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In this multicenter cross-sectional study, we determined sensory profiles of patients with (NL-1) and without neuropathic pain (NL-0) after nerve lesion and assessed immune related systemic gene expression. Patients and matched healthy controls filled in questionnaires and underwent neurological examination, neurophysiological studies, quantitative sensory testing (QST), and blood withdrawal. Neuropathic pain was present in 67/95 (71%) patients (NL-1). Tactile hyperalgesia was the most prominent clinical sign in NL-1 patients (p<0.05). Questionnaires showed an association between neuropathic pain and the presence of depression, anxiety, and catastrophizing (p<0.05 to p<0.01). Neuropathic pain was frequently accompanied by other chronic pain (p<0.05). QST showed ipsilateral signs of small and large fiber impairment compared to the respective contralateral side, with elevated thermal and mechanical detection thresholds (p<0.001 to p<0.05) and lowered pressure pain threshold (p<0.05). Also, more loss of function was found in patients with NL-1 compared to NL-0. Pain intensity was associated with mechanical hyperalgesia (p<0.05 to p<0.01). However, QST did not detect or predict neuropathic pain. Gene expression of peptidylglycine α-amidating monooxygenase was higher in NL patients compared to healthy controls (NL-1, p<0.01; NL-0, p<0.001). Also, gene expression of tumor necrosis factor-α was higher in NL-1 patients compared to NL-0 (p<0.05), and interleukin-1ß was higher, but IL-10 lower in NL-1 patients compared to healthy controls (p<0.05 each). Our study reveals that nerve lesion presents with small and large nerve fiber dysfunction, which may contribute to the presence and intensity of neuropathic pain and which is associated with a systemic pro-inflammatory pattern.
Learn More >Cancer and its surgical treatment are among the most important triggering events for persistent pain, but additional factors need to be present for the clinical manifestation, such as variants in pain-relevant genes. In a cohort of 140 women undergoing breast cancer surgery, assigned based on a three-year follow-up to either a persistent or non-persistent pain phenotype, next generation sequencing was performed for 77 genes selected for known functional involvement in persistent pain. Applying machine learning and item categorization techniques, 21 variants in 13 different genes were found to be relevant to the assignment of a patient to either the persistent pain or the non-persistent pain phenotype group. In descending order of importance for correct group assignment, the relevant genes comprised DRD1, FAAH, GCH1, GPR132, OPRM1, DRD3, RELN, GABRA5, NF1, COMT, TRPA1, ABHD6, and DRD4, of which one in the DRD4 gene was a novel discovery. Particularly relevant variants were found in the DRD1 and GPR132 genes, or in a cis-eCTL position of the OPRM1 gene. Supervised machine learning based classifiers, trained with 2/3 of the data, identified the correct pain phenotype group in the remaining 1/3 of the patients at accuracies and areas under the receiver operator characteristic curves of 65 – 72 %. When using conservative classical statistical approaches, none of the variants passed α-corrected testing. The present data analysis approach, using machine learning and training artificial intelligences, provided biologically plausible results and outperformed classical approaches to genotype phenotype association.
Learn More >To determine if the perioperative administration of valproic acid reduces the incidence of chronic pain three months after amputation or revision surgery.
Learn More >Patient beliefs and perceptions about the causes and meaning of their chronic pain are related to their psychosocial functioning. Beliefs and perceptions about chronic pain held by spouses may also be related to patient functioning. We used a laboratory procedure to evaluate whether spouse beliefs about and perceptions of chronic pain were related to spouse negative responses toward patients with chronic low back pain during a conflictual discussion and to their attributions about patient pain behavior during a subsequent pain-induction task. Patients (n = 71) and their spouses (n = 71) participated in a 10-minute discussion followed by the patient undergoing a 10-minute structured pain behavior task. Findings were that a) spouse perceptions that patient's pain was a mystery were significantly related to greater patient perceived spouse critical/invalidating responses toward the patient during the discussion; and b) spouse perceptions that patient's pain was a mystery were related to internal and negative attributions spouses made while observing patients display pain behaviors during the structured pain behavior task. Inasmuch as both spouse critical/invalidating speech toward patients and negative attributions regarding the cause of patient behavior are related to poor patient functioning, spouse uncertainty about the source and potential legitimacy of their partner's pain may play crucial roles in affecting patient well-being. PERSPECTIVE: Spouse beliefs about and perceptions of patient chronic pain were related to spouse behavior toward patients during a discussion and to attributions explaining patient pain during physical activity. If spouse confusion and doubt about patient pain is related to negative behavior and attributions, then modifying these perceptions may be a fundamental intervention target.
Learn More >Despite the heightened urgency of the current prescription opioid crisis, few psychotherapies have been evaluated for chronic pain patients receiving long-term opioid analgesics. Current psychological pain treatments focus primarily on ameliorating negative affective processes, yet basic science suggests that risk for opioid misuse is linked with a dearth of positive affect. Interventions that modulate positive psychological processes may produce therapeutic benefits among patients with opioid-treated chronic pain. The aim of this study was to conduct a theory-driven mechanistic analysis of proximal outcome data from a Stage 2 randomized controlled trial of Mindfulness-Oriented Recovery Enhancement (MORE), an integrative intervention designed to promote positive psychological health.
Learn More >Effects from cognitive performance on pain tolerance have been documented, however, sample sizes are small and confounders often overlooked. We aimed to establish that performance on neuropsychological tests was associated with pain tolerance, controlling for salient confounders.
Learn More >To present data on psychometric properties of the Psychosocial Assessment Tool 2.0_General (PAT), a brief screener for psychosocial risk in families of youth with medical conditions, in youth with headache.
Learn More >Opioids are commonly prescribed to patients with painful and symptomatic degenerative joint disease preoperatively as a nonoperative intervention to reduce patients' symptoms and pain. The goal of total joint arthroplasty (TJA) is to reduce or eliminate the painful symptoms of degenerative joint disease. Due to the addictive property of opioid medications, some patients may develop a pattern of chronic opioid use after TJA.
Learn More >Children of chronic pain patients run greater risk for developing chronic pain themselves. Exposure to chronic pain of the parent might install cognitive (e.g., pain catastrophizing, interpretation and attentional bias) and affective (e.g., pain anxiety) vulnerability which increase the risk for the development of chronic pain complaints in offspring. This study examines whether pain-free offspring of parents with chronic pain complaints make more health-threatening interpretations and display a stronger pain-related attentional bias compared to the offspring of pain-free parents. We furthermore examined differences between both groups on pain catastrophizing, pain anxiety, and somatic symptoms, and explored the relations between parental pain catastrophizing and aforementioned pain vulnerability measures in offspring.
Learn More >People who are especially afraid of pain may display attention biases that increase their risk for developing chronic pain following an injury. However, specific neurophysiological mechanisms underlying associations between elevated trait fear of pain levels and environmental cues that signal potential pain experiences are not well understood. To address this gap, event-related potentials (ERPs) were recorded among 39 high pain-fearful (H-FOP) and 36 low pain-fearful (L-FOP) adults exposed to potentially painful somatosensory stimulation cued by sensory pain words versus non-painful stimulation cued by neutral words. H-FOP group members displayed slower reaction times in judging somatosensory stimulation and rated stimulation to be more intense than L-FOP group members did. H-FOP group members also exhibited comparatively earlier peak latencies of P2 and N2 components during word cue presentations as well as weaker P3 amplitudes in processing non-painful stimulation cued by sensory pain words. These findings suggested that, among the high trait pain-fearful, exposure to word cues signaling potential pain results in the allocation of fewer cognitive resources towards processing somatosensory stimuli that are not actually painful. This article is protected by copyright. All rights reserved.
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