Active clinical trials for "Hyperalgesia"

Assessments of mechanical skin sensitivity include psychophysical responses to stimulation with calibrated polyamide monofilaments. One of the applications of polyamide monofilaments are the assessments of magnitude of secondary hyperalgesia areas (SHAs), i.e. areas in normal skin near an injury with increased mechanical sensitivity. The objective of the study is to investigate the hypothesis, based on previous studies, that a light tactile stimulus delineates a larger SHA than stimulation with a more rigid monofilament. Twenty-three healthy participants were included in this randomized, two-observer, test-retest study. A highly significant positive correlation between the bending force of the polyamide filaments and the magnitude of SHA was demonstrated. The "weighted-pin" instrument showed significantly and consistently larger areas than the polyamide monofilaments. The hypothesis was rejected: a light tactile stimulus did not delineate a larger secondary hyperalgesia area than stimulation with a more rigid monofilament. The "weighted-pin" instrument seems an alternative to the conventional polyamide monofilaments.

In this prospective trial we aim to investigate the intra-individual and inter-individual variance in secondary hyperalgesia following pain elicited by the experimental pain model: Brief Thermal Sensitization. Furthermore we wish to investigate how precise the psychological tests, Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale predict the size of the area of secondary hyperalgesia.

The use of capsaicin as a potential analgesic drug for postoperative pain relies on the ability of capsaicin to induce membrane lysis of c-nerve fibers. In a previous randomized placebo controled blinded study of this effect we found a significant effect of capsaicin versus placebo. Before surgery all patients were examined by quantitative sensory testing to evaluate sensory function. In this study an identical sensory testing will examine if changes to the sensory function in capsaicin treated patients is identical to placebo treated patients.No new intervention will be performed

This study will examine how the brain processes pain signals and how the different parts of the brain work with each other in response to painful stimuli. A better understanding of how people experience pain may be helpful in developing more effective treatments. Healthy normal volunteers, patients requiring third molar (wisdom tooth) extraction, and patients with persistent pain due to disease, injury or other reason may be eligible for this study. Participants will receive one or more of the following sensory stimuli, which may cause brief discomfort or pain: Heat/Cold - applied by an electronically controlled device that touches the skin, or by temperature-controlled water baths, or by a thermally controlled brass cylinder the subject grasps Capsaicin (active ingredient in hot chili peppers) - injected in a small volume of fluid under the skin or into a muscle Mechanical stimulation - brushings or vibrations that do not normally cause pain Ischemic stimulation - inflation of a blood pressure cuff on the arm or leg for up to 30 minutes These stimuli will be applied both before and during positron emission tomography (PET) scanning. This test shows which parts of the brain are active and which are not and is important for studying how different parts of the brain work together to feel and react to specific sensations. For this procedure, the subject lies on a table in the PET scanner while a series of scans are taken during different sensory conditions. At the beginning of each scan, radioactive water is injected into an arm vein through a catheter (a thin plastic tube). A special camera records the arrival and disappearance of the radiation in various brain areas, creating a picture of the brain's activity in various regions. Oral surgery patients may have PET scans both before and after their wisdom tooth extraction. Alfentanil, a commonly used narcotic pain reliever, will also be given during the PET procedure to determine how the brain responds to sensory stimuli while under the effects of a pain killer. Participants will also have a magnetic resonance imaging (MRI) scan of the brain to help interpret the PET results. MRI uses a magnetic field and radio waves to show structural and chemical changes in tissues. During the scan, the subject lies on a table in a cylindrical machine (the scanner). He or she can speak with a staff member via an intercom system. Some sensory studies may require placing an arterial and/or intravenous line. Following injection of a local anesthetic, a catheter is placed in an artery in the arm. At regular intervals during various sensory stimuli, small blood samples are drawn from the artery to measure blood gases and other substances. Samples may also be drawn from a catheter placed in a vein. Subjects may also have ultrasound monitoring to evaluate blood flow in the arteries, veins and brain. A gel is spread over the skin above the blood vessel and a hand-foot-and-mouth device is placed on the gel. The device emits high-frequency sound waves to produce a picture of the speed of blood flow in the artery and the diameter of the vessel.

The concept of Enhanced Recovery After Surgery(ERAS) has been prevalent in recent years. In the ERAS guideline, short-acting anesthetics, instead of long-acting opioid anesthetics, were recommended during surgery to decrease post-operative complication and length of hospital stay. Propofol-remifentanil based total intravenous anesthesia (TIVA) can provide quicker emergence and decreased post-operative nausea and vomiting. However, the prescription of opioid (especially remifentanil) may induce opioid-induced hyperalgesia (OIH) and increase the requirement of analgesics. Previous studies provided some strategies to prevent OIH. The purpose of this study is to investigate the effect of adding remifentanil(1 mcg/kg) after emergence and endotracheal extubation in breast cancer females receiving breast surgery under propofol-remifentanil based TIVA for the prevention of OIH.

Postoperative hyperalgesia (POH) is a paradoxical clinical state of increased sensation of pain or increased sensitivity to non-painful stimuli at the site of surgery or at a surrounding area that was not directly injured. Opioid-induced hyperalgesia (OIH) and nociceptive-induced hyperalgesia (NIH) are the two main causes of POH.N-methyl-D-aspartate receptor (NMDAR) activation plays a central role in the development of POH.S-ketamine，which is a NMDA-receptor antagonist,has been on the market in china since 2019.The aim of this study is to evaluate the effects of S-ketamine on POH and chronic postoperative pain after video-assisted thoracic surgery.

To explore the effect of daytime variation on postoperative hyperalgesia induced by opioids. Patients receiving endoscopy surgery under general anesthesia during 08:00-12:00(morning group, n=30) and 14:00-18:00(afternoon group, n=30) using remifentanil for anesthesia maintenance were respectively included. Postoperative hyperalgesia at PACU and 24 hours after surgery were assessed through mechanical pain measurement. Comparative analysis of postoperative hyperalgesia levels, pain and analgesic requirements between morning group and afternoon group were performed.

Intraepidermal injection of nerve growth factor results in a non-inflammatory hyperalgesia for thermal and mechanical stimuli. This hyperalgesia is similar to the pathological ailments of patients with neuropathic pain. The mechanisms of the cognitive modulation of pain and hyperalgesia are not yet understood in this group of patients. The investigators plan to use NGF injection as a model of non-inflammatory neuropathic pain in healthy subjects to investigate the underlying neuronal mechanisms of this hyperalgesia using functional magnetic resonance imaging and resting state network analysis.

The use of pre-emptive analgesia to prevent pain following sternotomy for cardiac surgery

Noncardiac chest pain (NCCP) is a common clinical problem worldwide. In Hong Kong, it has been estimated that about 20% of patients with chest pain are misdiagnosed to have coronary heart disease. Despite its benign nature, this condition causes anxiety, impairs quality of life and consumes a substantial amount of healthcare resources. While acid reflux and motility disorder in the esophagus are often attributed as the cause of NCCP, visceral hyperalgesia of esophagus is now recognized to play a central role in the pathogenesis of this condition. This research project aims to evaluate the role of visceral hyperalgesia in Chinese patients with NCCP. NCCP patients will be evaluated for the prevalence of gastroesophageal reflux disease and esophageal motility disorder by endoscopy, manometry and pH study. The visceral sensory and pain thresholds of these patients will be compared with asymptomatic controls.