Pain
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Editorial Comment Historical Article
Personality and pain: back to the four humours?
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The mechanisms underlying trigeminal pain conditions are incompletely understood. In vitro animal studies have elucidated various targets for pharmacological intervention; however, a lack of clinical models that allow evaluation of viable innervated human tissue has impeded successful translation of many preclinical findings into clinical therapeutics. Therefore, we developed and characterized an in vitro method that evaluates the responsiveness of isolated human nociceptors by measuring basal and stimulated release of neuropeptides from collected dental pulp biopsies. ⋯ Superfusion with phorbol 12-myristate 13-acetate (PMA) increased basal and stimulated release, whereas PGE2 augmented only basal release. Compared with vehicle treatment, pretreatment with PGE2 induced competence for DAMGO to inhibit capsaicin-stimulated iCGRP release, similar to observations in animal models where inflammatory mediators induce competence for opioid inhibition. These results indicate that the release of iCGRP from human dental pulp provides a novel tool to determine the effects of pharmacological compounds on human nociceptor sensitivity.
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Clinical Trial
Thermal hyperalgesia as a marker of oxaliplatin neurotoxicity: a prospective quantified sensory assessment study.
Neurotoxicity represents a major complication of oxaliplatin. This study aimed to identify early clinical markers of oxaliplatin neurotoxicity, in comparison with cisplatin, and detect predictors of chronic neuropathy. Forty-eight patients with mainly colorectal cancer were evaluated prospectively before oxaliplatin (n=28) or cisplatin (n=20) administration and then 2 weeks after the third (C3), sixth (C6) and ninth (C9) cycles. ⋯ In contrast, thermal testing identified sustained (irreversible between cycles) neurotoxicity two weeks after C3 in the oxaliplatin group only, characterized by hyperalgesia to cold (5-25 degrees C) (F=11.4; p=0.0002 relative to cisplatin patient responses in the hand) and heat stimuli (38-48 degrees C) (F=4.1; p=0.049 for the hand). Cold-evoked symptoms lasting 4 days or more after C3 predicted chronic neuropathy (OR: 22; 95% CI: 1.54-314.74; p=0.02) whereas enhanced pain in response to cold (20 degrees C stimulus on the hand) predicted severe neuropathy (OR: 39; 95% CI: 1.8-817.8 p=0.02). Thermal hyperalgesia is a relevant clinical marker of early oxaliplatin neurotoxicity and may predict severe neuropathy.
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Comparative Study
Exploring relationships for visceral and somatic pain with autonomic control and personality.
The autonomic nervous system (ANS) integrates afferent and motor activity for homeostatic processes including pain. The aim of the study was to compare hitherto poorly characterised relations between brainstem autonomic control and personality in response to visceral and somatic pain. Eighteen healthy subjects (16 females, mean age 34) had recordings during rest and pain of heart rate (HR), cardiac vagal tone (CVT), cardiac sensitivity to baroreflex (CSB), skin conductance level (SC), cardiac sympathetic index (CSI) and mean blood pressure (MBP). ⋯ Visceral pain-related parasympathetic change correlated with personality. ANS defence responses are nuanced and may relate to personality type for visceral pain. Clinical relevance of these findings warrants further exploration.
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Clinical Trial
Prospective judgments of acceptable outcomes for pain, interference and activity: Patient-determined outcome criteria.
The selection of outcome criteria for chronic pain, both the domain of measurement and the magnitude of change, in RCTs is largely determined by the investigators. The present study investigated patient-determined criteria for the magnitude of change necessary to achieve an 'acceptable outcome' (endpoint) on the brief pain inventory and two subscales of the multidimensional pain inventory. Seventy-eight patients attending a chronic pain out-patient clinic were asked to rate their current state on the measures and then complete the scales as they would if treatment were to result in an acceptable outcome. ⋯ Neither adequately fit the data. There were discrepancies between the patients' judgments of acceptable outcomes and the RCI and SCS criteria. Suggestions for future research and possible clinical implications are discussed.