Pain Pathways in the Brain

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00078364
Recruitment Status : Completed
First Posted : February 24, 2004
Last Update Posted : March 4, 2008
Information provided by:
National Institutes of Health Clinical Center (CC)

Brief Summary:

This study will evaluate brain pathways involved in feeling pain and pain relief following administration of pain medication. Magnetic resonance imaging (MRI) will be used to measure brain activity at sites that become more active following oral surgery and then to see if the activity changes after pain medication is administered. MRI combines a powerful magnet with an advanced computer system and radio waves to produce detailed pictures of organs and tissues. During the scan, the subject lies on a table in a narrow cylinder containing a magnetic field. He or she can speak with a staff member via an intercom system at all times during the procedure.

Healthy dental patients recruited through the NIH Clinical Research Volunteer Program may enroll in this study. Participants will undergo the following tests and procedures in two clinic visits:

Visit 1 - Sensitivity Testing

Participants are tested for sensitivity to warm and hot temperatures. A probe is applied to the skin (usually the forearm) and heated to temperatures ranging from room temperature to that of a hot cup of coffee. Participants rate the temperature using a scale ranging from "no pain" to the "worst pain imaginable" and rate the unpleasantness of the heat using a similar scale. The probe is applied up to 30 times, using random heat intensities. Participants are also asked compare the heat intensity to varying levels of sounds and to rate the magnitude of different sensations they have experienced in the past, such as the brightness of the sun and the loudness of a jet plane. A blood sample of about 2 ounces is also collected at this visit for DNA analysis to look for genes related to pain.

Visit 2 - Oral Surgery

Under local anesthetic, participants undergo extraction of their lower right wisdom tooth. After surgery, the patient is moved to the MRI scanner for brain imaging over 1-2 hours while the local anesthetic wears off. Patients may request a postoperative pain drug (Toradol) during the procedure, if needed. When the scan is complete, patients are dismissed from the clinic with additional pain medication (flurbiprofen) to use at home as directed.

Condition or disease Intervention/treatment Phase
Healthy Tooth Extraction Procedure: MRI Phase 2

Detailed Description:
Functional neuroimaging provides a powerful tool for understanding how the brain may be involved in the perception of pain. It has made it possible to identify areas of the brain that are involved in the perception of experimental pain but very few studies have evaluated the sites in the brain that are activated during clinical pain and the effects of analgesic drugs. The proposed study will use the surgical removal of an impacted third molar as a model of acute clinical pain to identify sites that are activated following the offset of local anesthesia and to examine the effects of the NSAID analgesic ketorolac on attenuating sites that are activated as pain is relieved. Scans will be performed under non-pain baseline conditions, and again immediately following surgery as the local anesthetic wears off, clinical pain occurs, and following administration of the NSAID ketorolac. Differences among subjects in the amount of pain reported and brain activation will be compared to subjects' prior ratings of experimental pain and the presence of any genetic polymorphisms that are related to pain perception, inflammation, known pain pathways, or psychological factors related to pain. The findings from this research may help to reveal how pain is appreciated in the central nervous system, pharmacologically modified by NSAID analgesics and differs among individuals due to genetic factors.

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 30 participants
Primary Purpose: Treatment
Official Title: Imaging Neural Mechanisms Underlying Pain Modulation
Study Start Date : February 2004
Estimated Study Completion Date : August 2005

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No


Subjects will be a convenience sample selected from the pool of 500 - 700 new patients screened annually for acute pain studies. Inclusion and Exclusion criteria will be applied to result in a homogeneous population of subjects with respect to the surgical difficulty of the tooth being extracted, a single lower right third molar.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00078364

United States, Maryland
National Institute of Dental And Craniofacial Research (NIDCR)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institute of Dental and Craniofacial Research (NIDCR)