A Mayo Clinic research team is focusing on a hormone previously identified in the venom of the green mamba snake for the role it may play in a dangerous blood vessel narrowing in stroke patients that can lead to a second stroke, reduced blood flow and brain damage.
Called “cerebral vasospasm,” this common complication of stroke occurs in approximately one-third of patients who experience a ruptured brain blood vessel. Its cause is not known. By discovering a possible role for this hormone, Mayo Clinic researchers are establishing the conceptual foundations for a new treatment for cerebral vasospasm. Their report occurs in the current issue of Neurosurgery, (http://www.neurosurgery-online.com ).
In their pilot study, the Mayo Clinic researchers discovered that a specific pair of amino acids -- a “peptide” known as DNP -- was significantly elevated (29 percent) in aneurysm patients who went on to develop complications of cerebral vasospasm. Among the six patients in the study who were followed for seven days after their initial aneurysm ruptured, four patients showed evidence of cerebral vasospasm -- a much higher frequency than the 30 percent figure commonly cited. Of the four patients who had cerebral vasospasm, three -- 75 percent -- had increased DNP levels.
The study was a pilot study, which means it was kept deliberately small to test the validity of the idea. Though the sample of patients was small because it is a pilot study, researchers say the results are so promising they justify a larger, case-controlled formal study. They want to pursue the possibility that DNP may one day provide a target for new therapies to stop cerebral vasospasm. Says Mayo Clinic neurologist Eelco Wijdicks, M.D., lead investigator, “If these results hold up in larger investigations, it could help us develop a very valuable specific therapeutic tool that would greatly reduce a major disabling complication of our patients.”
The pilot study patients all suffered a spontaneous rupture of a brain blood vessel known as an “aneurysm” that bled into the space between the brain and the middle membrane. This condition is known as a “subarachnoid hemorrhage” and is a type of stroke. It occurs in an estimated one out of 10,000 people, and it is most common in people 20 to 60 years old. About 30 percent of patients with aneurysm-caused subarachnoid hemorrhage develop cerebral vasospasm three to seven days later. Of those who develop cerebral vasospasm, about one-fourth experience a second stroke and are therefore at risk for brain damage and other complications. Background