RESEARCH TRIANGLE PARK, N.C. -- New Army research provides a better understanding of the swelling that occurs in the brain during a stroke, which could contribute to new treatment strategies for stroke patients and have potential implications for traumatic brain injuries.

Cerebral edema, swelling that occurs in the brain, is a severe and potentially fatal complication for stroke victims. Research, funded in part by the Army Research Office and conducted at The University of Rochester Medical Center, shows for the first time that the glymphatic system -- normally associated with the beneficial task of waste removal -- goes awry during a stroke and floods the brain, promoting edema and drowning brain cells.

The research, conducted with mice, appears in the journal Science.
"These findings show that the glymphatic system plays a central role in driving the acute tissue swelling in the brain after a stroke", said Maiken Nedergaard, M.D., D.M.Sc., co-director of the University of Rochester Medical Center Center for Translational Neuromedicine and senior author of the article. "Understanding this dynamic -- which is propelled by storms of electrical activity in the brain -- point the way to potential new strategies that could improve stroke outcomes."

The glymphatic system, first discovered by the Nedergaard lab in 2012, consists of a network that piggybacks on the brain's blood circulation system and is comprised of layers of plumbing, with the inner blood vessel encased by a 'tube' that transports cerebrospinal fluid. The system pumps the fluid through brain tissue primarily during sleep, washing away toxic proteins and other waste.

Before the findings of the new study, scientists assumed that the source of brain swelling was exclusively the result of fluid from blood.

"Our hope is that this new finding will lead to novel interventions to reduce the severity of ischemic events, as well as other brain injuries to which Soldiers may be exposed," said Matthew Munson, Ph.D., program manager, fluid dynamics, ARO, an element of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "What's equally exciting is that this new finding was not part of the original research proposal. That is the power of basic science research and working across disciplines. Scientists 'follow their nose' where the data and their hypotheses lead them -- often to important unanticipated applications."

AN ELECTRICAL WAVE, THEN THE FLOOD

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