Tiny Aneurysms Research Articles

Blood blisterlike aneurysms of the internal carotid artery.

An aneurysm arising from the anterior wall of the internal carotid artery (ICA) is a poorly understood entity. A small hemispherical bulge from the anterior wall of the ICA, which is called a "blood blisterlike aneurysm" (BBA), may be confused with a tiny berry aneurysm although the clinical features are distinctly different. This paper summarizes the clinical course of patients with this lesion to clarify the nature of the BBA. Six patients with BBAs who presented with subarachnoid hemorrhage (SAH) are described. In all patients, the initial angiogram obtained soon after SAH showed only a small bulge from the anterior wall of the ICA. In three of the six patients this bulge had progressed to a saccular appearance within a few weeks. The wall of the lesion was so thin and fragile that the aneurysm ruptured at the base during clipping or within a few hours after clipping in two patients. From the authors' experience, as well as a review of the literature, which includes an autopsy study of similar cases, it is inferred that these lesions are focal wall defects covered only with thin fibrous tissue and that they are therefore not true aneurysms. Direct clipping often causes laceration of the lesion, whereas complete wrapping or clipping after wrapping is effective, but may fail to prevent growth of the aneurysm. Endovascular occlusion of the cervical ICA with or without bypass surgery, which is less risky than direct surgery, is another option.

Abstracts of Literature

Abstracts of Literature

Mechanism of intracranial rebleeding in Moyamoya disease

Intracranial hemorrhage is the major catastrophic event in the natural course of Moyamoya disease, and outcome of the patients with rebleeding is very poor. However, the mechanism underlying intracranial rebleeding is not well elucidated. We retrospectively analyzed 15 patients who bled two times or more among 46 bled patients with Moyamoya disease. The results indicated that there were two different types in the manner of rebleeding. One group consisted of seven cases, which bled two times or more at the same site than the original bleeding site. In four of these seven cases, a ruptured aneurysm was identified at the distal part of collateral vessel or on the major vessel. In the other three cases, no source of bleeding was identified. In all of these cases, rebleeding occurred within 2 months after the initial insult except for one case. Another group consisted of eight cases, which bled repeatedly but at different sites from the initial bleeding site. In any of these cases, neither aneurysms nor other vascular abnormalities were identified. In all of these cases, rebleeding occurred more than 2 months after the initial bleeding. The present result indicated that intracranial bleeding might occur as a result of rupture of a tiny aneurysm at the periphery of collateral vessels. These aneurysms may be blown out after the initial bleeding. When they persist after the event, they may rupture again in a fairly short interval. In other cases, bleeding occur at different sites from the initial site. They are considered to be a result of ruptured weak Moyamoya vessels which are forced to act as collateral pathways and are under unusually increased hemodynamic stress.

Experience with Computed Tomographic Angiography for the Detection of Intracranial Aneurysms in the Setting of Acute Subarachnoid Hemorrhage

OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for the presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysm lobes, aneurysm neck size (≤ 4 mm), and the number of adjacent arterial branches were assessed. The images obtained with CTA were then compared with the images obtained with DSA, with the latter images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysm, six CT angiograms showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes(<3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.

Intracranial rebleeding in moyamoya disease

Cerebral ischaemia and intracranial haemorrhage are the major catastrophic events in the natural course of moyamoya disease. To prevent cerebral ischaemia extracranial/intracranial (EC/IC) bypass surgery has been done and the results of the surgery have been well documented. However, the mechanism(s) underlying intracranial bleeding and the therapeutic modalities used to prevent bleeding have not been well elucidated. We have retrospectively analysed 45 cases with intracranial haemorrhage among 192 patients with moyamoya disease treated and followed at our institute. Analysis of the initial patients with haemorrhage did not provide any new information other than the already reported theories about the origin and mechanism of bleeding. Analysis of 15 patients in whom haemorrhage occurred at least twice suggested that there were two different mechanisms of rebleeding. One group consisted of 7 cases, where haemorrhages were confined to the original bleeding site. In 3 of these 7 cases a small aneurysm was identified at the periphery of a moyamoya vessel. In 1 case a ruptured aneurysm was found on a major vessel. In 3 other cases no source of bleeding was identified. In all but 1 of these cases rebleeding occurred within 2 months after the initial ictus. The second group consisted of 8 cases where haemorrhage occurred repeatedly but at variable sites. In none of these cases were aneurysms or other vascular abnormalities identified to suggest the source of bleeding and in all of these cases rebleeding occurred more than 2 months after the initial ictus. In moyamoya disease intracranial bleeding may occur as a result of rupture of a tiny aneurysm situated at the periphery of the moyamoya vessels and which may have been destroyed after the initial bleeding. If the aneurysms persist after rupture they may re-rupture after a fairly short interval. In other cases bleeding occurs at different sites from the initial haemorrhage; these are considered to be a result of rupture of weak moyamoya vessels which are forced to act as collateral pathways and are under unusually increased haemodynamic stress. EC/IC bypass surgery is considered to be effective for the prevention of rebleeding in both groups of patients but in selected cases. Direct surgery is recommended when a peripheral aneurysm is found on a moyamoya vessel which has bled once.

未破裂椎骨脳底動脈瘤の治療方針

Together with current advances in neuroimaging techniques, the chance for incidental discovery of unruptured cerebral aneurysms has greatly increased, and the selection of their appropriate management remains controversial, especially for the unruptured aneurysms arising from the posterior circulation. To provide current data about the management for such patients with unruptured vertebrobasilar artery aneurysms, we reviewed 36 consecutive patients with such aneurysms treated either by surgical or conservative means. Sixteen patients were treated surgically. Twelve aneurysms (including 5 large or giant aneurysms) were clipped, and the remaining 4 aneurysms (2 giant aneurysms and 2 vertebral artery aneurysms) were treated by the endovascular approach. There were no surgical mortality but 2 poor results in this series. These 2 poor outcomes were attributable to perforator vessel injuries during direct clipping of the large basilar bifurcation aneurysms. Twenty patients were managed conservatively. Three (15%) of the 20 conservatively managed patients died from the aneurysm rupture during the follow-up period, which averaged 4.6 years. It was confirmed, however, that none of the 7 tiny aneurysms smaller than 5mm in diameter had ruptured. The authors conclude that the unruptured aneurysms of posterior circulation should be considered for surgical treatment, if the aneurysm can easily be approached surgically and the patient's age and medical conditions do not contraindicate surgery. Even for surgically high-risk patients with the giant aneurysms of posterior circulation aneurysms, the surgical indications are now being expanded with the development of the neurosurgical and endovascular surgical techniques.

Endovascular treatment of ruptured tiny aneurysms.

ObjectiveEndovascular coiling of ruptured tiny aneurysms (RTAs) in the brain has been known to be technically challenging owing to the higher rate of adverse events, such as thromboembolism and intraoperative rupture. The aim of this study was to report our ex-periences of endovascular treatment of RTAs (size, ≤3 mm).MethodsFrom January 2006 to December 2017, 35 RTAs in 35 patients were treated at our institution with an endosaccular coiling. Procedural data and clinical and angiographic results were retrospectively reviewed.ResultsThe mean size of the RTAs was 2.53 mm (SD: 0.38). The neck remodeling technique was applied to 14 aneurysms, including stent-assisted coiling (n=7) and balloon-assisted coiling (n=7). Procedure-related complications included intraprocedural rupture (n=2), thromboembolic event (n=1), and early rebleeding (n=2), which needed recoiling. Regarding immediate angiographic control, complete occlusion was achieved in 25 aneurysms (71.4%), small neck remnant in 5 (14.3%), and definite remnant in 5 (14.3%). At the end of follow-up, 31 of the 35 patients (88.6%) were able to function independently. Twenty-two of the 35 patients underwent follow-up conventional angiography (mean, 468 days). Stable occlusion was achieved in 20 of the 22 patients (90.9%), minor recanalization in 1 (4.5%), and major recanalization, which required recoiling, in 1 (4.5%).ConclusionOur experiences demonstrate that endovascular treatment for RTAs is both feasible and effective. However, periprocedural rebleedings were found to occur more often (11.4%) than what is generally suspected.

Hereditary Hemorrhagic Telangiectasia

HEREDITARY hemorrhagic telangiectasia (Rendu-Osler-Weber disease) is a disorder in which tiny arteriovenous aneurysms may present in virtually every visceral organ and on every body surface. There are vascular sinuses lined by a thin layer of endothelium interposed between arteries and veins. Because of the lack of elastic tissue in their walls, the vessels, when injured, bleed severely before stopping. The cause is unknown. The disorder may be passed as a simple dominant trait from either parent to both male and female children. There is a tendency for new telangiectases to appear as the person grows older. Although the telangiectases may effect any body structure, it is the nose that bleeds most commonly, and epistaxis is the bane of the patient's life. A typical patient usually starts to have nosebleeds about puberty. The nosebleeds, often only a few drops every day but sometimes a quart or more at a time, weaken