The Levels of Insulin-Like Growth Factor in Patients with Myofascial Pain Syndrome and in Healthy Controls.

BACKGROUND: Insulin-like growth factor-1 (IGF-1) plays an important role in muscle maintenance and repair. The role of IGF-2 in the muscle is less clear. OBJECTIVE: To compare the levels of IGF-1 and IGF-2 in participants with acute myofascial pain syndrome (MPS) versus healthy controls and to determine whether age, gender, body mass index (BMI), region of pain, and pain intensity are associated with IGF levels. DESIGN: A case-control study design included a total of 74 participants. SETTING: Hospital emergency department. PARTICIPANTS: Participants presenting with acute MPS (n = 43) and non-MPS controls (n  =  31). MAIN OUTCOME MEASURES: Serum IGF-1 and IGF-2 (pg/mL) were measured in participants with MPS within 24 hours of symptom onset, and in non-MPS controls. Group and gender differences in serum IGF-1 and IGF-2 were assessed, with group and gender as factors, while controlling for age and BMI. RESULTS: The mean IGF-1 levels were not significantly different between MPS and controls (88 554.1, confidence interval [CI], 79 724.4-97 383.7 vs. 97 911.2, CI, 85 322.8-110 493.6). Significant differences were also not observed in IGF-1 levels between men and women with MPS nor between men and women in the control group. Mean levels of IGF-2 were significantly lower in patients with MPS than in controls (226 608.9, CI, 180 057.3-273 160.5 versus 460 343.9, CI, 387 809.4-532 878.2, P < .001). There were no significant gender differences in the levels of IGF-2 in patients with MPS. Mean IGF-2 levels (pg/mL) of men and women with MPS were lower (253 343.0, CI, 179 891.0-326 795.0, and 204 524.2, CI, 141 176.4-267 872.0, respectively) than those of healthy men and women (428 177.2, CI, 368 345.7-488 008.6, and 511 274.4, 355 178.6-687 370.1, respectively). Lower BMI and younger age were associated with higher levels of IGF-2. Pain intensity was associated with IGF-2 but not with IGF-1, whereas region of pain was not associated with either IGF-1 or IGF-2 levels. CONCLUSIONS: IGF-2 levels were lower in patients with acute MPS versus healthy controls with no gender differences, and IGF-1 levels were not different among the groups. Future studies should investigate the role of IGF-2 in muscle maintenance and repair in MPS.

Influencing Pain Inferences Using Random Numerical Anchoring: Randomized Controlled Trial.

BACKGROUND: Numerical anchoring occurs when exposure to a numeric quantity influences a person's subsequent judgment involving other quantities. This could be applicable to the evaluation of pain, where exposure to an unrelated number before the evaluation of pain could influence pain ratings. OBJECTIVE: This study aimed to determine whether exposure to a random numeric anchor influences subsequent pain intensity ratings of a hypothetical patient. METHODS: In this study, 385 participants read a vignette describing a patient with chronic pain before being randomly assigned to one of four groups. Groups 1 and 2 spun an 11-wedge number wheel (0-10), which was, unbeknown to the participants, programmed to stop on a high number (8) or a low number (2), respectively. Group 3 spun a similar letter wheel (A-K), which was programmed to stop on either the letter C or I (control 1). Group 4 did not spin a wheel (control 2). Participants were then asked to rate the patient's pain intensity using a 0 to 10 numeric rating scale. RESULTS: The high-number group rated the patient's pain (median 8, IQR 2) significantly higher than the letter wheel control (median 7, IQR 2; P=.02) and the low-number group (median 6, IQR 2; P<.001). The low-number group rated the pain significantly lower than controls 1 and 2 (median 7, IQR 2; both P=.045). CONCLUSIONS: Pain ratings were influenced by prior exposure to a random number with no relevant information about the patient's pain, indicating anchoring had occurred. However, contrary to the traditional definition of anchoring where anchoring occurs even when participants are unaware of the anchor's influence, in this study, the anchoring effect was seen only in participants who believed that the anchor had influenced them. This suggests that anchoring effects could potentially occur among health care providers tasked with evaluating a patient's pain and should be evaluated further.

Evaluating the efficacy of an attention modification program for patients with fibromyalgia: a randomized controlled trial.

Persons with chronic musculoskeletal pain may be hypervigilant for pain-related cues which, paradoxically, may be maintaining their pain. Several randomized controlled trials have assessed whether a modified dot-probe protocol (ie, attention bias modification [ABM]) reduces chronic pain- and pain-related symptoms in persons with several diagnoses, including fibromyalgia. Scalability and economic efficiency potentiates the appeal of ABM protocols; however, research results have been mixed, with only some studies evidencing significant symptom gains from ABM and some evidencing gains for the control group. The current randomized controlled trial sought to replicate and extend previous ABM research using idiosyncratic word stimuli and a 1-month follow-up. Participants included treatment-seeking adult women (n = 117) with fibromyalgia who were randomly assigned to a standard (ie, control) or active (ie, ABM) condition. The protocol was delivered online and involved twice-weekly 15-minute sessions, for 4 weeks, with questionnaires completed at baseline, posttreatment, and 1-month follow-up. Symptom reports were analysed with mixed hierarchical modelling. There was no evidence of differences between the control and ABM groups. Both groups had small significant (Ps < 0.05) improvements in pain experiences at posttreatment, but not at follow-up (Ps > 0.05). There were no significant changes for either group on measures of anxiety sensitivity, illness/injury sensitivity, pain-related fear, pain-related anxiety, or attentional biases (Ps > 0.05). The current findings add to the emerging and mixed literature regarding ABM for pain by demonstrating that ABM produces no substantive improvements in pain or pain-related constructs in a large sample of patients with fibromyalgia.

Optimizing Pain and Rehabilitation After Knee Arthroplasty: A Two-Center, Randomized Trial.

BACKGROUND: This randomized trial compared (1) continuous femoral nerve block (cFNB), (2) single femoral nerve block (sFNB), and (3) local infiltration analgesia (LIA) with respect to analgesic and functional outcomes after primary tricompartmental knee arthroplasty (TKA). METHODS: One hundred twenty patients undergoing primary tricompartmental knee arthroplasty were randomly assigned to 1 of 3 interventions for postoperative analgesia: (1) cFNB-preoperative bolus of ropivacaine 0.5% 20 mL followed by ropivacaine 0.2% 5 mL per hour for 48 hours; (2) sFNB-preoperative bolus of ropivacaine 0.5% 20 mL with placebo 0.9% saline 5 mL per hour for 48 hours; or (3) LIA-intraoperative tricompartmental injection of ropivacaine 0.2% (150 mL) with epinephrine (10 µg/mL) and ketorolac 30 mg with femoral placebo 0.9% saline 20 mL preoperative bolus and 0.9% saline placebo 5 mL per hour for 48 hours. All participants received an identical, standardized, postoperative multimodal analgesic regimen. Participants, health care providers, data collectors, and analysts were blinded. All participants received identical perineural catheters and perineural/LIA solution (depending on randomized intervention) to maintain blinding. The primary outcome measure was numeric rating scale for pain (NRS) during physiotherapy on postoperative day (POD) 2 at 9:00 AM. Secondary outcomes included opioid consumption, NRS on POD 1 (rest/physiotherapy/worst), functional outcomes, and block complications. RESULTS: For the primary outcome, pain during physiotherapy on POD 2 at 9:00 AM, the overall analysis of covariance (ANCOVA) was significant (P = .049), but pairwise comparisons did not demonstrate any significant differences between treatment arms. NRS was 4.6 (95% confidence interval [CI], 3.3-6.0) for the cFNB group, 4.6 (95% CI, 3.3-6.0) for the sFNB group, and 3.4 (95% CI, 2.2-4.8) for the LIA group. The following is the mean difference in NRS on POD 2 at 9:00 AM among groups: cFNB-LIA (1.2, 95% CI, -0.1 to 2.5; P = .073); sFNB-LIA (1.2, 95% CI, -0.2 to 2.5; P = .097); cFNB-sFNB (0.0, 95% CI, -1.3 to 1.4; P = .996). There were no statistically significant differences between groups in cumulative 48-hour opioid consumption or functional outcomes. cFNB and LIA were superior to sFNB for NRS on POD 1 for worst pain experienced and pain during physiotherapy, respectively. There were no adverse events associated with study procedures reported among participants in the 3 groups. CONCLUSIONS: Our findings suggest no clinically significant differences between cFNB, LIA, and sFNB for pain during physiotherapy on POD 2 after TKA. Secondary analyses suggest that cFNB and LIA are superior to sFNB for early analgesic outcomes (NRS on POD 1) after TKA.

Relationship between pain and post-traumatic stress symptoms in palliative care.

CONTEXT: Previous research suggests that patients receiving palliative care may simultaneously experience poorly managed pain and post-traumatic stress disorder (PTSD)-related symptoms as a result of their deteriorating health. OBJECTIVES: To: 1) examine predictors of PTSD-related symptoms in patients requiring palliative care; 2) assess whether anxiety, depression, pain catastrophizing, and pain anxiety mediate the relationship between pain interference and PTSD-related symptoms; and 3) evaluate the impact of these variables on pain interference and PTSD-related symptoms. METHODS: One hundred patients receiving palliative care at one of two palliative care sites in London, ON, Canada, completed the PTSD Checklist-Civilian version (PCL-C), the Hospital Anxiety and Depression Scale (HADS), the Pain Catastrophizing Scale (PCS), the Brief Pain Inventory-Short Form (BPI-SF), and the Pain Anxiety Symptoms Scale-20 (PASS-20). Hierarchical multiple regressions were used to examine HADS-Anxiety, HADS-Depression, PCS and PASS-20 scores as predictors of PCL-C scores; and mediation analyses were used to test the effect of HADS-Anxiety, HADS-Depression, PCS, and PASS-20 on the relationship between BPI-SF interference and PCL-C. Mediators that significantly affected this relationship in the individual mediator models were entered into a multiple mediator model. RESULTS: Only pain anxiety and pain catastrophizing emerged as significant mediators of the relationship between pain interference and PTSD-related symptoms. After being entered in a multiple mediator model, pain anxiety emerged as the strongest mediator. CONCLUSION: The findings of the present study reveal that pain and PTSD-related symptoms are important concerns in palliative care, and that pain must be addressed to best meet the needs of this population.