Brain Tsunami

Neuroscientists in Germany and the US have recently shown that brain tsunamis, waves of cell depolarization — massive short-circuits of the neurons — sweep the cortex within ten minutes of cardiac arrest. These waves of spreading depolarization mark the beginning of the end, and trigger a gradual poisoning of neurons. They recorded brain tsunamis not just as people died but also after other critical events, such as a brain hemorrhage. Their findings coul have immediate application in emergency centers and critical-care wards.

Dr. Jens Dreier at the Center for Stroke Research Berlin and Dr. Jed Hartings at the University of Cincinnati saw an opportunity to apply these principles to their work in neurocritical care. Their centers monitor the brain activity of patients with brain conditions, such as traumatic brain injury or bleeding after an aneurysm. This neuromonitoring involves putting electrodes either directly onto the surface of the brain or deep into the cerebral cortex. Clinicians can then record electrical activity directly from the cortex.

Patients who were taken off of life-sustaining therapy whil neuromonitoring continued as the patient died revealed something striking. “Previously, it was thought that the end occurs when the brain stops its electrical activity and goes silent,” said Hartings. “But it doesn’t. We can show that the brain remains in a viable state for several minutes after this flatline, at which point a wave of depolarization sweep through the cortex. This is referred to as a brain tsunami.”
“The spreading depolarization shows that brain cells are dying, and gives a tremendously useful clinical marker for brain damage,” said Dreier. This is not just a curiosity, but something actionable in intensive care.”

By studying the brain at the end of life, these researchers have made the connection between death and spreading depolarization in a very controlled clinical setting with strong data. This may be the first step in discovering othe ways in which spreading depolarizations impact the brain and could inform breakthroughs in brain injury research and treatment.