Impacts of priming on distinct immunosuppressive mechanisms of mesenchymal stromal cells under translationally relevant conditions.

BACKGROUND: The multimodal properties of mesenchymal stromal cells (MSCs), particularly their ability to modulate immune responses is of high interest in translational research. Pro-inflammatory, hypoxic, and 3D culture priming are promising and often used strategies to improve the immunosuppressive potency of MSCs, but the underlying mechanisms are not well understood. Therefore, the aims of this study were (i) to compare the effects of pro-inflammatory, hypoxic, and 3D culture priming on the in vitro immunosuppressive potential of MSCs, (ii) to assess if immunosuppressive priming effects are temporally preserved under standard and translationally relevant culture conditions, and (iii) to investigate if the three priming strategies engage the same immunosuppressive mechanisms. METHODS: Functional in vitro T cell suppressive potency measurements were conducted to assess the impact of pro-inflammatory, hypoxic, and 3D culture priming on the immunosuppressive potential of human bone marrow-derived MSCs. Primed MSCs were either cultured under standard cell culture conditions or translationally relevant culture conditions, and their transcriptomic adaptations were monitored over time. Next-generation sequencing was performed to assess if different priming strategies activate distinct immunosuppressive mechanisms. RESULTS: (i) Pro-inflammatory, hypoxic, and 3D culture priming induced profound transcriptomic changes in MSCs resulting in a significantly enhanced T cell suppressive potential of pro-inflammatory and 3D culture primed MSCs. (ii) Priming effects rapidly faded under standard cell culture conditions but were partially preserved under translationally relevant conditions. Interestingly, continuous 3D culture priming of MSCs maintained the immunosuppressive potency of MSCs. (iii) Next-generation sequencing revealed that priming strategy-specific differentially expressed genes are involved in the T cell suppressive capacity of MSCs, indicating that different priming strategies engage distinct immunosuppressive mechanisms. CONCLUSION: Priming can be a useful approach to improve the immunosuppressive potency of MSCs. However, future studies involving primed MSCs should carefully consider the significant impact of translationally relevant conditions on the preservation of priming effects. Continuous 3D culture could act as a functionalized formulation, supporting the administration of MSC spheroids for a sustainably improved immunosuppressive potency.

Morphological and Quantitative Parametric MRI Follow-up of Cartilage Changes Before and After Intra-articular Injection Therapy in Patients With Mild to Moderate Knee Osteoarthritis: A Randomized, Placebo-Controlled Trial.

BACKGROUND: Intra-articular injections are routinely used for conservative treatment of knee osteoarthritis (OA). The detailed comparative therapeutic effects of these injections on cartilage tissue are still unclear. OBJECTIVE: The aim of this study was to detect and compare knee cartilage changes after intra-articular injection of glucocorticoid, hyaluronic acid, or platelet-rich plasma (PRP) to placebo using quantitative (T2 and T2* mapping) and morphological magnetic resonance imaging parameters in patients with mild or moderate osteoarthritis. MATERIALS AND METHODS: In a double-blinded, placebo-controlled, single-center trial, knees with mild or moderate osteoarthritis (Kellgren-Lawrence grade 1-3) were randomly assigned to an intra-articular injection with 1 of these substances: glucocorticoid, hyaluronic acid, PRP, or placebo. Cartilage degeneration on baseline and follow-up magnetic resonance imaging scans (after 3 and 12 months) was assessed by 2 readers using quantitative T2 and T2* times (milliseconds) and morphological parameters (modified Outerbridge grading, subchondral bone marrow edema, subchondral cysts, osteophytes). RESULTS: One hundred twenty knees (30 knees per treatment group) were analyzed with a median patient age of 60 years (interquartile range, 54.0-68.0 years). Interreader reliability was good for T2 (ICC, 0.76; IQR, 0.68-0.83) and T2* (ICC, 0.83; IQR, 0.76-0.88) measurements. Morphological parameters showed no significant changes between all groups after 3 and 12 months. T2 mapping after 12 months showed the following significant ( P = 0.001-0.03) changes between groups in 6 of 14 compartments: values after PRP injection decreased compared with glucocorticoid in 4 compartments (complete medial femoral condyle and central part of lateral condyle) and compared with placebo in 2 compartments (anterior and central part of medial tibial plateau); values after glucocorticoid injection decreased compared with placebo in 1 compartment (central part of medial tibial plateau). No significant changes were seen for T2 and T2* times after 3 months and T2* times after 12 months. No correlation was found between T2/T2* times and Kellgren-Lawrence grade, age, body mass index, or pain (Spearman ρ, -0.23 to 0.18). CONCLUSIONS: Platelet-rich plasma injection has a positive long-term effect on cartilage quality in the medial femoral compartment compared to glucocorticoid, resulting in significantly improved T2 values after 12 months. For morphological cartilage parameters, injections with glucocorticoid, PRP, or hyaluronic acid showed no better effect in the short or long term compared with placebo.

Bone marrow stromal cells in Modic type 1 changes promote neurite outgrowth.

The pain in patients with Modic type 1 changes (MC1) is often due to vertebral body endplate pain, which is linked to abnormal neurite outgrowth in the vertebral body and adjacent endplate. The aim of this study was to understand the role of MC1 bone marrow stromal cells (BMSCs) in neurite outgrowth. BMSCs can produce neurotrophic factors, which have been shown to be pro-fibrotic in MC1, and expand in the perivascular space where sensory vertebral nerves are located. The study involved the exploration of the BMSC transcriptome in MC1, co-culture of MC1 BMSCs with the neuroblastoma cell line SH-SY5Y, analysis of supernatant cytokines, and analysis of gene expression changes in co-cultured SH-SY5Y. Transcriptomic analysis revealed upregulated brain-derived neurotrophic factor (BDNF) signaling-related pathways. Co-cultures of MC1 BMSCs with SH-SY5Y cells resulted in increased neurite sprouting compared to co-cultures with control BMSCs. The concentration of BDNF and other cytokines supporting neuron growth was increased in MC1 vs. control BMSC co-culture supernatants. Taken together, these findings show that MC1 BMSCs provide strong pro-neurotrophic cues to nearby neurons and could be a relevant disease-modifying treatment target.

Modic type 2 changes are fibroinflammatory changes with complement system involvement adjacent to degenerated vertebral endplates.

Background: Vertebral endplate signal intensity changes visualized by magnetic resonance imaging termed Modic changes (MC) are highly prevalent in low back pain patients. Interconvertibility between the three MC subtypes (MC1, MC2, MC3) suggests different pathological stages. Histologically, granulation tissue, fibrosis, and bone marrow edema are signs of inflammation in MC1 and MC2. However, different inflammatory infiltrates and amount of fatty marrow suggest distinct inflammatory processes in MC2. Aims: The aims of this study were to investigate (i) the degree of bony (BEP) and cartilage endplate (CEP) degeneration in MC2, (ii) to identify inflammatory MC2 pathomechanisms, and (iii) to show that these marrow changes correlate with severity of endplate degeneration. Methods: Pairs of axial biopsies (n = 58) spanning the entire vertebral body including both CEPs were collected from human cadaveric vertebrae with MC2. From one biopsy, the bone marrow directly adjacent to the CEP was analyzed with mass spectrometry. Differentially expressed proteins (DEPs) between MC2 and control were identified and bioinformatic enrichment analysis was performed. The other biopsy was processed for paraffin histology and BEP/CEP degenerations were scored. Endplate scores were correlated with DEPs. Results: Endplates from MC2 were significantly more degenerated. Proteomic analysis revealed an activated complement system, increased expression of extracellular matrix proteins, angiogenic, and neurogenic factors in MC2 marrow. Endplate scores correlated with upregulated complement and neurogenic proteins. Discussion: The inflammatory pathomechanisms in MC2 comprises activation of the complement system. Concurrent inflammation, fibrosis, angiogenesis, and neurogenesis indicate that MC2 is a chronic inflammation. Correlation of endplate damage with complement and neurogenic proteins suggest that complement system activation and neoinnervation may be linked to endplate damage. The endplate-near marrow is the pathomechanistic site, because MC2 occur at locations with more endplate degeneration. Conclusion: MC2 are fibroinflammatory changes with complement system involvement which occur adjacent to damaged endplates.

The role of the bone in complex regional pain syndrome 1-A systematic review.

OBJECTIVE: The aim of this systematic review was to appraise and analyse the knowledge on bone-related biochemical and histological biomarkers in complex regional pain syndrome 1 (CRPS 1). DATABASE: A total of 7 studies were included in the analysis (biochemical analyses n = 3, animal study n = 1, histological examination n = 3). RESULTS: Two studies were classified as having a low risk of bias and five studies with a moderate risk of bias. Biochemical analysis indicated an increased bone turnover with increased bone resorption (elevated urinary levels of deoxypyridinoline) and bone formation (increased serum levels of calcitonin, osteoprotegerin and alkaline phosphatase). The animal study reported an increased signalling of proinflammatory tumour necrosis factor 4 weeks postfracture, which did, however, not contribute to local bone loss. Histological examination from biopsies revealed thinning and resorption of cortical bone, rarefication and reduction in trabecular bone and vascular modification in the bone marrow in acute CRPS 1, and replacement of the bone marrow by dystrophic vessels in chronic CRPS 1. CONCLUSION: The limited data reviewed revealed certain potential bone-related biomarkers in CRPS. Biomarkers hold the potential to identify patients who may benefit from treatments that influence bone turnover. Thus, this review identifies important areas for future research in CRPS1 patients.

Role of C-reactive protein in the bone marrow of Modic type 1 changes.

Modic type 1 changes (MC1) are vertebral bone marrow lesions and associate with low back pain. Increased serum C-reactive protein (CRP) has inconsistently been associated with MC1. We aimed to provide evidence for the role of CRP in the tissue pathophysiology of MC1 bone marrow. From 13 MC1 patients undergoing spinal fusion at MC1 levels, vertebral bone marrow aspirates from MC1 and intrapatient control bone marrow were taken. Bone marrow CRP, interleukin (IL)-1, and IL-6 were measured with enzyme-linked immunosorbent assays; lactate dehydrogenase (LDH) was measured with a colorimetric assay. CRP, IL-1, and IL-6 were compared between MC1 and control bone marrow. Bone marrow CRP was correlated with blood CRP and with bone marrow IL-1, IL-6, and LDH. CRP expression by marrow cells was measured with a polymerase chain reaction. Increased CRP in MC1 bone marrow (mean difference: +0.22 mg CRP/g, 95% confidence interval [CI] [-0.04, 0.47], p = 0.088) correlated with blood CRP (r = 0.69, p = 0.018), with bone marrow IL-1ß (ρ = 0.52, p = 0.029) and IL-6 (ρ = 0.51, p = 0.031). Marrow cells did not express CRP. Increased LDH in MC1 bone marrow (143.1%, 95% CI [110.7%, 175.4%], p = 0.014) indicated necrosis. A blood CRP threshold of 3.2 mg/L detected with 100% accuracy increased CRP in MC1 bone marrow. In conclusion, the association of CRP with inflammatory and necrotic changes in MC1 bone marrow provides evidence for a pathophysiological role of CRP in MC1 bone marrow.

Influence of pregnancy/childbirth on long-term bone marrow edema and subchondral sclerosis of sacroiliac joints.

OBJECTIVE: To investigate long-term effects of pregnancy/childbirth on bone marrow edema (BME) and subchondral sclerosis of sacroiliac joints (SIJ) in comparison to MRI changes caused by spondyloarthritis (SpA) and assess the influence of birth method and number of children on SIJ-MRI changes. MATERIALS AND METHODS: This is a retrospective cohort study with 349 women (mean age 47 ± 14 years) suffering low back pain. Four subgroups were formed based on SpA diagnosis and childbirth (CB) history. Two musculoskeletal radiologists scored the presence of BME and sclerosis on SIJ-MRI using the Berlin method. Further, an 11-point "global assessment score" representing the overall confidence of SpA diagnosis based on MRI was evaluated in addition to the ASAS (Assessment of Spondyloarthritis International Society) criterion of "positive MRI" for sacroiliitis. RESULTS: CB did not correlate with BME score (p = 0.38), whereas SpA diagnosis was associated with a higher BME score (r = 0.31, p < 0.001). Both CB (r = 0.21, p < 0.001) and SpA diagnosis (r = 0.33, p < 0.001) were correlated with a higher sclerosis score. CB was not associated with a higher confidence level in diagnosing SpA based on MRI (p = 0.07), whereas SpA diagnosis was associated with a higher score (r = 0.61, p < 0.001). Both CB (phi = 0.13, p = 0.02) and SpA diagnosis (phi = 0.23, p < 0.001) were significantly associated with a positive ASAS criterion for sacroiliitis. In non-SpA patients with CB, number of children (p = 0.001) was an independent predictor of sclerosis score, while birth method yielded no significant effect (p = 0.75). CONCLUSION: Pregnancy/CB has no impact on long-term BME on SIJ, however, may cause long-term subchondral sclerosis-similar to SpA-associated sclerosis. Number of children is positively correlated with SIJ sclerosis. Birth method yields no effect on SIJ sclerosis.

The influence of comorbidities on the treatment outcome in symptomatic lumbar spinal stenosis: A systematic review and meta-analysis.

BACKGROUND: Lumbar spinal stenosis (LSS) affects mainly elderly patients. To this day, it is unclear whether comorbidities influence treatment success. The aim of this systematic review and meta-analysis was to assess the impact of comorbidities on the treatment effectiveness in symptomatic LSS. METHODS: We conducted a systematic review and meta-analysis and reviewed prospective or retrospective studies from Medline, Embase, Cochrane Library and CINAHL from inception to May 2020, including adult patients with LSS undergoing surgical or conservative treatment. Main outcomes were satisfaction, functional and symptoms improvement, and adverse events (AE). Proportions of outcomes within two subgroups of a comorbidity were compared with risk ratio (RR) as summary measure. Availability of ≥3 studies for the same subgroup and outcome was required for meta-analysis. RESULTS: Of 72 publications, 51 studies, mostly assessing surgery, there was no evidence reported that patients with comorbidities were less satisfied compared to patients without comorbidities (RR 1.06, 95% confidence interval (CI) 0.77 to 1.45, I 2 94%), but they had an increased risk for AE (RR 1.46, 95% CI 1.06 to 2.01, I 2 72%). A limited number of studies found no influence of comorbidities on functional and symptoms improvement. Older age did not affect satisfaction, symptoms and functional improvement, and AE (age >80 years RR 1.22, 95% CI 0.98 to 1.52, I 2 60%). Diabetes was associated with more AE (RR 1.72, 95% CI 1.19 to 2.47, I 2 58%). CONCLUSION: In patients with LSS and comorbidities (in particular diabetes), a higher risk for AE should be considered in the treatment decision. Older age alone was not associated with an increased risk for AE, less functional and symptoms improvement, and less treatment satisfaction.

Long-term Results After Surgical or Nonsurgical Treatment in Patients With Degenerative Lumbar Spinal Stenosis: A Prospective Multicenter Study.

STUDY DESIGN: Prospective, multicenter cohort study. OBJECTIVE: The aim of our study was to assess the course of patients over a period of 3 years undergoing surgical or nonsurgical treatments for degenerative lumbar spinal stenoses (DLSS) based on data from the Lumbar Stenosis Outcome Study (LSOS), prospectively performed in eight hospitals. SUMMARY OF BACKGROUND DATA: The optimal treatment strategy for patients with DLSS is still debated. METHODS: The outcomes of patients with verified DLSS were quantified by Spinal Stenosis Measure (SSM) symptoms- and SSM function-scores, and EQ-5D-3L (quality of life) summary index (SI) over time (up to 36-month follow-up), and minimal clinically important difference (MCID) in SSM symptoms, SSM function, and EQ-5D-3L SI from baseline to 36-month follow-up. RESULTS: For this study, 601 patients met the inclusion criteria; 430 underwent surgery, 18 of them only after more than a year after enrolment, 171 received nonsurgical treatment only. At baseline, patients in the surgical and nonsurgical groups had similar values for the SSM symptoms and SSM function scores, but patients in the surgical group suffered significantly more from buttocks pain and reported more worsening symptoms over the last 3 months before enrollment in the study. Surgically treated patients (except changers) performed significantly better in all clinical outcome measures (P < 0.001) with a plateau at 12-month follow-up staying constant until the follow-up ended. Further, two-thirds of patients in the surgical group had a relevant improvement in function, symptoms, and quality of life, compared with only about half of those in terms of symptoms and even less in terms of function and quality of life with nonsurgical treatment. CONCLUSIONS: Surgical treatment of DLSS results in more favorable clinical outcomes with a sustained effect over time, compared to nonsurgical treatment. LEVEL OF EVIDENCE: 3.

MRI of complex regional pain syndrome in the foot.

PURPOSE: To evaluate the diagnostic potential of MRI in patients with suspected CRPS (complex regional pain syndrome). METHOD: A retrospective health-record search was conducted for patients with suspected CRPS (foot). Fifty patients with initially suspected CRPS were included (37 females (51 ± 13 years) and 13 males (44 ± 15 years)). All patients underwent MRI. Two radiologists assessed skin, bone, and soft tissue parameters on MRI. The final diagnosis was CRPS (Gold standard: Budapest criteria) or non-CRPS. MRI parameters were compared between CRPS patients and non-CRPS patients. RESULTS: CRPS was diagnosed in 22/50(44 %) patients. Skin thickness (1.9 ± 0.5 mm vs. 1.7 ± 0.3 mm, p = 0.399), enhancement, and subcutaneous edema showed no differences between CRPS and non-CRPS patients. Bone marrow edema presence and pattern were not different between groups. Up to 50 % of CRPS patients showed no bone marrow edema. Subcortical enhancement and periosteal enhancement were not different between groups. For reader 1, muscle edema score was higher in the non-CRPS group compared to the CRPS group (0.1 ± 0.2 vs. 0.6 ± 1.0, p = 0.008), but not different for reader 2 (0.1 ± 0.5 vs. 0.2 ± 0.8, p = 0.819). Perfusion pattern was more extensive in non-CRPS patients for reader 1 (p = 0.048), but not for reader 2 (p = 0.157). Joint effusions showed no difference between groups. CONCLUSIONS: MRI cannot distinguish between CRPS and non-CRPS patients. The role of MR imaging in patients with suspected CRPS is to exclude alternative diagnoses that would better explain patients' symptoms.

Serum Biomarkers for Connective Tissue and Basement Membrane Remodeling are Associated with Vertebral Endplate Bone Marrow Lesions as Seen on MRI (Modic Changes).

Vertebral endplate bone marrow lesions, visualized on magnetic resonance imaging (MRI) as Modic changes (MC), are associated with chronic low back pain (cLBP). Since guidelines recommend against routine spinal MRI for cLBP in primary care, MC may be underdiagnosed. Serum biomarkers for MC would allow early diagnosis, inform clinical care decisions, and supplement treatment monitoring. We aimed to discover biomarkers in the blood serum that correlate with MC pathophysiological processes. For this single-site cross-sectional study, we recruited 54 subjects with 38 cLBP patients and 16 volunteers without a history of LBP. All subjects completed an Oswestry Disability Index (ODI) questionnaire and 10-cm Visual Analog Score (VAS) for LBP (VASback) and leg pain. Lumbar T1-weighted and fat-saturated T2-weighted MRI were acquired at 3T and used for MC classification in each endplate. Blood serum was collected on the day of MRI. Biomarkers related to disc resorption and bone marrow fibrosis were analyzed with enzyme-linked immune-absorbent assays. The concentration of biomarkers between no MC and any type of MC (AnyMC), MC1, and MC2 were compared. The Area Under the Curve (AUC) of the Receiver Operating Characteristics were calculated for each biomarker and for bivariable biomarker models. We found that biomarkers related to type III and type IV collagen degradation and formation tended to correlate with the presence of MC (p = 0.060-0.088). The bivariable model with the highest AUC was PRO-C3 + C4M and had a moderate diagnostic value for AnyMC in cLBP patients (AUC = 0.73, specificity = 78.9%, sensitivity = 73.7%). In conclusion, serum biomarkers related to the formation and degradation of type III and type IV collagen, which are key molecules in bone marrow fibrosis, correlated with MC presence. Bone marrow fibrosis may be an important pathophysiological process in MC that should be targeted in larger biomarker and treatment studies.

Evaluating the Minimal Clinically Important Difference of EQ-5D-3L in Patients With Degenerative Lumbar Spinal Stenosis: A Swiss Prospective Multicenter Cohort Study.

STUDY DESIGN: Analysis of a prospective, multicenter cohort study. OBJECTIVE: The aim of our study was to compare thresholds of published minimal clinically important differences (MCID) for the three-level EuroQol-5D health survey (EQ-5D-3L) summary index (range -0.53 to 1.00) with our anchor-based estimate and evaluate how useful these thresholds are in determining treatment success in patients undergoing surgery for degenerative lumbar spinal stenosis (DLSS). SUMMARY OF BACKGROUND DATA: MCID values for EQ-5D-3L are specific to the underlying disease and only three studies have been published for DLSS patients reporting different values. METHODS: Patients of the multicenter Lumbar Stenosis Outcome Study with confirmed DLSS undergoing first-time decompression or fusion surgery with 12-month follow-up were enrolled in this study. To calculate MCID we used the Spinal Stenosis Measure satisfaction subscale as anchor. RESULTS: For this study, 364 patients met the inclusion criteria; of these, 196 were very satisfied, 72 moderately satisfied, 43 somewhat satisfied, and 53 unsatisfied 12 months after surgery. The MCID calculation estimated for EQ-5D-3L a value of 0.19. Compared with published MCID values (ranging from 0.30 to 0.52), our estimation is less restrictive. CONCLUSIONS: In patients with LSS undergoing surgery, we estimated an MCID value for EQ-5D-3L summary index of 0.19 with the help of the average change anchor-based method, which we find to be the most suitable method for assessing patient change scores. LEVEL OF EVIDENCE: 3.

What is the treatment effect of surgery compared with nonoperative treatment in patients with lumbar spinal stenosis at 1-year follow-up?

Objective: The aim of this study was to obtain an unbiased causal treatment estimate of the between-group difference of surgery versus nonoperative treatment with respect to outcomes on quality of life, pain, and disability in patients with degenerative lumbar spinal stenosis (DLSS) 12 months after baseline. Methods: The authors included DLSS patients from a large prospective multicenter observational cohort study. Propensity score matching was used, including 15 demographic, clinical, and MRI variables. Linear and logistic mixed-effects regression models were applied to quantify the between-group treatment effect. Unmeasured confounding was addressed in a sensitivity analysis, assessing the robustness of the results. Results: A total of 408 patients were included in this study, 222 patients after matching, with 111 in each treatment group. Patients with nonoperative treatment had lower quality of life at the 12-month follow-up (−6.21 points, 95% CI −9.93 to −2.49) as well as lower chances of reaching a minimal clinically important difference in Spinal Stenosis Measure (SSM) symptoms (OR 0.26, 95% CI 0.13 to 0.53) and SSM function (OR 0.26, 95% CI 0.14 to 0.49), than patients undergoing surgery. These results were very robust in case of unmeasured confounding. The surgical complication rate was low; 5 (4.5%) patients experienced a durotomy during intervention, and 5 (4.5%) patients underwent re-decompression. Conclusions: The authors used propensity score matching to assess the difference in treatment efficacy of surgery compared with nonoperative treatment in elderly patients with DLSS. This study delivers strong evidence that surgical treatment is superior to nonoperative treatment. It helps in clinical decision-making, especially when patients suffer for a long time, sometimes over many years, hoping for a spontaneous improvement of their symptoms. In light of these new results, the number of years with disability can hopefully be reduced by providing adequate treatment at the right time for this ever-growing elderly and frail population. Abbreviations: DLSS = degenerative lumbar spinal stenosis; HADS = Hospital Anxiety and Depression Scale; ITT = intention-to-treat; LSOS = Lumbar Stenosis Outcome Study; MCID = minimal clinically important difference; RCT = randomized controlled trial; SMD = standardized mean difference; SSM = Spinal Stenosis Measure.

Standards for the diagnosis and management of complex regional pain syndrome: Results of a European Pain Federation task force.

BACKGROUND: Complex regional pain syndrome is a painful and disabling post-traumatic primary pain disorder. Acute and chronic complex regional pain syndrome (CRPS) are major clinical challenges. In Europe, progress is hampered by significant heterogeneity in clinical practice. We sought to establish standards for the diagnosis and management of CRPS. METHODS: The European Pain Federation established a pan-European task force of experts in CRPS who followed a four-stage consensus challenge process to produce mandatory quality standards worded as grammatically imperative (must-do) statements. RESULTS: We developed 17 standards in 8 areas of care. There are 2 standards in diagnosis, 1 in multidisciplinary care, 1 in assessment, 3 for care pathways, 1 in information and education, 4 in pain management, 3 in physical rehabilitation and 2 on distress management. The standards are presented and summarized, and their generation and consequences were discussed. Also presented are domains of practice for which no agreement on a standard could be reached. Areas of research needed to improve the validity and uptake of these standards are discussed. CONCLUSION: The European Pain Federation task force present 17 standards of the diagnosis and management of CRPS for use in Europe. These are considered achievable for most countries and aspirational for a minority of countries depending on their healthcare resource and structures. SIGNIFICANCE: This position statement summarizes expert opinion on acceptable standards for CRPS care in Europe.

Prognostic function to estimate the probability of meaningful clinical improvement after surgery - Results of a prospective multicenter observational cohort study on patients with lumbar spinal stenosis.

BACKGROUND: Approximately two thirds of patients with lumbar spinal stenosis (LSS) who undergo surgical treatment benefit from the surgery. The objective of this study was to derive a prognostic probability function (PPF) to identify patients with a high probability of post-surgical improvement because there is currently no method available. METHODS: In this multicenter, prospective, observational study, we collected data from eight medical centers in Switzerland in which patients underwent surgery for LSS. The endpoints were meaningful clinically important differences (MCID) in pain and disability one year after baseline. We developed a PPF named PROCESS (PostopeRative OutComE Spinal Stenosis), based on a large set of prognostic indicators extracted from the literature. The PPF was derived using data from a random subset of two thirds of the patients and validated in the remaining third. We addressed overfitting by shrinking the regression coefficients. The area under the ROC curve (AUC) and calibration determined the accuracy of the PPF. RESULTS: In this study, 452 LSS patients received surgery. 73% of the 300 patients in the derivation subset reached an MCID in pain and 68% reached an MCID in disability. The corresponding values were 70% and 63% in the validation subset, respectively. In the derivation subsample, the AUC was 0.64 (95% CI 0.57 to 0.71) for of the PPF predicting MCID in pain and 0.71 (0.64 to 0.77) for MCID in disability, after shrinkage. The corresponding numbers were 0.62 (0.52 to 0.72) and 0.70 (0.60 to 0.79) in the validation subsample, and the PPF showed good calibration. CONCLUSIONS: Surgical treatment for patients with lumbar spinal stenosis is being performed with increasing frequency. PROCESS is conditional on the individual pattern of preoperatively available prognostic indicators, and may be helpful for clinicians in counselling patients and in guiding the discussion on individual treatment decision in the era of personalized medicine.

Systematic evaluation of RNA quality, microarray data reliability and pathway analysis in fresh, fresh frozen and formalin-fixed paraffin-embedded tissue samples.

Formalin-fixed paraffin-embedded (FFPE) tissues are valuable resources commonly used in pathology. However, formalin fixation modifies nucleic acids challenging the isolation of high-quality RNA for genetic profiling. Here, we assessed feasibility and reliability of microarray studies analysing transcriptome data from fresh, fresh-frozen (FF) and FFPE tissues. We show that reproducible microarray data can be generated from only 2 ng FFPE-derived RNA. For RNA quality assessment, fragment size distribution (DV200) and qPCR proved most suitable. During RNA isolation, extending tissue lysis time to 10 hours reduced high-molecular-weight species, while additional incubation at 70 °C markedly increased RNA yields. Since FF- and FFPE-derived microarrays constitute different data entities, we used indirect measures to investigate gene signal variation and relative gene expression. Whole-genome analyses revealed high concordance rates, while reviewing on single-genes basis showed higher data variation in FFPE than FF arrays. Using an experimental model, gene set enrichment analysis (GSEA) of FFPE-derived microarrays and fresh tissue-derived RNA-Seq datasets yielded similarly affected pathways confirming the applicability of FFPE tissue in global gene expression analysis. Our study provides a workflow comprising RNA isolation, quality assessment and microarray profiling using minimal RNA input, thus enabling hypothesis-generating pathway analyses from limited amounts of precious, pathologically significant FFPE tissues.

The impact of incidental durotomy on the outcome of decompression surgery in degenerative lumbar spinal canal stenosis: analysis of the Lumbar Spinal Outcome Study (LSOS) data--a Swiss prospective multi-center cohort study.

BACKGROUND: Incidental durotomy is a well-known complication during surgery for degenerative lumbar spinal stenosis (DLSS). In this prospective multicenter cohort study including eight medical centers our aim was to assess whether incidental durotomy during first-time lumbar spinal stenosis decompression surgery without fusion has an impact on long-term outcome. METHODS: Patients of the multi-center Lumbar Stenosis Outcome Study (LSOS) with confirmed DLSS undergoing first-time decompression without fusion were enrolled in this study. Baseline patient characteristics and outcomes were analyzed at 6, 12, and 24 months follow-up respectively with the Spinal Stenosis Measure (SSM), the Numeric Rating Scale (NRS), Feeling Thermometer (FT), the EQ-5D-EL, and the Roland and Morris Disability Questionnaire (RMDQ). RESULTS: A total of 167 patients met the inclusion criteria. Fifteen (9%) of those patients had an incidental durotomy. Baseline characteristics were similar between the durotomy and no-durotomy group. All patients improved over time. In the group of durotomy patients, the median improvement in SSM symptoms scale was 1.1 points at 6 months, 1.1 points at 12 months, and 1.6 points at 24 months after baseline. For the no-durotomy group, these improvements were 0.8, 0.9, and 0.9. For SSM function the improvements were 1.0, 0.8, and 0.9 in the durotomy group, and 0.6, 0.8, and 0.8 in the no-durotomy group. None of the between-group differences were statistically significant. CONCLUSIONS: Incidental durotomy in patients with DLSS undergoing first-time decompression surgery without fusion did not have negative effect on long-term outcome and quality of life. However, only 15 patients were included in the durotomy group but these findings remained even after adjusting for observed differences in baseline characteristics.

Is There an Association Between Pain and Magnetic Resonance Imaging Parameters in Patients With Lumbar Spinal Stenosis?

STUDY DESIGN: A prospective multicenter cohort study. OBJECTIVE: The aim of this study was to identify an association between pain and magnetic resonance imaging (MRI) parameters in patients with lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: At present, the relationship between abnormal MRI findings and pain in patients with LSS is still unclear. METHODS: First, we conducted a systematic literature search. We identified relationships of relevant MRI parameters and pain in patients with LSS. Second, we addressed the study question with a thorough descriptive and graphical analysis to establish a relationship between MRI parameters and pain using data of the LSS outcome study (LSOS). RESULTS: In the systematic review including four papers about the associations between radiological findings in the MRI and pain, the authors of two articles reported no association and two of them did. Of the latters, only one study found a moderate correlation between leg pain measured by Visual Analog Scale (VAS) and the degree of stenosis assessed by spine surgeons. In the data of the LSOS study, we could not identify a relevant association between any of the MRI parameters and buttock, leg, and back pain, quantified by the Spinal Stenosis Measure (SSM) and the Numeric Rating Scale (NRS). Even by restricting the analysis to the level of the lumbar spine with the most prominent radiological "stenosis," no relevant association could be shown. CONCLUSION: Despite a thorough analysis of the data, we were not able to prove any correlation between radiological findings (MRI) and the severity of pain. There is a need for innovative "methods/techniques" to learn more about the causal relationship between radiological findings and the patients' pain-related complaints. LEVEL OF EVIDENCE: 2.

The Impact of Obesity on the Outcome of Decompression Surgery in Degenerative Lumbar Spinal Canal Stenosis: Analysis of the Lumbar Spinal Outcome Study (LSOS): A Swiss Prospective Multicenter Cohort Study.

STUDY DESIGN: Prospective, multicenter cohort study including 8 medical centers of the Cantons Zurich, Lucerne, and Thurgau, Switzerland. OBJECTIVE: The aim of the study was to assess whether obese patients benefit after decompression surgery for degenerative lumbar spinal stenosis (DLSS). SUMMARY AND BACKGROUND DATA: Lumbar decompression surgery has been shown to improve quality of life in patients with DLSS. In the existing literature, the efficacy of lumbar decompression in the obese population remains controversial. METHODS: Baseline patient characteristics and outcomes were analyzed at 6 and 12 months follow-up with the Spinal Stenosis Measure (SSM), the Numeric Rating Scale (NRS), Feeling Thermometer (FT), the EQ-5D-EL, and the Roland and Morris Disability Questionnaire (RMDQ). Body mass index (BMI) was classified into 3 categories according to the WHO. Minimal clinically important differences (MCIDs) in SSM for different BMI categories were considered as main outcome. RESULTS: Of the 656 patients in the Lumbar Spinal Outcome Study database as of end of October 2014, 166 patients met the inclusion criteria. Fifty (30.1%) had a BMI less than 25 (underweight and normal weight group), 72 (43.4%) had a BMI between 25 and less than 30 (preobesity group), and 44 (26.5%) patients had a BMI at least 30 (obese group). We found for the main outcome that in obese patients 36% reached MCID at 6 months, and 48% at 12 months. The estimated odds ratios for MCID in the obese group were 0.78 (0.34-1.82) at 6 months and 0.99 (0.44-2.23) at 12 months in a logistic regression model adjusting for levels of laminectomy. In the additional outcomes, SSM, NRS, FT, and RMDQ showed statistically significant mean improvements in the 6 and 12 months follow-up. CONCLUSION: Obese patients can expect clinical improvement after lumbar decompression for DLSS, but the percentage of patients with a meaningful improvement is lower than in the group of patients with underweight, normal weight, and preobese weight at 6 and 12 months.

LumbSten: the lumbar spinal stenosis outcome study.

BACKGROUND: Lumbar spinal stenosis is the most frequent reason for spinal surgery in elderly people. For patients with moderate or severe symptoms different conservative and surgical treatment modalities are recommended, but knowledge about the effectiveness, in particular of the conservative treatments, is scarce. There is some evidence that surgery improves outcome in about two thirds of the patients. The aims of this study are to derive and validate a prognostic prediction aid to estimate the probability of clinically relevant improvement after surgery and to gain more knowledge about the future course of patients treated by conservative treatment modalities. METHODS/DESIGN: This is a prospective, multi-centre cohort study within four hospitals of Zurich, Switzerland. We will enroll patients with neurogenic claudication and lumbar spinal stenosis verified by Computer Tomography or Magnetic Resonance Imaging. Participating in the study will have no influence on treatment modality. Clinical data, including relevant prognostic data, will be collected at baseline and the Swiss Spinal Stenosis Questionnaire will be used to quantify severity of symptoms, physical function characteristics, and patient's satisfaction after treatment (primary outcome). Data on outcome will be collected 6 weeks, and 6, 12, 24 and 36 months after inclusion in the study. Applying multivariable statistical methods, a prediction rule to estimate the course after surgery will be derived. DISCUSSION: The ultimate goal of the study is to facilitate optimal, knowledge based and individualized treatment recommendations for patients with symptomatic lumbar spinal stenosis.