Growth and Rupture Mechanism of Partially Thrombosed Aneurysms

Abstract

<jats:p> Within the group of giant and large aneurysms the subgroup of the so-called “partially thrombosed” aneurysms can be differentiated according to clinical and neuroimaging findings. The present study was carried out to determine the site of bleeding of these aneurysms and what implications concerning their pathomechanism can be drawn from these findings. </jats:p><jats:p> Twenty patients aged two to 77 (mean 44) years who exhibited a partially thrombosed aneurysm that had recently bled were included. Images (MRI including T1 pre- and postcontrast and T2 weighted images in multiple planes, CT and digital subtraction angiography) and patients' charts were reviewed. </jats:p><jats:p> MRI showed an onion-skin appearance of the thrombus in 19 patients, rim enhancement of the aneurysm wall (either partial or complete) in 17, and a perifocal edema in 16 patients. The acute hemorrhage was typically crescent-shaped and located at the periphery of the aneurysm, distant from the perfused lumen of the aneurysm within the thrombosed part of the aneurysm. </jats:p><jats:p> The current denomination “partially thrombosed” intracranial arterial aneurysms leads to the presumption that thrombus is present endoluminal whereas in fact the site of hemorrhage is within the vessel wall. A more accurate nomination would, therefore, be “aneurysms with intra mural hemorrhage”. The enhancing wall and the edematous reaction of the adjacent brain parenchyma might be a sign for an inflammatory pathomechanism which is reinforced by histological and pathophysiological studies. This disease should be regarded as a clinical entity separate from saccular or non-thrombosed giant or large aneurysms. </jats:p>

Partially Thrombosed Intracranial Aneurysms Presenting with Mass Effect: Long-Term Clinical and Imaging Follow-Up after Endovascular Treatment

“…Some propose that the vasa vasorum of the aneurysmal wall play a crucial role in the development and growth of aneurysms with intraluminal thrombus by proliferation, inflammation, and rupture. [25][26][27] These authors suggest that these aneurysms should be treated by targeting the outer vessel wall and not the aneurysmal lumen. Our study does not confirm this theory.…”

Clinical and Imaging Follow-Up of Patients with Coiled Basilar Tip Aneurysms Up to 20 Years

“…Our study also demonstrated that most late mortality was due to continuous growth of some basilar tip aneurysms despite adequate first-time occlusion with coils and additional coiling when possible. 22,23 Why this phenomenon occurs in some aneurysms remains unclear. We were unable to identify risk factors for this infrequent event.…”

Evolution of a chronic dissecting aneurysm on magnetic resonance imaging in a pediatric patient

“…10 Subsequent MRI studies revealed repeated episodes of intramural hematoma, gradually evolving into a lesion with imaging characteristics as previously described in PTAs, including T1 hyperintensity indicating methemoglobin and an onion skin-like layering of hematomas of varying ages. 1,6,17 Growth of the aneurysm was revealed to occur due to the repeated hemorrhages that were distant from the perfused lumen, with stable imaging characteristics of the focally dilated lumen.…”