Introduction: Distal intracranial aneurysms are rare, have unclear origins, and are frequently non-saccular in their morphology. Published clinical experience with these aneurysms is limited. We examined the differences between distal aneurysms of cerebral and cerebellar arteries, and the results associated with surgical therapy in 140 patients.
Methods: Distal aneurysms in the cerebral arteries were defined as outside the circle of Willis, on or beyond the A2 anterior cerebral artery (ACA), M2 middle cerebral artery (MCA), or P2 posterior cerebral (PCA) segments. Distal aneurysms in the cerebellar arteries were on or beyond the s2 superior cerebellar artery (SCA), a2 anterior inferior cerebellar artery (AICA), or p2 posterior inferior cerebellar artery (PICA) segments. Clinical data, microsurgical technique, and patient outcomes were reviewed.
Results: The incidence of distal cerebellar artery aneurysms was 4.3 times greater than distal cerebral artery aneurysms (6.5% vs. 28.6%, p<0.01). The A3 ACA segment and the p2 and p3 PICA segments were the most common sites. Presentation with aneurysm rupture was more frequent with cerebellar aneurysms (65% vs. 40%, p<0.05). Distal cerebellar artery aneurysms were less likely than distal cerebral artery aneurysms to be clippable (40% versus 72%, p<0.01), with 42% treated with trapping alone. Overall, 14% requiring a bypass.
Conclusions: Distal intracranial aneurysms have a predilection for cerebellar arteries and are not as rare as the literature suggests. Application of standardized nomenclature for segmental anatomy to these lesions will increase the precision of anatomical description and clarity of clinical discourse. Although technically difficult, good clinical results can be expected with surgical management.
Patient Care: This research will improve patient care by: 1)Raising awareness of the good surgical results with these lesions; 2)Helping neurosurgeons to understand the appropriate surgical technique for each location; 3)Providing a unified nomenclature that can be taken as the base to report all these cases in the same way and, therefore, helping advance the knowledge about this pathology
Learning Objectives: By the conclusion of this session, participants should be able to: 1)Describe the differences between distal aneurysms of cerebral and cerebellar arteries; 2)Discuss the appropriate surgical technique for every location; 3)Determine the results associated with surgical therapy