Within our brains are two small fluid-filled areas called ventricles. Cerebrospinal fluid is manufactured within these ventricles. Just to the right and left sides of the ventricles is the periventricular tissue. This tissue gets its blood supply from the arteries just before the arteries narrow down into capillaries. Because this tissue is at the "end of the row," it can be deprived of its blood supply by changes in blood pressure or the amount of oxygen in the blood supplying this area. When the periventricular tissue does not receive an adequate blood supply, the tissue may die.When the tissue dies, it leaves fluid in its place. This fluid appears as a small fluid collection called a cyst.
The cysts themselves are not a problem, but they represent brain tissue that has died and been replaced by fluid. PVL is the appearance of these cysts on an ultrasound, CT or MRI scan of the head. The brain tissue that has been lost is important to the control of muscle movements in the legs and sometimes in the arms. PVL is often associated with cerebral palsy and other developmental problems.