![]() ![]() “When you force every single cell, which is essentially a battery, to release its charge it represents the single largest disruption of brain function you can achieve-you basically discharge the entire brain surface in one fell swoop,” says lead author Humberto Mestre, a PhD student in the Nedergaard lab. These depolarization waves can continue in the brain for days and even weeks after the stroke, compounding the damage. The already vulnerable brain cells in the path of the flood essentially drown in CSF and the brain begins to swell. CSF then flows into the ensuing vacuum, inundating brain tissue and causing edema. ![]() This causes the smooth muscles cells that line the walls of blood vessels to seize up and contract, cutting off blood flow in a process known as spreading ischemia. As the cells release energy and fire, they trigger neighboring cells, creating a domino effect that results in an electrical wave that expands outward from the site of the stroke, called spreading depolarization.Īs this occurs, neurons release vast amounts of potassium and neurotransmitters into the brain. Denied nutrients and oxygen, brain cells become compromised and depolarize-often within minutes of a stroke. ![]() Ischemic stroke, the most common form of stroke, occurs when a vessel in the brain is blocked. Prior to the findings of the new study, it has been assumed that the source of swelling was the result of fluid from blood. ![]() In extreme cases and often as a last resort, surgeons will remove a part of the skull to relieve the pressure on the brain. If the swelling is severe, it can push in on important structures such as the brainstem, which regulates the cardiovascular and respiratory systems, resulting in death. Because the brain is trapped in the skull, it has little room to expand. While edema is a well-known consequence of stroke, there are limited treatment options and the severity of swelling in the brain depends upon the extent and location of the stroke. The system pumps CSF through brain tissue, primarily while we sleep, washing away toxic proteins and other waste. “Understanding this dynamic-which is propelled by storms of electrical activity in the brain-points the way to potential new strategies that could improve stroke outcomes.”įirst discovered by the Nedergaard lab in 2012, the glymphatic system 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 (CSF). “These findings show that the glymphatic system plays a central role in driving the acute tissue swelling in the brain after a stroke,” says senior author Maiken Nedergaard, codirector of the University of Rochester Medical Center (URMC) Center for Translational Neuromedicine. The research may “point the way to potential new strategies that could improve stroke outcomes.” During a stroke, the glymphatic system-normally associated with the beneficial task of waste removal-goes awry and floods the brain, triggering edema and drowning brain cells, new research in mice shows.Ĭerebral edema, swelling that occurs in the brain, is a severe and potentially fatal complication of stroke. ![]()
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