Atlas of neurosurgery basic approaches to cranial Meyer

Chapter 6: Modified Pterional Approach The modified pterional craniotomy, or anterior temporal approach, developed by Sundt provides good access to the upper basilar artery and the basilar caput. One of the major principles of the modified pterional approach is that the temporal lobe is retracted in an anterior-to-posterior direction to allow access to an aneurysm along the floor of the middle cranial fossa. This type of anterior-to-posterior retraction is well tolerated as long as the Sylvian fissure is widely divided. Another advantage of this approach is that it usually is possible to repair the aneurysm without a cutout clip, which sometimes can be difficult to place precisely. Furthermore, it is easier to identify and to dissect the opposite P1 segment of the posterior cerebral artery through a modified pterional approach than with a subtemporal approach.

When contemplating the approach to a basilar caput aneurysm, two important considerations are the relationship of the neck of the aneurysm to the posterior clinoid process and the projection of the dome of the aneurysm. The modified pterional approach is best suited for aneurysms that are within 1.5 cm in either direction of the posterior clinoid process. For high basilar caput aneurysms, a subtemporal approach through a frontotemporal zygomatic craniotomy may offer a better line of site, with less retraction of the brain. For low basilar caput or basilar trunk aneurysms, a subtemporal transtentorial approach works well.

Approximately one-half of the aneurysms of the basilar caput have a dome that projects posteriorly.

Therefore, the back wall of the aneurysm is related intimately to the thalamoperforating arteries that 235 Neurosurgery Books