Microsurgery of teratoma and germinoma involving the diencephalon and the brain stem.

The authors encountered 95 cases of germinoma (two-cell pattern pinealoma) and teratoma involving the third ventricle and the pineal region from 1962 to 1980. Germinoma is radiosensitive. However, removal (extensive or total) of the tumour followed by postoperative irradiation showed better results than simple radiotherapy. In the recent 62 cases, 5-year and 10-year survival rates were 80.2% and 69.3% respectively (in children under 15 years, both were 86.9%). Teratoma is not radiosensitive and requires operation. For operating on a pineal germinoma, either an infratentorial supracerebellar approach or an occipital transtentorial approach is indicated. A teratoma, however, is sometimes too large for these approaches, when exposed, and therefore, the author prefers the transcallosal approach (for huge tumours the frontal transcallosal approach). Technical details will be reported and discussed.