Progressive multifocal leukoencephalopathy
Progressive multifocal leukoencephalitis (or leukoencephalopathy) is a rare disorder that is characterized by progressive inflammation (
-itis) of the white matter (
leuko-) of the brain (
-encephalo-) at multiple locations (
multifocal). The white matter is mostly composed of axons of the nerve cells that are emerging from the outermost parts of the
brain (
cortex). The
myelin sheath covering the axons and increasing their conduction velocities is preferentially affected. It appears to be a virus-induced disease and is most frequently observed in patients with immune deficiency (e.g.
AIDS).