The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial
Migraine prevention using different frequencies of transcutaneous occipital nerve stimulation: A randomized controlled trial.
This study's objective was to evaluate the efficacy and tolerability of transcutaneous occipital nerve stimulation (tONS) in patients with migraine, and to explore whether different tONS frequencies influenced treatment effectiveness. This was a randomized, controlled trial of tONS for prevention of migraine. Patients were randomized to 1 of 5 therapeutic groups before treatment for 1 month. ⋯ From baseline to the 1-month treatment period, the tONS group with 100 Hz and topiramate group exhibited significant decreases in headache duration. We conclude that tONS therapy is a new promising approach for migraine prevention. It has infrequent and mild adverse events and may be effective among patients who prefer nonpharmacological treatment.
-
Prominent clinical models of chronic pain propose a fundamental role of classical conditioning in the development of pain-related disability. If classical conditioning is key to this process, then people with chronic pain may show a different response to pain-related conditioned stimuli than healthy control subjects. We set out to determine whether this is the case by undertaking a comprehensive and systematic review of the literature. To identify studies comparing classical conditioning between people with chronic pain and healthy control subjects, the databases MEDLINE, PsychINFO, PsychARTICLES, Scopus, and CINAHL were searched using key words and medical subject headings consistent with 'classical conditioning' and 'pain.' Articles were included when: 1) pain-free control and chronic pain groups were included, and 2) a differential classical conditioning design was used. The systematic search revealed 7 studies investigating differences in classical conditioning between people with chronic pain and healthy control participants. The included studies involved a total of 129 people with chronic pain (fibromyalgia syndrome, spinal pain, hand pain, irritable bowel syndrome), and 104 healthy control participants. Outcomes included indices of pain-related conditioning such as unconditioned stimulus (US) expectancy and contingency awareness, self-report and physiological measures of pain-related fear, evaluative judgements of conditioned stimulus pleasantness, and muscular and cortical responses. Because of variability in outcomes, meta-analyses included a maximum of 4 studies. People with chronic pain tended to show reduced differential learning and flatter generalization gradients with respect to US expectancy and fear-potentiated eyeblink startle responses. Some studies showed a propensity for greater muscular responses and perceptions of unpleasantness in response to pain-associated cues, relative to control cues. ⋯ The review revealed preliminary evidence that people with chronic pain may exhibit less differential US expectancy and fear learning. This characteristic may contribute to widespread fear-avoidance behavior. The assumption that altered classical conditioning may be a predisposing or maintaining factor for chronic pain remains to be verified.
-
The presence of bimodal outcome distributions has been used as a justification for conducting responder analyses, in addition to, or in place of analyses of the mean between-group difference, in clinical trials and systematic reviews of interventions for pain. The aim of this study was to investigate the distribution of participants' pain outcomes for evidence of bimodal distribution. We sourced data on participant outcomes from a convenience sample of 10 trials of nonsurgical interventions (exercise, manual therapy, medication) for spinal pain. ⋯ We found no compelling evidence suggesting that outcomes were bimodally distributed for any of the intervention groups. Responder analysis would not meaningfully alter our interpretation of these data compared with the mean between group difference. Our findings suggest that bimodal distribution of outcomes should not be assumed in interventions for spinal pain and do not support the automatic prioritization of responder analysis over the between group difference in the evaluation of treatment effectiveness for pain.
-
Acute postsurgical pain (APSP) is a common and anticipated problem after surgery with detrimental consequences if not appropriately managed. This study examined the independent and joint contribution of presurgical demographic, clinical, and psychological variables as predictors of APSP intensity, evaluated using an 11-point numeric rating scale, after inguinal hernioplasty, one of the most performed surgeries worldwide. In a prospective observational cohort study, a consecutive sample of 135 men undergoing hernioplasty was assessed before and 48 hours after surgery. ⋯ The integrative predictive model found in this study revealed the simultaneous influence that demographic, clinical, and psychological factors have on APSP after inguinal hernioplasty. Therefore, these results improve knowledge on APSP predictors after inguinal hernioplasty and highlight potential modifiable intervention targets, such as anxiety and pain catastrophizing (rumination), for the design of interventions focused on APSP prevention and management. Hence, taken together, these findings lend support for the inclusion of presurgical screening and psychological interventions among surgical patients at risk for higher APSP intensity.
-
Cancer-induced bone pain (CIBP) remains a major challenge in advanced cancer patients because of our lack of understanding of its mechanisms. Previous studies have shown the vital role of γ-aminobutyric acid B receptors (GABABRs) in regulating nociception and various neuropathic pain models have shown diminished activity of GABABRs. However, the role of spinal GABABRs in CIBP remains largely unknown. ⋯ Our behavioral results show that acute as well as chronic intrathecal treatment with baclofen, a GABABR agonist, significantly attenuated CIBP-induced mechanical allodynia and ambulatory pain. The expression levels of GABABRs were significantly decreased in a time-dependent manner and colocalized mostly with neurons and a minority with astrocytes and microglia. Chronic treatment with baclofen restored the expression of GABABRs and markedly inhibited the activation of cyclic adenosine monophosphate (cAMP)-dependent protein kinase and the cAMP-response element-binding protein signaling pathway.