Complex internal carotid artery aneurysms

Ville Nurminen

Research output: ThesisDoctoral ThesisCollection of Articles


Complex intracranial aneurysms represent vascular lesions with attributes complicating their treatment. Giant intracranial aneurysms (GIA; ≥25 mm) are a rare subgroup of complex aneurysms with a particularly poor natural history. Due to their large size, giant aneurysms often present with cranial nerve dysfunctions. In this retrospective study, we aimed to provide a comprehensive description of the anatomical features of giant aneurysms in the internal carotid artery (ICA). Complex aneurysms are often difficult to approach directly, necessitating indirect treatment strategies. We therefore analysed a case series of bypass surgery and flow diversion in relation to the execution and outcomes in different segments of the ICA. All patients were admitted to the Helsinki University Hospital and for the analyses they were retrospectively recalled from the aneurysm database. For the series of giant aneurysms, we identified 125 patients with 129 GIAs (50 aneurysms in the ICA), from 1987 to 2007. For the series of bypass surgeries, included were 39 patients with 41 complex ICA aneurysms that were treated between 1998 and 2016. For the series of flow diversions, 62 patients with 76 ICA aneurysms were included from 2014 to 2019. In the treatment-oriented series, we analysed the internal carotid artery in segments, as this dictates the selection of treatment strategy. All the imaging studies and medical records were reviewed for relevant features in relation to aneurysms, complications and patient outcomes. The ICA was the most frequent location for GIAs in the cerebral arteries (39%) and most of these aneurysms were located specifically in the cavernous ICA segment (42%). Half of all GIAs presented mainly with symptoms of mass effect (50%). The cavernous GIAs were only rarely ruptured (10%) in contrary to the supraclinoid GIAs (36%). In general, wall calcification and intraluminal thrombosis were more seldom diagnosed in ruptured than in unruptured GIAs. In treatment of the complex ICA aneurysms with bypass procedures, the strategic goal of aneurysm treatment was achieved in 95% of cases (occlusion, 83%; flow modification, 12%). With flow diversion of the ICA aneurysms, 61% of aneurysms were occluded at 6-month follow-up and 69% at the latest follow-up. In both groups of treatment, the cavernous aneurysms became occluded slightly more often than the aneurysms in the supraclinoid region. Posttreatment large-scale strokes were rare (3-6%), but minor complications were seen more often. The pretreatment cranial nerve dysfunctions improved only moderately at best (cranial nerve-specific improvement rate of up to 60%). Respectively in groups of bypass and flow diversion, 74% and 85% of patients with unruptured aneurysms had favourable outcome at the latest follow-up. In both groups, only 25% of patients having unruptured aneurysms and presenting with poor functional status improved significantly to having a favourable outcome. The ICA is the most common location for GIAs and patients often present with symptoms of mass effect. Indirect treatment of complex ICA aneurysms with bypass procedures or flow diversion is feasible. Major treatment-related complications are rare, but minor complications occur at a non-negligible rate. Cranial nerve dysfunctions improve only in a proportion of patients. Lately, flow diverters have taken over the treatment of many complex ICA aneurysms, but the best treatment strategy should be assessed on a case-by-case basis, taking into consideration the burden of complex features of these aneurysms.
Original languageEnglish
  • Lehecka, Martin, Supervisor
  • Kivisaari, Riku, Supervisor
Place of PublicationHelsinki
Print ISBNs978-951-51-6014-0
Electronic ISBNs978-951-51-6015-7
Publication statusPublished - 2020
MoE publication typeG5 Doctoral dissertation (article)

Bibliographical note

M1 - 143 s. + liitteet

Fields of Science

  • Intracranial Aneurysm
  • +diagnostic imaging
  • +surgery
  • +therapy
  • Aneurysm
  • Carotid Artery, Internal
  • Cerebral Arteries
  • Angiography
  • Arteries
  • Blood
  • Computed Tomography Angiography
  • Hemorrhage
  • Magnetic Resonance Angiography
  • Middle Cerebral Artery
  • Subarachnoid Hemorrhage
  • Tomography
  • Treatment Outcome
  • 3112 Neurosciences
  • 3126 Surgery, anesthesiology, intensive care, radiology

Cite this