New look at mini-strokes

The word stroke is usually associated with the blockage of a large blood vessel that leads to devastating loss of brain tissue, but small blood vessels get occluded too, and much more frequently than their large counterparts. These mini-strokes can be so small it is not even apparent when one has occurred, yet clinical research has shown that the more of these small strokes an individual has, the more precipitous their cognitive decline will be as they age.

Little research has been done to study the effect of blockages in small blood vessels on the health and function of nearby neurons. Part of the problem has been that there were no good ways to produce blockages in small venules in the brain of an animal model.

Now Cornell University doctoral candidate John Nguyen and his advisor Chris Schaffer have developed an animal model for looking at the effect of small strokes in the tiny venules in the brain of rodents. They are using a powerful laser and nonlinear optics to target and clot vessels of the venule system and then monitor the effect on blood flow in upstream capillaries in the brain. They find that blockages in venules can cause a significant decrease in blood flow in upstream capillaries, which in turn could cause the death of neurons.

These findings suggest that small occlusions in the venule system may play a role in cognitive dysfunction. Pockets of dead tissue, perhaps caused by venule occlusions, are often seen in autopsies of people who had dementia late in life, says Nguyen, and now researchers have a way to study this phenomenon.-Optical Society of America