Göhre, Felix
(Helsingin yliopisto, 2016)
Objective:
Aneurysms of the posterior cerebral artery are rare vascular lesions. The overall incidence is less than 1%, representing around 7% of posterior circulation aneurysms. Due to this low incidence, most of the institutional series on PCA aneurysms are small and contain less than 25 patients. Only one other series comparable in scope to ours has been previously published. The presented study analyzes and describes the characteristic features of PCA aneurysms as well as investigates the relevant treatment strategies and their outcomes. A particular focus is in the description and analysis of PCA aneurysms treated from a subtemporal approach and the pres - entation of an associated aneurysm treatment from a lateral supraorbital approach.
Patients and Methods:
We reviewed 121 patients diagnosed with 135 PCA aneurysms, all of whom were treated between 1980 and 2012 at two Finnish neurosurgical units (Department of Neurosurgery at the University of Eastern Finland, Kuopio and Department of Neurosurgery at the University of Helsinki). Additionally, twelve historical (pre-1980) cases were presented. Detailed analyses of cerebral angiographies were conducted for 93 PCA aneurysms in 81 patients. A further subgroup analysis of 34 patients diagnosed with 37 PCA aneurysms treated via subtemporal approach was also performed.
Results:
Of the 121 patients with 135 PCA aneurysms, 52 (39%) aneurysms were ruptured and 83 (61%) unruptured . The following distribution along the PCA segments was observed: P1 segment (n=53), P1/2 junction (n=39), P2 segment (n=28), and P3 segment (n=15); no P4 segment aneurysms were found. Saccular aneurysms were more common than fusiform PCA aneurysms (76% vs. 24%). The detailed angiographic analysis showed that the median aneurysm size was 7 mm for ruptured PCA aneurysms and 4 mm for unruptured aneurysms. Saccular aneurysms (n=69, 74%) had a characteristic dome projection for each location: P1 segment, upward (67%); P1/P2 junction, anterior/upward (80%); P2 segment, lateral (67%); and P3 segment, posterior (50%). The following treatment results at 1-year follow-up were achieved for patients with: unruptured PCA aneurysms (n=19; 12 good outcomes, 63%; 6 moderate, 31%; 1 poor, 5%), ruptured PCA aneurysms (n=27; 10 good, 37%; 9 moderate, 33%; 8 poor, 30%), and patients with complex neurovascular pathologies and PCA aneurysms (n=96; 42 good, 43%; 40 moderate, 42%; 14 poor, 15%). Analyzing the subtemporal approach we found that most complications were not related to the subtemporal approach itself but to the specific nature of the PCA aneurysms treated and the chosen strategy. The most common (12 out of 34; 35%) serious complication in this series was an ipsilateral PCA infarction after parent vessel occlusion.
Conclusion:
PCA aneurysms are infrequent vascular lesions that are often associated with other vascular pathologies. Most ruptured PCA aneurysms are smaller than 10 mm and distally located. The saccular PCA aneurysms have a typical dome orientation at each PCA segment. Microsurgery and endovascular treatment are effective options for the occlusion of PCA aneurysms. As a result, individual treatment strategies are required. Despite commonly adequate vessel collateralization of the distal PCA territory, preservation or reconstruction of the parent vessel is crucial for favorable treatment outcomes. The subtemporal approach is favorable for the treatment of PCA aneurysms in proximity to the tentorium. Frontolateral approaches allow the treatment of proximal PCA aneurysms and ipsilateral anterior circulation aneurysms inside the Circle of Willis.