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- Essai clinique NCT00357058
Role of Brain Region Changes in Tactile (Touch) Ability Following Nerve Block
Substrates Mediating Deafferentiation-Induced Enhancement of Tactile Spatial Acuity
This study will examine the role of different brain regions in tactile (touch) ability after application of a tourniquet (inflated blood pressure cuff). When the forearm is deprived of blood for a short period of time, tactile ability in the other hand improves. This study will try to learn what causes this improvement.
Healthy normal volunteers are eligible for this study. Candidates will have a brief medical history and physical examination.
Volunteers will undergo two experiments, described below, that involve the following procedures:
- Ischemic nerve block - A blood pressure cuff is inflated for 35-40 minutes around the elbow area (also around the calf for Experiment 2 - see below). The resulting numbness, tingling, loss of muscle strength, and discoloration of the forearm and hand disappear within minutes after the cuff is deflated.
- Magnetic resonance imaging (MRI) - This test uses a magnetic field and radio waves instead of X-rays to produce images of brain structure and function. The volunteer lies on a stretcher that is moved into the scanner (a cylinder containing a strong magnet), wearing earplugs to protect the ears from loud thumping noises that occur with electrical switching of radio frequency circuits. The subject can communicate with an investigator by intercom at all times during the scan.
- Transcranial magnetic stimulation (TMS) - An insulated wire coil is placed on the patient's scalp. A brief electrical current passes through the coil, creating a magnetic pulse that travels through the scalp and skull and causes small electrical currents in the outer part of the brain. The stimulation may cause muscle hand or arm twitching or transient tingling in the forearm, head or face muscles.
- Tactile spatial acuity testing - The subject's left arm is placed in a cast and the left index finger is immobilized for this test which involves identifying the direction of grooves applied to the finger.
Experiment 1
This experiment measures changes in tactile acuity and brain activation following cuff inflation. The subject lies in the MRI scanner, with the left arm immobilized. Tactile acuity is measured repetitively at the left index finger during placement and inflation of a pressure cuff around the right forearm. The experiment consists of two sessions with the cuff around the forearm and one with the cuff around the calf and lasts from 90 minutes to 2 hours.
Experiment 2
This experiment measures changes in tactile acuity linked to TMS stimulation. The subject sits in an armchair with the left arm immobilized. Tactile acuity is measured repetitively at the left index finger during placement and inflation of a pressure cuff around the right forearm. In addition, TMS pulses (about one pulse per second) are delivered at different locations over the right side of the head for up to 30 minutes. The experiment consists of 10 separate sessions on different days, each lasting about 1 hour.
Aperçu de l'étude
Statut
Les conditions
Description détaillée
Type d'étude
Inscription
Contacts et emplacements
Lieux d'étude
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Maryland
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Bethesda, Maryland, États-Unis, 20892
- National Institutes of Health Clinical Center, 9000 Rockville Pike
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Critères de participation
Critère d'éligibilité
Âges éligibles pour étudier
Accepte les volontaires sains
Sexes éligibles pour l'étude
La description
- INCLUSION CRITERIA:
Normal volunteers who are willing and able to remain relaxed and immobile during active scans, for a period of up to 2 hours.
EXCLUSION CRITERIA:
Subjects with: metal in the cranium except for crowns or fillings in mouth and permanent metal dental braces, metal fragments from occupational exposure or surgical clips in or near the brain.
Subjects with eye, blood vessel, cochlear or eye implants, with increased intracranial pressure as evaluated by clinical means, with cardiac or neural pacemakers, intracardiac lines and/or implanted medication pumps.
Subjects with large hemorrhagic or brain stem stroke.
Subjects with multiple cerebral lesions with residual deficits.
Subjects with history of head injury with loss of consciousness.
Subjects with history of severe alcohol or drug abuse or psychiatric illness.
Subjects with unstable cardiac dysrhythmia or unresponsive arterial hypertension (greater than 160/100 mmHg).
Subjects with history of hyperthyroidism or individuals receiving drugs acting primarily on the central nervous system or disorders of the blood coagulation system.
Subjects with excessive callus at their fingers.
Preganant women will be excluded from the study.
SUBJECTS DISCONTINUATION CRITERIA:
Subject's poor compliance with protocol evaluations or examinations and subject's request to withdraw.
Plan d'étude
Comment l'étude est-elle conçue ?
Collaborateurs et enquêteurs
Publications et liens utiles
Dates d'enregistrement des études
Dates principales de l'étude
Début de l'étude
Achèvement de l'étude
Dates d'inscription aux études
Première soumission
Première soumission répondant aux critères de contrôle qualité
Première publication (Estimation)
Mises à jour des dossiers d'étude
Dernière mise à jour publiée (Réel)
Dernière mise à jour soumise répondant aux critères de contrôle qualité
Dernière vérification
Plus d'information
Termes liés à cette étude
Mots clés
Autres numéros d'identification d'étude
- 020079
- 02-N-0079
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