MR imaging of giant intracranial aneurysm.

We reviewed the clinical features and findings of magnetic resonance imaging (MRI) in 17 cases of giant intracranial aneurysm (GIA). All were confirmed by digital subtraction angiography (DSA). Seven were non-thrombosed and 10 were partially thrombosed.All thrombosed parts showed no enhancement. The majority of the lumen showed good enhancement in the post-contrast study (89%). About 80% of the partially thrombosed aneurysms had an onion skin appearance on non-contrast T1WI. On T2WI about 80% of partially thrombosed aneurysms had a low signal inside the thrombus or its wall from the susceptibility effect of blood elements such as haemosiderin. Flow void sign was noted in 88% on non-contrast T1WI and T2WI. Flow artifacts along the phase-encoding direction from the lumen of the aneurysm were noted in 41% of non-contrast T1WI, 56% of contrast-enhanced T1WI, and 29% of T2WI.Non-enhancement inside the thrombus and an onion skin appearance were important signs of thrombosis of the aneurysm. Flow artifacts along the phase-encoding direction from the lumen of the aneurysm provided an important clue of a patent lumen inside an aneurysm. The following signs provided clues to the diagnosis of patency lumen instead of thrombosis with high sensitivity and specificity: flow void sign on noncontrast T1WI (sensitivity 88%, specificity 100%), enhancement on contrast-enhanced T1WI (sensitivity 89%, specificity 100%), presence of either flow void sign or enhancement on contrast-enhanced T1WI (sensitivity 100%, specificity 100%).     

Recanalization of Completely Thrombosed Non-Giant Saccular Aneurysm Mimicking as De Novo Aneurysm

Partial thrombosis of giant aneurysms is not uncommon however, complete angiographic occlusion occurs less frequently. In the case of non-giant aneurysms, complete thrombosis and recanalization has been rarely reported. A 31-year-old man presented to the emergency department with sudden bursting headache. Brain computed tomography (CT) revealed diffuse subarachnoid hemorrhage on the left side. Both CT angiography (CTA) and digital subtraction angiography showed suspicion of small left anterior choroidal artery aneurysm. We performed surgical exploration. In the operation field, anterior choroidal artery aneurysm of 2 × 2 mm with broad neck and friable appearance was observed. Because we could not clip without sacrificing the anterior choroidal artery, we performed wrapping only. Follow up CTA after 7 months demonstrated 4 mm right internal carotid artery bifurcation aneurysm. The patient underwent aneurismal neck clipping. During the operation, 9 × 13 mm sized thrombosed aneurysm was detected and completely clipped. We initially thought this aneurysm to be a de novo aneurysm however, it was an aneurysm that had recanalized from a completely thrombosed aneurysm. This case report provides an insight into the potential for complete thrombosis and recanalization of non-giant aneurysms.     

Flow diversion for intracranial aneurysms: a review

The introduction of flow diverters for treatment of intracranial aneurysms represents a major paradigm shift in the treatment of these lesions. The theoretical hallmark of flow diverters is the treatment of the diseased segment harboring the aneurysm instead of treating the aneurysm itself. Flow diverters are designed to induce disruption of flow near the aneurysm neck while preserving flow into parent vessel and adjacent branches. After flow diversion, intra-aneurysmal thrombosis occurs, followed by shrinkage of the aneurysmal sac as the thrombus organizes and retracts. Preliminary clinical series document effective treatment of wide-neck and/or large and giant aneurysms with acceptable complication rates. However, several questions remain unanswered related to the incidence and mechanisms of aneurysm rupture after treatment with flow diverters, fate of small perforating vessels, and long-term patency rates.     

Flow Diversion for Intracranial Aneurysm Management: A New Standard of Care

Endovascular treatment of intracranial aneurysms with complex morphologies such as giant, wide-necked, or fusiform aneurysms is challenging. Stent-assisted coiling and balloon-assisted coiling are alternative techniques to treat such complex aneurysms, but studies have shown less-than-expected efficacy, as suggested by their high rate of recanalization. The management of complex aneurysms via microsurgery or conventional neuroendovascular strategies has traditionally been poor. However, over the last few years, flow-diverting stents (FDS) have revolutionized the treatment of such aneurysms. FDS are implanted within the parent artery rather than the aneurysm sac. By modifying intra-aneurysmal and parent-vessel flow dynamics at the aneurysm/parent vessel interface, FDS trigger a cascade of gradual intra-aneurysmal thrombosis. As endothelialization of the FDS is complete, the parent vessel reconstructs while preserving the patency of normal perforators and side branch vessels. As with any intervention, the practice and application of flow-diversion technology is inherent, with risks that include vessel rupture or perforation, in-stent thrombosis, perforator occlusion, procedural and delayed hemorrhages, and perianeurysmal edema. Herein, we review the devices, their mechanisms of actions, clinical applications, complications, and ongoing studies.     

Thrombosis and recanalization of symptomatic nongiant saccular aneurysm

Complete thrombosis followed by recanalization of giant aneurysms is an infrequent process that has been exceptionally mentioned in relation to nongiant saccular aneurysms. A 25-year-old male presented with a right temporal hematoma and associated subarachnoid hemorrhage. Cerebral angiography revealed a small blister-like dilatation at the right middle cerebral artery bifurcation. The cerebral hematoma was surgically removed and a large thrombosed aneurysm was discovered and was wrapped. Follow-up angiography revealed complete recanalization of the aneurysm with preservation of all the arterial branches and the aneurysm was then completely occluded with detachable coils. This case provides insight into the well-known but poorly understood dynamic process of thrombosis and recanalization of cerebral aneurysms. The possible role of a cerebral hematoma in the pathogenesis of this process is discussed.     

Thrombosis and recanalization of symptomatic nongiant saccular aneurysm

Abstract

Complete thrombosis followed by recanalization of giant aneurysms is an infrequent process that has been exceptionally mentioned in relation to nongiant saccular aneurysms. A 25-year-old male presented with a right temporal hematoma and associated subarachnoid hemorrhage. Cerebral angiography revealed a small blister-like dilatation at the right middle cerebral artery bifurcation. The cerebral hematoma was surgically removed and a large thrombosed aneurysm was discovered and was wrapped. Follow-up angiography revealed complete recanalization of the aneurysm with preservation of all the arterial branches and the aneurysm was then completely occluded with detachable coils. This case provides insight into the wellknown but poorly understood dynamic process of thrombosis and recanalization of cerebral aneurysms. The possible role of a cerebral hematoma in the pathogenesis of this process is discussed.     

儿童颅内动脉瘤的临床特征及治疗

目的 探讨儿童颅内动脉瘤的发病特点、影像学特征及其治疗策略.方法 对宣武医院神经外科及神经介入中心1985年10月至2008年5月共23例14岁以下(含14岁)儿童的24个颅内动脉瘤的发病方式、部位、大小等影像学特点、治疗方式及其结果进行回顾性分析.结果 儿童颅内动脉瘤占所有年龄组颅内动脉瘤的1.3%,男:女=1.56:1;24个动脉瘤中,16个位于前循环,8个位于后循环;14个属于复杂动脉瘤;以蛛网膜下腔出血为表现者11例;14例采用神经介入治疗,4例采用显微手术治疗,5例未行外科治疗,其中2例在随访过程中动脉瘤及载瘤动脉自行闭塞而自愈;1例死亡,1例因术前动脉瘤再破裂导致中度致残,其余21例结果良好.结论 (1)儿童颅内动脉瘤较为罕见,发病率男性高于女性;(2)颈内动脉及大脑中动脉是儿童颅内动脉瘤的好发部位;(3)与成人相比,巨大动脉瘤、夹层动脉瘤及后循环动脉瘤、感染或外伤性动脉瘤比例较高;(4)神经介入及显微手术都是治疗儿童颅内动脉瘤的有效方法,但对于复杂动脉瘤首选神经介入治疗,相当一部分动脉瘤甚至不得不采用载瘤动脉闭塞的方法治疗.     

Superficial Temporal Artery to Anterior Cerebral Artery Hemi-bonnet Bypass Using Radial Artery Graft for Prevention of Complications after Surgical Treatment of Partially Thrombosed Large/Giant Anterior Cerebral Artery Aneurysm

Background

Partially thrombosed large/giant aneurysm of the anterior cerebral artery is still challenging because this complex aneurysm requires arterial revascularization in the deep operation field. Therefore, direct neck clipping is often impossible. We describe our experiences with extracranial-intracranial bypass as an insurance bypass prior to clipping of partially thrombosed anterior cerebral artery aneurysms, and discuss the microsurgical technique and strategy.

Thrombosis of non-giant unruptured aneurysms causing ischemic stroke

Abstract

Objectives: To describe a series of patients with stroke secondary to thrombosis in unruptured non-giant aneurysms and to classify them.

Methods: Patients with saccular non-giant aneurysm thrombosis presenting with ischemic events were identified. The clinical and imaging attributes were then used to build a novel classification scheme for aneurysm-related stroke.

Results: Six patients were included representing 0.15% of all strokes. The proposed mechanisms for stroke were classified as dislodgement of aneurysm thrombi to distal vessels, extension of aneurysm clot into the parent vessel and parent vessel occlusion due to extrinsic compression by the thrombosed aneurysm. Stroke severity was minor and outcome was excellent in all patients.

Conclusions: Strokes caused by unruptured aneurysms are rare and can be caused by several mechanisms. Clinicians should be aware of this rare form of stroke as it may represent a contraindication to systemic thrombolysis due to increased risk of aneurysm recanalization and rupture.     

Visual failure and recovery after thrombosis of a giant carotid ophthalmic aneurysm following vascular bypass and carotid artery ligation

Thrombosis via Hunterian ligation, with or without high-flow bypass, is the definitive treatment for unclippable giant aneurysms; however, secondary deterioration may occur. We present a 67-year-old woman with an unclippable giant (33 mm) carotid ophthalmic aneurysm. High-flow external carotid artery to middle cerebral artery bypass and proximal cervical internal carotid artery Hunterian ligation achieved complete thrombosis. Subsequent expansion of the thrombosed aneurysm created mass effect with hydrocephalus, leading to marked cognitive and visual decline. Aneurysmal decompression led to improved vision and near-normal neurological function.     

Giant middle cerebral aneurysm presenting as hemiathetosis in a child and its spontaneous thrombosis

A 10-year-old girl presented with a 6-week history of gradually increasing, abnormal movements and weakness of the right upper and lower limbs. There were no features of raised intracranial pressure. Computed tomography scan and magnetic resonance imaging (MRI) of the brain showed the features of a partially thrombosed giant middle cerebral artery aneurysm, located deep in the left lentiform region and compressing the basal ganglia and the mesencephalon. The angiogram confirmed the aneurysm and its origin from the main trunk of the artery with occlusion of all the branches. A direct approach was unsuitable for the treatment of the aneurysm, so an embolization procedure to occlude the neck of the aneurysm was considered. During the waiting period, the patient improved and became asymptomatic. Follow-up MRI showed complete thrombosis of the aneurysm and eventually, reduction in its size and mass effect. The hemiathetosis may have been the result of direct pressure on the basal ganglia by the aneurysm. The spontaneous intra-aneurysmal thrombosis may have been due to the massive size of the aneurysm and its narrow neck.     

Giant true posterior communicating artery aneurysm.

The case of a giant posterior communicating artery (PCoA) aneurysm is reported in which the clinical presentation was Korsakoff's syndrome. Left carotid angiography revealed a partially thrombosed giant PCoA aneurysm. Three-dimensional computed tomography angiography showed the precise neck of aneurysm and surrounding structures from a multidirectional view. Hypoperfusion of the bilateral frontal, temporal, and medial inferior thalamus was seen on single-photon emission computed tomography. According to previous reports, giant true PCoA aneurysms are rare; in fact, there has been only one report of a giant true PCoA aneurysm. We discuss the radiological characteristics and the clinical presentation of giant true PCoA aneurysms.     

Totally thrombosed giant P2 aneurysm: a case report and review of literature.

The diagnosis and treatment of intracranial saccular giant aneurysms is still difficult despite developments in neuroradiology, neuroanesthesiology and micro-neurosurgery. These aneurysms are usually located on major intracranial arteries and are rarely on distal branches of these arteries. An extra-axial 4 x 5 cm mass lesion in the left mediobasal temporal region was detected on the CT and MRI examinations of a 37 year old male patient who was admitted to our institution with headache and slight right-sided hemiparesis lasting for 2 months. The lesion was avascular on angiography. Surgery proved that the lesion was a totally thrombosed giant aneurysm of the P2 segment of posterior cerebral artery (PCA). The P2 segment was clipped proximal to the aneurysm with pterional-transsylvian approach and the aneurysm was totally excised. Giant aneurysms of the P2 segment are rare and 15 cases have been reported in the literature. This report presents a rarely seen totally thrombosed giant P2 aneurysms and discusses the difficulties in diagnosis and treatment.     

Ossified peripheral middle cerebral artery aneurysm in a 30-year-old man

A 30-year-old man presented with a history of several convulsive episodes. A CT scan showed a calcified focus in the right temporal lobe. Cerebral angiography yielded no abnormal findings. At craniotomy, the M3 portion of the middle cerebral artery was found to terminate with a blind end at the junction with the calcified mass. A pathological diagnosis of an ossified cerebral aneurysm was made. Calcified cerebral aneurysms are not rare; they are thought to be the result of intra-aneurysmal thrombosis or degenerative changes in the aneurysmal wall. However, complete mural ossification of a cerebral aneurysm is seldom seen, and ossified peripheral middle cerebral artery aneurysms are extremely rare in young individuals. The ossified aneurysm that we report developed over a prolonged period and may have arisen during childhood.     

Giant thrombosed fusiform aneurysm at the basilar trunk successfully treated with endovascular coil occlusion following bypass surgery: a case report and review of the literature

OBJECTIVE: Giant fusiform aneurysms at the basilar trunk tend to have a poor natural history, and the surgical management for these aneurysms remains controversial. For these aneurysms, basilar trunk occlusion may offer a potentially long-lasting cure. However, the strategy for these aneurysms is difficult when the collateral supply from the carotid circulation is poor. The authors herein present a successful case of a thrombosed giant fusiform aneurysm at the basilar trunk with a poor collateral supply using repeated balloon test occlusion (BTO) and a second bypass surgery. CASE REPORT: A 46-year-old female was admitted to our institute because of progressing double vision. A radiologic examination revealed a thrombosed giant fusiform aneurysm at the upper basilar trunk, and the collateral supply from carotid circulation was poor. We attempted to perform a second bypass surgery before the basilar trunk coil occlusion due to intolerance after the repeated BTO. After confirmation of her tolerance against the third BTO, the aneurysm was successfully trapped using the endovascular technique. CONCLUSION: Various kind of bypass surgery should be tried for endovascular trapping of giant fusiform basilar trunk aneurysms, and repeated BTO is necessary to confirm the tolerance after bypass surgery especially for the complex aneurysms without a sufficient collateral supply.     

Optic chiasm enhancement associated with giant aneurysm and yttrium treated pituitary adenoma

A patient with a history of pituitary tumour treated with yttrium 29 years before presented with an asymmetrical chiasmal neuropathy. Magnetic resonance imaging showed a partially thrombosed giant aneurysm of the right internal carotid artery, with enhancement of the chiasm and right optic tract adjacent to the aneurysm. It was thought that, in addition to the effects of compression, a peri-aneurysmal inflammatory reaction had developed, causing breakdown of the blood-brain barrier and consequent inflammatory changes in the optic chiasm. High dose steroid treatment led to significant improvement in vision within two weeks. Steroids may have a role in the acute preservation of vision in similar cases, as well as in cases of deterioration following coiling or embolisation of aneurysms where thrombosis within the aneurysm has been induced.     

Computer-Assisted Intraaneurysmal Thrombus Visualization

OBJECTIVE: Improved visualization of intraaneurysmal thrombi can contribute to understanding their impact on clinical courses and treatments. Digital subtraction angiography (DSA) demonstrates the hemodynamic portion of aneurysm domes and vasculature structures and has been considered by many to be the principal technique used for aneurysm diagnosis. An intraaneurysmal thrombus may be visualized as a filling defect on DSA, but DSA does not reliably indicate the presence of an intraaneurysmal thrombus or its details. Computerized tomography (CT) and magnetic resonance (MR) imaging may have advantages over DSA, particularly because of their capacity to visualize soft tissue. Hence, we investigated the reconstruction of MR and CT images and compared it to DSA for assessment of intraaneurysmal thrombi. METHODS: Thirty-one patients with 34 aneurysms were enrolled. The entire group was examined with DSA. Sixteen cases were also examined with MR imaging; the remaining 15 were examined with CT imaging. Images of intraaneurysmal thrombi were rendered from corresponding MRI and soft tissue scans using CT. Intracranial vessels and aneurysms were defined from MR and CT angiography. Whole images were linked via imaging software for the reconstruction of vasculature structures. Images were superimposed to produce visualizations of thrombi situated in aneurysmal bodies. RESULTS: Reconstruction of the MR and CT images clearly demonstrated the presence and details of intraaneurysmal thrombi in 9 (26.4 %) of 34 aneurysms. DSA detected only 4 (11.7 %) of the cases as a filling defect. Significant differences in thrombus visualization were observed between DSA used alone or in conjunction with either MRA (P = .02) or CTA (P = .04) images. Mean volume of thrombosed aneurysms was 3.2 +/- 0.84 mL (mean +/- SEM) and thrombosis volume was 0.9 +/- 0.31 mL. Aneurysm and nested thrombus volumes were highly correlated (r = 0.987; P < .001). CONCLUSION: Intraaneurysmal thrombi were clearly visualized by computerized MR and CT image reconstruction. MR and CT were superior to DSA alone in demonstrating the presence of intra-aneurysmal thrombi. Computer-assisted 3-D visualization can be invaluable in understanding the shape and volume of intraaneurysmal thrombi, which may contribute to more accurate assessment and effective treatment of aneurysms cases.     

The utility of contrast-enhanced MR-angiography for posterior fossa giant cerebral aneurysm management

Abstract

The utility of magnetic resonance angiography is sometimes 1imited in the diagnostic workup of cerebral aneurysms with low flow and/or partial thrombosis when weighed against digital subtraction angiography. We present the case of a rare superior cerebellar artery giantl partially thrombosed aneurysm in which additional i.v. contrast-enhanced MRA sequences were comparable to digital subtraction angiography. It demonstrated not only the exact spatial resolution and correct anatomical relation but also the hemodynamics which were confirmed by intraoperative Doppler ultrasound. This report supports the feasibility and utility of i. v. contrast-enhanced MRA for posterior fossa giant cerebral aneurysm management. [Neural Res 1998; 20: 705-708]     

Endovascular treatment of a large partially thrombosed basilar tip aneurysm

Despite the remarkable developments in neurosurgical and neuro-interventional procedures, the optimal treatment for large or giant partially thrombosed aneurysms with a mass effect remains controversial. The authors report a case of a partially thrombosed aneurysm with a mass effect, which was successfully treated by stent-assisted coil embolization. A 41-year-old man presented with headache. Brain computed tomography depicted an 18×18 mm sized thrombosed aneurysm in the interpeducular cistern. More than 80% of the aneurysm volume was filled with thrombus and the canalized portion beyond its neck measured 6.8×5.6 mm by diagnostic cerebral angiography. Stent-assisted endovascular coiling was performed on the canalized sac and the aneurysm was completely obliterated. Furthermore, most of the thrombosed aneurysm disappeared in the interpeduncular cistern was clearly visualized follow-up brain magnetic resonance imaging conducted at 21 months. The authors report a case of selective coiling of a large, partially thrombosed basilar tip aneurysm.     

Strategy for the treatment of inaccessible unruptured giant and large aneurysms of the internal carotid artery

Abstract

Our goal was to clarify the optimum management of the inaccessible unruptured giant and large aneurysms of the internal carotid artery (ICA). Since 1981, we have treated 18 patients with unclippable unruptured giant or large aneurysms of the ICA. Aneurysms were classified as either intracavernous or intradural. We performed proximal carotid occlusion in 12 patients and conservatively treated six patients. We retrospectively analyzed long-term outcomes in these patients. Four of seven patients with intradural aneurysm underwent proximal carotid occlusion, with good long-term outcomes. The three patients with intradural aneurysm, who were treated conservatively, died of subarachnoid hemorrhage. Eight of 11 patients with intracavernous aneurysm underwent proximal carotid occlusion, one dying of massive nasal bleeding 25 months after the procedure. In this case, the aneurysm was partially thrombosed, and residual lumen growth was revealed 22 months after proximal carotid occlusion. Cranial nerve paresis improved in five of the eight patients (63%), and two patients had a minor ischemic attack. Neurological problems failed to occur in the three patients with intracavernous aneurysm who were treated conservatively. The risk of rupture is relatively high in intradural giant and large aneurysms. Proximal carotid occlusion can effectively prevent bleeding from intradural aneurysms. Aggressive management is justified for intradural aneurysms with poor collateral circulation. Operative procedures in the management of an intracavernous aneurysm require careful consideration.