Periventricular leukomalacia. Cross-sectional view shows blood vessels that supply brain with blood (left) and brain structures (right). Area surrounding ventricles contains “white matter” that includes descending neuronal pathways of motor control system. This area, especially farther forward in brain, is susceptible to damage in premature infants because of relative paucity of blood vessels. Fluctuations in blood flow, blood oxygen, or blood glucose levels can cause damage in this area, resulting in disturbance of motor control system and subsequent (usually spastic) cerebral palsy.