A Secondary Analysis: Comparison of Experimental Pain and Psychological Impact in Individuals with Carpometacarpal and Knee Osteoarthritis.

Purpose: Evaluate sensory and psychological differences in individuals with thumb carpometacarpal (CMC) and/or knee osteoarthritis (OA) pain. This secondary analysis focuses on comparing the effects of OA at large and small joints in community-dwelling adults. Patients and Methods: A total of 434 individuals were recruited from communities in Gainesville, FL and Birmingham, AL. Each participant completed health and clinical history questionnaires, quantitative sensory testing, and physical functional tests. Participants were divided into four groups based on their pain ("CMC pain" (n = 33), "knee pain" (n = 71), "CMC + knee pain" (n = 81), and "pain-free" controls (n = 60)). ANCOVAs were performed to identify significant differences in experimental pain and psychological variables across groups. Results: The "CMC + knee pain" group had lower pressure pain thresholds (lateral knee site, p < 0.01) and higher temporal summation of mechanical pain (knee, p < 0.01) when compared to "CMC pain" and "pain-free" groups. The "knee pain" group had lower heat pain tolerance at the forearm site (p = 0.02) and higher mechanical pain (p < 0.01) at both tested sites in comparison to the "CMC pain" group. Lastly, the "CMC + knee pain" group had the highest self-reported pain (p < 0.01) and disability (p < 0.01) compared to all other groups. Conclusion: Results suggest knee OA compounded with CMC OA increases disease impact and decreases emotional health compared to OA at either the CMC or knee joint alone. Results also support a relationship between the number of painful joints and enhanced widespread pain sensitivity. Measuring pain at sites other than the primary OA location is important and could contribute to more holistic treatment and prevention of OA progression.

Self-Reported Pain Treatment Practices Among U.S. and Canadian Adults: Findings From a Population Survey.

Background and Objectives: Pain treatments and their efficacy have been studied extensively. Yet surprisingly little is known about the types of treatments, and combinations of treatments, that community-dwelling adults use to manage pain, as well as how treatment types are associated with individual characteristics and national-level context. To fill this gap, we evaluated self-reported pain treatment types among community-dwelling adults in the United States and Canada. We also assessed how treatment types correlate with individuals' pain levels, sociodemographic characteristics, and country of residence, and identified unique clusters of adults in terms of treatment combinations. Research Design and Methods: We used the 2020 "Recovery and Resilience" United States-Canada general online survey with 2 041 U.S. and 2 072 Canadian community-dwelling adults. Respondents selected up to 10 pain treatment options including medication, physical therapy, exercise, etc., and an open-ended item was available for self-report of any additional treatments. Data were analyzed using descriptive, regression-based, and latent class analyses. Results: Over-the-counter (OTC) medication was reported most frequently (by 55% of respondents, 95% CI 53%-56%), followed by "just living with pain" (41%, 95% CI 40%-43%) and exercise (40%, 95% CI 38%-41%). The modal response (29%) to the open-ended item was cannabis use. Pain was the most salient correlate, predicting a greater frequency of all pain treatments. Country differences were generally small; a notable exception was alcohol use, which was reported twice as often among U.S. versus Canadian adults. Individuals were grouped into 5 distinct clusters: 2 groups relied predominantly on medication (prescription or OTC), another favored exercise and other self-care approaches, one included adults "just living with" pain, and the cluster with the highest pain levels employed all modalities heavily. Discussion and Implications: Our findings provide new insights into recent pain treatment strategies among North American adults and identify population subgroups with potentially unmet need for more adaptive and effective pain management.

Circulating Polyunsaturated Fatty Acids and Pain Intensity in Five Chronic Pain Conditions.

Pain intensity is well-known to be influenced by a wide range of biobehavioral variables. Nutritional factors, however, have not been generally considered for their potential importance. This cross-sectional study examined associations between erythrocyte omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFAs) and pain intensity in 605 adults. Pain intensity was computed on a 0 to 100 numeric rating scale from questions about 5 chronic pain conditions: orofacial pain, headache, low back pain, irritable bowel syndrome, and bodily pain. For each pain condition, multiple linear regression tested the hypothesis that a higher ratio of n-6 arachidonic acid to the sum of n-3 eicosapentaenoic acid and docosahexaenoic acid (AA/(EPA+DHA) was associated with greater pain intensity. In covariate-adjusted analysis, orofacial pain intensity increased 5.7 points (95% CI: 1.4, 9.9) per unit increase in n-6/n-3 PUFA ratio. Likewise, a 1 unit increase in n-6/n-3 PUFA ratio was associated with significant increases in pain intensity (range 5-8 points) of headache pain, low back pain, and bodily pain, but not abdominal pain. Separate multiple linear regression models investigated the independent strength of association of individual PUFAs to the intensity of each pain condition. Overall, n-3 docosahexaenoic acid was most strongly, and inversely, associated with pain intensity. PERSPECTIVE: A higher ratio of n-6/n-3 long-chain polyunsaturated fatty acids was associated greater pain intensity for orofacial pain, headache, low back pain, and bodily pain, but not abdominal pain. The n-6/n-3 PUFA ratio was more consistently associated with pain intensity than any individual constituent of the long-chain PUFA ratio.

Clinical vitamin D levels are associated with insular volume and inferior temporal gyrus white matter surface area in community-dwelling individuals with knee pain.

Context: Vitamin D is an essential, fat soluble micronutrient long-known for its effects on calcium homeostasis and bone health. With advances in technology, it is being discovered that Vitamin D exerts its effects beyond the musculoskeletal system. Vitamin D has since been noted in nervous system health and functioning, and is becoming a target of interest in brain health, aging, and chronic pain outcomes. Objectives: We and others have previously shown that deficient Vitamin D status is associated with greater pain severity across a variety of conditions, however the reason as to why this relationship exists is still being understood. Here, we sought to examine associations between Vitamin D status and brain structure in those with chronic knee pain. Methods: Structural MRI imaging techniques and whole brain analyses were employed and serum Vitamin D were collected on 140 participants with chronic pain. Covariates included age, sex, race and site, as these data were collected at two separate institutions. ANOVAs using the clinical cut points for Vitamin D status (deficient, insufficient, and optimal) as well as continuous regression-based Vitamin D effects were employed to observe differences in brain volume. P-value was set to 0.017 after correction for multiple comparisons. Results: We discovered that individuals in our sample (age = 50+; 63.6% female; 52.1% Non-Hispanic Black) who were either clinically deficient (<20 ng/mL) or insufficient (20-30 ng/mL) in serum Vitamin D had significant differences in the gray matter of the left circular insular cortex, left inferior temporal gyrus, right middle temporal gyrus, as well as decreased white matter surface area in the right inferior temporal gyrus compared to those considered to have optimal levels (>30 ng/mL) of serum Vitamin D. Conclusion: Evidence from these data suggests that Vitamin D, or lack thereof, may be associated with pain outcomes by mediating changes in regions of the brain known to process and interpret pain. More research understanding this phenomenon as well as the effects of Vitamin D supplementation is warranted.

Circulating Omega-6 and Omega-3 Polyunsaturated Fatty Acids in Painful Temporomandibular Disorder and Low Back Pain.

Preclinical studies demonstrate opposing effects of long-chain polyunsaturated fatty acid (PUFA) metabolites on inflammation and nociception. Omega-6 (n-6) PUFAs amplify both processes while omega-3 (n-3) PUFAs inhibit them. This cross-sectional study examined relationships between PUFAs in circulating erythrocytes and 2 chronic idiopathic pain conditions: temporomandibular disorder (TMD) and low back pain in a community-based sample of 503 U.S. adults. Presence or absence of TMD and low back pain, respectively, were determined by clinical examination and by responses to established screening questions. Liquid chromatography-tandem mass spectrometry quantified PUFAs. In multivariable logistic regression models, a higher ratio of n-6/n-3 long-chain PUFAs was associated with greater odds of TMD (odds ratio ((OR) = 1.75, 95% confidence limits (CL): 1.16, 2.64) and low back pain (OR = 1.63, 95% CL: 1.07, 2.49). Higher levels of the pronociceptive n-6 long-chain arachidonic acid (AA) were associated with a greater probability of both pain conditions for women, but not men. Higher levels of the antinociceptive long-chain n-3 PUFAs eicosapentaenoic and docosahexaenoic acids were associated with a lower probability of both pain conditions for men, but not women. As systemic inflammation is not a hallmark of these conditions, PUFAs may influence idiopathic pain through other mechanisms. PERSPECTIVE: This cross-sectional clinical study found that a higher ratio of circulating n-6/n-3 long-chain PUFAs was associated with greater odds of 2 common chronic overlapping pain conditions. This suggests that the pro and antinociceptive properties of n-6 and n-3 PUFAs, respectively, influence pain independently of their well-established inflammatory pathways.

Ratio of Omega-6/Omega-3 Polyunsaturated Fatty Acids Associated With Somatic and Depressive Symptoms in People With Painful Temporomandibular Disorder and Irritable Bowel Syndrome.

Somatic symptom disturbance is among the strongest predictors of painful temporomandibular disorder (TMD). Related psychological constructs, such as anxiety and depression, respond therapeutically to omega-3 polyunsaturated fatty acids (PUFAs) in clinical trials. This cross-sectional study investigated associations between the omega-6/omega-3 PUFA ratio and somatic symptom disturbance and depressive symptoms in a community-based sample of 501 adults and determined whether these associations differed between adults with and without TMD or irritable bowel syndrome (IBS). Liquid chromatography tandem mass spectrometry quantified PUFAs in circulating erythrocytes. Somatic symptoms and depression were quantified using Symptom Checklist-90-Revised subscales. Presence or absence of TMD and IBS, respectively, were determined by clinical examination and Rome III screening questions. The standardized beta coefficient for the omega-6/omega-3 long-chain PUFA ratio was 0.26 (95% confidence limits (CL): 0.08, 0.43) in a multivariable linear regression model in which somatic symptom disturbance was the dependent variable. When modelling depressive symptoms as the dependent variable, the standardized beta coefficient was 0.17 (95% CL:0.01, 0.34). Both associations were stronger among TMD cases and IBS cases than among non-cases. Future randomized control trials that lower the omega-6/omega-3 PUFA ratio could consider somatic or depressive symptoms as a therapeutic target for TMD or IBS pain. PERSPECTIVE: In people with TMD or IBS, a high n-6/n-3 PUFA ratio was positively associated with somatic symptom disturbance and depressive symptoms. Both measures of psychological distress were elevated in people with painful TMD and IBS. Future randomized clinical trials will determine whether lowering the n-6/n-3 ratio is therapeutic for pain.

Associations between Vitamin D, Omega 6:Omega 3 Ratio, and Biomarkers of Aging in Individuals Living with and without Chronic Pain.

Elevated inflammatory cytokines and chronic pain are associated with shorter leukocyte telomere length (LTL), a measure of cellular aging. Micronutrients, such as 25-hydroxyvitamin D (vitamin D) and omega 3, have anti-inflammatory properties. Little is known regarding the relationships between vitamin D, omega 6:3 ratio, LTL, inflammation, and chronic pain. We investigate associations between vitamin D, omega 6:3 ratio, LTL, and C-reactive protein (CRP) in people living with/without chronic pain overall and stratified by chronic pain status. A cross-sectional analysis of 402 individuals (63% women, 79.5% with chronic pain) was completed. Demographic and health information was collected. Chronic pain was assessed as pain experienced for at least three months. LTL was measured in genomic DNA isolated from blood leukocytes, and micronutrients and CRP were measured in serum samples. Data were analyzed with general linear regression. Although an association between the continuous micronutrients and LTL was not observed, a positive association between omega 6:3 ratio and CRP was detected. In individuals with chronic pain, based on clinical categories, significant associations between vitamin D, omega 6:3 ratio, and CRP were observed. Findings highlight the complex relationships between anti-inflammatory micronutrients, inflammation, cellular aging, and chronic pain.

Optimizing Chronic Pain Treatment with Enhanced Neuroplastic Responsiveness: A Pilot Randomized Controlled Trial.

Chronic pain affects mental and physical health and alters brain structure and function. Interventions that reduce chronic pain are also associated with changes in the brain. A number of non-invasive strategies can promote improved learning and memory and increase neuroplasticity in older adults. Intermittent fasting and glucose administration represent two such strategies with the potential to optimize the neurobiological environment to increase responsiveness to recognized pain treatments. The purpose of the pilot study was to test the feasibility and acceptability of intermittent fasting and glucose administration paired with a recognized pain treatment activity, relaxation and guided imagery. A total of 32 adults (44% W, 56% M), 50 to 85 years of age, with chronic knee pain for three months or greater participated in the study. Four sessions were completed over an approximate two-week period. Findings indicate the ability to recruit, randomize, and retain participants in the protocol. The procedures and measures were reasonable and completed without incident. Participant adherence was high and exit interview feedback positive. In summary, the pilot study was feasible and acceptable, providing the evidence necessary to move forward with a larger clinical trial.

Innovations in Geroscience to enhance mobility in older adults.

Aging is the primary risk factor for functional decline; thus, understanding and preventing disability among older adults has emerged as an important public health challenge of the 21st century. The science of gerontology - or geroscience - has the practical purpose of "adding life to the years." The overall goal of geroscience is to increase healthspan, which refers to extending the portion of the lifespan in which the individual experiences enjoyment, satisfaction, and wellness. An important facet of this goal is preserving mobility, defined as the ability to move independently. Despite this clear purpose, this has proven to be a challenging endeavor as mobility and function in later life are influenced by a complex interaction of factors across multiple domains. Moreover, findings over the past decade have highlighted the complexity of walking and how targeting multiple systems, including the brain and sensory organs, as well as the environment in which a person lives, can have a dramatic effect on an older person's mobility and function. For these reasons, behavioral interventions that incorporate complex walking tasks and other activities of daily living appear to be especially helpful for improving mobility function. Other pharmaceutical interventions, such as oxytocin, and complementary and alternative interventions, such as massage therapy, may enhance physical function both through direct effects on biological mechanisms related to mobility, as well as indirectly through modulation of cognitive and socioemotional processes. Thus, the purpose of the present review is to describe evolving interventional approaches to enhance mobility and maintain healthspan in the growing population of older adults in the United States and countries throughout the world. Such interventions are likely to be greatly assisted by technological advances and the widespread adoption of virtual communications during and after the COVID-19 era.

Pain relief for osteoarthritis through combined treatment (PROACT): Protocol for a randomized controlled trial of mindfulness meditation combined with transcranial direct current stimulation in non-Hispanic black and white adults with knee osteoarthritis.

Knee osteoarthritis (OA) is a leading cause of late life pain and disability, and non-Hispanic black (NHB) adults experience greater OA-related pain and disability than non-Hispanic whites (NHWs). Recent evidence implicates psychosocial stress, cognitive-attentional processes, and altered central pain processing as contributors to greater OA-related pain and disability among NHBs. To address these ethnic/race disparities, this clinical trial will test whether a mindfulness intervention (Breathing and Attention Training, BAT) combined with transcranial direct current stimulation (tDCS) will enhance pain modulatory balance and pain-related brain function, reduce clinical pain, and attenuate ethnic differences therein, among NHBs and NHWs with knee OA. Participants will complete assessments of clinical pain, function, psychosocial measures, and quantitative sensory testing (QST), including mechanical temporal summation and conditioned pain modulation. Neuroimaging will be performed to examine pain-related brain structure and function. Then, participants will be randomized to one of four groups created by crossing two BAT conditions (Real vs. Sham) with two tDCS conditions (Real vs. Sham). Participants will then undergo five treatment sessions during which the assigned BAT and tDCS interventions will be delivered concurrently for 20 min over one week. After the fifth intervention session, participants will undergo assessments of clinical pain and function, QST and neuroimaging identical to the pretreatment measures, and monthly follow-up assessments of pain will be conducted for three months. This will be the first study to determine whether mindfulness and tDCS treatments will show additive or synergistic effects when combined, and whether treatment effects differ across ethnic/race groups.

Omega-6: Omega-3 PUFA Ratio, Pain, Functioning, and Distress in Adults With Knee Pain.

OBJECTIVES: Osteoarthritis (OA) is associated with inflammation, chronic pain, functional limitations, and psychosocial distress. High omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are associated with lower levels of inflammatory mediators, anti-nociception, and adaptive cognitive/emotional functioning. High omega-6 (n-6) PUFAs are associated with inflammation, nociception, and psychological distress. While findings related to n-3 supplementation in knee OA are mixed, consideration of the n-6:n-3 ratio and additional outcome measures may provide improved understanding of the potential relevance of these fatty acids in OA. On the basis of recommended and typical ranges of the n-6:n-3 ratio, we hypothesized that in adults with knee pain, those with a high n-6:n-3 ratio would have greater pain/functional limitations, experimental pain sensitivity, and psychosocial distress compared with those with a low n-6:n-3 ratio. MATERIALS AND METHODS: A cross-sectional investigation of clinical and experimental pain and physical and psychosocial functioning was completed in 167 adults ages 45 to 85 meeting knee OA screening criteria. Blood samples were collected and the plasma n-6:n-3 PUFA ratio determined. Quartile splits were computed and low (n=42) and high (n=41) ratio groups were compared. RESULTS: The high ratio group reported greater pain and functional limitations, (all Ps<0.04), mechanical temporal summation (hand and knee, P<0.05), and perceived stress (P=0.008) but not depressive symptoms. DISCUSSION: In adults with knee pain, a high n-6:n-3 ratio is associated with greater clinical pain/functional limitations, experimental pain sensitivity, and psychosocial distress compared with a low ratio group. Findings support consideration of the n-6:n-3 PUFA ratio and additional clinical endpoints in future research efforts.

Age Group Comparisons of TENS Response Among Individuals With Chronic Axial Low Back Pain.

UNLABELLED: Chronic low back pain (CLBP) is a highly prevalent and disabling musculoskeletal pain condition among older adults. Transcutaneous electrical nerve stimulation (TENS) is commonly used to treat CLBP, however response to TENS in older adults compared with younger adults is untested. In a dose-response study stratified by age, 60 participants with axial CLBP (20 young, 20 middle-aged, 20 older) received four 20-minute sessions of high-frequency high-intensity TENS over a 2- to 3-week period in a laboratory-controlled setting. Experimental measures of pain sensitivity (mechanical pressure pain detection threshold) and central pain excitability (phasic heat temporal summation and heat aftersensations) were assessed before and after TENS. Episodic or immediate axial CLBP relief was assessed after TENS via measures of resting pain, movement-evoked-pain, and self-reported disability. Cumulative or prolonged axial CLBP relief was assessed by comparing daily pain reports across sessions. Independent of age, individuals experienced episodic increase in the pressure pain detection threshold and reduction in aftersensation after TENS application. Similarly, all groups, on average, experienced episodic axial CLBP relief via improved resting pain, movement-evoked pain, and disability report. Under this design, no cumulative effect was observed as daily pain did not improve for any age group across the 4 sessions. However, older adults received higher TENS amplitude across all sessions to achieve TENS responses similar to those in younger adults. These findings suggest that older adults experience similar episodic axial CLBP relief to that of younger individuals after high-frequency, high-intensity TENS when higher dose parameters are used. PERSPECTIVE: This study examined age group differences in experimental and axial CLBP response to TENS, delivered under the current recommended parameters of strong, but tolerable amplitude. Older adults had comparable TENS response although at higher TENS amplitude than younger adults, which may have important mechanistic and clinical implications.

Vitamin D status and pain sensitization in knee osteoarthritis: a critical review of the literature.

Diagnostic imaging of disease severity has been found thus far to be a relatively modest predictor of knee osteoarthritis (OA) pain and disability, suggesting that other factors likely contribute to clinical symptoms in this condition. Recent evidence suggests that sensitization of the peripheral and central pathways that process nociceptive information (i.e., pain sensitization) is an important contributor to knee OA clinical symptoms. Furthermore, low levels of vitamin D have been found to be associated with the presence of pain sensitization, as well as the overall experience of clinical pain severity in knee OA. African-Americans with knee OA may be at increased risk for poor clinical outcomes given evidence of lower vitamin D levels as well as greater pain sensitization compared with non-Hispanic whites. Whether vitamin D supplementation is effective for alleviating knee OA clinical symptoms is an important topic to be addressed in future research with racially diverse samples that include sufficient numbers of African-Americans.

An endogenous pain control system is altered in subjects with interstitial cystitis.

PURPOSE: Multiple studies have demonstrated that in healthy subjects, painful stimuli applied to one part of the body inhibit pain sensation in other parts of the body, a phenomenon referred to as conditioned pain modulation. Conditioned pain modulation is related to the presence of endogenous pain control systems. Studies have demonstrated deficits in conditioned pain modulation associated inhibition in many but not all chronic pain disorders. In this study we determine whether conditioned pain modulation is altered in subjects with interstitial cystitis/bladder pain syndrome. MATERIALS AND METHODS: Female subjects with and without the diagnosis of interstitial cystitis/bladder pain syndrome were studied psychophysically using quantitative cutaneous thermal, forearm ischemia and ice water immersion tests. Conditioned pain modulation was assessed by quantifying the effects of immersion of the hand in ice water (conditioning stimulus) on threshold and tolerance of cutaneous heat pain (test stimulus) applied to the contralateral lower extremity. RESULTS: The conditioned pain modulation responses of the subjects with interstitial cystitis/bladder pain syndrome were statistically different from those of healthy control subjects for cutaneous thermal threshold and tolerance measures. Healthy control subjects demonstrated statistically significant increases in thermal pain tolerance whereas subjects with the diagnosis of interstitial cystitis/bladder pain syndrome demonstrated statistically significant reductions in thermal pain tolerance. CONCLUSIONS: An endogenous pain inhibitory system normally observed with conditioned pain modulation was altered in subjects with interstitial cystitis/bladder pain syndrome. This finding identifies interstitial cystitis/bladder pain syndrome as similar to several other chronic pain disorders such as fibromyalgia and irritable bowel syndrome, and suggests that a deficit in endogenous pain inhibitory systems may contribute to such chronic pain disorders.

Reduction of conditioned pain modulation in humans by naltrexone: an exploratory study of the effects of pain catastrophizing.

The current study tested the hypothesis that conditioned pain modulation is mediated by the release of endogenous opioids with a placebo-controlled (sugar pill) study of naltrexone (50 mg) in 33 healthy volunteers over two counter-balanced sessions. Pain modulation consisted of rating of heat pain (palm) during concurrent cold water immersion (foot). Compared to baseline heat pain ratings, concurrent foot immersion lowered pain intensity ratings, which suggests an inhibitory effect, was reduced with naltrexone, suggesting at least partial dependence of inhibition on endogenous opioids. An exploratory analysis revealed that individual differences in catastrophizing moderated the effects of naltrexone; endogenous opioid blockade abolished modulation in subjects lower in catastrophizing while modulation was unaffected by naltrexone among high catastrophizers. The results suggest a role of endogenous opioids in endogenous analgesia, but hint that multiple systems might contribute to conditioned pain modulation, and that these systems might be differentially activated as a function of individual differences in responses to pain.

Pain sensitivity and vasopressin analgesia are mediated by a gene-sex-environment interaction.

Quantitative trait locus mapping of chemical/inflammatory pain in the mouse identified the Avpr1a gene, which encodes the vasopressin-1A receptor (V1AR), as being responsible for strain-dependent pain sensitivity to formalin and capsaicin. A genetic association study in humans revealed the influence of a single nucleotide polymorphism (rs10877969) in AVPR1A on capsaicin pain levels, but only in male subjects reporting stress at the time of testing. The analgesic efficacy of the vasopressin analog desmopressin revealed a similar interaction between the drug and acute stress, as desmopressin inhibition of capsaicin pain was only observed in nonstressed subjects. Additional experiments in mice confirmed the male-specific interaction of V1AR and stress, leading to the conclusion that vasopressin activates endogenous analgesia mechanisms unless they have already been activated by stress. These findings represent, to the best of our knowledge, the first explicit demonstration of analgesic efficacy depending on the emotional state of the recipient, and illustrate the heuristic power of a bench-to-bedside-to-bench translational strategy.

Quantitative sensory testing for spinal cord stimulation in patients with chronic neuropathic pain.

OBJECTIVE: A prospective pilot study was conducted, attempting to identify objective tests that would help clinicians to assess the efficacy of spinal cord stimulation (SCS) trial preceding permanent device implantation. SETTING: Four university hospitals in the United States and Israel. PARTICIPANTS: Thirteen patients with radicular leg pain due to failed back surgery syndrome (FBSS) or leg pain due to complex regional pain syndrome (CRPS) who were candidates for SCS. METHODS: PARTICIPANTS underwent a series of quantitative sensory tests prior to, and seven days after the initiation of SCS trial. These tests included: vibration threshold (conducted using the VSA 3000; Medoc Inc., Ramat Ishay, Israel), cold threshold, warm threshold, heat pain threshold, phasic heat pain threshold, tonic heat pain threshold (conducted using the TSA 2001; Medoc Inc.), and electrical pain tolerance at 5, 250 and 2000 Hz (administered using the NerveScan 2000; Neurotron, Inc., Baltimore, MD, USA). RESULTS: Useful data were obtained from 12 patients. The results of the vibration threshold and the tolerance to electrical stimulation at 5 and 250 Hz changed with an SCS trial. These results also correlated with the decision regarding the permanent implantation, which was made independently of them. In contrast, the results of thermal thresholds and tolerance to electrical stimulation at 2000 Hz tests did not change with the SCS trial. CONCLUSIONS: Our findings, which agree with those of a few other studies, suggest that the vibration threshold and the tolerance to electrical stimulation at 5 and 250 Hz tests can assist the clinician to select the right patients for permanent stimulation.

Placebo analgesia: friend or foe?

The magnitude of placebo analgesia is influenced by environmental and perceptual factors. Environmental factors include past exposure to effective analgesic agents and verbal suggestions and cues that foster a perception of being given an effective treatment. Environmental factors, in turn, influence the proximate psychologic mediators of placebo analgesia, which include decreased desire for and increased expectations of pain relief. Strategies to maximize placebo analgesic effects in clinical practice could focus on using verbal suggestions and external cues to increase expectations of pain relief and/or decrease the perceived need for pain reduction. Placebo analgesic effects could be minimized in clinical trials by avoiding these same suggestions and cues.

Sensory and affective pain discrimination after inhalation of essential oils.

OBJECTIVE: The purpose of this investigation was to examine the effects of olfactory absorption of two commonly used therapeutic essential oils on sensory and affective responses to experimentally induced pain. METHODS: A sex-balanced (13 men and 13 women) randomized crossover design was used to obtain pre- and posttreatment change scores for quantitative sensory ratings of contact heat, pressure, and ischemic pain across separate inhalation treatment conditions using essential oil of lavender, essential oil of rosemary, and distilled water (control). Subjective reports of treatment-related changes in pain intensity and pain unpleasantness were obtained for each condition using a visual analog scale. We interpret our findings with respect to the separate dimensions of sensory and affective processing of pain. RESULTS: Analyses revealed the absence of changes in quantitative pain sensitivity ratings between conditions. However, retrospectively, subjects' global impression of treatment outcome indicated that both pain intensity and pain unpleasantness were reduced after treatment with lavender and marginally reduced after treatment with rosemary, compared with the control condition. CONCLUSION: These findings suggest that aromatherapy may not elicit a direct analgesic effect but instead may alter affective appraisal of the experience and consequent retrospective evaluation of treatment-related pain.