OK, well when a surgeon does an operation of the brain, like implanting a a radioactive seed (brachytherapy) they need to go through the BBB and in to the brain.
This kind of procedures injures the BBB leaving it more permeable for toxins to enter the brain. Because this is known, surgeon have come up with several new less invasive techniques for brain surgery (such as gelatin covered implants, non invasive or minimal invasive therapies etc.) Unfortunately they didn't have those techniques when I got the implant...