Intracranial Studies by Ventriculograms

Abstract

VENTRICULOGRAMS are radiographs of the ventricular system after the cerebrospinal fluid has been completely or partially replaced by air. In order to understand the abnormalities in the ventricular system it is necessary to have a minute knowledge of anatomy and physiology. To review these briefly, let us recall that the intracranial ventricular system is composed of two lateral ventricles, a third ventricle, and a fourth ventricle. One lateral ventricle lies in each hemisphere of the brain and is composed of anterior, posterior, and temporal horns. The anterior horns are somewhat larger and more rounded, while the posterior horns come more to a point and are separated much farther apart than the anterior horns. The temporal horns are the smaller and extend downward and forward. These horns form more or less a wishbone-shape, as is seen in the lateral view. The capacity of the normal ventricle is about 60 c.c. From near the center of the anterior horn on the medial side is the foramen of Monro, which connects each lateral ventricle with the third ventricle. The third ventricle is slightly oblong in shape, is situated just below and between the two lateral ventricles, and is seen between the anterior and temporal horns on the lateral view. From the posterior portion of the floor of the third ventricle there is seen a funnel-shaped opening, leading downward and backward into a comparatively narrow channel, the aqueduct of Sylvius, which connects with the fourth ventricle. As is seen laterally, the fourth ventricle is a small triangular shaped cavity located in the posterior fossa. From this triangular shaped cavity, at the upper and posterior portion of the triangle, is seen the foramen of Magendie, and at the lower and most dependent angle are seen the foramina of Luschka. These three foramina connect the ventricular system with the subarachnoid space. The cerebrospinal fluid enters the lateral ventricles through the choroid plexuses, one of which lies on the floor of each anterior horn, and passes through the foramen of Monro into the third ventricle, and from the third ventricle through the aqueduct of Sylvius into the fourth ventricle; then through the foramina of Luschka and Magendie to the subarachnoid space, where it is taken up by the blood stream. This anatomy is illustrated by Figures 1 and 2. This illustration is made by taking a brain after autopsy and, before hardening or shrinking, injecting the ventricular system with neosilvol and radiographing from above downward and laterally. Indications for ventricular study are: persistent headaches that cannot be accounted for otherwise, tumors, abscesses, edema, hydrocephalus, epilepsy other than congenital types, congenital deformity. The value of the study depends, first, on the safety of the procedure; second, on the reliability of the technic, and third, on the interpretation of the findings.