The journal of pain : official journal of the American Pain Society
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Offset analgesia (OA) is observed when pain relief is disproportional to the reduction of noxious input and is based on temporal contrast enhancement (TCE). This phenomenon is believed to reflect the function of the inhibitory pain modulatory system. However, the mechanisms contributing to this phenomenon remain poorly understood, with previous research focusing primarily on painful stimuli and not generalizing to nonpainful stimuli. ⋯ More research is needed to confirm a peripheral influence. PERSPECTIVE: This psychophysical study presents the observation of temporal contrast enhancement during NH, NC, and innocuous cold stimuli but not during stimulation with innocuous warm temperatures in healthy volunteers. A better understanding of endogenous pain modulation mechanisms might be helpful in explaining the underlying aspects of pain disorders.
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Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD), which affects up to 4.3% of individuals, is a distressing and poorly understood condition characterized by persistent, unwanted, and often painful sensations of genito-pelvic arousal (eg, throbbing) in the absence of sexual desire. PGAD/GPD is associated with significant negative impacts on psychosocial well-being and daily functioning. Recent research has indicated that PGAD/GPD shares many similarities with other forms of chronic genito-pelvic pain. ⋯ Interventions targeting fear-avoidance factors may help to reduce PGAD/GPD symptom intensity, distress, and increase psychological well-being and daily functioning. PERSPECTIVE: This article provides support for the applicability of the fear-avoidance model of chronic pain to Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD). These results suggest that interventions targeting fear-avoidance cognitions and behaviors (catastrophizing, fear, avoidance, hypervigilance) may help to reduce PGAD/GPD symptom intensity and improve psychological well-being and daily functioning.
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The platinum chemotherapeutic oxaliplatin produces dose-limiting pain, dysesthesia, and cold hypersensitivity in most patients immediately after infusion. An improved understanding of the mechanisms underlying these symptoms is urgently required to facilitate the development of symptomatic or preventative therapies. In this study, we have used skin-saphenous nerve recordings in vitro and behavioral experiments in mice to characterize the direct effects of oxaliplatin on different types of sensory afferent fibers. ⋯ PERSPECTIVE: The chemotherapeutic drug oxaliplatin rapidly gives rise to dose-limiting cold pain and dysesthesia. Here, we have used behavioral and electrophysiological studies of mice to characterize the responsible neurons. We show that oxaliplatin directly confers aberrant cold responsiveness to subsets of A-fibers while silencing other fibers of the same type.
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Most reports agree that aging negatively impacts pain processing and that the prevalence of chronic pain increases significantly with age. To improve current therapies, it is critical that aged animals be included in preclinical studies. Here we compared sensitivities to pain and itch-provoking stimuli in naïve and injured young and aged mice. ⋯ That observation is consistent with our finding of contralateral hypersensitivity after nerve injury in the aged but not the young mice. We conclude that aging has opposite effects on baseline versus postinjury pain and itch processing. PERSPECTIVE: Aged male and female mice (22-24 months) are less sensitive to mechanical, thermal (heat), and itch-provoking stimuli than are younger mice (6 months).