View clinical trials related to Hyperalgesia.
Filter by:The purpose of this study is to learn more about the role of genetics in pain sensitivity. Pain perception varies widely among individuals, and information gained from this trial may lead to better methods of preventing and controlling pain. The study consists of two parts, described below. All enrollees will participate in part 1; patients needing oral surgery for removal of third molars may also participate in part 2. Normal volunteers, oral surgery patients, and family members of both groups may be eligible for this study. Part 1 -Sensitivity testing for hot and cold. Participants will rate their pain response to hot and cold stimuli on a scale from "no pain" to the "worst pain imaginable." Heat sensitivity is measured using a small probe placed on the skin for a few seconds. The hottest temperature tested may cause pain for a few seconds but will not produce a burn. Response to cold is measured by placing the hand in cold water for up to 3 minutes and occasionally flexing the fist. Participants will rate their pain level every 15 seconds. In addition to the testing, a blood sample will be drawn to examine for genes related to pain. Part 2 - Oral surgery. Patients will have their third molar removed under a local anesthetic (lidocaine) injected in the mouth and a sedative (Versed) given through a vein in the arm. A small tissue biopsy will be taken from the tissue over one of the third molars. Patients will stay in the clinic for up to 7 hours after surgery while the anesthetic wears off and will rate any pain they may have according to the rating scale used in Part 1 of the study. Pain medication (ketorolac, or Toradol) will be given when needed, and patients will complete pain questionnaires for 3 hours after the drug is given to rate its effectiveness. Patients will receive additional pain relievers, if needed. A second biopsy on the side opposite the first will be taken under local anesthetic to measure changes in chemical signals produced in response to the surgery.
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.