Factors affecting outcome after endovascular treatment of intracranial aneurysms

Abstract

This brief review highlights some factors affecting the short-term and long-term outcomes after endovascular treatment (EVT) of patients with intracranial aneurysms. The principal procedural risks associated with EVT are symptomatic thromboembolic events affecting 2.4-5.2% of treatments, and aneurysm perforation which occurs in 0.5-2.4% of the patients with unruptured aneurysms and 2.3-6.5% of patients with subarachnoid haemorrhage. The risk of subsequent aneurysm recurrence requiring retreatment is about 10% and does not negate the morbidity advantage (relative to surgical clipping) of the initial EVT. This risk is about three-fold greater in aneurysms with a neck width more than 4 mm and sac maximum diameter greater than 10 mm. The incidence of rebleeding after EVT is 0.11-0.32% per annum and is probably lower if EVT achieves complete occlusion. EVT dramatically reduces the risk of rebleeding in patients with subarachnoid haemorrhage. Treatment risks and rates of incomplete occlusions are increased in ruptured in comparison with unruptured aneurysms. Large aneurysms have higher risk of procedural thromboembolism, incomplete treatment and rate of recurrences with strong interdependence between these variables. The low risk of rebleeding in patients with subarachnoid haemorrhage is probably increased in incompletely treated aneurysms and in patients revealing aneurysm growth over time.