Congenital craniocerebral abnormalities and computed tomography

Abstract

U NTIL NOW, neuroradiologic techniques have demonstrated either ventricular and cisternal alterations or direct or indirect effects on the intracranial vessels. Computed tomography (CT) has added another dimension. It defines a specific tissue pattern of the brain itself, so that solid or fluid-filled lesions within and surrounding the brain can be identified. Although CT is a relatively noninvasive and certainly safe examination, especially in infants, the nuances of the often complex congenital anomalies it uncovers often require additional neuroradiologic procedures. It is not that CT fails to provide satisfactory images, but that such images are often more difficult to understand and interpret than those provided by angiography or pneumography. Intracranial anomalies of the brain are deviations in form and structure induced during the brain’s intrauterine development. It is the interaction between the genetic and the intrauterine environmental factors that ultimately produce the malformation. Ebaugh and Holt6 state that chromosome deviations account for lo%, inheritance (either recessive or dominant) for 20%, and intrauterine environmental factors such as infection for 10% of intracerebral malformations. No pathogenetic factor is present in the remaining 60%. Many segments of the immature central nervous system may be so completely altered in utero that a logical cause cannot be deduced. Cerebral dysgenesis may occur in the formative period of neural tube development (3 weeks or before) or during its later intrauterine maturation and development. A malformation may result from nonlethal neural tissue destruction, cessation of growth, or altered development of a large or small portion of the brain. Inflammatory reactions within the fetal brain are uncommon before the sixth month of fetal life. Yakovlev14 subdivided alterations of form and