Treatment of tumours of the pineal region and posterior part of the third ventricle.

Abstract

The evaluation of tumours located in the posterior part of the third ventricle or pineal region is achieved best by magnet resonance imaging (MRI). It shows the exact localization and extent, the involvement of neighbouring structures like thalamus or quadrigeminal plate and the displacement of the large veins, the internal cerebral veins, the vein of Galen and the veins of Rosenthal. If only CT is available, angiography should be performed prior to operation to identify the course of the veins. In children with a pineal region tumour the "tumour markers" AFP and beta-HCG should be determined before operation. We approach the rare tumours entirely located within the posterior part of the third ventricle by the posterior interhemispheric transcallosal route with the patient in prone position with the head elevated. The same approach is used for pineal region tumours extending above the internal cerebral veins. Tumours arising from the posterior thalamus extending into the thalamus and ventricle as well, are better approached by the posterior transcortical transventricular route since the lateral view is rather limited by the midline approach. The most frequent tumours in the pineal region are approached if they are located below the internal veins by the infratentorial, supracerebellar route in the sitting position. A total of 60 cases are evaluated. If AFP and/or beta-HCG are positive a highly malignant nongerminomatous germ-cell tumour must be suspected. We recommend initial chemotherapy with a combination of Vinblastine, Ifosfamide and Cis-platin without biopsy to avoid tumour seeding. After the "markers" are normalized operative removal of the residual tumour and radiotherapy should be carried out. In a series of 13 children operated on for pineal region tumours a rigid neuropsychological and endocrine evaluation was performed with encouraging results. During the last 10 years we have performed 49 open operations and 11 stereotactic biopsies. 40% of the patients were children under the age of 18. 40% of the tumours in childhood and 60% in adults were benign. In childhood 24% were germinomas and 20% non-germinomatous germ cell tumours.