Protocol Number: 92-D-0243

Title:

Somatosensory Studies of Pain and Pain Control Measured with Oxygen-15 Water Positron Emission Tomography and Functional MRI in Normals and Patients with Neuropathic or Chronic Pain Conditions

Number:

92-D-0243

Summary:

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.

Sponsoring Institute:

National Institute of Dental And Craniofacial Research (NIDCR)

Recruitment Detail

Type: Active Accrual Of New Subjects

Gender: Male & Female

Referral Letter Required: No

Population Exclusion(s): None

Eligibility Criteria:

INCLUSION CRITERIA

Healthy Normal Volunteers between the ages of 18 and 80 years

Certain Chronic Pain Patients

EXCLUSION CRITERIA

Structural or Functional Brain Defects

Metallic Surgical Implants

Chronic Drug Treatments

Special Instructions: Currently Not Provided

Keywords:

Analgesia

PET

Positron Emission

Functional Brain Imaging

Allodynia

Thalamus

Somatosensory Cortex

Reflex Sympathetic Dystrophy

Recruitment Keywords:

Normal Volunteer

Chronic Pain

Conditions:

Healthy

Hyperalgesia

Pain

Peripheral Nervous System Disease

Investigational Drug(s):

Oxygen-15 Water

Capsaicin

Investigational Device(s):

None

Contacts:

Patient Recruitment and Public Liaison Office
Building 61
10 Cloister Court
Bethesda, Maryland 20892-4754
Toll Free: 1-800-411-1222
TTY: 301-594-9774 (local),1-866-411-1010 (toll free)
Fax: 301-480-9793

Electronic Mail:prpl@mail.cc.nih.gov

Citations:

Positron emission tomographic analysis of cerebral structures activated specifically by repetitive noxious heat stimuli

Distributed processing of pain and vibration in the human brain

The roles of spatial recruitment and discharge frequency in nociception in spinal cord coding of pain: a combined electrophysiological and imaging investigation

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Warren Grant Magnuson Clinical Center (CC)
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Bethesda, Maryland 20892. Last update: 10/23/2004