Nitric oxide reduces risk of stroke in aneurysm patients
Researchers working at the Hopkins School of Medicine have developed a novel treatment for a common, often fatal, condition that strikes down patients days after an aneurysm.
About 30 percent of patients who suffer from subarachnoid hemorrhage (SAH) - bleeding into the area between the brain and the beginning of the spinal cord - as a result of a ruptured aneurysm go on to develop vasospasm, where vessels contract and constrict. Four to fourteen days after hemorrhage, the blood vessels going to the brain become inflamed and dangerously constricted. The narrow vessels cut off the brain's supply of oxygen and put patients at a high risk for stroke. Vasospasm is the primary cause of death in patients who have suffered SAH.
A research team led by Rafael Tamargo of the Department of Neurosurgery has shown that nitric oxide, delivered to the brain in small polymers, greatly decreases the risk of vasospasm after SAH in a mouse model.
"One of the most difficult problems that we face is that we can fix an aneurysm that has ruptured. Then I saw one third of patients developed this problem of vasospasm, and we didn't have a way to treat it," Tamargo, who is a neurosurgeon and specializes in aneurysms, said.
Nitric oxide, which has the chemical formula NO and is not to be confused with the more notorious nitrous oxide, or laughing gas, is a gas normally produced and used in the body as a rapidly-diffusing signaling molecule. For example, nitric oxide dilates blood vessels by signaling the surrounding smooth muscle to relax, and is used by the immune system to combat bacterial infections.
Tamargo's previous research found that the root cause of vasospasm is not narrowing blood vessels as once believed, but instead an inflammation of the brain. The spastic and constricting vessels are just one symptom of inflammation. "One of the things I've been doing is trying to find drugs that will both inhibit the inflammation and dilate the vessels," Tamargo said. "That's how we became interested in nitric oxide. It's a very good drug for both."
About 30 percent of patients who suffer from subarachnoid hemorrhage (SAH) - bleeding into the area between the brain and the beginning of the spinal cord - as a result of a ruptured aneurysm go on to develop vasospasm, where vessels contract and constrict. Four to fourteen days after hemorrhage, the blood vessels going to the brain become inflamed and dangerously constricted. The narrow vessels cut off the brain's supply of oxygen and put patients at a high risk for stroke. Vasospasm is the primary cause of death in patients who have suffered SAH.
A research team led by Rafael Tamargo of the Department of Neurosurgery has shown that nitric oxide, delivered to the brain in small polymers, greatly decreases the risk of vasospasm after SAH in a mouse model.
"One of the most difficult problems that we face is that we can fix an aneurysm that has ruptured. Then I saw one third of patients developed this problem of vasospasm, and we didn't have a way to treat it," Tamargo, who is a neurosurgeon and specializes in aneurysms, said.
Nitric oxide, which has the chemical formula NO and is not to be confused with the more notorious nitrous oxide, or laughing gas, is a gas normally produced and used in the body as a rapidly-diffusing signaling molecule. For example, nitric oxide dilates blood vessels by signaling the surrounding smooth muscle to relax, and is used by the immune system to combat bacterial infections.
Tamargo's previous research found that the root cause of vasospasm is not narrowing blood vessels as once believed, but instead an inflammation of the brain. The spastic and constricting vessels are just one symptom of inflammation. "One of the things I've been doing is trying to find drugs that will both inhibit the inflammation and dilate the vessels," Tamargo said. "That's how we became interested in nitric oxide. It's a very good drug for both."
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posted 3/21/10 @ 7:57 PM EST
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