Anatomical considerations in the treatment of intracranial aneurysms.

Comprehensive understanding of the vascular anatomy, including anatomic variations, anatomy of the perforators, and areas of irrigation for each specific vascular trunk is relevant for the treatment of intracranial aneurysms. Understanding the microanatomy of the cerebral vessels helps surgeons to select the most appropriate microsurgical approach for each case. Anterior circulation aneurysms may be originated from the internal carotid artery and its branches, anterior cerebral artery, middle cerebral artery and anterior communicating artery. Although presenting different surgical nuances, we favor the use of the pterional approach for most anterior circulation aneurysms. In some instances, extensions of the pterional approach improve the surgical exposure and may be selected. In its turn, posterior fossa aneurysms remain a challenge to the neurosurgeon. The exquisite eloquence and complexity of posterior fossa contents require a through knowledge of microsurgical anatomy of this region. Such anatomic background guides the surgeon to the most appropriate approach, which may vary dependind on the size, position of the aneuryms and its relatonship to the surrounding structures.