Third Ventricle

Numerous approaches via the third ventricle have been described. For supra-sellar tumors, the most common indication for these approaches is to remove a craniopharyngioma.

With a pituitary adenoma, if it is possible to debulk the suprasellar component from below, this removes the need to access the tumor in the third ventricle directly.

The two most useful approaches are the transcallosal and the translaminal terminalis. These routes allow access to the anterior part of the ventricle into which suprasellar lesions most commonly extend. We do not provide a detailed description in this chapter.

Translamina Terminalis

First described by King (33), the translaminal terminalis approach may be used in conjunction with the subfrontal operation, especially when the optic nerves are short and the chiasm, therefore, lies immediately in front of the tumor (34). A bifrontal flap may be used to approach the lamina along the midline, which gives symmetric visualization of the third ventricle. The lamina terminalis is identified superior to the chiasm and incised. Additional maneuvers have been described to enhance access, including division of the anterior communicating artery or the chiasm (35).

Transcallosal

This is applicable to the superior component of a suprasellar tumor, which cannot be brought down and accessed by an inferior approach. It has rarely been used by the authors for tumors of suprasellar origin, but is mentioned here for completeness. Transforaminal, interforniceal, or transchoroidal routes into the third ventricle may be used (36).

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