Neuroradiology

Abstract

Assessment of the external appearance of the cranium as a part of the clinical examination is of importance for decisions regarding appropriate diagnostic procedures. Abnormal variations in shape and size of the cranium occur with significant frequency in the systemic brain malformations involving defects of the corpus callosum (Probst, 1973), but in the various forms of prosencephaly they seem to be almost invariably present. In the latter conditions, there are often additional dysplasias or stigmata in the forehead and orbito-ethmoidal regions (trigonocephaly, hypotelorism, microphthalmia, etc.), as well as midfacial defects, and these are the features that have received much attention because they are readily diagnosed by inspection. As stated earlier, this correlation has given rise to a classification (Kundrat’s) in which the type of facial deformity has been used as an essential criterion. There are, on the other hand, prosencephalies belonging to all of the main categories which often lack craniofacial dysplasias of clinical significance. Electroencephalography, echo-encephalography, or even isotope cisternography can indicate the presence of forms of very low differentiation with some degree of certainty. The absence of cortical activity over the dorsal sac, for instance, as demonstrated by De Myer and Zeman (1963) and also observed as a typical feature in case 18 in the present study, may be suggestive of this diagnosis. Similarly, the absence of a midline echo (Patel et al., 1972) or the accumulation of activity in an undivided ventricle might also be indicative, especially when these are combined with faciocranial dysplasias of the type mentioned above. With all these methods, there are possible sources of error, and to obtain a reliable diagnosis it is necessary to demonstrate the gross morphology of such a brain by radiology.