Brain injury and ocular motor abnormalities in surviving preterm infants.

Editorials Brain injury and ocular motor abnormalities in surviving preterm infants Advances in neonatal care over the past 10 years have resulted in increased survival of very immature preterm infants but there has not been a corresponding improvement in neurodevelopmental outcome. 1 Serious neonatal morbidity is associated with decreasing gestational age. The survival of infants of extremely low birth weight and gestational age is associated with an increased incidence of brain injury in the survivors. The immature central nervous system of premature infants is particularly susceptible to cerebrovascular damage. 2–4 Intracranial, particularly intraventricular, haemorrhage is common, especially in smaller infants and may be associated with post-haemorrhagic hydrocephalus and with focal infarction of the white matter. The haemorrhage arises from the subependymal germinal matrix, a fine vascular gelatinous structure lying beneath the ependyma of the ventricular system and containing cells which will form mature glial cells that will later populate the cortex. 2 4 The germinal matrix is present from 10 weeks' gestational age and has disappeared by term. Most haemorrhage occurs in the first 72 hours after birth and may break through into the intra-ventricular space. Bleeding may also occur into the brain parenchyma. Between 24 and 32 weeks' gestational age the risk of white matter damage is particularly high. It is during this period that the brain is undergoing time limited maturational changes including myelogenesis. 3 The cause of the haemorrhage and the mechanism of white matter necrosis are not entirely clear but, like retinopathy of pre-maturity, are probably multifactorial. 3 4 Intraventricular haemorrhage is common in preterm infants; it occurs in about 40% of those weighing <1500 g at birth. It is often silent but a large haemorrhage may be associated with loss of visual responses, the development of dilated unresponsive pupils, and ocular motor signs including large angle esotropia and tonic downgaze. 5 Although most of the signs may resolve the convergent strabismus usually persists. 5 6 Large haemorrhages may also be complicated by post-haemorrhagic hydrocephalus which may in itself be a cause of ocular morbidity. Periventricular leucomalacia (PVL) is a separate ischae-mic lesion of white matter that is often associated with intraventricular haemorrhage. 3 4 It occurs in a characteristic distribution in the white matter dorsal and lateral to the outer angle of the lateral ventricles and commonly aVects the optic radiations. Until the advent of imaging techniques , particularly ultrasound, these white matter changes could …