Pathology pathophysiology absence of normal parenchymal changes capillary system within and around the usual function displaced lesion asymptomatic at birth site frequency is vessels change with proportional to brain time volume may develop aneurysmsparenchymal changes within and around the lesion site frequency is proportional to brain volume Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms