Influence of Genetics in Pain Sensitivity

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: NCT00001956
Recruitment Status : Completed
First Posted : January 19, 2000
Last Update Posted : June 30, 2006
Information provided by:
National Institutes of Health Clinical Center (CC)

Brief Summary:

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.

Condition or disease Intervention/treatment Phase
Healthy Hyperalgesia Pain Procedure: Blood draw Procedure: Oral surgery Procedure: Tissue biopsy Phase 2

Detailed Description:
Variability in pain sensitivity is a well known phenomena. Clinicians involved in the care of post-surgical patients are very familiar with this variation in sensitivity. The variability also extends to experimental pain stimuli (e.g., a thermal pulse to the forearm) and can be demonstrated with normal volunteers. In our clinic, variation in the intensity and onset of acute pain in the oral surgery model, in subjects matched for similar levels of tissue injury ranges from little or no post-operative pain to reports of severe pain unrelieved by standard analgesics. While a variety of factors may account for the variability such as race or gender (Gordon 1998), preclinical data indicate that genetic factors profoundly influence pain sensitivity. Thus, the proposed study seeks to investigate genetic contributions to acute experimental and clinical post-operative pain. We have recently shown a strong correspondence between pain reports using thermal heat stimuli and post-operative pain reports. This observation has given us an important quantitative screening tool for genetic analysis of a moderate-sized cohort of subjects that has direct clinical relevance. Normal subjects and their siblings and/or parents will undergo two somatosensory tests to determine pain phenotype and will provide a blood sample which will be analyzed for genetic polymorphisms contributing to sensitivity to pain. Some of these subjects will also be candidates for the oral surgery protocol and similar pain ratings will be obtained from them post-operatively. The initial study will examine known polymorphisms for candidate genes that code for pain sensing and pain suppressing molecules.

Study Type : Interventional  (Clinical Trial)
Enrollment : 800 participants
Primary Purpose: Treatment
Study Start Date : January 2000
Study Completion Date : February 2005

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes


Patients in need of oral surgery for removal of impacted third molar will be recruited from the local community and by physician or dental referrals.


Use of prescription and nonprescription analgesics, antihistamines, and antidepressants. No history of psychiatric or neurological disorders or a positive score on the Beck Depression Inventory, those females who are pregnant or nursing.

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): NCT00001956

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)

Publications: Identifier: NCT00001956     History of Changes
Other Study ID Numbers: 000055
First Posted: January 19, 2000    Key Record Dates
Last Update Posted: June 30, 2006
Last Verified: February 2005

Keywords provided by National Institutes of Health Clinical Center (CC):
Genetic Markers
Thermal Pain
Oral Surgery
Cold Pain
Peripheral Nerve
Spinal Cord
Personality Traits
Pain Ratings

Additional relevant MeSH terms:
Somatosensory Disorders
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases
Signs and Symptoms