This pathological description refers to cystic areas deep in brain white matter that develop after hemorrhagic or ischemic infarction. Tissue ischemia leads to regional necrosis. Because brain tissue does not regenerate and the preterm neonate has minimal gliosis, these irreversibly damaged areas appear as echolucent cysts in neuroimaging studies. Generally, they require at least 2 weeks to form but may develop as long as 4 months after the initial insult. hus, their presence at birth may help to determine the timing of an inciting event.
This term refers to a group of conditions that are characterized by chronic movement or posture abnormalities that are cerebral in onglll, arise early in life, and are nonprogressive (Nelson, 2003). Epilepsy and mental retardation frequently accom pany CP. Its cause(s) are diferent in preterm and term infants (Chap. 33, p. 622).
CP is commonly classified by the type of neurological dys function-spastic, dyskinetic, or ataxic-as well as the num ber and distribution of limbs involved-quadriplegia, diplegia, hemiplegia, or monoplegia. The major types and their frequen their associates:
Spastic quadrplegia, which has a strong association with developmental retardation and seizure disorders-20 percent
Diplegia, which is common in preterm or low-birthweight
Mixed varieties.
According to the Centers for Disease Control and Prevention (2016), the prevalence of CP in the United States approximates 3 in 1000 children. In some countries, the incidence has risen because advances in care of very preterm newborns have improved their survival but not their neurological prognosis (O'Callaghan, 2011). For example, Moster and coworkers (2008) presented long-term follow-up of more than 900,000 births in Norway. he CP rate was 0.1 percent in nonanomalous term newborns but was 9.1 percent in those born at 23 to 27 weeks.
Various clinical and pathological data link CP with associated severe IVH (grade III or IV) and resulting PVL. In one study of nearly 1500 neonates born before ;28 weeks, the rate of CP was fivefold greater in those who had grade III or IV hemorrhage compared with those who sufered no IVH (Bolisetty, 2014).
Preterm newborns are most susceptible to brain ischemia and PVL. Before 32 weeks' gestation, the vascular anatomy of the brain is composed of two systems. One penetrates into the cortex-the ventrieulopedal system. The other reaches down to the ventricles, but then curves to flow outward-the ventrieulofugal system (Weindling, 1995). There are no vascular anastomoses connecting these two systems. As a result, the area between these systems, through which the pyramidal tracts pass near the lateral cerebral ventricles, is a watershed area vulnerable to ischemia. Vascular insuiciency before 32 weeks leading to ischemia would afect this watershed area first. Resulting damage of the pyramidal tracts may cause spastic diplegia. After 32 weeks, vascular flow shifts toward the cortex, and hypoxic injury after this time primarily damages the cortical region.
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