Positron Emission Tomography to Measure Pain and Pain Control
Information source: National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov processed this data on August 20, 2015 Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Healthy; Hyperalgesia; Pain; Peripheral Nervous System Disease
Intervention: Oxygen-15 Water (Drug); Capsaicin (Drug)
Phase: N/A
Status: Completed
Sponsored by: National Institute of Dental and Craniofacial Research (NIDCR)
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.
Clinical Details
Official 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
Study design: N/A
Detailed description:
Regional cerebral blood flow (rCBF) will be measured while normal subjects, patients with
post-operative pain, and patients with neuropathic abnormalities of pain sensation are
exposed to a battery of somatosensory stimuli that activate known pathways subserving touch,
temperature and pain sensations. We have performed a series of studies on the genetics of
pain, which assessed sensitivity (via subjective ratings) to a series of warm and painfully
hot thermal pulses. Subjects ranged from insensitive (i. e. rating 49 degrees C as a 0. 8
versus a 10 on a 10 point scale), yet mathematically we could define an inflection point at
the transition from warm to hot in nearly everyone, thus they most subjects encode the
nociceptive input and they all alter their ratings at the threshold for C-fiber afferent
firing (45 degrees C). We need to understand how the brain responds using objective blood
flow endpoints. Our previous studies disclosed distinct pain-intensity driven network of
regions activated by hot thermal stimuli and we will use repetitive scans to determine the
degree of activation of this network in the sensitive and insensitive subjects. We have
also developed a new treatment for cancer and arthritic pain that involves deletion of the
primary afferent C-fibers. We are in the midst of getting approval from the FDA for use of
this in patients with cancer pain. Assuming we obtain approval, we may then have the
potential to scan some of the appropriate patients before and after treatment to determine
the impact of the treatment and to explore alterations in the pain network in subjects with
and without C-fiber afferents using experimental stimuli. We also expect to eventually
treat patients with peripheral neuropathies and other chronic pain conditions that cause
spontaneous pain, hyperalgesia, and allodynia (pain sensation to a normally non-noxious
stimulus) and they will be examined with and without applied experimental stimuli before and
after treatment.
Eligibility
Minimum age: N/A.
Maximum age: N/A.
Gender(s): Both.
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
Locations and Contacts
National Institute of Dental And Craniofacial Research (NIDCR), Bethesda, Maryland 20892, United States
Additional Information
Related publications: Casey KL, Minoshima S, Berger KL, Koeppe RA, Morrow TJ, Frey KA. Positron emission tomographic analysis of cerebral structures activated specifically by repetitive noxious heat stimuli. J Neurophysiol. 1994 Feb;71(2):802-7. Coghill RC, Talbot JD, Evans AC, Meyer E, Gjedde A, Bushnell MC, Duncan GH. Distributed processing of pain and vibration by the human brain. J Neurosci. 1994 Jul;14(7):4095-108. Coghill RC, Mayer DJ, Price DD. The roles of spatial recruitment and discharge frequency in spinal cord coding of pain: a combined electrophysiological and imaging investigation. Pain. 1993 Jun;53(3):295-309.
Starting date: August 1992
Last updated: March 3, 2008
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