Mass Effect After Flow Diversion for Unruptured Large and Giant Cavernous or Paraclinoid Internal Carotid Artery Aneurysm

OBJECTIVE: The mass effect associated with large or giant intracranial aneurysms is difficult for traditional endovascular treatment. This study investigated whether flow diverters can relieve the aneurysmal mass effect caused by aneurysmal compression symptoms.METHODS: Fifty-five patients with unruptured large and giant intracranial aneurysms treated by a flow diverter at our institution from January 2014 to February 2022 were retrospectively evaluated.RESULTS: In this study, 53 patients were included. Initially, 27 patients (51.9%), including 10 with compressive optic neuropathy, 12 with third nerve palsy, 2 with facial hyperesthesia, and 11 with sixth nerve palsy, were symptomatic. The symptom duration was shorter in the improved group (n = 2.2 +/- 4.0 vs. n = 3.1 +/- 3.9, P = 0.49). Thrombus formation following the flow diversion procedure was typically observed on magnetic resonance imaging (MRI) performed immediately and was not significantly associated with symptomatic improvement (OR = 0.395; 95% CI (0.058-2.698), P = 0.343). However, symptomatic improvement was seen in most patients when the aneurysm size decreased on MRI. A reduction in the aneurysm size on the MRI at the 3-month follow-up was correlated with symptomatic improvement in the multivariate analysis (OR = 0.08, 95% CI (0.013-0.485), P < 0.05).CONCLUSIONS: A flow diverter might help alleviate compression symptoms caused by large or giant intracranial aneurysms. Shrinkage of the aneurysm within 3 months postoperatively and a shorter duration of symp-toms contribute to the favorable outcomes of mass effect. Ultimately, prompt treatment is crucial for improving symptomatic intracranial artery aneurysms.