Convergent Validity of the Dutch Central Sensitization Inventory: Associations with Psychophysical Pain Measures, Quality of Life, Disability, and Pain Cognitions in Patients with Chronic Spinal Pain.

OBJECTIVE: Symptoms of central sensitization (CS) have been described in patients with chronic spinal pain (CSP). Although a gold standard to diagnose CS is lacking, psychophysical pain measures are often used. The Central Sensitization Inventory (CSI) is proposed as an alternative method and indirect tool for the evaluation of CS symptomatology. The aim of the current study was to evaluate the convergent validity of the CSI by investigating the association with psychophysical pain measures and self-reported measures of current pain intensity, quality of life, disability, and catastrophizing in CSP patients. METHODS: One hundred sixteen patients with nonspecific CSP were included in the present study. Patients completed the CSI, were subjected to pressure pain thresholds (PPTs) and a conditioned pain modulation (CPM) paradigm, and completed questionnaires for current pain intensity, quality of life, pain disability, and pain catastrophizing. RESULTS: Higher CSI scores were weakly correlated with lower PPTs (-0.276 ≤ r ≤ -0.237; all P ≤ 0.01) and not with CPM efficacy (r = 0.017; P = 0.858). Higher CSI scores were moderately correlated with higher current pain intensity (r = 0.320; P < 0.001), strongly correlated with lower physical (r = -0.617; P < 0.001) and emotional (r = -0.635; P < 0.001) quality of life, and moderately correlated with higher pain disability (r = 0.472; P < 0.001) and higher pain catastrophizing (r = 0.464; P < 0.001). CONCLUSION: The CSI was weakly associated with PPTs and not with CPM efficacy in CSP patients. Moderate to strong associations were found with current pain intensity, quality of life, disability, and catastrophizing. The current results illustrate that the CSI does not reflect a direct measure of CS, yet is a representation of general distress, possible originating from CS symptoms.

Fiber Typing of the Erector Spinae and Multifidus Muscles in Healthy Controls and Back Pain Patients: A Systematic Literature Review.

OBJECTIVE: Understanding the changes in muscle fiber typing is relevant in the context of muscle disorders because it provides information on the metabolic profile and functional capacity. The aim of this study was to systematically review the literature comparing muscle fiber typing in the back muscles of healthy subjects with low back pain (LBP) patients. METHODS: Predefined keywords regarding muscle fiber typing and back muscles were combined in PubMed and Web of Science electronic search engines from inception to August 2014. Full-text articles were independently screened by 2 independent, blinded researchers. Full texts fulfilling the predefined inclusion criteria were assessed on risk of bias by 2 independent researchers, and relative data were extracted. Data were not pooled because of heterogeneity in biopsy locations and population. RESULTS: From the 214 articles that were identified, 18 met the inclusion criteria. These articles evaluated the muscle fiber type distribution or proportional fiber type area between muscles, muscle layers, men, and women or healthy subjects and LBP patients. Regarding muscle fiber type distribution, findings in healthy subjects and LBP patients show no or inconclusive evidence for intermuscular and interindividual differentiation. Studies evaluating the proportional fiber type area also suggest little intermuscular differentiation but provide plausible evidence that the proportional area occupied by type I fibers is higher in women compared to men. The evidence for differentiation based on the presence of low back pain is conflicting. CONCLUSION: This study found that the evidence regarding muscle fiber typing in back muscles is either inconclusive or shows little differences. The most plausible evidence exists for differentiation in proportional fiber type area depending on sex.