Pain
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Persistent postsurgical pain (PPSP) is a common and often disabling postoperative morbidity, but many questions remain about factors associated with PPSP. This systematic review and meta-analysis aimed to identify preoperative, intraoperative, and postoperative factors associated with PPSP after gynecological surgeries, namely, hysterectomy and cesarean section, and urological surgeries, namely, prostatectomy and donor nephrectomy. Overall, 18 gynecological surgery studies, 4 prostatectomy studies, and 2 donor nephrectomy studies met the review criteria, providing data that could be meta-analyzed. ⋯ Persistent postsurgical pain after gynecological and urological surgeries is common. This systematic review identified important factors associated with cesarean section and hysterectomy that can help identify women who are at high risk of PPSP. More high-quality studies with consistent methodology are needed to understand the factors associated with PPSP risk, particularly for surgeries such as prostatectomy and nephrectomy.
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Quantitative sensory testing (QST) can be useful to identify high-risk patients for the development of chronic postsurgical pain. This systematic review aims to assess if presurgical sensory sensitivity measured using QST is associated with acute and chronic postsurgical pain after total joint arthroplasty. A systematic search was performed in September 2020 in PubMed, EMBASE, Web of Science, and Scopus, using terms related to total joint arthroplasty and QST. ⋯ Fourteen studies reported at least one statistically significant association between QST and pain (acute: 4 studies, subacute: 1 study, and chronic: 9 studies). Pressure pain threshold was associated with postsurgical pain in 6 studies (of 11, 55%), heat pain threshold in 2 studies (of 6, 33%), conditioned pain modulation in 1 study (of 6, 17%), and temporal summation of pain in 5 studies (of 8, 63%). The predictive role of presurgical QST for postarthroplasty pain remains unclear, mainly because of heterogeneous methodologies and inconsistent results.
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Parvalbumin-expressing interneurons (PVINs) in the spinal dorsal horn are found primarily in laminae II inner and III. Inhibitory PVINs play an important role in segregating innocuous tactile input from pain-processing circuits through presynaptic inhibition of myelinated low-threshold mechanoreceptors and postsynaptic inhibition of distinct spinal circuits. ⋯ Here, we use neuroanatomical and optogenetic approaches to show that ePVINs comprise a larger proportion of the PVIN population than previously reported and that both ePVIN and inhibitory PVIN populations form synaptic connections among (and between) themselves. We find that these cells contribute to neuronal networks that influence activity within several functionally distinct circuits and that aberrant activity of ePVINs under pathological conditions is well placed to contribute to the development of mechanical hypersensitivity.
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Meta Analysis
Different routes of administration in chronic migraine prevention lead to different placebo responses: a meta-analysis.
Placebo response is a powerful determinant of health outcomes in several disorders. Meta-analysis of clinical trials in pain conditions shows that it can contribute up to 75% of the overall treatment effect. Placebo response deriving from different routes of administration is poorly understood in primary headaches' pharmacological prevention. ⋯ Administration route affects placebo responses in CM preventive treatment. Elucidating the underlying mechanisms that mediate a placebo response in migraine treatment is beneficial to clinical practice and drug development, especially when comparing drugs with different routes of administration, with the effect of application to the head being superior to the other routes in this study. In our study the placebo response accounted for approximately 75% of the therapeutic gain in the treatment of CM.