Ana M. Velly

Pharmacological management of chronic neuropathic pain - Consensus statement and guidelines from the Canadian Pain Society

Neuropathic pain (NeP), generated by disorders of the peripheral and central nervous system, can be particularly severe and disabling. Prevalence estimates indicate that 2% to 3% of the population in the developed world suffer from NeP, which suggests that up to one million Canadians have this disabling condition. Evidence-based guidelines for the pharmacological management of NeP are therefore urgently needed. Randomized, controlled trials, systematic reviews and existing guidelines focusing on the pharmacological management of NeP were evaluated at a consensus meeting. Medications are recommended in the guidelines if their analgesic efficacy was supported by at least one methodologically sound, randomized, controlled trial showing significant benefit relative to placebo or another relevant control group. Recommendations for treatment are based on degree of evidence of analgesic efficacy, safety, ease of use and cost-effectiveness. Analgesic agents recommended for first-line treatments are certain antidepressants (tricyclics) and anticonvulsants (gabapentin and pregabalin). Second-line treatments recommended are serotonin noradrenaline reuptake inhibitors and topical lidocaine. Tramadol and controlled-release opioid analgesics are recommended as third-line treatments for moderate to severe pain. Recommended fourth-line treatments include cannabinoids, methadone and anticonvulsants with lesser evidence of efficacy, such as lamotrigine, topiramate and valproic acid. Treatment must be individualized for each patient based on efficacy, side-effect profile and drug accessibility, including cost. Further studies are required to examine head-to-head comparisons among analgesics, combinations of analgesics, long-term outcomes, and treatment of pediatric and central NeP.

Contributing factors to chronic myofascial pain: a case-control study.

This case–control study was designed to investigate the contributing factors for chronic masticatory myofascial pain (MFP). Eighty‐three patients with MFP, selected from the dental clinics of the Jewish General and Montreal General Hospitals, Montreal, Canada, and 100 concurrent controls selected only at the first clinic, participated in this study. The association with MFP was evaluated for bruxism, head–neck trauma, psychological factors (symptom check list 90 revised questionnaire, SCL‐90R) and sociodemographic characteristics by using unconditional logistic regression. Clenching–grinding was associated with chronic MFP in multiple models including anxiety (OR=8.48; 95% CI: 2.85; 25.25) and depression (OR=8.13; 95% CI: 2.76; 23.97). This association also remained for MFP, excluding all other temporomandibular disorders (TMD). Clenching‐only (OR=2.54; 95% CI: 1.10; 5.87) and trauma (OR=2.10; 95% CI: 1.0; 4.50) were found to be associated with the chronic MFP, when the level of anxiety was adjusted in the model. No significant change was noted when the effects of clenching‐only (2.76; 95% CI: 1.20; 6.35) and trauma (OR=2.08; 95% CI: 1.03; 4.40) were adjusted for depression. Clenching‐only and clenching–grinding remained related to MFP regardless of patients being informed about these habits. A higher score of anxiety (OR=5.12; 95% CI: 1.36; 19.41) and depression (OR=3.51; 95% CI: 1.07; 11.54) were associated with MFP, as well as other psychological symptoms. In addition, female gender had almost three times the risk of chronic MFP than males when the model was also adjusted for psychological symptoms. Grinding‐only, age, household income and education were not related with chronic MFP. Tooth clenching, trauma and female gender may contribute to MFP even when other psychological symptoms are similar between subjects.

Single-dose dexamethasone reduces dynamic pain after total hip arthroplasty.

BACKGROUND: Preoperative glucocorticoids reduce postoperative nausea but may also improve analgesia and decrease opioid consumption. METHODS: Fifty consecutive patients undergoing elective, unilateral, primary total hip arthroplasty under spinal anesthesia with propofol sedation received in a randomized, double-blind, placebo-controlled manner either 40 mg of dexamethasone or saline placebo IV before the start of surgery. IV patient-controlled analgesia morphine, ibuprofen 400 mg po q6 h and acetaminophen 650 mg po q6 h were given for 48 h. Pain (0–10 numeric rating scale, NRS) at rest, side effects, and total cumulative patient-controlled analgesia morphine consumption were recorded q4 h for 48 h. Dynamic pain NRS score was recorded at 24 h. C-reactive protein levels were measured in a subgroup of 25 patients at 48 h. RESULTS: The intraoperative sedation requirement with propofol was significantly increased in the dexamethasone group (234.6 ± 160.1 vs 138.8 ± 122.7 mg, P = 0.02). Dynamic pain was greatly reduced in the dexamethasone group (NRS score: 2.7, 95% CI: 2.2–3.1 vs 6.8, 6.4–7.2; P < 0.0001). There was no significant effect on pain at rest or cumulative morphine consumption at any time. C-reactive protein levels at 48 h were markedly reduced by dexamethasone (52.4 mg/mL, 28.2–76.6 vs 194.2, 168.9–219.4; P < 0.0001). Seven patients in the control group, but only one in the dexamethasone group, were treated for nausea (P = 0.05). CONCLUSIONS: A single, preoperative IV dose of dexamethasone 40 mg has a prolonged suppressive effect on the inflammatory response and decreases dynamic pain 24 h after total hip arthroplasty.

Pain, perceived injustice and the persistence of post-traumatic stress symptoms during the course of rehabilitation for whiplash injuries.

ABSTRACT The present study assessed the role of pain and pain‐related psychological variables in the persistence of post‐traumatic stress symptoms following whiplash injury. Individuals (N = 112) with whiplash injuries who had been admitted to a standardized multidisciplinary rehabilitation program were asked to complete measures of pain, post‐traumatic stress symptoms, physical function and pain‐related psychological variables at three different points during their treatment program. The findings are consistent with previous research showing that indicators of injury severity such as pain, reduced function and disability, and scores on pain‐related psychological were associated with more severe post‐traumatic stress symptoms in individuals with whiplash injuries. Contrary to expectations, indicators of pain severity did not contribute to the persistence of post‐traumatic stress symptoms. Univariate analyses revealed that self‐reported disability, pain catastrophizing and perceived injustice were significant determinants of the persistence of post‐traumatic stress symptoms. In multivariate analyses, only perceived injustice emerged as a unique predictor of the persistence of post‐traumatic stress symptoms. The results suggest that early adequate management of pain symptoms and disability consequent to whiplash injury might reduce the severity of post‐traumatic stress symptoms. The development of effective intervention techniques for targeting perceptions of injustice might be important for promoting recovery of post‐traumatic stress symptoms consequent to whiplash injury.

The effect of catastrophizing and depression on chronic pain – a prospective cohort study of temporomandibular muscle and joint pain disorders

Summary Catastrophizing and depression are shown to contribute to the progression of temporomandibular muscle and joint disorders. Abstract Although most cases of temporomandibular muscle and joint disorders (TMJD) are mild and self‐limiting, about 10% of TMJD patients develop severe disorders associated with chronic pain and disability. It has been suggested that depression and catastrophizing contributes to TMJD chronicity. This article assesses the effects of catastrophizing and depression on clinically significant TMJD pain (Graded Chronic Pain Scale [GCPS] II–IV). Four hundred eighty participants, recruited from the Minneapolis/St. Paul area through media advertisements and local dentists, received examinations and completed the GCPS at baseline and at 18‐month follow‐up. In a multivariable analysis including gender, age, and worst pain intensity, baseline catastrophizing (&bgr; 3.79, P < 0.0001) and pain intensity at baseline (&bgr; 0.39, P < 0.0001) were positively associated with characteristic of pain intensity at the 18th month. Disability at the 18‐month follow‐up was positively related to catastrophizing (&bgr; 0.38, P < 0.0001) and depression (&bgr; 0.17, P = 0.02). In addition, in the multivariable analysis adjusted by the same covariates previously described, the onset of clinically significant pain (GCPS II–IV) at the 18‐month follow‐up was associated with catastrophizing (odds ratio [OR] 1.72, P = 0.02). Progression of clinically significant pain was related to catastrophizing (OR 2.16, P < 0.0001) and widespread pain at baseline (OR 1.78, P = 0.048). Results indicate that catastrophizing and depression contribute to the progression of chronic TMJD pain and disability, and therefore should be considered as important factors when evaluating and developing treatment plans for patients with TMJD.

The Effect of Fibromyalgia and Widespread Pain on the Clinically Significant Temporomandibular Muscle and Joint Pain Disorders—A Prospective 18-Month Cohort Study

UNLABELLED Although most cases of temporomandibular muscle and joint disorders (TMJD) are mild and self-limiting, about 10% of TMJD patients develop severe disorders associated with chronic pain and disability. It has been suggested that fibromyalgia and widespread pain play a significant role in TMJD chronicity. This paper assessed the effects of fibromyalgia and widespread pain on clinically significant TMJD pain (GCPS II-IV). Four hundred eighty-five participants recruited from the Minneapolis/St. Paul area through media advertisements and local dentists received examinations and completed the Graded Chronic Pain Scale (GCPS) at baseline and at 18 months. Baseline widespread pain (OR: 2.53, P = .04) and depression (OR: 5.30, P = .005) were associated with onset of clinically significant pain (GCPS II-IV) within 18 months after baseline. The risk associated with baseline fibromyalgia was moderate, but not significant (OR: 2.74, P = .09). Persistence of clinically significant pain was related to fibromyalgia (OR: 2.48, P = .02) and depression (OR: 2.48, P = .02). These results indicate that these centrally generated pain conditions play a role in the onset and persistence of clinically significant TMJD. PERSPECTIVE Fibromyalgia and widespread pain should receive important consideration when evaluating and developing a treatment plan for patients with TMJD.

Obturator Versus Femoral Nerve Block for Analgesia After Total Knee Arthroplasty

BACKGROUND:Both femoral and obturator nerve blocks have been suggested to be useful in relieving pain after total knee arthroplasty (TKA). We sought to compare their efficacy. METHODS:Sixty patients undergoing elective unilateral TKA under spinal anesthesia received in a randomized, double-blind manner a femoral, obturator, or sham nerve block at the end of surgery. Blocks were performed using nerve stimulation and 20 mL bupivacaine 0.5% containing epinephrine 5 &mgr;g/mL. Patient-controlled IV analgesia with fentanyl, celecoxib 100 mg PO bid, and acetaminophen 650 mg PO every 6 h were started on arrival in the recovery room. Pain (0–10 numeric rating scale, NRS) at rest and with movement, analgesic use, and side effects were recorded for 48 h. Maximum knee flexion and total days in hospital were recorded as functional outcomes. RESULTS:There were no significant differences in the obturator block group and the control group in any outcome variable. With baseline pain scores subtracted, femoral block resulted in less pain at rest compared with control (NRS difference from baseline 2.1 ± 0.4 sem vs 3.4 ± 0.4, respectively; P = 0.02) and less pain with movement (NRS difference 2.6 ± 0.6, 4.3 ± 0.6, P = 0.05) at recovery room discharge. Neither block had a significant effect on opioid use, functional outcome, or side effects. Only one (5%) patient with femoral block developed obturator motor block. CONCLUSION:Femoral nerve blocks rarely block the obturator nerve. Single-injection femoral nerve block improved multimodal analgesia after spinal anesthesia for TKA, but this effect did not persist beyond the day of surgery. Obturator nerve block alone was of no benefit.

Effects of four treatment strategies for temporomandibular joint closed lock

A previous randomized controlled trial (RCT) by Schiffman et al. (2007)(15) compared four treatments strategies for temporomandibular joint (TMJ) disc displacement without reduction with limited mouth opening (closed lock). In this parallel group RCT, 106 patients with magnetic resonance imaging (MRI)-confirmed TMJ closed lock were randomized between medical management, non-surgical rehabilitation, arthroscopic surgery, and arthroplasty. Surgical groups also received rehabilitation post-surgically. The current paper reassesses the effectiveness of these four treatment strategies using outcome measures recommended by the International Association of Oral and Maxillofacial Surgeons (IAOMS). Clinical assessments at baseline and at follow-up (3, 6, 12, 18, 24, and 60 months) included intensity and frequency of TMJ pain, mandibular range of motion, TMJ sounds, and impairment of chewing. TMJ MRIs were performed at baseline and 24 months, and TMJ tomograms at baseline, 24 and 60 months. Most IAOMS recommended outcome measures improved significantly over time (P≤0.0003). There was no difference between treatment strategies relative to any treatment outcome at any follow-up (P≥0.16). Patient self-assessment of treatment success correlated with their ability to eat, with pain-free opening ≥35mm, and with reduced pain intensity. Given no difference between treatment strategies, non-surgical treatment should be employed for TMJ closed lock before considering surgery.

Salivary biomarkers of oxidative stress: A critical review

Human saliva is an increasingly attractive medium for biomarker discovery due to its amenability to noninvasive and repeated sampling, ease of collection and processing, and suitability for single analyte or metabolomic measurements. Salivary biomarkers of oxidative stress reflect local and systemic pathologies and may inform on the diagnosis, prognosis, and therapeutic responsiveness of numerous human diseases. However, for many of the disorders investigated, data reporting on alterations in salivary redox homeostasis are often highly conflicted across studies. We surveyed the available biomedical literature on this topic and noted significant discrepancies in the study designs, target populations, and operating procedures which likely contribute to the discordant data sets reported. Based on these observations, guidelines are provided to minimize interlaboratory variability in redox biomarker discovery based on human saliva.

Pain Catastrophizing Scale for Francophone Adolescents: A Preliminary Validation

BACKGROUND In adults, it is well known that high levels of pain catastrophizing are related to increased pain and disability as well as to heightened anxiety and depression. However, due to the lack of a measure of pain catastrophizing adapted for francophone adolescents, little is known about the role of catastrophizing in this population. OBJECTIVES To adapt the French version of the Pain Catastrophizing Scale (PCS) and to examine the psychometric properties and factorial structure of the PCS for Francophone Adolescents (PCS-Ado). METHODS The French version of the PCS was modified by a group of experts. The format of the questions was modified to be appropriate for adolescents aged between 12 and 18 years. To assess the psychometric properties of the PCS-Ado, 345 adolescents completed the PCS-Ado and questionnaires measuring depression, anxiety and intensity of pain. Twelve to 16 weeks later, participants completed the questionnaires again to examine the test-retest reliability of the PCS-Ado. RESULTS Results revealed a three-factor solution similar to the original PCS. In addition, results revealed that PCS-Ado had good internal consistency (PCS-Ado total: 0.85; rumination: 0.72; magnification: 0.66; helplessness: 0.74), and high test-retest reliability (r=0.73). Finally, significant correlations among catastrophizing, depression, anxiety and pain intensity support the construct validity of the PCS-Ado. CONCLUSIONS The results suggest that the PCS-Ado is valid and reliable with francophone adolescents. Further research is required to assess the validity of the PCS-Ado in clinical settings.