Measurement of a lesion of the brain, the portion of the central nervous system enclosed within the cranium which is composed of gray matter and white matter and is the primary center for the regulation and control of bodily activities, receiving and interpreting sensory impulses, and transmitting information to the muscles and body organs. A lesion is a localized pathological change in structure of an organ or tissue due to injury or disease; especially one that is circumscribed and well defined.