The brain has been traditionally a difficult part of the body to treat disease because of a barrier that prevents, viruses, bacteria, and many medications from entering, and treating diseased parts of the brain. This has been frustrating for ages. Tumors, and diseases such as Alzheimer's have hidden behind this barrier since our origins. The brain Has this "Great wall of China" as a protective measure because the neural tissue has little room for defense mechanisms within the "Keep". This is why we have a fortified wall tho keep invaders out. Now Ultrasound allows medicine to breach certain soncated areas of brain tissue to allow medications to enter into the brain tissue itself. Trials are under-way to see if this is a safe and effective way of allowing medications to treat brain disease. This is certainly a great leap in terms of treating brain lesion, and may open up other doors in many areas. Here is an article from Sonoworld to explain the science:
KULLERVO HYNYNEN is preparing to cross neuroscience's final frontier. In July he will work with a team of doctors in the first attempt to open the blood-brain barrier in humans – the protective layer around blood vessels that shields our most precious organ against threats from the outside world.
If successful, the method would be a huge step in the treatment of pernicious brain diseases such as cancer, Parkinson's and Alzheimer's, by allowing drugs to pass into the brain.
The blood-brain barrier (BBB) keeps toxins in the bloodstream away from the brain. It consists of a tightly packed layer of endothelial cells that wrap around every blood vessel throughout the brain. It prevents viruses, bacteria and any other toxins passing into the brain, while simultaneously ushering in vital molecules such as glucose via specialised transport mechanisms.