Pain
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Comparative Study
Neural mechanisms mediating the effects of expectation in visceral placebo analgesia: an fMRI study in healthy placebo responders and nonresponders.
This functional magnetic resonance imaging study analysed the behavioural and neural responses during expectation-mediated placebo analgesia in a rectal pain model in healthy subjects. In N=36 healthy subjects, the blood oxygen level-dependent (BOLD) response during cued anticipation and painful rectal stimulation was measured. Using a within-subject design, placebo analgesia was induced by changing expectations regarding the probability of receiving an analgesic drug to 0%, 50%, and 100%. ⋯ Compared with nonresponders, responders demonstrated greater placebo-induced decreases in activation of dorsolateral prefrontal cortex during anticipation and in somatosensory cortex, posterior cingulate cortex, and thalamus during pain. In conclusion, the expectation of pain relief can substantially change perceived painfulness of visceral stimuli, which is associated with activity changes in the thalamus, prefrontal, and somatosensory cortices. Placebo analgesia constitutes a paradigm to elucidate psychological components of the pain response relevant to the pathophysiology and treatment of chronic abdominal pain.
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Multicenter Study
Patient perspective on herpes zoster and its complications: an observational prospective study in patients aged over 50 years in general practice.
Understanding the effect of herpes zoster and zoster-related pain should inform care to improve health-related quality of life in elderly patients. A 12-month, longitudinal, prospective, multicenter observational study conducted in primary care in France enrolled patients aged ≥ 50 years with acute eruptive herpes zoster. Patient-reported zoster-related pain was assessed by validated questionnaires (Douleur Neuropathique en 4 Questions [DN4], Zoster Brief Pain Inventory [ZBPI], and Neuropathic Pain Symptom Inventory [NPSI]) on days 0 and 15, and at months 1, 3, 6, 9, and 12. ⋯ Patients with persistent pain had lower scores on the physical and mental component summaries of the SF-12 and the ZBPI interference score than those without pain. By logistic regression analysis, main predictive factors on day 0 for postherpetic neuralgia at month 3 were age, male sex, ZBPI interference score, Physical Component Summary score of the SF-12, and neuropathic quality of pain (DN4 score ≥ 4). Despite early diagnosis and treatment with antiviral agents, many patients with herpes zoster experience persistent pain and marked long-term reduction in health-related quality of life.
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The combination of pain and depression or anxiety is commonly seen in clinical practice. Little is known about the influence of pain on psychopathology over time, as previous studies have been mainly cross-sectional. The objectives of this study are to determine the impact of pain on the course of depressive and/or anxiety disorders, and investigate to what extent the association between pain and course of these mental disorders is mediated by psychiatric characteristics. ⋯ This study shows that patients with pain are more prone to a chronic course of depressive and anxiety disorders. More attention to pain seems to be necessary when diagnosing and treating these disorders. Future research should focus on treatment modalities for this co-occurrence, with joint pain in particular.
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Multiple firing of C nociceptors upon a single electrical stimulus has been suggested to be a possible mechanism contributing to neuropathic pain. Because this phenomenon maybe based on a unidirectional conduction block, it might also be related to neuropathic changes without a direct link to pain. We investigated painful neuropathy patients using microneurography and analysed nociceptors for the occurrence of multiple spiking and spontaneous activity. ⋯ Multiple spiking of nociceptors coincides with spontaneous activity in nociceptors of painful neuropathy patients. We therefore conclude that rather than being a generic sign of neuropathy, multiple spiking is linked to axonal hyperexcitability and spontaneous activity of nociceptors. It is still unclear whether it also is mechanistically related to the clinical pain level.