evaluate the association of SCI with postinjury opioid use and dependence and evaluate the effect of this opioid dependence on postinjury health care utilization.

Methods

Using the MarketScan Database, health care utilization claims data were queried to extract 7187 adults with traumatic SCI from 2000 to 2019. Factors associated with post-SCI opioid use and dependence, postinjury health care utilization, and payments were analyzed with generalized linear regression models.

Results

After SCI, individuals were more likely to become opioid users or transition from nondependent to dependent users (negative change: 31%) than become nonusers or transition from dependent to nondependent users (positive change: 14%, p < .0001). Individuals who were opioid-dependent users pre-SCI had more than 30 times greater odds of becoming dependent after versus not (OR 34; 95% CI, 26-43). Dependent users after injury (regardless of prior use status) had 2 times higher utilization payments and 1.2 to 6 times more health care utilization than nonusers.

Conclusion

Opioid use and dependence were associated with high health care utilization and cost after SCI. Pre-SCI opioid users were more likely to remain users post-SCI and were heavier consumers of health care. Pre- and postopioid use history should be considered for treatment decision-making in all individuals with SCI.

Litigation involving sports-related spinal injuries: a comprehensive review of reported legal claims in the United States in the past 70 years

BACKGROUND CONTEXT

Sports-related spinal injuries can be catastrophic in nature. Athletes competing in collision sports (eg, football) may be particularly prone to injury given the high-impact nature of these activities. Due to the oftentimes profound impact of sports-related spinal injuries on health and quality-of-life, they are also associated with a substantial risk of litigation. However, no study to date has assessed litigation risks associated with sports-related spinal injuries. A better understanding of the risk factors surrounding these legal claims may provide insights into injury prevention and other strategies to minimize litigation risks. In addition, it may allow the spine surgeon to better recognize the health, socioeconomic, and legal challenges faced by this patient population.

PURPOSE

To provide a comprehensive assessment of reported legal claims involving sports-related spinal injuries, including a comparative analysis of legal outcomes between collision and non-collision sports. To discuss strategies to prevent sports-related spinal injuries and minimize litigation risks.

STUDY DESIGN/SETTING

Retrospective review.

PATIENT SAMPLE

Athletes experiencing spinal injuries during sports.

OUTCOME MEASURES

Outcomes included verdict outcome (defendant vs. plaintiff), legal claims, injuries sustained, clinical symptoms, and award payouts.

METHODS

The legal research database Westlaw Edge (Thomson Reuters) was queried for legal claims brought in the United States from 1950 to 2021 involving sports-related spinal injuries. Verdict or settlement outcomes were collected as well as award payouts, time to case closure, case year, and case location. Demographic data, including type of sport (ie collision vs. non-collision sport) and level of play were obtained. Legal claims, spinal injuries sustained, and clinical symptoms were also extracted. Furthermore, the nature of injury, injured spinal region, and treatment pursued were collected. Descriptive statistics were reported for all cases and independent-samples t-tests and chi-square tests were used to compare differences between collision and non-collision sports.

RESULTS

Of the 840 cases identified on initial search, 78 met our criteria for in-depth analysis. This yielded 62% (n=48) defendant verdicts, 32% (n=25) plaintiff verdicts, and 6% (n=5) settlements, with a median inflation-adjusted award of $780,000 (range: $5,480-$21,585,000) for all cases. The most common legal claim was negligent supervision (n=38, 46%), followed by premises liability (n=23, 28%), and workers' compensation/no fault litigation (n=10, 12%). The most common injuries sustained were vertebral fractures (n=34, 44%) followed by disc herniation (n=14, 18%). Most cases resulted in catastrophic neurological injury (n=37, 49%), either paraplegia (n=6, 8%) or quadriplegia (n=31, 41%), followed by chronic/refractory pain (n=32, 43%). Non-collision sport cases had a higher percentage of premises liability claims (41% vs. 11%, p=.006) and alleged chronic/refractory pain (53% vs. 28%, p=.04). Conversely, collision sport cases had a higher proportion of workers' compensation/no fault litigation (23% vs. 4%, p=.03) and cases involving disc herniation (29% vs. 9%, respectively; p=.04).

CONCLUSION

Sports-related spinal injuries are associated with multiple and complex health, socioeconomic, and legal consequences, with median inflation-adjusted award payouts nearing $800,000 per case. In our cohort, the most commonly cited legal claims were negligent supervision and premises liability, emphasizing the need for prevention guidelines for safe sports practice, especially in non-professional settings. Cases involving athletes participating in non-collision sports were significantly associated with claims citing chronic/refractory pain, highlighting the importance of long-term care in severely injured athletes.

Combined non-psychoactive Cannabis components cannabidiol and β-caryophyllene reduce chronic pain via CB1 interaction in a rat spinal cord injury model

The most frequently reported use of medical marijuana is for pain relief. However, its psychoactive component Δ9-tetrahydrocannabinol (THC) causes significant side effects. Cannabidiol (CBD) and β-caryophyllene (BCP), two other cannabis constituents, possess more benign side effect profiles and are also reported to reduce neuropathic and inflammatory pain. We evaluated the analgesic potential of CBD and BCP individually and in combination in a rat spinal cord injury (SCI) clip compression chronic pain model. Individually, both phytocannabinoids produced dose-dependent reduction in tactile and cold hypersensitivity in male and female rats with SCI. When co-administered at fixed ratios based on individual A50s, CBD and BCP produced enhanced dose-dependent reduction in allodynic responses with synergistic effects observed for cold hypersensitivity in both sexes and additive effects for tactile hypersensitivity in males. Antinociceptive effects of both individual and combined treatment were generally less robust in females than males. CBD:BCP co-administration also partially reduced morphine-seeking behavior in a conditioned place preference (CPP) test. Minimal cannabinoidergic side effects were observed with high doses of the combination. The antinociceptive effects of the CBD:BCP co-administration were not altered by either CB2 or μ-opioid receptor antagonist pretreatment but, were nearly completely blocked by CB1 antagonist AM251. Since neither CBD or BCP are thought to mediate antinociception via CB1 activity, these findings suggest a novel CB1 interactive mechanism between these two phytocannabinoids in the SCI pain state. Together, these findings suggest that CBD:BCP co-administration may provide a safe and effective treatment option for the management of chronic SCI pain.

Comprehensive phenotyping of cutaneous afferents reveals early-onset alterations in nociceptor response properties, release of CGRP, and hindpaw edema following spinal cord injury

Spinal cord injury (SCI) is a complex syndrome that has profound effects on patient well-being, including the development of medically-resistant chronic pain. The mechanisms underlying SCI pain have been the subject of thorough investigation but remain poorly understood. While the majority of the research has focused on changes occurring within and surrounding the site of injury in the spinal cord, there is now a consensus that alterations within the peripheral nervous system, namely sensitization of nociceptors, contribute to the development and maintenance of chronic SCI pain. Using an ex vivo skin/nerve/DRG/spinal cord preparation to characterize afferent response properties following SCI, we found that SCI increased mechanical and thermal responding, as well as the incidence of spontaneous activity (SA) and afterdischarge (AD), in below-level C-fiber nociceptors 24 hr following injury relative to naïve controls. Interestingly, the distribution of nociceptors that exhibit SA and AD are not identical, and the development of SA was observed more frequently in nociceptors with low heat thresholds, while AD was found more frequently in nociceptors with high heat thresholds. We also found that SCI resulted in hindpaw edema and elevated cutaneous calcitonin gene-related peptide (CGRP) concentration that were not observed in naïve mice. These results suggest that SCI causes a rapidly developing nociceptor sensitization and peripheral inflammation that may contribute to the early emergence and persistence of chronic SCI pain.

Macrophage Migration Inhibitory Factor (MIF) Makes Complex Contributions to Pain-Related Hyperactivity of Nociceptors after Spinal Cord Injury

Neuropathic pain is a major, inadequately treated challenge for people with spinal cord injury (SCI). While SCI pain mechanisms are often assumed to be in the CNS, rodent studies have revealed mechanistic contributions from primary nociceptors. These neurons become chronically hyperexcitable after SCI, generating ongoing electrical activity that promotes ongoing pain. A major question is whether extrinsic chemical signals help to drive ongoing electrical activity after SCI. People living with SCI exhibit acute and chronic elevation of circulating levels of macrophage migration inhibitory factor (MIF), a cytokine implicated in preclinical pain models. Probable nociceptors isolated from male rats and exposed to an MIF concentration reported in human plasma (1 ng/ml) showed hyperactivity similar to that induced by SCI, although, surprisingly, a 10-fold higher concentration failed to increase excitability. Conditioned behavioral aversion to a chamber associated with peripheral MIF injection suggested that MIF stimulates affective pain. A MIF inhibitor, Iso-1, reversed SCI-induced hyperexcitability. Unlike chronic SCI-induced hyperexcitability, acute MIF-induced hyperexcitability was only partially abrogated by inhibiting ERK signaling. Unexpectedly, MIF concentrations that induced hyperactivity in nociceptors from naive animals, after SCI induced a long-lasting conversion from a highly excitable nonaccommodating type to a rapidly accommodating, hypoexcitable type, possibly as a homeostatic response to prolonged depolarization. Treatment with conditioned medium from cultures of DRG cells obtained after SCI was sufficient to induce MIF-dependent hyperactivity in neurons from naive rats. Thus, changes in systemic and DRG levels of MIF may help to maintain SCI-induced nociceptor hyperactivity that persistently promotes pain.SIGNIFICANCE STATEMENT Chronic neuropathic pain is a major challenge for people with spinal cord injury (SCI). Pain can drastically impair quality of life, and produces substantial economic and social burdens. Available treatments, including opioids, remain inadequate. This study shows that the cytokine macrophage migration inhibitory factor (MIF) can induce pain-like behavior and plays an important role in driving persistent ongoing electrical activity in injury-detecting sensory neurons (nociceptors) in a rat SCI model. The results indicate that SCI produces an increase in MIF release within sensory ganglia. Low MIF levels potently excite nociceptors, but higher levels trigger a long-lasting hypoexcitable state. These findings suggest that therapeutic targeting of MIF in neuropathic pain states may reduce pain and sensory dysfunction by curbing nociceptor hyperactivity.

Treatments that are perceived to be helpful for non-neuropathic pain after traumatic spinal cord injury: a multicenter cross-sectional survey

STUDY DESIGN

Cross-sectional survey.

OBJECTIVES

The objective of the study was to identify the treatments that people with traumatic spinal cord injury (SCI) used for their non-neuropathic pains (nonNeuPs) and how they subjectively rated the helpfulness of those treatments.

SETTING

Six centers from the Spinal Cord Injury Model Systems.

METHODS

Three hundred ninety one individuals who were at least 1-year post-traumatic SCI were enrolled. A telephone survey was conducted for pharmacologic and non-pharmacologic treatments utilized in the last 12 months for each participant's three worst pains and the perceived helpfulness of each treatment for each pain.

RESULTS

One hundred ninety (49%) participants reported at least one nonNeuP (Spinal Cord Injury Pain Instrument score < 2) in the previous 7 days. NSAIDs/aspirin, acetaminophen, opioids, and cannabinoids were the most commonly used and helpful pharmacologic treatments for overall nonNeuP locations (helpful in 77-89% of treated pains). Body position adjustment, passive exercise, massage, resistive exercise, and heat therapy were reported as the most commonly used non-pharmacological treatments for nonNeuPs. Heat therapy, aerobic exercise, massage, and body position adjustment were the most helpful non-pharmacological treatments for overall nonNeuP locations (helpful in 71-80% of treated pains). Perceived helpfulness of treatments varied by pain locations, which may be due to different mechanisms underlying pains in different locations.

CONCLUSIONS

Results of the study may help guide clinicians in selecting pain-specific treatments for nonNeuPs. The self-reported helpfulness of heat therapy, exercise, and massage suggests a possible direction for clinical trials investigating these treatments of nonNeuP while limiting the side effects accompanying pharmacologic treatments.

On the therapeutic targets and pharmacological treatments for pain relief following spinal cord injury: A mechanistic review

Spinal cord injury (SCI) is globally considered as one of the most debilitating disorders, which interferes with daily activities and life of the affected patients. Despite many developments in related recognizing and treating procedures, post-SCI neuropathic pain (NP) is still a clinical challenge for clinicians with no distinct treatments. Accordingly, a comprehensive search was conducted in PubMed, Medline, Scopus, Web of Science, and national database (SID and Irandoc). The relevant articles regarding signaling pathways, therapeutic targets and pharmacotherapy of post-SCI pain were also reviewed. Data were collected with no time limitation until November 2020. The present study provides the findings on molecular mechanisms and therapeutic targets, as well as developing the critical signaling pathways to introduce novel neuroprotective treatments of post-SCI pain. From the pathophysiological mechanistic point of view, post-SCI inflammation activates the innate immune system, in which the immune cells elicit secondary injuries. So, targeting the critical signaling pathways for pain management in the SCI population has significant importance in providing new treatments. Indeed, several receptors, ion channels, excitatory neurotransmitters, enzymes, and key signaling pathways could be used as therapeutic targets, with a pivotal role of n-methyl-D-aspartate, gamma-aminobutyric acid, and inflammatory mediators. The current review focuses on conventional therapies, as well as crucial signaling pathways and promising therapeutic targets for post-SCI pain to provide new insights into the clinical treatment of post-SCI pain. The need to develop innovative delivery systems to treat SCI is also considered.

Neurogenic Bowel in Acute Rehabilitation Following Spinal Cord Injury: Impact of Laxatives and Opioids

Objective: To explore the association between bowel dysfunction and use of laxatives and opioids in an acute rehabilitation setting following spinal cord injury (SCI). Methods: Data was collected regarding individuals with acute traumatic/non-traumatic SCI over a two-year period (2012–2013) during both the week of admission and discharge of their inpatient stay. Results: An increase in frequency of bowel movement (BM) (p = 0.003) and a decrease in frequency of fecal incontinence (FI) per week (p < 0.001) between admission and discharge was found across all participants. There was a reduction in the number of individuals using laxatives (p = 0.004) as well as the number of unique laxatives taken (p < 0.001) between admission and discharge in our cohort. The number of individuals using opioids and the average dose of opioids in morphine milligram equivalents (MME) from admission to discharge were significantly reduced (p = 0.001 and p = 0.02, respectively). There was a positive correlation between the number of laxatives and frequency of FI at discharge (r = 0.194, p = 0.014), suggesting that an increase in laxative use results in an increased frequency of FI. Finally, there was a significant negative correlation between average dose of opioids (MME) and frequency of BM at discharge, confirming the constipating effect of opioids (r = −0.20, p = 0.009).

Opioid Use Among Individuals With Spinal Cord Injury: Prevalence Estimates Based on State Prescription Drug Monitoring Program Data

OBJECTIVE

To identify the prevalence of opioid use in individuals with chronic spinal cord injury (SCI) living in South Carolina.

DESIGN

Cohort study.

SETTING

Data from 2 statewide population-based databases, an SCI Registry and the state prescription drug monitoring program, were linked and analyzed.

PARTICIPANTS

The study included individuals (N=503) with chronic (>1y) SCI who were injured between 2013 and 2014 in South Carolina and who survived at least 3 years postinjury.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Filled opioid prescriptions over a 2-year period (months 13-36 after injury). The main outcomes were total number of days with an opioid prescription over the 2-year period, length of coverage period [(final day of prescription coverage+the days supplied)-first day of prescription coverage], average daily morphine milligram equivalents (MME) over the coverage period, and concurrent days covered by an opioid and a prescription for benzodiazepines, sedatives, or hypnotics.

RESULTS

A total of 53.5% of the cohort (269 individuals) filled at least 1 opioid prescription during their second or third year after SCI. In total, there were 3386 opioid fills during the 2-year study. On average, the total number of opioid prescription days was 293±367. The average coverage period was 389±290 days, and the average daily MME during the coverage period was 41±70 MME. Of those who filled an opioid prescription, 23% had high-risk fills (>50 MME), and 38% had concurrent prescriptions for benzodiazepines, sedatives, or hypnotics.

CONCLUSIONS

The prevalence of opioid use was high among individuals with chronic SCI, exceeding rates observed in the general population. Also concerning were the rates of high-risk fills, based on average daily MME and concurrent benzodiazepine, sedative, or hypnotic prescriptions. These findings, taken together with those of earlier studies, should be used by providers to assess and monitor opioid use, decrease concurrent high-risk medication use, and attenuate the risk of adverse outcomes.

Effects of hypnosis, cognitive therapy, hypnotic cognitive therapy, and pain education in adults with chronic pain: a randomized clinical trial

Chronic pain is a significant health problem worldwide with limited pharmacological treatment options. This study evaluated the relative efficacy of 4 treatment sessions each of 4 nonpharmacological treatments: (1) hypnotic cognitive therapy (using hypnosis to alter the meaning of pain); (2) standard cognitive therapy; (3) hypnosis focused on pain reduction, and (4) pain education. One hundred seventy-three individuals with chronic pain were randomly assigned to receive 4 sessions of 1 of the 4 treatments. Primary (pain intensity) and secondary outcome measures were administered by assessors unaware of treatment allocation at pretreatment, posttreatment, and 3-, 6-, and 12-month follow-up. Treatment effects were evaluated using analysis of variance, a generalized estimating equation approach, or a Fisher exact test, depending on the outcome domain examined. All 4 treatments were associated with medium to large effect size improvements in pain intensity that maintained up to 12 months posttreatment. Pretreatment to posttreatment improvements were observed across the 4 treatment conditions on the secondary outcomes of pain interference and depressive symptoms, with some return towards pretreatment levels at 12-month follow-up. No significant between-group differences emerged in omnibus analyses, and few statistically significant between-group differences emerged in the planned pairwise analyses, although the 2 significant effects that did emerge favored hypnotic cognitive therapy. Future research is needed to determine whether the significant differences that emerged are reliable.

Prevalence of Prescribed Opioid Claims Among Persons With Traumatic Spinal Cord Injury in Ontario, Canada: A Population-Based Retrospective Cohort Study

OBJECTIVES

To examine prescription opioid claims among individuals with traumatic spinal cord injury (SCI) and to identify factors associated with both chronic opioid and chronic high-dose opioid use.

DESIGN

Retrospective cohort study using population-level administrative data.

SETTING

Ontario, Canada.

PARTICIPANTS

Individuals (N=1842) with traumatic SCI between April 1, 2004 and March 31, 2015.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Proportion of cohort with chronic opioid use (≥90d supply) and proportion with chronic high-dose opioid use (≥90d supply exceeding 90 mg morphine equivalent) between April 1, 2016 and March 31, 2017 (observation period).

RESULTS

A total of 1842 individuals with traumatic SCI were identified (74% men), with a median age of 51 years (interquartile range [IQR], 34-64y) and median duration of injury of 6 years (IQR, 4-9y). During the observation period, 35% were dispensed at least 1 opioid and 19.8% received chronic opioids, 39% of whom received more than 90 mg daily (chronic high dose). The median daily morphine equivalent dose was 212 mg morphine equivalent (IQR, 135.5-345.3 mg) for chronic high-dose users. Significant risk factors for chronic opioid use were male sex; age between 40 and 60 years; lower income; multimorbidity; thoracic, lumbar, or sacral level of injury; and having a previous diagnosis of osteoarthritis. Risk factors for chronic high-dose opioid use were an extended time since injury, age between 40 and 50 years, and increasing comorbidity.

CONCLUSIONS

A large proportion of individuals with traumatic SCI were dispensed an opioid in a recent 1-year period. A substantial proportion were dispensed more than 90 mg of morphine equivalents, which is the maximum recommended by the Canadian opioid guideline. Further research is needed to understand the risk factors associated with chronic, high-dose opioid use in this population.

Depolarization-Dependent C-Raf Signaling Promotes Hyperexcitability and Reduces Opioid Sensitivity of Isolated Nociceptors after Spinal Cord Injury

Chronic pain caused by spinal cord injury (SCI) is notoriously resistant to treatment, particularly by opioids. After SCI, DRG neurons show hyperactivity and chronic depolarization of resting membrane potential (RMP) that is maintained by cAMP signaling through PKA and EPAC. Importantly, SCI also reduces the negative regulation by Gαi of adenylyl cyclase and its production of cAMP, independent of alterations in G protein-coupled receptors and/or G proteins. Opioid reduction of pain depends on coupling of opioid receptors to Gαi/o family members. Combining high-content imaging and cluster analysis, we show that in male rats SCI decreases opioid responsiveness in vitro within a specific subset of small-diameter nociceptors that bind isolectin B4. This SCI effect is mimicked in nociceptors from naive animals by a modest 5 min depolarization of RMP (15 mm K⁺; -45 mV), reducing inhibition of cAMP signaling by μ-opioid receptor agonists DAMGO and morphine. Disinhibition and activation of C-Raf by depolarization-dependent phosphorylation are central to these effects. Expression of an activated C-Raf reduces sensitivity of adenylyl cyclase to opioids in nonexcitable HEK293 cells, whereas inhibition of C-Raf or treatment with the hyperpolarizing drug retigabine restores opioid responsiveness and blocks spontaneous activity of nociceptors after SCI. Inhibition of ERK downstream of C-Raf also blocks SCI-induced hyperexcitability and depolarization, without direct effects on opioid responsiveness. Thus, depolarization-dependent C-Raf and downstream ERK activity maintain a depolarized RMP and nociceptor hyperactivity after SCI, providing a self-reinforcing mechanism to persistently promote nociceptor hyperexcitability and limit the therapeutic effectiveness of opioids.SIGNIFICANCE STATEMENT Chronic pain induced by spinal cord injury (SCI) is often permanent and debilitating, and usually refractory to treatment with analgesics, including opioids. SCI-induced pain in a rat model has been shown to depend on persistent hyperactivity in primary nociceptors (injury-detecting sensory neurons), associated with a decrease in the sensitivity of adenylyl cyclase production of cAMP to inhibitory Gαi proteins in DRGs. This study shows that SCI and one consequence of SCI (chronic depolarization of resting membrane potential) decrease sensitivity to opioid-mediated inhibition of cAMP and promote hyperactivity of nociceptors by enhancing C-Raf activity. ERK activation downstream of C-Raf is necessary for maintaining ongoing depolarization and hyperactivity, demonstrating an unexpected positive feedback loop to persistently promote pain.

Cannabinoid receptors in osteoporosis and osteoporotic pain: a narrative update of review

OBJECTIVE

Osteoporosis is a skeletal disease with decreased bone mass and alteration in microarchitecture of bone tissue, and these changes put patients in risk of bone fracture. As a common symptom of osteoporosis and complication of osteoporotic fracture, chronic pain is a headache for clinicians. Nonsteroidal anti-inflammatory drugs (NSAIDs), selective COX-2 inhibitors and opioid drugs can temporarily reduce osteoporotic pain but have relevant side effects, such as addiction, tolerability and safety. The review summarized the recent advancements in the study of CB receptors in osteoporosis and osteoporotic pain and related mechanisms.

KEY FINDINGS

Recent studies indicated the two nociceptive receptors, cannabinoid receptor (CB) and transient receptor potential vanilloid type 1 (TRPV1) channel, are co-expressed in bone cells and play important role in the metabolism of bone cells, suggesting that dualtargeting these 2 receptors/channel may provide a novel approach for osteoporotic pain. In addition, both CB receptor and TRPV1 channel are found to be expressed in the glial cells which play vital role in mediating inflammation, chronic pain and metabolism of bone cells, suggesting a role of glial cells inosteoporotic pain.

SUMMARY

Multiple-targeting against glial cells, CB receptors and TRPV1 channel may be one effective therapeutic strategy for osteoporotic pain in the future, following the elucidation of the complicated mechanism.

Pulse article: opioid prescription for pain after spinal cord damage (SCD), differences from recommended guidelines, and a proposed algorithm for the use of opioids for pain after SCD

Study design

Online questionnaire of spinal cord injury (SCI) physicians.

Objectives

The objective of this study is to characterize the approach to opioid prescription for persons with spinal cord damage (SCD).

Setting

An international online questionnaire.

Methods

A survey was posted online and circulated among international societies within the field of SCI medicine from August to November 2018.

Results

One hundred and twenty-three physicians responded to the survey. Of these, 107 (92%) managed pain for persons with SCD. Most (82%) felt that opioid prescription was appropriate for uncontrolled acute pain, but fewer (67%) felt it was appropriate for chronic pain. Of those who felt opioids had a role in the treatment of neuropathic pain, 46% did not think there should be a specific upper limit of opioid dose. The majority (85%) would continue prescribing high doses (250 morphine milligram equivalent (MME) doses/day) if that dose were effective. Tramadol was the most common opioid prescribed first line.

Conclusion

Most physicians who responded to this survey prescribe opioids for intractable pain after SCD. A significant proportion of respondents believed that there should not be a specific upper limit of opioid dose prescribed if the drug is tolerated; this does not align with current recommendations. Most physicians do not feel influenced in their prescribing habits by regulatory bodies. If physicians decide to taper an opioid that is being tolerated well, it is most commonly related to a fear of the patient developing an opioid-use disorder. The authors propose an algorithm that may help align practice patterns with current recommended practice guidelines.

Survey on current treatments for pain after spinal cord damage

Study design

An online questionnaire.

Objectives

To assess the international spinal cord medicine and rehabilitation community's utilization of pharmacological and non-pharmacological treatments for spinal cord damage (SCD)-related pain and to determine whether approaches to SCD-related pain differ between developed and less developed nations.

Setting

An international collaboration of authors.

Methods

An on-line survey querying availability and utilization of a number of approaches to SCD-related pain was developed, distributed, and made available for 6 months. Responses were analyzed for the entire cohort and according to participants' descriptions of their home nations' economies.

Results

A total of 153 responses were submitted, mostly from developed nations. Nearly three quarters of subjects reported offering their patients with SCD narcotics; only 13% reported offering their patients with SCD medical cannabis. Subjects from developing countries were more likely than those from developed countries to prescribe buprenorphine (20.0% vs 15.6%; p = 0.001) and less likely to prescribe medical cannabis (0% vs 15.6%; p = 0.001) and acupuncture (4.0% vs 23.4%; p = 0.02).

Conclusions

Most spinal cord medicine clinicians employ a multimodal approach to pain. There are significant differences in utilization of pharmacologic and non-pharmacologic approach to SCD-related pain between clinicians from more and less developed countries.

Severe chronic pain following spinal cord damage: a pragmatic perspective for prescribing opioids

The controversial issue of prescribing opioids to people with spinal cord damage who have severe pain is discussed in this paper. The reasons for concern regarding the increase in opioid prescription over recent years are outlined, along with a summary of the major potential adverse outcomes associated with opioids, such as falls, respiratory suppression, adverse endocrine effects, cognitive impairment, and the potential for opioid abuse, addiction and death. Situations when opioids are more appropriate are considered to be in the immediate post-trauma or post-operative periods. More controversial is the use of opioids in chronic non-cancer pain. A brief review of the evidence regarding opioids in chronic non-cancer pain is presented, and strategies outlined for reducing the risk of adverse consequences from opioid use in chronic non-cancer pain. These strategies include considerations before starting opioids, during initiation, monitoring activities and the cessation process. A vital consideration before starting opioids includes ensuring that all alternatives to opioids have been fully considered and trialled. Finally, some pragmatic proposals for prescribing opioids in people with SCD are suggested. It is recommended that before opioids are commenced, that the informed consent process should be complimented by a treatment agreement, with an initial 4-week trial period, and close monitoring of established goals.