In perinatal leukomalacia, the brain pathology exhibits several different distribution patterns, according to cerebrovascular and glial maturity or various causal factors. Periventricular leukomalacia occurs in the prenatal as well as the postnatal period, and is caused by, in addition to predisposing factors, cerebral hypoperfusion which is in turn caused by systemic hypotension or intracranial vascular constriction and circulatory disturbance. Oligodendroglial damage or diffuse astrogliosis associated with leukomalacia may lead to delayed or reduced myelination in the cerebral white matter.