An unusual keyword to say the least, but someone surfing the net found sciencebase with it. So, here’s a quick definition:
Progressive multifocal leukencephalopathy (PML) is rare but debilitating. It is an inflammatory response to viral infection observed in immunocompromised patients, such as AIDS sufferers. The inflammation leads to loss of the myelin that insulates nerves within the white matter of the brain. Visual defects, headaches, and speech/language problems result.
There is no dedicated treatment but AIDS patients undergoing therapy with highly active antiretroviral therapy (HAART) often improve significantly.