View clinical trials related to Sensitization, Central.
Filter by:Persistent post-surgical pain is a significant adverse effect after total knee arthroplasty, present in around 20% of the patients. Central sensitization may contribute to developing and maintaining pain. Therefore studies should investigate if pain processing altered mechanisms are present in this population.
The objective of this study in healthy volunteers is to evaluate whether the composition of the gut microbiota and sleep quality influence the susceptibility to develop peripheral and central sensitization of pain pathways. In two different experimental sessions, the following factors will be tested: the influence of the composition of the gut microbiota on the susceptibility to develop peripheral sensitization of nociceptors, and the susceptibility to develop central sensitization of pain pathways. To assess susceptibility to peripheral sensitization, a solution of capsaicin (the active component of chili pepper) will be applied to the skin to induce neurogenic inflammation produced by the release of substances from nociceptors at the peripheral level. This neurogenic inflammation is characterized by a transient redness of the skin that will be measured with an infrared camera. To evaluate the susceptibility to sensitization at the central level, a high frequency electrical stimulation will be applied to the skin. This stimulation induces an increase in sensitivity to mechanical stimulation secondary to central sensitization. The intensity, extent and duration of this mechanical hyperalgesia will therefore be used as a measure of susceptibility to central sensitization. A stool sample and a blood sample will be taken. These samples will be used to characterize the composition of the intestinal microbiota, as well as the metabolites produced by this microbiota. These analyses will allow a comparison of the composition of the microbiota and the metabolites in subjects with a tendency to develop low vs. high sensitization at the peripheral and central levels. Similarly, sleep quality and average sleep duration will be assessed using questionnaires and a measurement of the participant's activity using a wrist movement sensitive bracelet. This information will be used to assess whether some of the interindividual variability in developing peripheral or central sensitization might be related to differences in sleep quality. Finally, systemic inflammation could be a factor modulated by sleep and gut microbiota, influencing pain perception and susceptibility to sensitization. For this reason, systemic pro- and anti-inflammatory cytokines will be measured in the blood sample.
Recent studies have focused on the role of endogenous opioids on central sensitization. Central sensitization is known to be impaired or altered in chronic pain conditions, as fibromyalgia or chronic tension headache. Animal studies have shown reinstatement of mechanical hypersensitivity following naloxone administration after resolution of an injury. This suggests latent sensitization. In the present study, the investigators hypothesize that a high-dose target-controlled naloxone infusion (total dose: 3.25 mg/kg) can reinstate pain and hyperalgesia 6-8 weeks after a unilateral primary open groin hernia repair procedure. The investigators aim to show that latent sensitization is present in humans and is modulated by endogenous opioids.