An Explanation for the Ribbing Seen in the Walls of Dilated Cerebral Ventricles *

It is a common experience to find in cases with dilated cerebral ventrides that the continuous smooth walls of these cavities give way to irregular contours. The irregularities are composed of transverse rib-like arches which project more deeply into the lumina of the cavities the greater the dilatation. Some patients, however, show large ventricles but may show few and shallow projections into the ventricles. The bands of tissue which produce these arches are most pronounced in the roofs of the lateral ventricles and grow less prominent as they reach the side walls. In examining pneumoencephalograms of cases with internal hydrocephalus of various degrees, the irregularities above described are seen frequently. They are most marked in the roofs of the bodies of the lateral ventricles, less marked in the anterior and occipital horns, and are not seen in the temporal horns. They may be apparent although not pronounced in cases with moderate internal hydrocephalus and, on the other hand, be absent in some cases with quite marked ventricular dilatation. When prominent, they give a scalloped appearance to the boundary of the ventricular gas shadows (Fig. 1). Since they are of no practical pathological significance their etiology, as far as we know, has not been previously investigated. Recently in the case of a child with advanced internal hydrocephalus the ribbing of the ventricles drew our attention because it was particularly well marked. The child subsequently died and the striking irregularities in the ventriculograms led us to investigate the anatomical basis for them. On horizontal section of the preserved brain the ridges were prominently displayed and it was noted that at the apex of each ridge running longitudinally with it was a blood vessel (Fig. 2). It seemed to us that the presence of these ridges could be ascribed to the blood vessels.