Zoledronic acid after spinal cord injury mitigates losses in proximal femoral strength independent of ambulation ability.

Rapid bone loss can occur after spinal cord injury (SCI) and a standard of care to prevent or treat this phenomenon is an active area of research. Using advanced analysis techniques, this study demonstrates that zoledronic acid, a possible treatment, prevented loss of bone strength at the hip following SCI. INTRODUCTION: Bone loss below the level of neurological lesion is a well-known complication of spinal cord injury (SCI), and effective preventive treatment for this phenomenon is an active area of research. Zoledronic acid has demonstrated efficacy to attenuate bone loss at the hip after SCI, but previous studies relied on measurements from dual-energy X-ray absorptiometry. The purpose of this investigation was to more thoroughly characterize changes to bone mineral and strength at the proximal femur in individuals receiving zoledronic acid in the acute SCI stage; we also examined the influence of ambulatory ability on bone outcomes. METHODS: Participants randomized to either zoledronic acid (n = 29) or placebo (n = 30) received computed tomography (CT) scans and ambulatory assessments at baseline and 6 and 12 months following drug infusion. CT-based finite element (FE) modeling was used to predict changes in proximal femoral strength associated with treatment. RESULTS: After 12 months, FE-predicted bone strength was reduced by a mean (SD) of 9.6 (17.9)% in the zoledronic acid group versus 24.6 (24.5)% in the placebo group (p = 0.007). These differences in strength were explained by reductions in CT measurements of both trabecular (p < 0.001) and cortical (p ≤ 0.021) bone at the femoral neck and trochanteric region. Ambulation ability influenced select trabecular and cortical parameters, but we were unable to detect an impact on FE-predicted bone strength. CONCLUSION: These findings demonstrate that treatment with zoledronic acid in acute SCI attenuates losses in proximal femoral strength, which may reduce the risk of hip fractures across patients with varying degrees of ambulatory abilities.

Bone Mineral Loss at the Distal Femur and Proximal Tibia Following Spinal Cord Injury in Men and Women.

PURPOSE: Spinal cord injury (SCI) causes rapid bone loss and increases risk of fragility fractures in the lower extremities. The majority of individuals with SCI are men, and few studies have investigated sex as a biological variable in SCI-induced osteoporosis. This cross-sectional study aimed to quantify sex-specific differences in bone mineral following SCI. METHODS: Quantitative computed tomography (QCT) scans of the distal femur and proximal tibia were obtained at baseline of one of four clinical trials enrolling people who sustained SCI 1 month to 50 years prior to recruitment. Bone volume (BV), bone mineral content (BMC), bone mineral density (BMD), and bending strength index (BSI) were quantified in the integral, trabecular, and cortical bone in the epiphysis, metaphysis and diaphysis. Scans from 106 men and 31 women were analyzed to measure sex-specific effects on bone loss over time post-SCI. RESULTS: BMC and BSI declined exponentially as a function of time post-SCI and were best described by separate decay curves for men and women. Women had BV, BMC, and BSI at 58-77% that of men in the acute and plateau phases, with both sexes showing similar rates of loss as a function of time post-SCI. Trabecular BMD was best described as an exponential decay versus time post-SCI, with no sex-specific differences. CONCLUSIONS: Due to consistently lower BV, BMC, and BSI, women may be more susceptible to fractures after SCI than men.

Identification of traits and functional connectivity-based neurotraits of chronic pain.

Psychological and personality factors, socioeconomic status, and brain properties all contribute to chronic pain but have essentially been studied independently. Here, we administered a broad battery of questionnaires to patients with chronic back pain (CBP) and collected repeated sessions of resting-state functional magnetic resonance imaging (fMRI) brain scans. Clustering and network analyses applied on the questionnaire data revealed four orthogonal dimensions accounting for 56% of the variance and defining chronic pain traits. Two of these traits-Pain-trait and Emote-trait-were associated with back pain characteristics and could be related to distinct distributed functional networks in a cross-validation procedure, identifying neurotraits. These neurotraits showed good reliability across four fMRI sessions acquired over five weeks. Further, traits and neurotraits all related to the income, emphasizing the importance of socioeconomic status within the personality space of chronic pain. Our approach is a first step in providing metrics aimed at unifying the psychology and the neurophysiology of chronic pain applicable across diverse clinical conditions.

Factors associated with physician-reported treatment status of patients with osteoarthritis pain.

BACKGROUND: Osteoarthritis (OA) is typically associated with pain, but many patients are not treated. METHODS: This point in time study explored factors associated with treatment status, using logistic regression of data from the Adelphi OA Disease Specific Programme conducted in the United States. Patients' treatment status was based on physician-reported, current: 1) prescription medication for OA vs. none; and 2) physician treatment (prescription medication and/or recommendation for specified nonpharmacologic treatment for OA [physical or occupational therapy, acupuncture, transcutaneous electrical nerve stimulation, or cognitive behavior therapy/psychotherapy]) vs. self-management (no prescription medication or specified nonpharmacologic treatment). RESULTS: The 841 patients (including 57.0% knee OA, 31.9% hip OA) reported mild (45.4%) or moderate or severe (54.6%) average pain intensity over the last week. The majority were prescribed medication and/or recommended specified nonpharmacologic treatment; 218 were not prescription-medicated and 122 were self-managed. Bivariate analyses showed less severe patient-reported pain intensity and physician-rated OA severity, fewer joints affected by OA, lower proportion of joints affected by knee OA, better health status, lower body mass index, and lower ratings for cardiovascular and gastrointestinal risks, for those not prescribed medication (vs. prescription-medicated). Multivariate analyses confirmed factors significantly (p < 0.05) associated with prescription medication included (odds ratio): physician-rated current moderate OA severity (vs. mild, 2.03), patient-reported moderate OA severity 6 months ago (vs. mild, 1.71), knee OA (vs. not, 1.81), physician-recommended (0.28) and patient-reported (0.43) over-the-counter medication use (vs. not), prior surgery for OA (vs. not, 0.37); uncertain income was also significant. Factors significantly (p < 0.05) associated with physician treatment included (odds ratio): physician-recommended nonpharmacologic therapy requiring no/minimal medical supervision (vs. not, 2.21), physician-rated current moderate OA severity (vs. mild, 2.04), patient-reported over-the-counter medication use (vs. not, 0.26); uncertain time since diagnosis was also significant. Patient-reported pain intensity and most demographic factors were not significant in either model. CONCLUSIONS: Approximately 1 in 4 patients were not prescribed medication and 1 in 7 were self-managed, although many were using over-the-counter medications or nonpharmacologic therapies requiring no/minimal medical supervision. Multiple factors were significantly associated with treatment status, including OA severity and over-the-counter medication, but not pain intensity or most demographics.

Reorganization of functional brain network architecture in chronic osteoarthritis pain.

Osteoarthritis (OA) manifests with chronic pain, motor impairment, and proprioceptive changes. However, the role of the brain in the disease is largely unknown. Here, we studied brain networks using the mathematical properties of graphs in a large sample of knee and hip OA (KOA, n = 91; HOA, n = 23) patients. We used a robust validation strategy by subdividing the KOA data into discovery and testing groups and tested the generalizability of our findings in HOA. Despite brain global topological properties being conserved in OA, we show there is a network wide pattern of reorganization that can be captured at the subject-level by a single measure, the hub disruption index. We localized reorganization patterns and uncovered a shift in the hierarchy of network hubs in OA: primary sensory and motor regions and parahippocampal gyrus behave as hubs and insular cortex loses its central placement. At an intermediate level of network structure, frontoparietal and cingulo-opercular modules showed preferential reorganization. We examined the association between network properties and clinical correlates: global disruption indices and isolated degree properties did not reflect clinical parameters; however, by modeling whole brain nodal degree properties, we identified a distributed set of regions that reliably predicted pain intensity in KOA and generalized to hip OA. Together, our findings reveal that while conserving global topological properties, brain network architecture reorganizes in OA, at both global and local scale. Network connectivity related to OA pain intensity is dissociated from the major hub disruptions, challenging the extent of dependence of OA pain on nociceptive signaling.

Brain Connectivity Predicts Placebo Response across Chronic Pain Clinical Trials.

Placebo response in the clinical trial setting is poorly understood and alleged to be driven by statistical confounds, and its biological underpinnings are questioned. Here we identified and validated that clinical placebo response is predictable from resting-state functional magnetic-resonance-imaging (fMRI) brain connectivity. This also led to discovering a brain region predicting active drug response and demonstrating the adverse effect of active drug interfering with placebo analgesia. Chronic knee osteoarthritis (OA) pain patients (n = 56) underwent pretreatment brain scans in two clinical trials. Study 1 (n = 17) was a 2-wk single-blinded placebo pill trial. Study 2 (n = 39) was a 3-mo double-blinded randomized trial comparing placebo pill to duloxetine. Study 3, which was conducted in additional knee OA pain patients (n = 42), was observational. fMRI-derived brain connectivity maps in study 1 were contrasted between placebo responders and nonresponders and compared to healthy controls (n = 20). Study 2 validated the primary biomarker and identified a brain region predicting drug response. In both studies, approximately half of the participants exhibited analgesia with placebo treatment. In study 1, right midfrontal gyrus connectivity best identified placebo responders. In study 2, the same measure identified placebo responders (95% correct) and predicted the magnitude of placebo's effectiveness. By subtracting away linearly modeled placebo analgesia from duloxetine response, we uncovered in 6/19 participants a tendency of duloxetine enhancing predicted placebo response, while in another 6/19, we uncovered a tendency for duloxetine to diminish it. Moreover, the approach led to discovering that right parahippocampus gyrus connectivity predicts drug analgesia after correcting for modeled placebo-related analgesia. Our evidence is consistent with clinical placebo response having biological underpinnings and shows that the method can also reveal that active treatment in some patients diminishes modeled placebo-related analgesia. Trial Registration ClinicalTrials.gov NCT02903238 ClinicalTrials.gov NCT01558700.

Open-label clinical trial of alendronate after teriparatide therapy in people with spinal cord injury and low bone mineral density.

STUDY DESIGN: Non-randomized open-label clinical trial of oral alendronate after teriparatide therapy in people with spinal cord injury (SCI) and low bone mineral density (BMD). OBJECTIVES: To determine if alendronate would prevent bone loss after discontinuation of teriparatide. SETTING: Outpatient research clinic at Northwestern University Feinberg School of Medicine. METHODS: Seventeen participants with chronic SCI who recently completed 12-24 months of teriparatide treatment received oral alendronate 70 mg once weekly for 12 months. Participants were evaluated at baseline, 6 months and 12 months. Bone was assessed by: DXA at the spine and hip, CT at the distal femur/proximal tibia, serum collected for bone markers, and bone strength determined by finite element (FE) analysis of the proximal tibia. RESULTS: Areal BMD showed no significant change from baseline at the total hip or femoral neck, where mean change (SD) was 1.3% (4.7) and 0.54% (5.0), respectively. However, areal BMD increased significantly at the spine by 2.5% (4.6). CT demonstrated significant increases in bone mineral content at the femoral epiphysis, metaphysis, and diaphysis, 15% (18), 7.7% (12), and 3.0% (3.5), respectively. Measurements at the tibia illustrated improvements and reductions, but no changes to FE-predicted strength were observed. Biomarkers illustrated inhibition of bone formation and resorption, with P1NP and CTX decreasing by 52% (82) and 62% (74), respectively. CONCLUSION: Twelve months of alendronate after discontinuation of teriparatide in people with SCI can prevent bone loss and may increase bone mass and preserve bone strength at the spine, hip, and some sites of the knee.

Effect of Tanezumab on Joint Pain, Physical Function, and Patient Global Assessment of Osteoarthritis Among Patients With Osteoarthritis of the Hip or Knee: A Randomized Clinical Trial.

Importance: Patients with osteoarthritis (OA) may remain symptomatic with traditional OA treatments. Objective: To assess 2 subcutaneous tanezumab dosing regimens for OA. Design, Setting, and Participants: A randomized, double-blind, multicenter trial from January 2016 to May 14, 2018 (last patient visit). Patients enrolled were 18 years or older with hip or knee OA, inadequate response to OA analgesics, and no radiographic evidence of prespecified joint safety conditions. Interventions: Patients received by subcutaneous administration either tanezumab, 2.5 mg, at day 1 and week 8 (n = 231); tanezumab, 2.5 mg at day 1 and 5 mg at week 8 (ie, tanezumab, 2.5/5 mg; n = 233); or placebo at day 1 and week 8 (n = 232). Main Outcomes and Measures: Co-primary end points were change from baseline to week 16 in Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) Pain (0-10, no to extreme pain), WOMAC Physical Function (0-10, no to extreme difficulty), and patient global assessment of osteoarthritis (PGA-OA) (1-5, very good to very poor) scores. Results: Among 698 patients randomized, 696 received 1 or more treatment doses (mean [SD] age, 60.8 [9.6] years; 65.1% women), and 582 (83.6%) completed the trial. From baseline to 16 weeks, mean WOMAC Pain scores decreased from 7.1 to 3.6 in the tanezumab, 2.5 mg, group; 7.3 to 3.6 in the tanezumab, 2.5/5 mg, group; and 7.3 to 4.4 in the placebo group (least squares mean differences [95% CI] vs placebo were -0.60 [-1.07 to -0.13; P = .01] for tanezumab, 2.5 mg, and -0.73 [-1.20 to -0.26; P = .002] for tanezumab, 2.5/5 mg). Mean WOMAC Physical Function scores decreased from 7.2 to 3.7 in the 2.5-mg group, 7.4 to 3.6 in the 2.5/5-mg group, and 7.4 to 4.5 with placebo (differences vs placebo, -0.66 [-1.14 to -0.19; P = .007] for tanezumab, 2.5 mg, and -0.89 [-1.37 to -0.42; P < .001] for tanezumab, 2.5/5 mg). Mean PGA-OA scores decreased from 3.4 to 2.4 in the 2.5-mg group, 3.5 to 2.4 in the 2.5/5-mg group, and 3.5 to 2.7 with placebo (differences vs placebo, -0.22 [-0.39 to -0.05; P = .01] for tanezumab, 2.5 mg, and -0.25 [-0.41 to -0.08; P = .004] for tanezumab, 2.5/5 mg). Rapidly progressive OA occurred only in tanezumab-treated patients (2.5 mg: n = 5, 2.2%; 2.5/5 mg: n = 1, 0.4%). The incidence of total joint replacements was 8 (3.5%), 16 (6.9%), and 4 (1.7%) in the tanezumab, 2.5 mg; tanezumab, 2.5/5 mg; and placebo groups, respectively. Conclusions and Relevance: Among patients with moderate to severe OA of the knee or hip and inadequate response to standard analgesics, tanezumab, compared with placebo, resulted in statistically significant improvements in scores assessing pain and physical function, and in PGA-OA, although the improvements were modest and tanezumab-treated patients had more joint safety events and total joint replacements. Further research is needed to determine the clinical importance of these efficacy and adverse event findings. Trial Registration: ClinicalTrials.gov Identifier: NCT02697773.

Hippocampal morphology mediates biased memories of chronic pain.

Experiences and memories are often mismatched. While multiple studies have investigated psychological underpinnings of recall error with respect to emotional events, the neurobiological mechanisms underlying the divergence between experiences and memories remain relatively unexplored in the domain of chronic pain. Here we examined the discrepancy between experienced chronic low back pain (CBP) intensity (twice daily ratings) and remembered pain intensity (n = 48 subjects) relative to psychometric properties, hippocampus morphology, memory capabilities, and personality traits related to reward. 77% of CBP patients exaggerated remembered pain, which depended on their strongest experienced pain and their most recent mood rating. This bias persisted over nearly 1 year and was related to reward memory bias and loss aversion. Shape displacement of a specific region in the left posterior hippocampus mediated personality effects on pain memory bias, predicted pain memory bias in a validation CBP group (n = 21), and accounted for 55% of the variance of pain memory bias. In two independent groups (n = 20/group), morphology of this region was stable over time and unperturbed by the development of chronic pain. These results imply that a localized hippocampal circuit, and personality traits associated with reward processing, largely determine exaggeration of daily pain experiences in chronic pain patients.

Inferring distinct mechanisms in the absence of subjective differences: Placebo and centrally acting analgesic underlie unique brain adaptations.

Development and maintenance of chronic pain is associated with structural and functional brain reorganization. However, few studies have explored the impact of drug treatments on such changes. The extent to which long-term analgesia is related to brain adaptations and its effects on the reversibility of brain reorganization remain unclear. In a randomized placebo-controlled clinical trial, we contrasted pain relief (3-month treatment period), and anatomical (gray matter density [GMD], assessed by voxel-based morphometry) and functional connectivity (resting state fMRI nodal degree count [DC]) adaptations, in 39 knee osteoarthritis (OA) patients (22 females), randomized to duloxetine (DLX, 60 mg once daily) or placebo. Pain relief was equivalent between treatment types. However, distinct circuitry (GMD and DC) could explain pain relief in each group: up to 85% of variance for placebo analgesia and 49% of variance for DLX analgesia. No behavioral measures (collected at entry into the study) could independently explain observed analgesia. Identified circuitry were outside of nociceptive circuitry and minimally overlapped with OA-abnormal or placebo response predictive brain regions. Mediation analysis revealed that changes in GMD and DC can influence each other across remote brain regions to explain observed analgesia. Therefore, we can conclude that distinct brain mechanisms underlie DLX and placebo analgesia in OA. The results demonstrate that even in the absence of differences in subjective pain relief, pharmacological treatments can be differentiated from placebo based on objective brain biomarkers. This is a crucial step to untangling mechanisms and advancing personalized therapy approaches for chronic pain.

Corticolimbic anatomical characteristics predetermine risk for chronic pain.

SEE TRACEY DOI101093/BRAIN/AWW147 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Mechanisms of chronic pain remain poorly understood. We tracked brain properties in subacute back pain patients longitudinally for 3 years as they either recovered from or transitioned to chronic pain. Whole-brain comparisons indicated corticolimbic, but not pain-related circuitry, white matter connections predisposed patients to chronic pain. Intra-corticolimbic white matter connectivity analysis identified three segregated communities: dorsal medial prefrontal cortex-amygdala-accumbens, ventral medial prefrontal cortex-amygdala, and orbitofrontal cortex-amygdala-hippocampus. Higher incidence of white matter and functional connections within the dorsal medial prefrontal cortex-amygdala-accumbens circuit, as well as smaller amygdala volume, represented independent risk factors, together accounting for 60% of the variance for pain persistence. Opioid gene polymorphisms and negative mood contributed indirectly through corticolimbic anatomical factors, to risk for chronic pain. Our results imply that persistence of chronic pain is predetermined by corticolimbic neuroanatomical factors.

A randomized placebo-controlled pilot study of the efficacy and safety of D-cycloserine in people with chronic back pain.

BACKGROUND: Few effective pharmacological treatment options exist for chronic back pain, the leading cause of disability in the US, and all are associated with significant adverse effects. OBJECTIVE: To determine the efficacy and safety of D-cycloserine, a partial agonist to the N-methyl-D-aspartate receptor, in the treatment of chronic low back pain. METHODS: A total of 41 participants with chronic back pain who met all inclusion and exclusion criteria were enrolled in a double-blind, placebo-controlled randomized pilot trial of D-cycloserine. Treatment was administered orally for six weeks at escalating daily doses of 100 mg, 200 mg, and 400 mg, each for two weeks. The primary outcome measure was back pain intensity using the Numeric Rating Scale (0-10). Secondary measures were back pain-related questionnaires: McGill Pain Questionnaire short form, painDETECT, PANAS, and BDI. The pre-specified analysis was a two-way repeated measures analysis of variance. RESULTS: A treatment difference was observed between groups treated with D-cycloserine and placebo at six weeks of 1.05 ± 3.1 units on the Numeric Rating Scale, with an effect size of 0.4 and p = 0.14. This trend of better chronic back pain relief with D-cycloserine was also observed in the secondary measures. No safety issues were seen. CONCLUSION: The difference in mean pain between the D-cycloserine and placebo groups did not reach statistical significance. However, a clinically meaningful effect size in the magnitude of pain relief was observed with a consistent pattern across multiple outcome measures with good safety, supporting further research into the effectiveness of D-cycloserine for chronic back pain.

Smoking increases risk of pain chronification through shared corticostriatal circuitry.

Smoking is associated with increased incidence of chronic pain. However, the evidence is cross-sectional in nature, and underlying mechanisms remain unclear. In a longitudinal observational study, we examined the relationship between smoking, transition to chronic pain, and brain physiology. In 160 subjects with subacute back pain (SBP: back pain lasting 4-12 weeks, and no prior back pain [BP] for at least 1 year) pain characteristics, smoking status, and brain functional properties were measured repeatedly over 1 year. Sixty-eight completed the study, subdivided into recovering (SBPr, n = 31) and persisting (SBPp, n = 37), based on >20% decrease in BP over the year. Thirty-two chronic back pain (CBP: duration > 5 years) and 35 healthy controls were similarly monitored. Smoking prevalence was higher in SBP and CBP but not related to intensity of BP. In SBP, smoking status at baseline was predictive of persistence of BP 1 year from symptom onset (differentiating SBPp and SBPr with 0.62 accuracy). Smoking status combined with affective properties of pain and medication use improved prediction accuracy (0.82). Mediation analysis indicated the prediction of BP persistence by smoking was largely due to synchrony of fMRI activity between two brain areas (nucleus accumbens and medial prefrontal cortex, NAc-mPFC). In SBP or CBP who ceased smoking strength of NAc-mPFC decreased from precessation to postcessation of smoking. We conclude that smoking increases risk of transitioning to CBP, an effect mediated by corticostriatal circuitry involved in addictive behavior and motivated learning.

Efficacy and safety of tanezumab monotherapy or combined with non-steroidal anti-inflammatory drugs in the treatment of knee or hip osteoarthritis pain.

OBJECTIVE: To evaluate whether subjects with knee or hip osteoarthritis (OA) pain on non-steroidal anti-inflammatory drugs (NSAIDs) received greater benefit when tanezumab monotherapy replaced or was coadministered with NSAIDs. METHODS: Subjects (N=2700) received intravenous tanezumab (5 or 10 mg) or placebo every 8 weeks with or without oral naproxen 500 mg twice daily or celecoxib 100 mg twice daily. Efficacy was assessed as change from baseline to week 16 in three co-primary endpoints: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, WOMAC Physical Function and Patient's Global Assessment (PGA) of OA. Safety assessments included adverse events, physical and neurological examinations, laboratory tests and vital signs. RESULTS: Although all tanezumab treatments provided significant improvements in WOMAC Pain and Physical Function over either NSAID alone, only tanezumab+NSAIDs were significant versus NSAIDs with PGA and met the prespecified definition of superiority. Combination treatment did not substantially improve pain or function over tanezumab monotherapy. Adverse event frequency was higher with tanezumab than with NSAIDs and highest with combination therapy. Higher incidence of all-cause total joint replacements occurred with tanezumab+NSAID versus tanezumab monotherapy or NSAIDs. Rapidly progressive OA incidence was significantly greater versus NSAID in all tanezumab groups except tanezumab 5 mg monotherapy. CONCLUSIONS: Subjects receiving partial symptomatic relief of OA pain with NSAIDs may receive greater benefit with tanezumab monotherapy. While only coadministration of tanezumab with NSAIDs met the definition of superiority, combination treatment did not provide important benefits over tanezumab monotherapy; small differences in efficacy were negated by treatment-limiting or irreversible safety outcomes. TRIAL REGISTRATION NUMBER: NCT00809354.

Bone Imaging and Fracture Risk after Spinal Cord Injury.

Spinal cord injury (SCI) is characterized by marked bone loss and an increased risk of fracture with high complication rate. Recent research based on advanced imaging analysis, including quantitative computed tomography (QCT) and patient-specific finite element (FE) modeling, has provided new and important insights into the magnitude and temporal pattern of bone loss, as well as the associated changes to bone structure and strength, following SCI. This work has illustrated the importance of early therapeutic treatment to prevent bone loss after SCI and may someday serve as the basis for a clinical fracture risk assessment tool for the SCI population. This review provides an update on the epidemiology of fracture after SCI and discusses new findings and significant developments related to bone loss and fracture risk assessment in the SCI population based on QCT analysis and patient-specific FE modeling.

Reorganization of hippocampal functional connectivity with transition to chronic back pain.

The hippocampus has been shown to undergo significant changes in rodent models of neuropathic pain; however, the role of the hippocampus in human chronic pain and its contribution to pain chronification have remained unexplored. Here we examine hippocampal processing during a simple visual attention task. We used functional MRI to identify intrinsic and extrinsic hippocampal functional connectivity (synchronous neural activity), comparing subacute back pain (SBP, back pain 1-4 mo) and chronic back pain (CBP, back pain >10 yr) patients to control (CON) subjects. Both groups showed more extensive hippocampal connectivity than CON subjects. We then examined the evolution of hippocampal connectivity longitudinally in SBP patients who recovered (SBPr, back pain decreased >20% in 1 yr) and those with persistent pain (SBPp). We found that SBPp and SBPr subjects have distinct changes in hippocampal-cortical connectivity over 1 yr; specifically, SBPp subjects showed large decreases in hippocampal connectivity with medial prefrontal cortex (HG-mPFC). Furthermore, in SBP patients the strength of HG-mPFC reflected variations in back pain over the year. These relationships were replicated when examined in a different task performed by SBP patients (rating fluctuations of back pain), indicating that functional connectivity of the hippocampus changes robustly in subacute pain and the nature of these changes depends on whether or not patients recover from SBP. The observed reorganization of processing within the hippocampus and between the hippocampus and the cortex seems to contribute to the transition from subacute to chronic pain and may also underlie learning and emotional abnormalities associated with chronic pain.

Shape shifting pain: chronification of back pain shifts brain representation from nociceptive to emotional circuits.

Chronic pain conditions are associated with abnormalities in brain structure and function. Moreover, some studies indicate that brain activity related to the subjective perception of chronic pain may be distinct from activity for acute pain. However, the latter are based on observations from cross-sectional studies. How brain activity reorganizes with transition from acute to chronic pain has remained unexplored. Here we study this transition by examining brain activity for rating fluctuations of back pain magnitude. First we compared back pain-related brain activity between subjects who have had the condition for ∼2 months with no prior history of back pain for 1 year (early, acute/subacute back pain group, n = 94), to subjects who have lived with back pain for >10 years (chronic back pain group, n = 59). In a subset of subacute back pain patients, we followed brain activity for back pain longitudinally over a 1-year period, and compared brain activity between those who recover (recovered acute/sub-acute back pain group, n = 19) and those in which the back pain persists (persistent acute/sub-acute back pain group, n = 20; based on a 20% decrease in intensity of back pain in 1 year). We report results in relation to meta-analytic probabilistic maps related to the terms pain, emotion, and reward (each map is based on >200 brain imaging studies, derived from neurosynth.org). We observed that brain activity for back pain in the early, acute/subacute back pain group is limited to regions involved in acute pain, whereas in the chronic back pain group, activity is confined to emotion-related circuitry. Reward circuitry was equally represented in both groups. In the recovered acute/subacute back pain group, brain activity diminished in time, whereas in the persistent acute/subacute back pain group, activity diminished in acute pain regions, increased in emotion-related circuitry, and remained unchanged in reward circuitry. The results demonstrate that brain representation for a constant percept, back pain, can undergo large-scale shifts in brain activity with the transition to chronic pain. These observations challenge long-standing theoretical concepts regarding brain and mind relationships, as well as provide important novel insights regarding definitions and mechanisms of chronic pain.

Intra-articular hylastan versus steroid for knee osteoarthritis.

PURPOSE: To assess the efficacy and safety of one and two intra-articular (IA) injections of the new viscosupplement, hylastan, compared with a single IA corticosteroid injection for pain due to knee osteoarthritis (OA). Hylastan is a high-molecular-weight hyaluronan derivative prepared from bacterial fermented sodium hyaluronate that was developed to remain in the joint for longer than most other viscosupplements. METHODS: This 6-month, double-blind, randomized, parallel group, multicenter trial enrolled patients aged ≥40 years who met American College of Rheumatology criteria for knee OA and had continued pain despite conservative treatment. Patients were randomized 1:1:1 to one of three arms: 2 × 4 mL hylastan (n = 129; arthrocentesis then IA hylastan Day 0, same treatment Week 2); 1 × 4 mL hylastan (n = 130; arthrocentesis then IA hylastan Day 0, arthrocentesis only Week 2); steroid (n = 132; arthrocentesis then IA methylprednisolone acetate 40 mg Day 0, arthrocentesis only Week 2). Participants and evaluators were blinded to treatment. The primary clinical outcome measure was change from baseline in WOMAC A pain score over all postbaseline visits to Week 26. RESULTS: Statistically significant pain reduction was observed in all three arms, with similar mean (95 % CI) changes in WOMAC A: 2 × 4 mL hylastan -0.9 (-1.0, -0.7); 1 × 4 mL hylastan -0.8 (-0.9, -0.7); steroid -0.9 (-1.0, -0.8); all P < 0.0001 versus baseline. Changes in secondary outcomes (OMERACT-OARSI and WOMAC A responder rates, patient/clinical observer global assessments, and WOMAC A1 walking pain) were similar in all three arms. Target knee adverse events were comparable for all treatments. CONCLUSIONS: Both IA hylastan injection regimens were effective in relieving pain with an acceptable safety profile. IA hylastan did not show a difference versus IA corticosteroid; therefore, the hypothesis of superior pain relief was not met. Further research is needed to compare the efficacy and safety of hylastan with other viscosupplements.

Monthly treatment with romosozumab for 1 year increases bone mineral at the hip, but not the knee, in women with chronic spinal cord injury.

Bone loss below the level of neurological lesion is a well-known complication of spinal cord injury (SCI). To date, most research has focused on pharmaceutical intervention using antiresorptives to prevent bone loss during the acute phase of SCI; however, limited research has investigated treatments for established osteoporosis during chronic SCI. Romosozumab, a monoclonal antibody with both antiresorptive and anabolic effects, has demonstrated significant increases in BMD for women with established PMO. Therefore, the purpose of this study was to examine the efficacy of monthly treatment with romosozumab to improve DXA-derived areal BMD at the hip, and CT-derived BMC and strength at the hip and knee in women with chronic SCI and an inability to ambulate. Twelve female participants with chronic SCI were recruited to receive 1 yr of monthly subcutaneous injections of romosozumab (210 mg). DXA and CT scans were taken at baseline, and months 3, 6, and 12 to quantify bone mineral, and finite element (FE) analysis was used to predict bone strength. Longitudinal mixed effects models were employed to determine the impact of treatment on bone properties. After 12 mo of treatment, areal BMD at the lumbar spine and total hip were significantly increased with median changes of 10.2% (IQR: 8.3-15.2%, p<.001) and 4.2% (IQR: 3.4-7.7%, p = .009), respectively. Improvements at the hip were primarily due to increases in trabecular, not cortical, bone and effects were sufficient to significantly increase FE-predicted strength by 20.3% (IQR: 9.5-37.0%, p = .004). Treatment with romosozumab did not lead to any significant improvement in bone mineral at the distal femur or proximal tibia. These findings provide promising results for romosozumab treatment to improve bone mineral and reduce fracture risk at the hip, but not the knee, in women with chronic SCI.

Does sex affect the efficacy of systemic pharmacological treatments of pain in knee osteoarthritis? A systematic review.

Objective: To determine whether sex influences the analgesic efficacy of systemic pharmacological treatment in patients with knee osteoarthritis. Design: A systematic review, guided by Cochrane methods, sourced studies from Medline, Cochrane Library, Embase, and CINAHL Plus with Full Text as of October 10, 2022. Eligible studies were double-blind RCTs evaluating systemic pharmacological treatments for knee osteoarthritis in adults, with minimum 30-day treatment duration, reporting sex-specific results or mentioning sex subgroup analysis for analgesic efficacy. The risk of bias was assessed using the Cochrane Risk of Bias tool version 2 (RoB 2). Results: 9 studies (5201 participants) met inclusion criteria, analyzing drugs including duloxetine, etoricoxib, tapentadol, naproxcinod, lutikizumab, and rofecoxib. Only one study reported sex-specific results. Review findings suggested no significant sex-based differences in treatment efficacy, however, data were limited due to a lack of sex-specific reporting or inclusion of sex in subgroup analyses. Conclusions: Current evidence does not support the existence of sex differences in the analgesic efficacy of systemic knee osteoarthritis treatments. However, this conclusion is substantially limited by the paucity of sex-specific reporting of results or subgroup analyses in most primary studies, emphasizing the need for future research to report on sex-stratified data to allow for comprehensive, personalized treatment strategies.