Technical Points of Interhemispheric Approach for Anterior Communicating Aneurysms.

There are 2 approaches to perform clipping of anterior communicating aneurysms: the pterionaland the interhemispheric approach. The pterionalapproach is often applied as for anterior communicating aneurysms. We have used the interhemispheric approach for all anterior communicating aneurysms for 10 years. The interhemispheric approach is difficult to employ without injuring pia matter or pial capillary vessels, if the operator does not know the microanatomy of interhemispheric fissure in detail or does not have precise and stabile microsurgical technique. Itoh et al. described an interhemispheric approach in 1983 in which they recommended a 3-step procedure in the dissection of the interhemispheric approach. In the first step, the pericallosal cisternshould be exposed, in the second step the arachnoidtrabecullae between both cingurate gyruses are dissected, and in the third step, the bilateral gyrus rectusshould be separated, exposing the aneurysm. The advantage of the interhemispheric approach is that operators can identify the complete microanatomical structures of the anterior communicating arterycomplex and surrounding microstructures like hypothalamic arteries. We describe the key points of the interhemispheric approach in detail.