An Ischemic Stroke Kills 8.3 Trillion Synapses in 10 Hours

Although ischemic strokes can be treated by doctors, in 59 seconds, one can kill 1.9 million brain cells, a study published in the Journal of the American Heart Association says.

"Stroke is a highly treatable disease but, unfortunately, the time in which physicians can effectively reverse a stroke is short," author Jeffrey L. Saver, M.D., professor of neurology at the University of California, said.

"Precious tissue is lost every second. Patients need to get to the hospital at the first sign a stroke is occurring."

Ischemic strokes are caused when a clot blocks the flow of blood through one of the arteries feeding the brain. Deprived of oxygen, nerve cells in the affected area begin to die, and function is lost in the part of the body that area of the brain controls. Survivors can be left with paralysis, inability to speak and visual field deficits.

Professor Saver used data from numerous research studies to quantify the loss of brain cells that occurs during an ischemic stroke in a large blood vessel in the upper part of the brain. Using neuroimaging and quantitative neurostereology, a three-dimensional cell counting technique, he calculated the average rate at which ischemic stroke destroys neural circuitry.

"When a clot blocks a blood vessel and stroke occurs, blood is cut off completely to a small group of cells and they die almost immediately," Saver said.

"Surrounding that is a larger region of cells that suffers moderately reduced blood flow, a situation it can tolerate for a short period. This gives us a brief window of opportunity to intervene and save the threatened brai," he added.

For every minute of ischemic stroke, the brain loses 1.9 million neurons, 14 billion synapses and 12 kilometers of myelinated fibers, and if it lasts for 10 hours, the brain loses 1.2 billion neurons, 8.3 trillion synapses and approximately 7,200 kilometers of myelinated fibers.