Brain cells by millions die during a stroke

When a person suffers a stroke, 1.9 million nerve cells in the brain die every minute, and the brain denied of oxygen ages 3.6 years every hour, says a study.

The average stroke involves 54 milliliters of brain tissue or about 3 cubic inches, and takes 10 hours to evolve, the study author Dr Jeffrey L. Saver from the University of California reports in the American Heart Association's journal Stroke, January 2005 issue.

Thus, each minute of an untreated stroke, 1.9 million neurons die, resulting in the loss of 14 billion synapses (nerve junctions) and 7.5 miles of nerve fibers. The forebrain, the most common site of strokes, contains 22 billion neurons, on an average, says the study.

Those statistics highlight the importance of immediate action when the first symptoms of a stroke appear. 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, says Dr Saver. The calculation of damage was made possible by three different lines of research pursued in the past decade, Saver said. One is brain imaging, which allows precise measurement of the size of a typical stroke.

The second is stroke treatment, which has given us the first good evidence of how long it takes a stroke to evolve in humans. The third is quantitative neurostereology, a three-dimensional cell-counting technique that gives the first good evidence of the loss of brain circuitry."

The findings drive home the message that patients need to recognize stroke symptoms and call for help 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.

The good news is that this steady loss of brain cells can be curtailed through quick treatment, Saver said. A powerful clot-dissolving drug called tissue plasminogen activator (tPA) can effectively reduce long-term disability if given within three hours. Other treatments include anticoagulant drugs and surgery.

The American Heart association has mounted a campaign to alert people to the symptoms of stroke. These include sudden onset of weakness or numbness on one side of the body, sudden trouble seeing, inability to talk or understand what people are saying, loss of ability to walk or loss of balance and severe headache.

Those symptoms often make it impossible for the sufferer to take action, so the responsibility falls on those who notice the problem, he said.