Does low-energy ultrasound, known to enhance thrombolysis, affect the size of ischemic brain damage?

Abstract

In view of the potentially beneficial effects of ultrasound on fibrinolysis, we aimed to study possible drawbacks of low-energy ultrasound on nonperfused and perfused brain tissue. A model of transient focal ischemia in anesthetized rats was used. Rats were randomly assigned to 1 of 3 groups: the first exposed to ultrasound, the second a control of the ultrasound group, and the third a method control group. In each group, the right middle cerebral artery was occluded for 1.5 hours, during which time the rats in the ultrasound group were exposed to 1 hour of pulsed ultrasound (1 MHz; spatial-average temporal-average intensity, 0.1 W/cm2 at a duty cycle of 10%). The occlusion period was followed by a 24-hour recirculation period, after which the brains were excised and evaluated. Ultrasound did not affect the volume of ischemic damage in nonperfused brain tissue or add ischemic damage to perfused brain tissue. Under these experimental conditions, ultrasound does not cause additional ischemic damage to the rat brain during middle cerebral artery occlusion.