Transcallosal Approach

Indications

• Tumors of the lateral and anterior third ventricles.

Contraindications

• The transcallosal approach, although it provides exposure to tumors in the lateral and anterior third ventricle, is limited in providing satisfactory access to tumors in the posterior trigone, temporal horn, or superior frontal horn. Patients with these tumors are best approached by the transcortical route, with its own set of indications and complications.

• Although a partial callosotomy (usually anteriorly located) generally does not lead to significant neurologic deficit, serious impairment may arise because of poor patient selection, inattentive consideration of the vascular anatomy, or inadequate techniques.

• Crossed dominance, wherein the hemisphere controlling the dominant hand is contralateral to the hemisphere controlling speech and language, is a contraindication. Crossed dominance can arise after cerebral injury during childhood that resulted in cortical functional reorganization. These patients may develop writing and speech deficits postoperatively. Special consideration should be given to cases in which a more posterior callosotomy (splenium) is required, increasing the risks of cognitive dysfunction (e.g., alexia), particularly in patients with established preoperative visual field cuts (e.g., homonymous hemianopsia).

• Patients with slit ventricles represent a relative contraindication to this approach due to limited working space.

Planning and positioning