=====Transventricular preforniceal approach=====
The transventricular preforniceal approach was used in two cases of exophytic chiasmatic/hypothalamic astrocytoma. The approach is summarized in 4 procedures: 1) exposure of the anterior horn of the lateral ventricle by the transcallosal approach, 2) identification of the foramen of Monro and the fornix, 3) incision of the septum pellucidum or the wall of the lateral ventricle, in front of the columns of the fornix, and 4) removal of the tumor through the space between the anterior commissure and the columns of the fornix.
RESULTS:

Because the tumor compressed the foramen of Monro posteriorly and stretched the space between the anterior commissure and the columns of the fornix, the posterosuperior part of the tumor in the third ventricle was successfully removed through the surgical corridor in front of the columns of the fornix. In both cases, tumors were successfully removed using this approach without damaging the fornix and the anterior commissure. Residual tumor was removed using an anterior interhemispheric translamina terminalis approach in a two-stage surgery.
CONCLUSIONS:

The transventricular preforniceal approach can be applied for removing the superior part of exophytic chiasmatic/hypothalamic astrocytomas, because the space between the anterior commissure and the fornix is stretched by the tumor, providing an appropriate surgical corridor
((Yoshimoto K, Shono T, Matsukado K, Sasaki T. The transventricular preforniceal
approach for exophytic chiasmatic/hypothalamic astrocytomas extending into the
anterior third ventricle. Acta Neurochir (Wien). 2013 Apr;155(4):727-32. doi:
10.1007/s00701-013-1642-z. Epub 2013 Feb 21. PubMed PMID: 23430233.)).