TRANSCALLOSAL REMOVAL OF LESIONS AFFECTING THE 3RD VENTRICLE - AN ANATOMIC-STUDY AND CLINICAL-STUDY

A SERIES OF 54 patients with lesions affecting the third ventricle wit h a wide range of pathology were operated on by the transcallosal appr oach. Hydrocephalus was present in 68.5% of all patients, and preopera tive shunting was performed in 73.0% of them. Before the partial callo sotomy, 16 patients were studied by the use of a cognitive, affective, and behavioral battery, which was repeated 10 and 100 days after the operation. No physiological consequences were ever observed after the partial commissurotomy. The postoperative callosal defect was verified by magnetic resonance imaging. Furthermore, 40 formalin-fixed brains were sectioned to study the variations of the anterior cerebral arteri es. On the other hand, magnetic resonance imaging measurements of the corpus callosum in 40 normal subjects were performed to establish a cl assification system for the corpus callosal area. The results showed a wide variability of the cross-sectional area of the corpus callosum. The differences in the thickness of the truncus were responsible for t his variability; the length of the corpus callosum was uniform. This m ay suggest that subjects with a larger corpus callosum may have more i nterhemispheric connections with higher specialization of each hemisph ere and that a smaller number of callosal connections may correlate wi th more ipsilateral pathways and more independent hemispheres. The res ults and the clinical as well as anatomical material indicate that the anterior transcallosal route is a safe and feasible alternative in th e management of a wide spectrum of pathological lesions within the thi rd ventricle and deserves preference over the transcortical technique.