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5-HT, vasospasms, and TCD
Purpose of Study: The goal of this study will be to determine if there is a link between elevated levels of 5-HT in the CSF and the development of Cerebral vasospasm as defined by transcranial doppler.
Background: Cerebrovascular Vasospasm is the most deadly complication following Subarachnoid Hemorrhage from a ruptured aneurysm or AVM. Even after the source of a Subarachnoid hemorrhage has been dealt with, the patient is still at risk of significant morbidity and mortality from this dreaded complication. There has been much research into the cause of vasospasm, but the cause of this disease is still unknown. There have been a number of agents that have been studied as a possible source, however there is currently no clear-cut cause identified. Treatment for this disease is quite limited at this time and consists mainly of increasing the patient's blood pressure in order to increase blood flow through the constricted vessels. Another agent, Nimodipine is currently used and was originally tested as a means of causing arteries to relax and dilate, however there was no evidence that this compound actually caused arteries in the head to dilate. Even though the research failed to prove that Nimodipine worked as a cerebrovascular dilator, the research did show that patients receiving this drug did have improved outcomes compared to the control groups, and the drug is still used today.
There are a number of other vasospastic diseases that have been linked with 5-hydroxytryptamine as a possible source for the spasm including Raynauds disease1,2,3, Hereditary vascular retinopathy syndrome4, scleroderma5, coronary artery spasm6, and pre-eclampsia, and eclampsia7. Raynaud's disease in particular has had numerous studies that show elevated levels of 5-HT in the blood during vasospastic periods.
Due to the association of 5-HT with other vasospastic diseases, there is a possibility that this substance also plays a large role in the development of cerebral vasospasm. If this is the case then this information could lead to further research in developing a specific 5-HT receptor blocker to counteract the effect of the 5-HT in the CSF.
Relative hypercapnia and its effect on transcranial Doppler detected vasospasms following subarachnoid hemorrhage
Purpose: To better define the effects of expired pCO2 levels on cerebral vasculature during vasospastic periods following subarachnoid hemorrhage (SAH)
Background: It is well understood that cerebral vasculature will dilate under increasing CO2 tension and constrict as CO2 levels in the cerebral spinal fluid (CSF) fall. This physiologic response was
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