The perforator-free zone of the posterior communicating, artery and its relevance in approaches to the interpeduncular cistern, especially the transcavernous approach: An anatomic study

OBJECTIVE: Because the microsurgical working space in the interpeduncular fossa is very narrow, using different surgical approaches such as the pterional approach and/or the pretemporal transcavernous approach in combination with a division of the posterior communicating artery (PComm) at the longest perforator-free zone (PFZ) can help to enlarge the microscopic field of view and the working space in this area of the brain. METHODS: In this microanatomic study, the variability of several parameters of the PComm, especially the location of the longest PFZ of the PComm, was examined and described in 23 cadaveric heads. RESULTS: In most cases, the mean length of the longest PFZ was found to be between 2 and 6 mm. In 80% of the cases, the longest PFZ was located closer to the posterior cerebral artery than to the internal carotid artery. A total of 82.5% of all the PComms measured were of the adult type. In 55% of all arteries, a premamillary artery was identified. When a short and adult-type PComm obscures the microscopic view of the operative field, dividing the PComm is mandatory. In other situations, dividing the PComm is facultative. Because the PComm is usually predominantly irrigated by the internal carotid artery, it is of hemodynamic advantage that the longest PFZ is typically located closest to the posterior cerebral artery. CONCLUSION: On the basis of this descriptive anatomic Study, we conclude that when it is needed, division of an adult-type PComm at the longest PFZ is usually feasible and results in a low risk of compromising the blood flow to the branching perforators of the PComm.