Do expectations influence pain? Recognizing Irving Kirsch's contribution to our understanding of pain.

Pain is a universal experience that can take different forms, and it can be acute or chronic. Experimental pain, such as heat pain, can help us better understand the pain experience, as it induces transient, but robust central sensitization in participants. Central sensitization is considered a key underlying concept in the development and maintenance of chronic pain and is defined as an overly effective transmission of nociception in the central nervous system. Expectations can influence perceived pain intensity and treatment success. Irving Kirsch's work in the field of experimental pain has greatly contributed to our understanding of how expectations influence the pain experience. In this article, we present some of Kirsch's landmark studies in this area and discuss their (clinical) implications.

Nonpharmacological Interventions for Pediatric Migraine: A Network Meta-analysis.

CONTEXT: Migraine is a common neurologic disorder in children and adolescents. However, a comparison of multiple nonpharmacological treatments is lacking. OBJECTIVE: To examine whether nonpharmacological treatments are more effective than waiting list and whether there are differences between interventions regarding efficacy. DATA SOURCES: Systematic review and network meta-analysis of studies in Medline, Cochrane, Embase, and PsycINFO published through August 5, 2019. STUDY SELECTION: Randomized controlled trials of nonpharmacological treatments in children and adolescents diagnosed with episodic migraine. DATA EXTRACTION: Effect sizes, calculated as standardized mean differences (SMDs) for the primary outcome efficacy, were assessed in a random-effects model. RESULTS: Twelve studies (N = 576) were included. When interventions were classified into groups on the basis of similarity of treatment components, self-administered treatments, biofeedback, relaxation, psychological treatments, and psychological placebos were significantly more effective than waiting list with effect sizes ranging between SMD = 1.14 (95% confidence interval, 0.09 to 2.19) for long-term psychological placebos to SMD = 1.44 (95% confidence interval, 0.26 to 2.62) for short-term self-administered treatments. However, when all interventions were examined individually (ie, 1 node per intervention), none were significantly more effective compared with waiting list, mainly because of lack of statistical power. LIMITATIONS: Because of our focus on pediatric migraine, only a small number of studies could be included. CONCLUSIONS: Our findings reveal that components of nonpharmacological interventions are effective in treating pediatric migraine. Some effects have to be interpreted carefully because they are based on small studies. Future researchers should identify factors associated with individual responses in large, multicentered studies.

Efficacy, Safety, and Acceptability of Pharmacologic Treatments for Pediatric Migraine Prophylaxis: A Systematic Review and Network Meta-analysis.

Importance: Migraine is one of the most common neurologic disorders in children and adolescents. However, a quantitative comparison of multiple preventive pharmacologic treatments in the pediatric population is lacking. Objective: To examine whether prophylactic pharmacologic treatments are more effective than placebo and whether there are differences between drugs regarding efficacy, safety, and acceptability. Data Sources: Systematic review and network meta-analysis of studies in MEDLINE, Cochrane, Embase, and PsycINFO published through July 2, 2018. Study Selection: Randomized clinical trials of prophylactic pharmacologic treatments in children and adolescents diagnosed as having episodic migraine were included. Abstract, title, and full-text screening were conducted independently by 4 reviewers. Data Extraction and Synthesis: Data extraction was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis network meta-analysis guidelines. Quality was assessed with the Cochrane Risk of Bias tool. Effect sizes, calculated as standardized mean differences for primary outcomes and risk ratios for discontinuation rates, were assessed in a random-effects model. Main Outcomes and Measures: Primary outcomes were efficacy (ie, migraine frequency, number of migraine days, number of headache days, headache frequency, or headache index), safety (ie, treatment discontinuation owing to adverse events), and acceptability (ie, treatment discontinuation for any reason). Results: Twenty-three studies (2217 patients) were eligible for inclusion. Prophylactic pharmacologic treatments included antiepileptics, antidepressants, calcium channel blockers, antihypertensive agents, and food supplements. In the short term (<5 months), propranolol (standard mean difference, 0.60; 95% CI, 0.03-1.17) and topiramate (standard mean difference, 0.59; 95% CI, 0.03-1.15) were significantly more effective than placebo. However, the 95% prediction intervals for these medications contained the null effect. No significant long-term effects for migraine prophylaxis relative to placebo were found for any intervention. Conclusions and Relevance: Prophylactic pharmacologic treatments have little evidence supporting efficacy in pediatric migraine. Future research could (1) identify factors associated with individual responses to pharmacologic prophylaxis, (2) analyze fluctuations of migraine attack frequency over time and determine the most clinically relevant length of probable prophylactic treatment, and (3) identify nonpharmacologic targets for migraine prophylaxis.