Cerebral hemorrhage

In the late 1970s, computed tomography (CT), and shortly afterwards cranial ultrasound (cUS), was used for the first time to visualize intracranial lesions [1]. cUS initially used the temporal bone but soon the anterior fontanelle was preferred as an acoustic window. The first cUS studies used a low resolution linear mechanical sector transducer, limiting the field of view to the lateral ventricles. The adjacent white matter was poorly visualized, until mechanical sector scanning was introduced with a wider angle of insonation. Data collected in the early years is therefore very different from the data that can be obtained today, using high resolution cUS as well as magnetic resonance imaging (MRI). Since the more routine use of neonatal MRI, it has become clear that injury of the vulnerable white matter of the preterm infant is more important than hemorrhages in the germinal matrix and the ventricles (germinal matrix hemorrhage-intraventricular hemorrhage [GMH-IVH]). Lesions that were in the past visualized as GMH-IVH are often associated with subtle injury to the white matter, which can either be entirely overlooked using cUS or underestimated. Long-term outcome data of preterm infants studied in the eighties with cUS therefore need to be interpreted with care. A decline in the incidence of severe white matter lesions, referred to as cystic periventricular leukomalacia (PVL) has been reported [2, 3]. However, although a decline in the overall incidence of GMH-IVH has been reported as well, there appears to have been no decline in the incidence of more severe grades of GMH-IVH and these severe hemorrhagic lesions still have a major impact on neurodevelopmental outcome [2, 4]. Use of additional acoustic windows to the anterior fontanelle, for example the mastoid window, has allowed for the recognition of hemorrhagic lesions of the cerebellum, especially in very immature and extremely low-birth weight infants [5, 6].