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Case Western Reserve University Patents
Show moreDescription: 1. Field of the Invention: The invention relates to a surgically implantable device for measuring fluid pressure within a subject's skull or other body organs. 2. Background Articles: In hydrocephalic children, a birth defect causes excessive cerebro-spinal fluid to be generated in the brain. Excessive fluid pressure constricts the flow in blood vessels of the brain resulting in brain damage. Additionally, the brain under such pressure does not develop normally. Both of these conditions lead to mental retardation and, eventually, to death. A recently developed procedure to deal with this problem is to install what is known as a shunt. The shunt is a small conduit feeding from the brain area and "dumping" into the venous system, or into the stomach cavity. This relieves the pressure and sometimes prevents the tragic results. About 30% of the patients so treated will grow up to lead normal lives and sometimes the shunt can then be removed. Other problems result, however, if a shunt drains excessive fluid from the intracranial cavity. This causes the intracranial pressure to drop to an excessively low level. The brain is made up of various folds of tissue normally separated by pockets or cavities in between, called "ventricles". If insufficient fluid is present in the intracranial cavity, these ventricles will collapse. This also can result in brain damage and in severe headaches. It is therefore apparent that it is highly desirable to maintain the intracranial pressure within a rather narrow range. If intracranial pressure can be monitored on a frequent basis, there are ways of adjusting the pressure. Sometimes, the shunt can be provided with a valve which can adjust the flow of fluid from the intracranial cavity. In other instances, medical treatment by the use of drugs has been effective in adjusting pressure. Previously, pressure could be monitored only by an invasive technique. More specifically, a patch of the patient's hair is shaved off, and a needle is inserted through a small opening in the skull. A catheter attached to the needle delivers the fluid pressure to an external transducer which indicates intracranial pressure. The use of this invasive technique is limited in most patients to about once a month, and involves possible hazards of infection. Several attempts have been made to devise implantable telemetry devices which can more conveniently, safely, and frequently be used to monitor intracranial pressure. One of these devices is described in an article entitled "Intracranial Pressure Telemetry System" by KO et al Biotelemetry Patient Monitg. 8:131-150 (1981). This article also describes some of the history of the development of such apparatus and is incorporated here by reference.
http://www.google.com/patents?vid=USPAT4519401
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