December 8, 2005

Brain cells by millions die during a stroke

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - When someone suffers a stroke, 1.9 million nerve cells in the brain die each minute, and the oxygen-starved brain ages about 3.6 years each hour -- further emphasizing the need for rapid treatment -- researchers say.

"'Time is brain' is a popular saying: clinical outcomes have been shown to deteriorate the longer treatment is delayed," study author Dr. Jeffrey L. Saver, from the University of California in Los Angeles, told Reuters Health.

However, he added, until recently the technology did not exist to precisely count the number of neurons lost with each passing minute that the blood supply is interrupted to the affected region.

Advances in stroke neuroimaging coupled with data from previous research have allowed Saver to estimate the neuron loss that occurs during a typical stroke.

The average stroke involves 54 milliliters of brain tissue -- about 3 cubic inches -- and takes 10 hours to evolve, the investigator reports in the American Heart Association's journal Stroke.

As noted, each minute a stroke ticks by untreated, 1.9 million neurons die, resulting in the loss of 14 billion synapses (nerve junctions) and 7.5 miles of nerve fibers. According to the report, the forebrain, the most common site of strokes, contains a total of 22 billion neurons, on average.

"I was simultaneously not surprised by the findings, but astounded by the magnitude," Saver said. "From caring for patients whose lives are forever altered by crippling stroke, I knew intuitively that stroke is a devastating disease that evolves rapidly. On the other hand, seeing the raw numbers of exactly how much damage occurs astounds me."

The findings drive home the message that "patients need to recognize stroke symptoms and call 911 right away. ER physicians, neurologists, and nurses need to recognize that stroke is a treatable neuro emergency that has to be handled at the highest triage priority."

SOURCE: Stroke. January 2005.