Incidence and predictors of neck and widespread pain after motor vehicle collision among US litigants and nonlitigants

Biobehavioral Predictors of Pain Intensity, Pain Interference, and Chronic Pain Episodes: A Prospective Cohort Study of African-American Adults

Racial disparities in pain experiences are well-established, with African-American (AA) adults reporting higher rates of daily pain, increased pain severity, and greater pain-related interference compared to non-Hispanic Whites. However, the biobehavioral factors that predict the transition to chronic pain among AA adults are not well understood. This prospective cohort study provided a unique opportunity to evaluate predictors of chronic pain onset among 130 AA adults (81 women), ages 18 to 44, who did not report chronic pain at their baseline assessment and subsequently completed follow-up assessments at 6- and 12-months. Outcome measures included pain intensity, pain-related interference, and chronic pain status. Comprehensive assessments of sociodemographic and biobehavioral factors were used to evaluate demographics, socioeconomic status, stress exposure, psychosocial factors, prolonged hypothalamic-pituitary-adrenal secretion, and quantitative sensory testing responses. At baseline, 30 adults (23.1%) reported a history of prior chronic pain. Over the 12-month follow-up period, 13 adults (10.0%) developed a new chronic pain episode, and 18 adults (13.8%) developed a recurrent chronic pain episode. Whereas socioeconomic status measures (ie, annual income, education) predicted changes in pain intensity over the follow-up period, quantitative sensory testing measures (ie, pain threshold, temporal summation of pain) predicted changes in pain interference. A history of chronic pain and higher depressive symptoms at baseline independently predicted the onset of a new chronic pain episode. The present findings highlight distinct subsets of biobehavioral factors that are differentially associated with trajectories of pain intensity, pain-related interference, and onset of chronic pain episodes in AA adults. PERSPECTIVE: This prospective study sought to advance understanding of biobehavioral factors that predicted pain outcomes over a 12-month follow-up period among AA adults without chronic pain at their initial assessment. Findings revealed distinct subsets of factors that were differentially associated with pain intensity, pain-related interference, and onset of chronic pain episodes.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Twelve-month recovery following road trauma: Results from an inception cohort in Vancouver, Canada

BACKGROUND

Injury-related disability following road trauma is a major public health concern. Unfortunately, outcome following road trauma and risk factors for poor recovery are inadequately studied, especially for road trauma survivors with minor injuries that do not require hospitalization.

OBJECTIVES

This manuscript reports 12-month recovery outcomes for a large cohort of road trauma survivors.

METHODS

This was a prospective, observational inception cohort study of 1,480 road trauma survivors recruited between July 2018 and March 2020 from 3 trauma centres in British Columbia, Canada. Participants were aged ≥16 years and arrived in a participating emergency department within 24 h of a motor vehicle collision. Data on baseline health and injury severity were collected from structured interviews and medical records. Outcome measures, including the SF-12, were collected during follow-up interviews at 2, 4, 6 and 12 months. Predictors of recovery outcomes were identified using Cox proportional hazards models and summarized using hazard ratios.

RESULTS

Only 42 % of participants self-reported full recovery and only 66 % reported a return to usual daily activities. Females, older individuals, pedestrians, and those who required hospital admission had a poorer recovery than other groups. Similar patterns were observed for the SF-12 physical component. For the SF-12 mental component, no significant differences were observed between participants admitted to hospital and those discharged home from the ED. Return to work was reported by 77 % of participants who had a paying job at baseline, with no significant differences between sex and age groups.

CONCLUSIONS

In a large cohort of road trauma survivors, under half self-reported full recovery one year after the injury. Poor mental health recovery was observed in both participants admitted to hospital and those discharged home from the ED. This finding may indicate a need for early intervention and continued mental health monitoring for all injured individuals, including for those with less serious injuries.

Incidence of persistent opioid use following traumatic injury

INTRODUCTION

Major traumatic injuries are a known risk factor for persistent opioid use, but data describing the relationship between specific traumatic injuries and opioid use is lacking.

METHODS

We used insurance claims data from January 1, 2001 to December 31, 2020 to estimate the incidence of new persistent opioid use in three hospitalized trauma populations: individuals hospitalized after burn injury (3809, 1504 of whom required tissue grafting), individuals hospitalized after motor vehicle collision (MVC; 9041), and individuals hospitalized after orthopedic injury (47, 637). New persistent opioid use was defined as receipt of ≥1 opioid prescriptions 90-180 days following injury in an individual with no opioid prescriptions during the year prior to injury.

RESULTS

New persistent opioid use was observed in 12% (267/2305) of individuals hospitalized after burn injury with no grafting, and 12% (176/1504) of burn injury patients requiring tissue grafting. In addition, new persistent opioid use was observed in 16% (1454/9041) of individuals hospitalized after MVC, and 20% (9455/47, 637) of individuals hospitalized after orthopedic trauma. In comparison, rates of persistent opioid use in all trauma cohorts (19%, 11, 352/60, 487) were greater than the rates of persistent opioid use in both non-traumatic major surgery (13%) and non-traumatic minor surgery (9%).

CONCLUSIONS

These data demonstrate that new persistent opioid use frequently occurs in these common hospitalized trauma populations. Improved interventions to reduce persistent pain and opioid use in patients hospitalized after these and other traumas are needed.

Adversity type and timing predict temporal summation of pain in African-American adults

African Americans are disproportionately exposed to adversity across the lifespan, which includes both stressful and traumatic events. Adversity, in turn, is associated with alterations in pain responsiveness. Racial differences in pain responsiveness among healthy adults are well established. However, the extent to which adversity type and timing are associated with alterations in pain responsiveness among healthy African-American adults is not well understood. The present study included 160 healthy African-American adults (98 women), ages 18 to 45. Outcome measures included pain tolerance and temporal summation of pain to evoked thermal pain. Composite scores were created for early-life adversity (childhood trauma, family adversity) and recent adversity (perceived stress, chronic stress burden). A measure of lifetime racial discrimination was also included. Higher levels of recent adversity were associated with higher temporal summation of pain, controlling for gender, age, and education. Neither early-life adversity nor lifetime racial discrimination were associated with temporal summation of pain. The present findings suggest that heightened temporal summation of pain among healthy African-American adults is associated with exposure to recent adversity events. Improved understanding of how recent adversity contributes to heightened temporal summation of pain in African Americans could help to mitigate racial disparities in pain experiences by identifying at-risk individuals who could benefit from early interventions.

Interleukin-10-producing monocytes contribute to sex differences in pain resolution in mice and humans

Pain is closely associated with the immune system, which exhibits sexual dimorphism. For these reasons, neuro-immune interactions are suggested to drive sex differences in pain pathophysiology. However, our understanding of peripheral neuro-immune interactions on sex differences in pain resolution remains limited. Here, we have shown, in both a mouse model of inflammatory pain and in humans following traumatic pain, that males had higher levels of interleukin (IL)-10 than females, which were correlated with faster pain resolution. Following injury, we identified monocytes (CD11b+ Ly6C+ Ly6G-F4/80 mid ) as the primary source of IL-10, with IL-10-producing monocytes being more abundant in males than females. In a mouse model, neutralizing IL-10 signaling through antibodies, genetically ablating IL-10R1 in sensory neurons, or depleting monocytes with clodronate all impaired the resolution of pain hypersensitivity in both sexes. Furthermore, manipulating androgen levels in mice reversed the sexual dimorphism of pain resolution and the levels of IL-10-producing monocytes. These results highlight a novel role for androgen-driven peripheral IL-10-producing monocytes in the sexual dimorphism of pain resolution. These findings add to the growing concept that immune cells play a critical role in resolving pain and preventing the transition into chronic pain.

Graphical abstract

Neck Symptoms and Associated Clinical Outcomes in Patients Following Concussion

OBJECTIVE

To examine the frequency and association of neck pain symptoms in patients with a concussion.

STUDY SETTING AND PARTICIPANTS

Three-hundred and thirty-one consecutively enrolled patients aged 9 to 68 years with a diagnosed concussion 1 to 384 days post-injury were enrolled at a concussion clinic from a single integrated healthcare system in Western Pennsylvania between 2019 and 2021.

DESIGN

Retrospective cohort analysis of prospectively collected concussion screening tool intake survey responses and clinical outcomes data. The primary outcome was self-reported neck pain or difficulty with neck movement on the Concussion Clinical Profiles Screening (CP Screen) tool, recovery time, and incidence of treatment referral. Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) composite scores, Vestibular/Ocular Motor Screening (VOMS) item scores, type and severity of neck symptoms, mechanism of injury, time from injury to clinic presentation, medical history, and concussion symptom profile were secondary outcomes.

RESULTS

Of the 306 consecutively enrolled eligible patients in the registry, 145 (47%) reported neck pain, 68 (22.2%) reported difficulty moving their neck, and 146 (47.7%) reported either symptom. A total of 47 (15.4%) participants reported more severe neck symptoms, and this group took longer to recover (40 ± 27 days) than those not reporting neck symptoms (30 ± 28 days; U = 8316, P < .001). Stepwise logistic regression predicting more severe neck symptoms was significant (Nagelkerke R2 = 0.174, χ 2 = 9.315, P = .316) with older age ( P = .019) and mechanism of injury including motor vehicle collisions (MVCs) ( P = .047) and falls ( P = .044) as risk factors. MVCs and falls were associated with over 4 times and 2 times greater risk, respectively, for reporting more severe neck symptoms.

CONCLUSION

Neck pain and stiffness symptoms are common in patients with a concussion following high-energy mechanisms of injury including MVCs or falls from height. These symptoms are associated with prolonged recovery. Providers should evaluate neck symptoms and consider targeted treatment strategies to limit their effects in patients with a concussion.

CpG Methylation Levels in HPA Axis Genes Predict Chronic Pain Outcomes Following Trauma Exposure

Chronic post-traumatic musculoskeletal pain (CPTP) is a common outcome of traumatic stress exposure. Biological factors that influence the development of CPTP are poorly understood, though current evidence indicates that the hypothalamic-pituitary-adrenal (HPA) axis plays a critical role in its development. Little is known about molecular mechanisms underlying this association, including epigenetic mechanisms. Here, we assessed whether peritraumatic DNA methylation levels at 248 5'-C-phosphate-G-3' (CpG) sites in HPA axis genes (FKBP5, NR3C1, CRH, CRHR1, CRHR2, CRHBP, POMC) predict CPTP and whether identified CPTP-associated methylation levels influence expression of those genes. Using participant samples and data collected from trauma survivors enrolled into longitudinal cohort studies (n = 290), we used linear mixed modeling to assess the relationship between peritraumatic blood-based CpG methylation levels and CPTP. A total of 66 (27%) of the 248 CpG sites assessed in these models statistically significantly predicted CPTP, with the three most significantly associated CpG sites originating from the POMC gene region (ie, cg22900229 [β = .124, P < .001], cg16302441 [β = .443, P < .001], cg01926269 [β = .130, P < .001]). Among the genes analyzed, both POMC (z = 2.36, P = .018) and CRHBP (z = 4.89, P < .001) were enriched in CpG sites significantly associated with CPTP. Further, POMC expression was inversely correlated with methylation levels in a CPTP-dependent manner (6-months NRS<4: r = -.59, P < .001; 6-months NRS ≥ 4: r = -.18, P = .2312). Our results suggest that methylation of HPA axis genes including POMC and CRHBP predict risk for and may contribute to vulnerability to CPTP. PERSPECTIVE: Peritraumatic blood levels of CpG methylation sites in HPA axis genes, particularly CpG sites in the POMC gene, predict CPTP development. This data substantially advances our understanding of epigenetic predictors and potential mediators of CPTP, a highly common, morbid, and hard-to-treat form of chronic pain.

Tolerability and efficacy of duloxetine for the prevention of persistent musculoskeletal pain after trauma and injury: a pilot three-group randomized controlled trial

ABSTRACT

This study investigated the tolerability and preliminary efficacy of duloxetine as an alternative nonopioid therapeutic option for the prevention of persistent musculoskeletal pain (MSP) among adults presenting to the emergency department with acute MSP after trauma or injury. In this randomized, double-blind, placebo-controlled study, eligible participants (n = 78) were randomized to 2 weeks of a daily dose of one of the following: placebo (n = 27), 30 mg duloxetine (n = 24), or 60 mg duloxetine (n = 27). Tolerability, the primary outcome, was measured by dropout rate and adverse effects. Secondary outcomes assessed drug efficacy as measured by (1) the proportion of participants with moderate to severe pain (numerical rating scale ≥ 4) at 6 weeks (pain persistence); and (2) average pain by group over the six-week study period. We also explored treatment effects by type of trauma (motor vehicle collision [MVC] vs non-MVC). In both intervention groups, duloxetine was well tolerated and there were no serious adverse events. There was a statistically significant difference in pain over time for the 60 mg vs placebo group ( P = 0.03) but not for the 30 mg vs placebo group ( P = 0.51). In both types of analyses, the size of the effect of duloxetine was larger in MVC vs non-MVC injury. Consistent with the role of stress systems in the development of chronic pain after traumatic stress, our data indicate duloxetine may be a treatment option for reducing the transition from acute to persistent MSP. Larger randomized controlled trials are needed to confirm these promising results.

A longitudinal assessment of posttraumatic stress symptoms and pain catastrophizing after injury

PURPOSE/OBJECTIVE

Identifying individuals with high levels of pain catastrophizing (PC) may inform early psychological interventions to prevent the transition from acute to chronic post-injury pain. We examined whether pre-and post-injury posttraumatic stress symptoms (PTSS) predict post-injury PC among emergency department (ED) patients following acute motor vehicle crash (MVC).

RESEARCH METHOD/DESIGN

This study represents secondary data analysis of a randomized clinical trial (NCT03247179) examining the efficacy of the PTSD Coach app on post-injury PTSS (PTSSpost). Among 63 injured ED patients (63% female; 57% non-White; average age = 37) with moderate pain (≥4 of 10), we assessed recall of pre-injury PTSS (PTSSrecall: stemming from preexisting exposures) and baseline PC within 24 hr post-MVC; PTSSpost stemming from the MVC was assessed 30-days later, and the outcome of PC was assessed at 90-days post-injury. We controlled for group assignment (intervention vs. control) in all analyses.

RESULTS

Results revealed that at baseline and 90-days, PC was higher among non-White versus White participants. After adjusting for relevant covariates, PTSSrecall uniquely predicted post-injury PC and each subscale of PC (helplessness, magnification, and rumination). Similarly, after controlling for PTSSrecall and relevant covariates, PTSSpost uniquely predicted total and subscale post-injury PC. Intervention group participants reported less rumination than control group participants.

CONCLUSIONS/IMPLICATIONS

These novel findings highlight that injured Black patients may be vulnerable to post-injury PC, and that both PTSSrecall and PTSSpost significantly predict post-injury PC. Brief PTSS assessment in the ED can identify high-risk patients who may benefit from early intervention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Use of serial smartphone-based assessments to characterize diverse neuropsychiatric symptom trajectories in a large trauma survivor cohort

The authors sought to characterize adverse posttraumatic neuropsychiatric sequelae (APNS) symptom trajectories across ten symptom domains (pain, depression, sleep, nightmares, avoidance, re-experiencing, anxiety, hyperarousal, somatic, and mental/fatigue symptoms) in a large, diverse, understudied sample of motor vehicle collision (MVC) survivors. More than two thousand MVC survivors were enrolled in the emergency department (ED) and completed a rotating battery of brief smartphone-based surveys over a 2-month period. Measurement models developed from survey item responses were used in latent growth curve/mixture modeling to characterize homogeneous symptom trajectories. Associations between individual trajectories and pre-trauma and peritraumatic characteristics and traditional outcomes were compared, along with associations within and between trajectories. APNS across all ten symptom domains were common in the first two months after trauma. Many risk factors and associations with high symptom burden trajectories were shared across domains. Both across and within traditional diagnostic boundaries, APNS trajectory intercepts, and slopes were substantially correlated. Across all domains, symptom severity in the immediate aftermath of trauma (trajectory intercepts) had the greatest influence on the outcome. An interactive data visualization tool was developed to allow readers to explore relationships of interest between individual characteristics, symptom trajectories, and traditional outcomes ( http://itr.med.unc.edu/aurora/parcoord/ ). Individuals presenting to the ED after MVC commonly experience a broad constellation of adverse posttraumatic symptoms. Many risk factors for diverse APNS are shared. Individuals diagnosed with a single traditional outcome should be screened for others. The utility of multidimensional categorizations that characterize individuals across traditional diagnostic domains should be explored.

Duration of Reduction in Enduring Stress-Induced Hyperalgesia Via FKBP51 Inhibition Depends on Timing of Administration Relative to Traumatic Stress Exposure

Chronic pain development is a frequent outcome of severe stressor exposure, with or without tissue injury. Enduring stress-induced hyperalgesia (ESIH) is believed to play a central role, but the precise mechanisms mediating the development of chronic post-traumatic pain, and the time-dependency of these mechanisms, remain poorly understood. Clinical and preclinical data suggest that the inhibition of FK506-binding protein 51 (FKBP51), a key stress system regulator, might prevent ESIH. We evaluated whether peritraumatic inhibition of FKBP51 in an animal model of traumatic stress exposure, the single prolonged stress (SPS) model, reversed ESIH evaluated via daily mechanical von Frey testing. FKBP51 inhibition was achieved using SAFit2, a potent and specific small molecule inhibitor of FKBP51, administered to male and female Sprague-Dawley rats via intraperitoneal injection. To assess timing effects, FKBP51 was administered at different times relative to stress (SPS) exposure. SAFit2 administration immediately after SPS produced a complete reversal in ESIH lasting >7 days. In contrast, SAFit2 administration 72 hours following SPS produced only temporary hyperalgesia reversal, and administration 120h following SPS had no effect. Similarly, animals undergoing SPS together with tissue injury (plantar incision) receiving SAFit2 immediately post-surgery developed acute hyperalgesia but recovered by 4 days and did not develop ESIH. These data suggest that: 1) FKBP51 plays an important, time-dependent role in ESIH pathogenesis, 2) time windows of opportunity may exist to prevent ESIH via FKBP51 inhibition after traumatic stress, with or without tissue injury, and 3) the use of inhibitors of specific pathways may provide new insights into chronic post-traumatic pain development. PERSPECTIVE: The current work adds to a growing body of literature indicating that FKBP51 inhibition is a highly promising potential treatment strategy for reducing hyperalgesia. In the case of post-traumatic chronic pain, we show that such a treatment strategy would be particularly impactful if administered early after traumatic stress exposure.

Posttraumatic Stress Symptoms and Pain Sensitization After Whiplash Injury: A Longitudinal Cohort Study With Quantitative Sensory Testing

Posttraumatic stress symptoms (PTSS) are common after whiplash injury and are associated with poor recovery. The acute stress response may lead to pain sensitization and widespread pain, thereby compromising recovery. To our knowledge, no longitudinal study has assessed the associations between early PTSS and pain sensitization over time using quantitative sensory testing (QST). The aim of this study was to compare participants with different levels of PTSS, as measured by the impact of event scale (IES; subclinical 0–8, mild 9–25, and clinical ≥ 26) at baseline (<10-day post-injury) and at a follow-up of 1, 3, 6, and 12-month post-injury on pain sensitivity, neck mobility, pain distribution, and pain intensity. In total, 740 participants were recruited from emergency units or general practitioners with acute neck pain after a whiplash injury. The clinical PTSS group showed increased pain sensitivity on all QSTs at all time points compared to the subclinical PTSS group. Also, the clinical PTSS group showed significantly lower neck mobility at all time points except for a 3-month follow-up compared to the subclinical PTSS group. Moreover, the clinical PTSS group showed more widespread pain and self-reported headache and neck pain intensity at all time points compared to the subclinical PTSS group. This study emphasizes that participants with clinical levels of PTSS constitute a high-risk group that is sensitized to pain early after the injury. Hence, screening for PTSS within the 1st week after whiplash injury for those who experience high levels of pain intensity and distress may be an important clinical procedure in the assessment and treatment of whiplash-associated disorders (WAD).

Neurocognition after motor vehicle collision and adverse post-traumatic neuropsychiatric sequelae within 8 weeks: Initial findings from the AURORA study

BACKGROUND

Previous work has indicated that differences in neurocognitive functioning may predict the development of adverse post-traumatic neuropsychiatric sequelae (APNS). Such differences may be vulnerability factors or simply correlates of APNS-related symptoms. Longitudinal studies that measure neurocognitive functioning at the time of trauma are needed to determine whether such differences precede the development of APNS.

METHODS

Here, we present findings from a subsample of 666 ambulatory patients from the AURORA (Advancing Understanding of RecOvery afteR trumA) study. All patients presented to EDs after a motor vehicle collision (MVC). We examined associations of neurocognitive test performance shortly after MVC with peritraumatic symptoms in the ED and APNS (depression, post-traumatic stress, post-concussive symptoms, and pain) 2 weeks and 8 weeks later. Neurocognitive tests assessed processing speed, attention, verbal reasoning, memory, and social perception.

RESULTS

Distress in the ED was associated with poorer processing speed and short-term memory. Poorer short-term memory was also associated with depression at 2 weeks post-MVC, even after controlling for peritraumatic distress. Finally, higher vocabulary scores were associated with pain 2 weeks post-MVC.

LIMITATIONS

Self-selection biases among those who present to the ED and enroll in the study limit generalizability. Also, it is not clear whether observed neurocognitive differences predate MVC exposure or arise in the immediate aftermath of MVC exposure.

CONCLUSIONS

Our results suggest that processing speed and short-term memory may be useful predictors of trauma-related characteristics and the development of some APNS, making such measures clinically-relevant for identifying at-risk individuals.

Peritraumatic 17β-estradiol levels influence chronic posttraumatic pain outcomes

ABSTRACT

Biologic factors that predict risk for and mediate the development of common outcomes of trauma exposure such as chronic posttraumatic pain (CPTP) are poorly understood. In the current study, we examined whether peritraumatic circulating 17β-estradiol (E2) levels influence CPTP trajectories. 17β-estradiol levels were measured in plasma samples (n = 254) collected in the immediate aftermath of trauma exposure from 3 multiethnic longitudinal cohorts of men and women trauma survivors. Chronic posttraumatic pain severity was evaluated 6 weeks, 6 months, and 1 year after traumatic stress exposure. Repeated measures mixed models were used to test the relationship between peritraumatic E2 levels and prospective CPTP. Secondary analyses in a nested cohort assessed the influence of participant body mass index on the E2-CPTP relationship. In women, a statistically significant inverse relationship between peritraumatic E2 and CPTP was observed (β = -0.280, P = 0.043) such that higher E2 levels predicted lower CPTP severity over time. Secondary analyses identified an E2 * body mass index interaction in men from the motor vehicle collision cohort such that obese men with higher E2 levels were at greater risk of developing CPTP. In nonobese men from the motor vehicle collision cohort and in men from the major thermal burn injury cohort, no statistically significant relationship was identified. In conclusion, peritraumatic circulating E2 levels predict CPTP vulnerability in women trauma survivors. In addition, these data suggest that peritraumatic administration of E2 might improve CPTP outcomes for women; further research is needed to test this possibility.

Predicting nonrecovery in adults with incident traffic injuries including post-traumatic headache

IMPORTANCE

The management of traffic injuries is challenging for clinicians. Knowledge about predictors of nonrecovery from traffic injuries may help to improve patient care.

OBJECTIVE

To develop a prediction model for self-reported overall nonrecovery from traffic injuries six months post-collision in adults with incident traffic injuries including post-traumatic headache (PTH).

DESIGN

Inception cohort studies of adults with incident traffic injuries (including PTH) injured in traffic collisions between November 1997 and December 1999 in Saskatchewan, Canada; and between January 2004 and January 2005 in Sweden.

METHODS

Prediction model development and geographical external validation.

SETTING

The Saskatchewan cohort (development) was population-based (N = 4,162). The Swedish cohort (validation) (N = 379) were claimants from two insurance companies covering 20% of cars driven in Sweden in 2004.

PARTICIPANTS

All adults injured in traffic collisions who completed a baseline questionnaire within 30 days of collision. Excluded were those hospitalized > 2 days, lost consciousness > 30 min, or reported headache < 3/10 on the numerical rating scale. Follow-up rates for both cohorts were approximately 80%.

PREDICTORS

Baseline sociodemographic, pre-injury, and injury factors.

OUTCOME

Self-reported nonrecovery from all injuries (not "all better (cured)" on the self-perceived recovery scale) six months after traffic collision.

RESULTS

Both cohorts were predominantly female (69.8% in Saskatchewan, 65.2% in Sweden), with median ages 35.9 years (Saskatchewan), and 38.0 years (Sweden). Predictors were age, low back pain, symptoms in arms or hands, hearing problems, sleeping problems, pre-existing headache, and lower recovery expectations. With a positive score (i.e., ≥0.85 probability), the model can rule in the presence of self-reported nonrecovery from all injuries at six months (development: specificity = 91.3%, 95% CI 89.2%-93.0%; sensitivity = 27.8%, 95% CI 26.0%-29.7%; positive likelihood ratio (LR + ) = 3.2, 95% CI 2.5-4.0; negative likelihood ratio (LR-) = 0.79, 95% CI 0.76-0.82; validation: specificity = 72.6%, 95% CI 61.4%-81.5%; sensitivity = 60.5%, 95% CI 53.9%-66.7%); LR+ = 2.2, 95% CI 1.5-3.3; LR- = 0.5, 95% CI 0.4-0.7).

CONCLUSIONS AND RELEVANCE

In adults with incident traffic injuries including PTH, predictors other than those related to baseline head and neck pain drive overall nonrecovery. Developing and testing interventions targeted at the modifiable predictors may help to improve outcomes for adults after traffic collision.

Polygenic risk scoring to assess genetic overlap and protective factors influencing posttraumatic stress, depression, and chronic pain after motor vehicle collision trauma

Posttraumatic stress (PTS), depressive symptoms (DS), and musculoskeletal pain (MSP) are common sequelae of trauma exposure. Although these adverse posttraumatic neuropsychiatric sequelae (APNS) are often studied separately, clinical comorbidity is high. In a cohort of European American motor vehicle collision (MVC) trauma survivors (n = 781), substantial PTS (≥33, IES-R), DS (≥26, CES-D), and MSP (≥4, 0-10 NRS) were identified via a 6-month survey. Genetic risk was estimated using polygenic risk scores (PRSs) calculated from the largest available GWAS datasets of PTSD, MDD, and back pain. We then assessed comorbidity and genetic risk influence for developing chronic PTS, DS, and MSP after MVC. Secondary analyses explored whether common social determinants of health ameliorate genetic vulnerability. We found that 6 months after MVC, nearly half 357/781 (46%) of the participants had substantial PTS, DS, and/or MSP, and overlap was common (PTS + MSP (23%), DS + MSP (18%), PTS + DS (12%)). Genetic risk predicted post-MVC outcomes. PTSD-PRSs predicted PTS and DS (R² = 2.21% and 2.77%, p_adj < 0.01), MDD-PRSs predicted DS and MSP (R² = 1.89%, p_adj < 0.01) and 0.79%, p_adj < 0.05), and back pain-PRS predicted MSP (R² = 1.49%, p_adj < 0.01). Individuals in the highest quintile of PTSD-PRSs had 2.8 and 3.5 times the odds of developing PTS and DS vs. the lowest quintile (95% CI = 1.39-5.75 and 1.58-7.76). Among these high-risk individuals, those living in non-disadvantaged neighborhoods and with college education had 47% (p = 0.048) and 52% (p = 0.04) less risk of developing PTS, and those with high social support had 60% (p = 0.008) less risk of developing DS. Overall, genetic factors influence the risk of APNS after MVC, genetic risk of distinct APNS are overlapping, and specific social determinants greatly augment genetic risk of APNS development after MVC.

Reduction in movement-evoked pain and fatigue during initial 30-minute transcutaneous electrical nerve stimulation treatment predicts transcutaneous electrical nerve stimulation responders in women with fibromyalgia

ABSTRACT

We previously showed that 1 month of transcutaneous electrical nerve stimulation (TENS) reduces movement-evoked pain and fatigue in women with fibromyalgia (FM). Using data from this study (Fibromyalgia Activity Study with TENS [FAST]), we performed a responder analysis to identify predictors of clinical improvement in pain and fatigue with TENS, validated these models using receiver operator characteristic, and determined number needed to treat and number needed to harm. Participants were randomly assigned to active-TENS (2-125 Hz; highest-tolerable intensity), placebo-TENS, or no-TENS for 1 month. At the end of the randomized phase, placebo-TENS and no-TENS groups received active-TENS for 1 month. The predictor model was developed using data from the randomized phase for the active-TENS group (n = 103) and validated using data from placebo-TENS and no-TENS groups after active-TENS for 1 month (n = 155). Participant characteristics, initial response to TENS for pain and fatigue, sleep, psychological factors, and function were screened for association with changes in pain or fatigue using a logistic regression model. Predictors of clinical improvement in pain were initial response to pain and widespread pain index (area under the curve was 0.80; 95% confidence interval: 0.73-0.87). Predictors of clinical improvement in fatigue were marital status, sleep impairment, and initial response to TENS (area under the curve was 0.67; 95% confidence interval: 0.58-0.75). Number needed to treat for pain and fatigue ranged between 3.3 and 5.3. Number needed to harm ranged from 20 to 100 for minor TENS-related adverse events. The response to an initial 30-minute TENS treatment predicts who responds to longer-term TENS use in women with FM, making this a clinically useful procedure. Number needed to treat and number needed to harm suggest that TENS is effective and safe for managing pain and fatigue in FM.

Psycho-sensory relationships in chronic pain

BACKGROUND

Psychological variables contribute to pain- and injury-related outcomes. We examined the hypothesis that anatomical spread and intensity of persistent pain relate to anxiety-related variables: generalised anxiety, fear of pain and pain catastrophising.

METHODS

An online survey was used to gather data from 413 women with persistent pain (low back pain, n = 139; fibromyalgia syndrome, n = 95; neck pain, n = 55; whiplash, n = 41; rheumatoid arthritis, n = 37; migraine, n = 46). The spread and intensity of pain were assessed using the McGill pain chart and a Numerical Rating Scale. A Bayesian Structural Equation Model assessed if the intensity and spread of pain increased with anxiety-related variables. Men were also surveyed (n = 80), but the sample size was only sufficient for analysing if their data were consistent with the model for women.

RESULTS

Across subgroups of women, one standard deviation increase in catastrophising, generalised anxiety and fear corresponded to 27%, 7% and -1% additional pain areas and a 1.1, 0 and -0.1 change in pain intensity (on 0-10 scale), respectively. Overall, our clinical significance criterion - a 30% shift in pain variable in relation to one standard deviation increase in psychological variable - was not met. However, in subgroups it was met for pain spread (low back pain, neck pain and migraine) and pain intensity (migraine and neck pain) in relation to pain catastrophising. The model generally had low goodness-of-fit to men.

CONCLUSION

These data support a meaningful relationship between some anxiety-related variables and pain in women for some conditions. Since the model did not consistently fit the men, we may conclude that the relationships are moderated by sex. Clinician attention to psychological variables as potential contributing factors can be justified; however, research is needed to understand the relationship and whether psychological treatment can reduce pain.

Pain after a motor vehicle crash: The role of socio-demographics, crash characteristics and peri-traumatic stress symptoms

BACKGROUND

The vast majority of individuals who come to the emergency department (ED) for care after a motor vehicle collision (MVC) are diagnosed with musculoskeletal strain only and are discharged to home. A significant subset of this population will still develop persistent pain and posttraumatic psychological sequelae may play an important role in pain persistence.

METHODS

We conducted a multisite longitudinal cohort study of adverse post-traumatic neuropsychiatric sequelae among patients seeking ED treatment in the aftermath of a traumatic life experience. We report on a sub-group of patients (n = 666) presenting after an MVC, the most common type of trauma and we examine associations of socio-demographic and MVC characteristics, and persistent pain 8 weeks after MVC. We also examine the degree to which these associations are related to peritraumatic psychological symptoms and 2-week acute stress reactions using an applied approach.

RESULTS

Eight-week prevalence of persistent moderate or severe pain was high (67.4%) and positively associated with patient sex (female), older age, low socioeconomic status (education and income) and pain severity in the ED. Peritraumatic stress symptoms (distress and dissociation) appear to exert some influence on both acute pain and the transition from acute to persistent pain.

DISCUSSION AND CONCLUSIONS

The early aftermath of an MVC may be an important time period for intervening to prevent and reduce persistent pain. Substantial variation in mediating pathways across predictors also suggests potential diverse and complex underlying biological and psychological pathogenic processes are at work in the early weeks following trauma.

SIGNIFICANCE

The first several days after trauma may dictate recovery trajectories. Persistent pain, pain lasting beyond the expected time of recovery, is associated with pain early in the recovery period, but also mediated through other pathways. Future work is needed to understand the complex neurobiological processes in involved in the development of persistent and acute post-traumatic pain.

Predictors of poor health and functional recovery following road trauma: protocol of a British Columbian inception cohort study

Introduction

Road trauma (RT) is a major public health problem affecting physical and mental health, and may result in prolonged absenteeism from work or study. It is important for healthcare providers to know which RT survivors are at risk of a poor outcome, and policy-makers should know the associated costs. Unfortunately, outcome after RT is poorly understood, especially for RT survivors who are treated and released from an emergency department (ED) without the need for hospital admission. Currently, there is almost no research on risk factors for a poor outcome among RT survivors. This study will use current Canadian data to address these knowledge gaps.

Methods and analysis

We will follow an inception cohort of 1500 RT survivors (16 years and older) who visited a participating ED within 24 hours of the accident. Baseline interviews determine pre-existing health and functional status, and other potential risk factors for a poor outcome. Follow-up interviews at 2, 4, 6, and 12 months (key stages of recovery) use standardised health-related quality of life tools to determine physical and mental health outcome, functional recovery, and healthcare resource use and lost productivity costs.

Ethics and dissemination

The Road Trauma Outcome Study is approved by our institutional Research Ethics Board. This study aims to provide healthcare providers with knowledge on how quickly RT survivors recover from their injuries and who may be more likely to have a poor outcome. We anticipate that this information will be used to improve management of all road users following RT. Healthcare resource use and lost productivity costs will be collected to provide a better cost estimate of the effects of RT. This information can be used by policy-makers to make informed decisions on RT prevention programmes.

Prior sleep problems and adverse post-traumatic neuropsychiatric sequelae of motor vehicle collision in the AURORA study

STUDY OBJECTIVES

Many patients in Emergency Departments (EDs) after motor vehicle collisions (MVCs) develop post-traumatic stress disorder (PTSD) or major depressive episode (MDE). This report from the AURORA study focuses on associations of pre-MVC sleep problems with these outcomes 8 weeks after MVC mediated through peritraumatic distress and dissociation and 2-week outcomes.

METHODS

A total of 666 AURORA patients completed self-report assessments in the ED and at 2 and 8 weeks after MVC. Peritraumatic distress, peritraumatic dissociation, and pre-MVC sleep characteristics (insomnia, nightmares, daytime sleepiness, and sleep duration in the 30 days before the MVC, trait sleep stress reactivity) were assessed retrospectively in the ED. The survey assessed acute stress disorder (ASD) and MDE at 2 weeks and at 8 weeks assessed PTSD and MDE (past 30 days). Control variables included demographics, MVC characteristics, and retrospective reports about PTSD and MDE in the 30 days before the MVC.

RESULTS

Prevalence estimates were 41.0% for 2-week ASD, 42.0% for 8-week PTSD, 30.5% for 2-week MDE, and 27.2% for 8-week MDE. Pre-MVC nightmares and sleep stress reactivity predicted 8-week PTSD (mediated through 2-week ASD) and MDE (mediated through the transition between 2-week and 8-week MDE). Pre-MVC insomnia predicted 8-week PTSD (mediated through 2-week ASD). Estimates of population attributable risk suggest that blocking effects of sleep disturbance might reduce prevalence of 8-week PTSD and MDE by as much as one-third.

CONCLUSIONS

Targeting disturbed sleep in the immediate aftermath of MVC might be one effective way of reducing MVC-related PTSD and MDE.

microRNA let-7i-5p mediates the relationship between muscle fat infiltration and neck pain disability following motor vehicle collision: a preliminary study

Persistent neck-pain disability (PNPD) is common following traumatic stress exposures such as motor vehicle collision (MVC). Substantial literature indicates that fat infiltration into neck muscle (MFI) is associated with post-MVC PNPD. However, little is known about the molecular mediators underlying this association. In the current study, we assessed whether microRNA expression signatures predict PNPD and whether microRNA mediate the relationship between neck MFI and PNPD. A nested cohort of 43 individuals from a longitudinal study of MVC survivors, who provided blood (PAXgene RNA) and underwent magnetic resonance imaging (MRI), were included in the current study. Peritraumatic microRNA expression levels were quantified via small RNA sequencing, neck MFI via MRI, and PNPD via the Neck Disability Index two-weeks, three-months, and twelve-months following MVC. Repeated measures regression models were used to assess the relationship between microRNA and PNPD and to perform mediation analyses. Seventeen microRNA predicted PNPD following MVC. One microRNA, let-7i-5p, mediated the relationship between neck MFI and PNPD. Peritraumatic blood-based microRNA expression levels predict PNPD following MVC and let-7i-5p might contribute to the underlying effects of neck MFI on persistent disability. In conclusion, additional studies are needed to validate this finding.

Persistent and Widespread Pain Among African-Americans Six Weeks after MVC: Emergency Department-based Cohort Study

INTRODUCTION

African-Americans in the United States experience greater persistent pain than non-Hispanic Whites across a range of medical conditions, but to our knowledge no longitudinal studies have examined the risk factors or incidence of persistent pain among African-Americans experiencing common traumatic stress exposures such as after a motor vehicle collision (MVC). We evaluated the incidence and predictors of moderate to severe axial musculoskeletal pain (MSAP) and widespread pain six weeks after a MVC in a large cohort of Black adults presenting to the emergency department (ED) for care.

METHODS

This prospective, multi-center, cohort study enrolled Black adults who presented to one of 13 EDs across the US within 24 hours of a MVC and were discharged home after their evaluation. Data were collected at the ED visit via patient interview and self-report surveys at six weeks after the ED visit via internet-based, self-report survey, or telephone interview. We assessed MSAP pain at ED visit and persistence at six weeks. Multivariable models examined factors associated with MSAP persistence at six weeks post-MVC.

RESULTS

Among 787 participants, less than 1% reported no pain in the ED after their MVC, while 79.8 (95% confidence interval [CI], 77.1 - 82.2) reported MSAP and 28.3 (95% CI, 25.5 - 31.3) had widespread pain. At six weeks, 67% (95% CI, 64, 70%) had MSAP and 31% (95% CI, 28, 34%) had widespread pain. ED characteristics predicting MSAP at six weeks post-MVC (area under the curve = 0.74; 95% CI, 0.72, 0.74) were older age, peritraumatic dissociation, moderate to severe pain in the ED, feeling uncertain about recovery, and symptoms of depression.

CONCLUSION

These data indicate that African-Americans presenting to the ED for evaluation after MVCs are at high risk for persistent and widespread musculoskeletal pain. Preventive interventions are needed to improve outcomes for this high-risk group.

Revisiting Risk-stratified Whiplash-exposed Patients 12 to 14 Years After Injury

OBJECTIVE

The objective of this study was to evaluate the long-term predictive value of the Danish Whiplash Group Risk Assessment Score (DWGRAS) with 7 risk strata.

DESIGN

E-questionnaire-based follow-up study (n=927) combining 2 cohorts of whiplash-injured patients, 1 observational (n=187) and 1 interventional randomized controlled trial (n=740).

METHODS

Nine hundred twenty-seven previously healthy persons exposed to acute whiplash injury during motor vehicle collision were sent letter by postal service asking the addressee if they would respond to an E-questionnaire. Outcome measures were: whiplash-related disability, pain, use of medication/nonmedical treatment, work capacity.

RESULTS

The response rate was 37%. Fifty-five percent reported whiplash-related disability. Fourteen percent reported daily symptoms. A strong relationship was found between risk strata and impact of event and between risk strata and disabling symptoms.

CONCLUSIONS

Internal and long-term validation of DWGRAS was performed, but a low response rate indicates that results should be interpreted with caution. Furthermore, external validation needs to be done in long-term studies. An receiver operating characteristics curve of 0.73 (95% confidence interval 0.67; 0.79) predicting daily or weekly whiplash-related disability after 12 to 14 years was found using the DWGRAS risk score.

Sex differences in neuro(auto)immunity and chronic sciatic nerve pain

Chronic pain occurs with greater frequency in women, with a parallel sexually dimorphic trend reported in sufferers of many autoimmune diseases. There is a need to continue examining neuro-immune-endocrine crosstalk in the context of sexual dimorphisms in chronic pain. Several phenomena in particular need to be further explored. In patients, autoantibodies to neural antigens have been associated with sensory pathway hyper-excitability, and the role of self-antigens released by damaged nerves remains to be defined. In addition, specific immune cells release pro-nociceptive cytokines that directly influence neural firing, while T lymphocytes activated by specific antigens secrete factors that either support nerve repair or exacerbate the damage. Modulating specific immune cell populations could therefore be a means to promote nerve recovery, with sex-specific outcomes. Understanding biological sex differences that maintain, or fail to maintain, neuroimmune homeostasis may inform the selection of sex-specific treatment regimens, improving chronic pain management by rebalancing neuroimmune feedback. Given the significance of interactions between nerves and immune cells in the generation and maintenance of neuropathic pain, this review focuses on sex differences and possible links with persistent autoimmune activity using sciatica as an example.

The Effects of Exercise Dosage on Neck-Related Pain and Disability: A Systematic Review With Meta-analysis

OBJECTIVE

To (1) evaluate whether exercise therapy is effective for managing neck pain, and (2) investigate the relationship between exercise therapy dosage and treatment effect.

DESIGN

Intervention systematic review with meta-analysis and meta-regression.

LITERATURE SEARCH

An electronic search of 6 databases was completed for trials assessing the effects of exercise therapy on neck pain.

STUDY SELECTION CRITERIA

We included randomized controlled trials that compared exercise therapy to a no-exercise therapy control for treating neck pain. Two reviewers screened and selected studies, extracted outcomes, assessed article risk of bias, and rated the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

DATA SYNTHESIS

Data were pooled using random-effects meta-analysis. We used meta-regression to analyze the effect of exercise dosage on neck pain and disability.

RESULTS

Fourteen trials were included in the review. Seven trials were at high risk of bias, 4 were at unclear risk of bias, and 3 were at low risk of bias. Exercise therapy was superior to control for reducing pain (visual analog scale mean difference, -15.32 mm) and improving disability (Neck Disability Index mean difference, -3.64 points). Exercise dosage parameters did not predict pain or disability outcomes.

CONCLUSION

Exercise was beneficial for reducing pain and disability, regardless of exercise therapy dosage. Therefore, optimal exercise dosage recommendations remain unknown. We encourage clinicians to use exercise when managing mechanical neck pain. J Orthop Sports Phys Ther 2020;50(11):607-621. doi:10.2519/jospt.2020.9155.

DACC Resting State Functional Connectivity as a Predictor of Pain Symptoms Following Motor Vehicle Crash: A Preliminary Investigation

There is significant heterogeneity in pain outcomes following motor vehicle crashes (MVCs), such that a sizeable portion of individuals develop symptoms of chronic pain months after injury while others recover. Despite variable outcomes, the pathogenesis of chronic pain is currently unclear. Previous neuroimaging work implicates the dorsal anterior cingulate cortex (dACC) in adaptive control of pain, while prior resting state functional magnetic resonance imaging studies find increased functional connectivity (FC) between the dACC and regions involved in pain processing in those with chronic pain. Hyper-connectivity of the dACC to regions that mediate pain response may therefore relate to pain severity. The present study completed rsfMRI scans on N = 22 survivors of MVCs collected within 2 weeks of the incident to test whole-brain dACC-FC as a predictor of pain severity 6 months later. At 2 weeks, pain symptoms were predicted by positive connectivity between the dACC and the premotor cortex. Controlling for pain symptoms at 2 weeks, pain symptoms at 6 months were predicted by negative connectivity between the dACC and the precuneus. Previous research implicates the precuneus in the individual subjective awareness of pain. Given a relatively small sample size, approximately half of which did not experience chronic pain at 6 months, findings warrant replication. Nevertheless, this study provides preliminary evidence of enhanced dACC connectivity with motor regions and decreased connectivity with pain processing regions as immediate and prospective predictors of pain following MVC. PERSPECTIVE: This article presents evidence of distinct neural vulnerabilities that predict chronic pain in MVC survivors based on whole-brain connectivity with the dorsal anterior cingulate cortex.

Development and validation of a model predicting post-traumatic headache six months after a motor vehicle collision in adults

IMPORTANCE

The prognosis of post-traumatic headache is poorly understood.

OBJECTIVE

To develop and validate a prognostic model to predict the presence of post-traumatic headache six months after a traffic collision in adults with incident post-traumatic headache.

DESIGN

Secondary analyses of adults with incident post-traumatic headache injured in traffic collisions between November 1997 and December 1999 in Saskatchewan, Canada (development cohort); and between January 2004 and January 2005 in Sweden (validation cohort).

SETTING

The Saskatchewan cohort (development) was population-based (N = 4162). The Swedish cohort (validation) (N = 379) were claimants from two insurance companies covering 20 % of cars driven in Sweden in 2004.

PARTICIPANTS

All adults injured in traffic collisions who completed a baseline questionnaire within 30 days of collision. Excluded were those hospitalized >2 days, lost consciousness >30 min, or reported headache <3/10 on the numerical rating scale. Follow-up rates for both cohorts were approximately 80 %.

PREDICTORS

Baseline sociodemographic, pre-injury, and injury factors.

OUTCOME

Self-reported headache pain intensity ≥3 (numerical rating scale) six months after injury.

RESULTS

Both cohorts were predominantly female (69.7 % in Saskatchewan, 65.2 % in Sweden), with median ages 35.9 years (Saskatchewan), and 38.0 years (Sweden). Predictors were age, work status, headache pain intensity, symptoms in arms or hands, dizziness or unsteadiness, stiffness in neck, pre-existing headache, and lower recovery expectations. With a positive score (i.e., ≥0.75 probability), the model can rule in the presence of post-traumatic headache at six months (development: specificity = 99.8 %, 95 % CI 99.5 %-99.9 %; sensitivity = 1.6 %, 95 % CI 1.0 %-2.6 %; positive likelihood ratio (LR+) = 8.0, 95 % CI 2.7-24.1; negative likelihood ratio (LR-) = 1.0, 95 % CI 1.0-1.0; validation: specificity = 95.5 %, 95 % CI 91.1 %-97.8 %; sensitivity = 27.2 %, 95 % CI 20.4 %-35.2 %); LR+ = 6.0, 95 % CI 2.8-13.2; LR- = 0.8, 95 % CI 0.7-0.8).

CONCLUSIONS AND RELEVANCE

Clinicians can collect patient information on the eight predictors of our model to identify patients that will report ongoing post-traumatic headache six months after a traffic collision. Future research should focus on selecting patients at high risk of poor outcomes (using our model) for inclusion in intervention studies, and determining effective interventions for these patients.

Incident injury is strongly associated with subsequent incident temporomandibular disorder: results from the OPPERA study

Cross-sectional studies confirm, as expected, a positive association between jaw injury and painful temporomandibular disorders (TMDs), but prospective evaluations are lacking. We prospectively assessed incident jaw injury, injury type, and development of TMD in adults aged 18 to 44 years. Data were collected from 3258 individuals from communities surrounding 4 US academic institutes between 2006 and 2008. At enrollment, participants reported no TMD history and no facial injuries in the previous 6 months. Quarterly, follow-up questionnaires assessed incident jaw injury, which was classified as intrinsic (attributed to yawning or prolonged mouth opening) or extrinsic (attributed to other causes). Examiners classified incident TMD during a median follow-up period of 2.8 years (range 0.2-5.2 years). Cox regression models used jaw injury as a time-dependent covariate to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association with incident TMD. Among 1729 participants with complete data, 175 developed TMD. Eighty percent of injuries were intrinsic. Temporomandibular disorder annual incidence was nearly twice as high in those experiencing jaw injury (5.37%) compared with those who did not (3.44%). In the Cox model that accounted for timing of injury, the corresponding HR was 3.94 (95% CI = 2.82-5.50) after adjusting for study site, age, race, and sex. Hazard ratios did not differ (P = 0.91) for extrinsic injuries (HR = 4.03, 95% CI = 2.00-8.12) and intrinsic injuries (HR = 3.85, 95% CI = 2.70-5.49). Jaw injury was strongly associated with incident TMD. If surveillance and intervention after jaw injury is to be effective in preventing TMD, they should focus on both intrinsic and extrinsic injuries.

Pain Sensitivity Modifies Risk of Injury-Related Temporomandibular Disorder

This study evaluates contributions of jaw injury and experimental pain sensitivity to risk of developing painful temporomandibular disorder (TMD). Data were from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) nested case-control study of incident painful TMD. Injury and subsequent onset of painful TMD were monitored prospectively for ≤5 y in a community-based sample of 409 US adults who did not have TMD when enrolled. At baseline, thermal-pressure and pinprick pain sensitivity, as potential effect modifiers, were measured using quantitative sensory testing. During follow-up, jaw injury from any of 9 types of potentially traumatic events was determined using quarterly (3-monthly) health update questionnaires. Study examiners classified incident painful TMD, yielding 233 incident cases and 176 matched controls. Logistic regression models, estimated incidence odds ratios (IORs), and 95% confidence limits (CLs) were used for the association between injury and subsequent onset of painful TMD. During follow-up, 38.2% of incident cases and 13.1% of controls reported 1 or more injuries that were 4 times as likely to be intrinsic (i.e., sustained mouth opening or yawning) as extrinsic (e.g., dental visits, whiplash). Injuries due to extrinsic events (IOR = 7.6; 95% CL, 1.6–36.2), sustained opening (IOR = 5.4; 95% CL, 2.4–12.2), and yawning (IOR = 3.4; 95% CL, 1.6–7.3) were associated with increased TMD incidence. Both a single injury (IOR = 6.0; 95% CL, 2.9–12.4) and multiple injuries (IOR = 9.4; 95% CL, 3.4,25.6) predicted greater incidence of painful TMD than events perceived as noninjurious (IOR = 1.9; 95% CL, 1.1–3.4). Injury-associated risk of painful TMD was elevated in people with high sensitivity to heat pain (IOR = 7.4; 95% CL, 3.1–18.0) compared to people with low sensitivity to heat pain (IOR = 3.9; 95% CL, 1.7–8.4). Jaw injury was strongly associated with elevated painful TMD risk, and the risk was amplified in subjects who had enhanced sensitivity to heat pain at enrollment. Commonly occurring but seemingly innocuous events, such as yawning injury, should not be overlooked when judging prognostic importance of jaw injury.

The AURORA Study: a longitudinal, multimodal library of brain biology and function after traumatic stress exposure

Adverse posttraumatic neuropsychiatric sequelae (APNS) are common among civilian trauma survivors and military veterans. These APNS, as traditionally classified, include posttraumatic stress, postconcussion syndrome, depression, and regional or widespread pain. Traditional classifications have come to hamper scientific progress because they artificially fragment APNS into siloed, syndromic diagnoses unmoored to discrete components of brain functioning and studied in isolation. These limitations in classification and ontology slow the discovery of pathophysiologic mechanisms, biobehavioral markers, risk prediction tools, and preventive/treatment interventions. Progress in overcoming these limitations has been challenging because such progress would require studies that both evaluate a broad spectrum of posttraumatic sequelae (to overcome fragmentation) and also perform in-depth biobehavioral evaluation (to index sequelae to domains of brain function). This article summarizes the methods of the Advancing Understanding of RecOvery afteR traumA (AURORA) Study. AURORA conducts a large-scale (n = 5000 target sample) in-depth assessment of APNS development using a state-of-the-art battery of self-report, neurocognitive, physiologic, digital phenotyping, psychophysical, neuroimaging, and genomic assessments, beginning in the early aftermath of trauma and continuing for 1 year. The goals of AURORA are to achieve improved phenotypes, prediction tools, and understanding of molecular mechanisms to inform the future development and testing of preventive and treatment interventions.

A systematic review of the association between fault or blame-related attributions and procedures after transport injury and health and work-related outcomes

Attributions of fault are often associated with worse injury outcomes; however, the consistency and magnitude of these impacts is not known. This review examined the prognostic role of fault on health, mental health, pain and work outcomes after transport injury. A systematic search of five electronic databases (Medline, Embase, CINAHL, PsycINFO, Cochrane Library) yielded 16,324 records published between 2000 and January 2018. Eligibility criteria were: adult transport injury survivors; prospective design; multivariable analysis; fault-related factor analysed; pain, mental health, general health or work-related outcome. Citations (n = 10,558, excluding duplicates) and full text articles (n = 555) were screened manually (Reviewer 1), and using concurrent machine learning and text mining (Reviewer 2; using Abstrackr, WordStat and QDA miner). Data from 55 papers that met all inclusion criteria were extracted, papers were evaluated for risk of bias using the QUIPS tool, and overall level of evidence was assessed using the GRADE tool. There were six main fault-related factors classified as: fault or responsibility, fault-based compensation, lawyer involvement or litigation, blame or guilt, road user or position in vehicle, and impact direction. Overall there were inconsistent associations between fault and transport injury outcomes, and 60% of papers had high risk of bias. There was moderate evidence that fault-based compensation claims were associated with poorer health-related outcomes, and that lawyer involvement was associated with poorer work outcomes beyond 12 months post-injury. However, the evidence of negative associations between fault-based compensation claims and work-related outcomes was limited. Lawyer involvement and fault-based compensation claims were associated with adverse mental health outcomes six months post-injury, but not beyond 12 months. The most consistent associations between fault and negative outcomes were not for fault attributions, per se, but were related to fault-related procedures (e.g., lawyer engagement, fault-based compensation claims).

Genes known to escape X chromosome inactivation predict co-morbid chronic musculoskeletal pain and posttraumatic stress symptom development in women following trauma exposure

Co-morbid chronic musculoskeletal pain (CMSP) and posttraumatic stress symptoms (PTSS) are frequent sequelae of motor vehicle collision, are associated with greater disability than either outcome alone, and are more prevalent in women than men. In the current study we assessed for evidence that gene transcripts originating from the X chromosome contribute to sex differences in vulnerability to CMSP and PTSS after motor vehicle collision. Nested samples were drawn from a longitudinal study of African American individuals, and CMSP (0-10 numeric rating scale) and PTSS (impact of events scale, revised) outcomes were assessed 6 months following motor vehicle collision. Blood RNA were sequenced (n = 101) and the relationship between X chromosome mRNA expression levels and co-morbid CMSP and PTSS outcomes was evaluated using logistic regression analyses. A disproportionate number of peritraumatic X chromosome mRNA predicting CMSP and PTSS in women were genes previously found to escape X chromosome inactivation (11/40, z = -2.9, p = .004). Secondary analyses assessing gene ontology relationships between these genes identified an enrichment in genes known to influence neuronal plasticity. Further, the relationship of expression of two critical regulators of X chromosome inactivation, X-inactive specific transcript (XIST) and Yin Yang 1 (YY1), was different in women developing CMSP and PTSS. Together, these data suggest that X chromosome genes that escape inactivation may contribute to sex differences in vulnerability to CMSP and PTSS after motor vehicle collision.

Obesity increases the risk of chronic pain development after motor vehicle collision

Obesity has been found to increase the risk of musculoskeletal pain (MSP) in other settings, but to our knowledge, the influence of increased body mass index on pain outcomes after common trauma exposures such as motor vehicle collision (MVC) has not been assessed. In addition, obesity results in biomechanical changes, as well as physiologic changes including reduced hypothalamic pituitary adrenal axis negative feedback inhibition, but mechanisms by which obesity may result in worse post-traumatic outcomes remain poorly understood. In this study, we evaluated the influence of body mass index on axial and overall MSP severity (0-10 numeric rating scale) 6 weeks, 6 months, and 1 year after MVC among 917 European Americans who presented to the emergency department for initial evaluation. After adjusting for an array of sociodemographic factors, obesity (particularly morbid obesity) was an independent risk factor for worse MSP after MVC (eg, RR 1.41 [95% CI 1.11, 1.80] for moderate or severe MSP 6 months after MVC among morbidly obese vs normal weight MVC survivors). Interestingly, substantial effect modification was observed between obesity risk and a genetic variant known to reduce hypothalamic pituitary adrenal axis negative feedback inhibition (FKBP5 rs9380526). (eg, 41% vs 16% increased risk of moderate or severe MSP at 6 months among obese individuals with and without the risk allele.) Further studies are needed to elucidate mechanisms underlying chronic pain development in obese trauma survivors and to develop interventions that will reduce chronic pain severity among this common, at-risk group.

Racial differences in presentations and predictors of acute pain after motor vehicle collision

African Americans experience a greater burden of acute pain than non-Hispanic white individuals across of variety of acute medical conditions, but it is unknown whether this is the case after trauma. We evaluated pain, pain-related characteristics (eg, peritraumatic distress), and analgesic treatment in 2 cohorts of individuals (African American [n = 931] and non-Hispanic white [n = 948]) presenting to the emergency department (ED) after a motor vehicle collision. We performed a propensity-matched analysis (n = 796 in each group) to assess racial differences in acute pain in the ED. In multivariable models conducted within the matched sample, race was associated with moderate to severe axial pain (odds ratio [OR] 3.2; 95% confidence interval [CI]: 2.1-5.0, P < 0.001) and higher average numerical rating scale scores (1.3; 95% CI: 1.1-1.6; P < 0.001). After adjustment for pain and other covariates, non-Hispanic white patients were more likely to receive an opioid analgesic in the ED (OR 2.0; 95% CI: 1.4-3.0, P < 0.001) or at discharge (OR 4.9; 95% CI: 3.4-7.1, P < 0.001) and also less likely to receive an NSAID in the ED (OR 0.54; 95% CI: 0.38-0.78; P = 0.001) or at discharge (0.31; 95% CI: 0.43-0.84). Racial differences in the severity of acute posttraumatic pain after a motor vehicle collision are not explained by factors such as socioeconomic status or crash characteristics. Despite a higher burden of acute pain, African Americans were less likely to receive opioid analgesics and more likely to receive NSAIDs. Further work is needed to understand the relationship between pain severity, disparities in analgesic treatment, and longer term outcomes, such as post-motor vehicle collision chronic pain.

Minor Head Injury Symptoms and Recovery From Whiplash Injury: A 1-Year Prospective Study

Aim:

To examine concussion-related disability in neck injuries, the Rivermead Head Injury Follow-Up Questionnaire (RHFUQ) was applied. Furthermore, we wanted to investigate symptoms found in post-concussion syndrome (PCS) and global pain, neck pain intensities obtained from acute whiplash patients within 1 week and at 6 months after injury in a prospective study on 1-year work disability.

Methods:

A total of 143 consecutive acute whiplash-injured patients were admitted to the study from the Emergency Unit (Aarhus University Hospital). Patients with direct head trauma or reported retro- or anterograde amnesia were excluded from the study. Average neck pain and global pain intensity were measured on a Visual Analogue Scale (VAS 0-10). The RHFUQ (10 items, score from 0 to 4, total score from 0 to 40) was fulfilled after 1 week and 6 months. Patients underwent neurological examination within 1 week after injury. Recovery (return to work) was assessed 1 year post-injury.

Results:

In total, 97% completed the study, and 9% (12/138) did not recover. Non-recovered patients reported more neck pain and global pain after 1 week (P < .003) and 6 months (P < .008) and higher PCS symptom score after 1 week (P < .001) and 6 months (P < .002). Using the RHFUQ total score as a predictive test, a receiver-operating characteristic curve (ROC) area of 0.77 (0.61-0.92) and a cut-off at 10 points revealed a sensitivity of 75% and a specificity of 67.2%. At 1 week, 8 of 10 items reached higher scores among non-recovered and 10 of 10 items after 6 months post-injury.

Conclusions:

RHFUQ is useful in acute whiplash patients for predicting 1-year work disability. PCS-related symptoms along with neck pain and global pain are more burdensome in the non-recovered group. This emphasizes that post-concussion symptoms are not a sign of brain injury alone, but are found in other types of mishaps like whiplash injuries.

Study protocol for a randomised, double-blind, placebo-controlled clinical trial of duloxetine for the treatment and prevention of musculoskeletal pain: altering the transition from acute to chronic pain (ATTAC pain)

INTRODUCTION

Chronic musculoskeletal pain affects a substantial portion of adults visiting the emergency department (ED). Current treatment is limited in scope and does not effectively reduce musculoskeletal pain in patients. The study will evaluate the use of duloxetine, a serotonin-norepinephrine reuptake inhibitor Food and Drug Administration approved for the treatment of chronic pain, as a promising option in its prevention. The proposed study may present a well-tolerated and effective non-opioid treatment for patients with acute musculoskeletal pain that may also be effective in preventing the transition to persistent or chronic musculoskeletal pain.

METHODS AND ANALYSIS

The primary outcome of this study will be to assess the tolerability and preliminary effectiveness of duloxetine in patients with acute musculoskeletal pain. The study will take place at two EDs in Rhode Island, USA. The study will involve randomisation to one of three arms: duloxetine 30 mg, duloxetine 60 mg or placebo. Tolerability will be assessed by comparing the proportion of participants that report an adverse event and that drop-out across the three study arms. Effectiveness will be determined by self-reported pain over 6 weeks of follow-up. Specifically, we will compare the proportion of participants with persistent pain (ongoing pain at 6-week follow-up), across the three study arms. 60 adults (aged 18-59) presenting to the ED with acute axial musculoskeletal pain within 7 days of onset are expected to be enrolled in the proposed study.

ETHICS AND DISSEMINATION

Ethics approval was obtained by the Institutional Review Board (IRB). These results will be published in a peer reviewed scientific journal and presented at one or more scientific conferences.

TRIAL REGISTRATION NUMBER

NCT03315533.

Somatic experiencing® for patients with low back pain and comorbid posttraumatic stress disorder - protocol of a randomized controlled trial

BACKGROUND

Research has almost exclusively focused on the neck in order to explain the mechanisms of persistent pain after motor vehicle collisions (MVC). However, studies have shown that low back pain after MVC is as common as neck pain. Also, posttraumatic stress disorder (PTSD) is common after MVCs, and evidence indicate that PTSD may be linked to the development of pain and disability. PTSD has even been proposed as "the missing link" for some in the development of chronic low back pain. Unfortunately, PTSD often goes unattended in low back pain rehabilitation and very few randomized controlled studies exists targeting both conditions. Hence, the aim of the present study is to investigate the potential additional effect of the trauma therapy "Somatic Experiencing®" (SE) in addition to physiotherapy (PT) compared to PT alone for patients with chronic low back pain and comorbid PTSD.

METHODS

The study is a two-group randomized controlled clinical trial in which participants (n = 140) are recruited consecutively from a large Danish spine center in the Region of Southern Denmark, between January 2016 and December 2017. Patients are randomly allocated to one of the two conditions: SE + PT or PT alone. Measurements of effect are carried out at baseline before randomization, post-intervention, 6 and 12 months post-randomization. The primary outcome is a 20% reduction in disability (Rolland Morris Disability Questionnaire) at 6 months post-randomization. Secondary outcomes are: PTSD symptoms, pain intensity, pain-catastrophizing, fear of movement, anxiety and depression.

DISCUSSION

Comorbid PTSD is currently not targeted in back pain rehabilitation although highly prevalent. If the SE intervention shows to have an additional effect on disability and pain, the study is likely to have a positive impact on the management of chronic low back pain and will have immediate clinical applicability.

TRIAL REGISTRATION

Current Controlled Trials Registration August 4, 2017: NCT03244046 . Retrospectively registered.

A Functional riboSNitch in the 3' Untranslated Region of FKBP5 Alters MicroRNA-320a Binding Efficiency and Mediates Vulnerability to Chronic Post-Traumatic Pain

Previous studies have shown that common variants of the gene coding for FK506-binding protein 51 (FKBP5), a critical regulator of glucocorticoid sensitivity, affect vulnerability to stress-related disorders. In a previous report, FKBP5 rs1360780 was identified as a functional variant because of its effect on gene methylation. Here we report evidence for a novel functional FKBP5 allele, rs3800373. This study assessed the association between rs3800373 and post-traumatic chronic pain in 1607 women and men from two ethnically diverse human cohorts. The molecular mechanism through which rs3800373 affects adverse outcomes was established via in silico, in vivo, and in vitro analyses. The rs3800373 minor allele predicted worse adverse outcomes after trauma exposure, such that individuals with the minor (risk) allele developed more severe post-traumatic chronic musculoskeletal pain. Among these individuals, peritraumatic circulating FKBP5 expression levels increased as cortisol and glucocorticoid receptor (NR3C1) mRNA levels increased, consistent with increased glucocorticoid resistance. Bioinformatic, in vitro, and mutational analyses indicate that the rs3800373 minor allele reduces the binding of a stress- and pain-associated microRNA, miR-320a, to FKBP5 via altering the FKBP5 mRNA 3'UTR secondary structure (i.e., is a riboSNitch). This results in relatively greater FKBP5 translation, unchecked by miR-320a. Overall, these results identify an important gene-miRNA interaction influencing chronic pain risk in vulnerable individuals and suggest that exogenous methods to achieve targeted reduction in poststress FKBP5 mRNA expression may constitute useful therapeutic strategies.SIGNIFICANCE STATEMENT FKBP5 is a critical regulator of the stress response. Previous studies have shown that dysregulation of the expression of this gene plays a role in the pathogenesis of chronic pain development as well as a number of comorbid neuropsychiatric disorders. In the current study, we identified a functional allele (rs3800373) in the 3'UTR of FKBP5 that influences vulnerability to chronic post-traumatic pain in two ethnic cohorts. Using multiple complementary experimental approaches, we show that the FKBP5 rs3800373 minor allele alters the secondary structure of FKBP5 mRNA, decreasing the binding of a stress- and pain-associated microRNA, miR-320a. This results in relatively greater FKBP5 translation, unchecked by miR-320a, increasing glucocorticoid resistance and increasing vulnerability to post-traumatic pain.

A Prospective Evaluation of Patient-Reported Opioid Utilization After Nonoperative Treatment of Fractures and Dislocations

BACKGROUND

Prescription of opioid analgesics is currently a common practice to relieve pain for musculoskeletal injuries in many regions of the world, especially in the United States and Canada. However, overprescription may underlie opioid misuse. Details on the utilization of prescribed opioids after nonoperative treatment of fractures and dislocations and whether consumption is related to injury location are unknown.

METHODS

A total of 1,513 consecutive patients in China who underwent nonoperative treatment of a fracture and/or dislocation and who were prescribed opioids were studied over a 3-month period. Demographic information, alcohol consumption, smoking status, injury location, volume of prescription, and consumption patterns were recorded and were summarized.

RESULTS

The mean number of opioid pills prescribed was 14.7, and the mean patient-reported number of pills consumed was 7.2. Overall, 152 patients (10.0%) reported taking no prescribed opioid analgesics, and 924 patients (61.1%) ceased their prescribed opioids prior to completing the regimen. Injury location, alcohol consumption, and type of fracture or dislocation were all significantly associated with the patient-reported number of opioid pills consumed (p < 0.05). Patients with fracture and/or dislocation of the wrist or forearm (9.4 pills for 3.8 days); ankle, tibia, or fibula (9.3 pills for 3.7 days); or elbow or humerus (9.1 pills for 3.7 days) used more opioid pills compared with patients with injuries at other locations (not exceeding 6.4 pills and 3 days). When compared with patients who had no, low, or moderate daily alcohol consumption, there was more opioid use in patients with high daily alcohol consumption (8.5 pills for 3.4 days) and those with very high daily alcohol consumption (11.3 pills for 4.7 days). Patients with a dislocation and/or displaced fracture reported consuming 8.2 pills for 3.3 days, which was more than the consumption in patients with a nondisplaced fracture (6.2 pills for 2.5 days) and patients with an avulsion fracture (6.2 pills for 2.5 days).

CONCLUSIONS

Surgeons and patients should try to avoid opioids if possible after nonoperatively treated fractures and dislocations. If opioids are used, surgeons should prescribe the smallest dose for the shortest time after considering the injury location and type of fracture or dislocation.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?

The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy subjects using computed tomography angiography. We found significant differences in the area of the transverse foramen between double transverse and normal subjects (P < 0.001) but not between the vertebral artery area of double transverse and normal subjects (P = 0.829). The subjects with double transverse foramina have a reduced transverse foramen/vertebral artery ratio, which may be a possible risk for transient vertebral artery stenosis.

Anatomical distribution of musculoskeletal disorders following a road traffic collision in litigants presenting to physiotherapists within a private-clinic in North-East England

Introduction: Musculoskeletal disorders (MSDs) are common following a road traffic collision (RTC) in England. Establishing the anatomical distribution of MSDs following RTC that present to physiotherapists may improve understanding and clinical practice. This study examined anatomical distribution of MSDs that present to physiotherapists within a litigant population following a RTC in England. Methods: A retrospective review of physiotherapy records was conducted at a private practice in North-East England. Data were collected from 2105 patients between January 2014 and December 2015. The primary outcome was anatomical regions with MSDs. Descriptive data is reported. Results: Overall, 90% of patients presented with a neck/upper back disorder, while 52% presented with a lower back disorder. Of the assessed patients, 46% presented with one MSD, 45% presented with two MSDs while 9% presented with ≥3 MSDs. Further analysis showed that those who presented to physiotherapy later and were not motor vehicle occupants (MVOs) were more likely to have upper-limb, lower-limb, or lumbar MSDs. Younger patients, who presented sooner and were non-MVO were more likely to have multiple regions affected by MSDs. Conclusions: This study presents epidemiological evidence that MSDs following a RTC occur primarily in the neck/upper back or lower back regions, and that multiple MSDs are common.

Thoracic dysfunction in whiplash associated disorders: A systematic review

BACKGROUND

Research investigating Whiplash Associated Disorder (WAD) has largely focused on the cervical spine yet symptoms can be widespread. Thoracic spine pain prevalence is reported ~66%; perhaps unsurprising given the forceful stretch/eccentric loading of posterior structures of the spine, and the thoracic spine's contribution to neck mobility/function. Approximately 50% WAD patients develop chronic pain and disability resulting in high levels of societal and healthcare costs. It is time to look beyond the cervical spine to fully understand anatomical dysfunction in WAD and provide new directions for clinical practice and research.

PURPOSE

To evaluate the scope and nature of dysfunction in the thoracic region in patients with WAD.

METHODS

A systematic review and data synthesis was conducted according to a pre-defined, registered (PROSPERO, CRD42015026983) and published protocol. All forms of observational study were included. A sensitive topic-based search strategy was designed from inception to 1/06/16. Databases, grey literature and registers were searched using a study population terms and key words derived from scoping search. Two reviewers independently searched information sources, assessed studies for inclusion, extracted data and assessed risk of bias. A third reviewer checked for consistency and clarity. Extracted data included summary data: sample size and characteristics, outcomes, and timescales to reflect disorder state. Risk of bias was assessed using the Newcastle-Ottawa Scale. Data were tabulated to allow enabling a semi-qualitative comparison and grouped by outcome across studies. Strength of the overall body of evidence was assessed using a modified GRADE.

RESULTS

Thirty eight studies (n>50,000) which were conducted across a range of countries were included. Few authors responded to requests for further data (5 of 9 contacted). Results were reported in the context of overall quality and were presented for measures of pain or dysfunction and presented, where possible, according to WAD severity and time point post injury. Key findings include: 1) high prevalence of thoracic pain (>60%); higher for those with more severe presentations and in the acute stage, 2) low prevalence of chest pain (<22%), 3) evidence of thoracic outlet syndrome, with some association to and involvement of the brachial plexus, 4) muscle dysfunction in the form of heightened activity of the sternocleidomastoid or delayed onset of action of the serratus anterior, 5) high prevalence of myofascial pain and trigger points in the scalene muscles, sternocleidomastoid and mid/lower fibres of trapezius muscle (48-65%), and 6) inconclusive evidence of altered thoracic posture or mobility.

CONCLUSIONS

Considerable evidence supports thoracic pain and dysfunction in patients with WAD, involving primarily nerves and muscles. Notwithstanding the low/very low level of evidence from this review, our findings do support a more extensive clinical evaluation of patients presenting with WAD. Additional high quality research is required to further characterise dysfunction across other structures in the thoracic region, including but not limited to the thoracic spine (mobility and posture) and thoracic muscles (stiffness, activation patterns). In turn this may inform the design of clinical trials targeting such dysfunction.