Etiology of giant aneurysms and their treatment

The M2-M1 middle cerebral artery reimplantation bypass with protective superficial temporal artery to middle cerebral artery bypass for giant partially thrombosed middle cerebral artery aneurysm in the hybrid operating suite

BACKGROUND

Giant middle cerebral artery (MCA) aneurysms are complex and challenging. Revascularization is frequently required in addition to trapping or clip reconstruction, and the MCA reimplantation bypass is ultimately needed when aneurysm excision is planned.

METHOD

The operation was conducted in the hybrid operating suite, where an intraoperative cerebral angiography revealed a compromised MCA after multiple attempts of clip reconstruction. Therefore, we decided to perform an M2-M1 reimplantation bypass in conjunction with trapping and aneurysmectomy.

CONCLUSION

Reimplantation bypass can be a rescue procedure for revascularization in complex aneurysms. The angioarchitecture varies among individuals; therefore, the optimal bypass technique should be tailored.

Partially thrombosed giant basilar artery aneurysm with attenuated contrast enhancement of the intraluminal thrombus on vessel wall MRI after flow diversion treatment: illustrative case

BACKGROUND

The effect of vessel wall magnetic resonance imaging (VW-MRI) enhancement in partially thrombosed aneurysms has previously indicated aneurysmal instability and a rupture risk. However, whether the contrast effect of the wall changes before or after flow diversion treatment is still under investigation.

OBSERVATIONS

The authors report a case of a partially thrombosed basilar artery aneurysm that increased in size over a short period, worsened brainstem compression symptoms, and was treated with a flow diverter stent with good results. In this case, VW-MRI after surgery showed a reduced contrast effect on the intraluminal thrombus within the aneurysm. The aneurysm thrombosed and markedly regressed over the next 5 months, with remarkable improvement in the brainstem compression symptoms.

LESSONS

This finding on VW-MRI may indicate an attenuation of neovascularization in the thrombus wall and be a sign of aneurysm stabilization.

Case report: Unruptured small middle cerebral artery aneurysm with perianeurysmal edema

Background

Perianeurysmal edema (PAE) has a tendency to occur in embolized aneurysms but also in partially thrombosed, large, or giant aneurysms. However, there are only a few cases recorded in which PAE was detected in untreated or small aneurysms. We suspected that PAE might be an impending sign of aneurysm rupture in these cases. Herein, we presented a unique case of PAE that was related to an unruptured small middle cerebral artery aneurysm.

Case description

A 61-year-old woman was referred to our institute due to a newly formed abnormal fluid-attenuated inversion recovery (FLAIR) hyperintense lesion in the right medial temporal cortex. Upon admission, the patient did not present with any symptoms or complaints; however, FLAIR and CT angiography (CTA) suggested an increased risk of aneurysm rupture. Aneurysm clipping was conducted, and no evidence of subarachnoid hemorrhage and hemosiderin deposits around the aneurysm and brain parenchyma was noted. The patient was discharged home without any neurological symptoms. MRI taken at eight months post-clipping revealed complete regression of the FLAIR hyperintense lesion around the aneurysm.

Conclusion

PAE in unruptured, small aneurysm is thought to be an impending sign of aneurysm rupture. Early surgical intervention is critical even for small aneurysms with PAE.

Partially thrombosed giant basilar tip aneurysm that remarkably decreased in size after stent-assisted coiling associated with the disappearance of neovascularization

Endovascular treatment for partially thrombosed giant basilar tip aneurysms has not been established because of its low cure rate and numerous associated comorbidities. Although some authors reported the growth mechanism of partially thrombosed aneurysm, there is no report for the process of its shrinkage after treatment. We describe a case of a partially thrombosed giant basilar tip aneurysm presenting with disturbance of consciousness because of a mass effect and brain edema. The patient underwent stent-assisted coiling using a low-profile visualized intraluminal support stent (Terumo). Although pre-operative magnetic resonance imaging (MRI) and angiography revealed prominent neovascularization of the inner aneurysmal layer, this vessel was absent on follow-up angiography 1 month after treatment. Repeat angiography demonstrated the gradual recanalization of the aneurysm. However, repeat MRI examinations showed remarkable shrinkage of the thrombosed aneurysm, and the complete disappearance of the thrombosed component was noted 6 months after treatment. The disappearance of neovascularization 1 month after the treatment may have contributed to the shrinkage of the thrombosed aneurysm. Stent-assisted coiling combined with alteration caused a hemodynamic change in this aneurysm, and the flow-diverting effect might have controlled this partially thrombosed giant aneurysm.

Decompressive Craniectomy: the Right Call at the Right Moment

Introduction:Massive intracerebral hemorrhages and large internal carotid artery infarcts may cause early death due to severe cerebral edema with elevated intracranial pressure, despite maximal medical therapy. Decompressive craniectomy may be of benefit to these patients in terms of survival and even functional outcome. The aim of our paper is to present two cases that illustrate the use of decompressive craniectomy both in ischemic and hemorrhagic stroke, followed by a discussion on the indication and right timing of the intervention, but also on the outcome of these patients. Materials and methods: We present the cases of a 38-year-old man with a right lenticular and capsular hemorrhage who underwent decompressive craniectomy in the first 24 hours from onset of symptoms and a 64-year-old patient with an ischemic stroke in the territory of the left carotid artery with a decompressive craniectomy performed at more than 72 hours from the beginning. For each of the two cases, we analyzed the following parameters: neurologic status, Glasgow Coma Scale, aspect of the cerebral computed tomography before and after surgery, in-hospital complications and modified Rankin Scale at discharge. Outcomes: While the intervention was life-saving in both cases, the procedure had different functional outcomes. Conclusion: Decompressive craniectomy may be a life-saving procedure for patients with both hemorrhagic or ischemic strokes complicated with massive edema and increased intracranial pressure. When performed in the first 48 hours, especially in patients with ischemic stroke aged less than 60, it may also improve the functional outcome compared to conservative treatment.

Unruptured Giant Intracerebral Aneurysms: Serious Trouble Requiring Serious Treatment - Case Report and Literature Review

Giant intracranial aneurysms (ICGA) represent 3 to 5% of all intracranial aneurysms in adults. They are defined as arterial dilatations, with more than 25 mm in diameter. Despite important advances in the research of endovascular techniques of treating giant intracranial aneurysms, the management of these vascular malformations still poses great difficulties for neurologists and interventional radiologists. In particular, these challenges arise from the difficult and modified cerebral anatomy of patients with ICGA. Choosing the best treatment for patients with ICGA involves not only finding the perfect balance between the potential risks and benefits of endovascular treatment, but also taking into consideration the patient's biological condition and associated diseases. The aim of this paper is to describe the decisional algorithm of treating patients with giant intracranial aneurysms and factors which could influence the choice of endovascular technique. We report a clinical case of a 63-year-old female with cardio-vascular risk factors (atrial fibrillation, high blood pressure), diagnosed with a symptomatic giant aneurysm of the right internal carotid artery and multiple cerebral micro-bleeds. Given the very large size of the aneurysm, its characteristics as well as patient's associated comorbidities, it was decided to exclude the ICA aneurysm from circulation by occluding the parent vessel (right internal carotid artery) by using endovascular techniques. Also, a review of the literature on the currently available endovascular methods for treating patients with giant intracranial aneurysms was performed in order to see the indications and possible long-term complications of each method. In selected cases, the risks of serious complications associated with occluding a large cervical-cerebral vessel (as the internal carotid artery) are far exceeded by the risk for rupture of giant aneurysms, which is fatal in many cases. Nevertheless, it is of utmost importance to mention that, although the use of endovascular methods leads to a significant increase in life expectancy, a severe decline in quality of life might be experienced by these patients.

Interobserver variability in the characterization of giant intracranial aneurysms with special emphasis on aneurysm diameter and shape

BACKGROUND

The Giant Intracranial Aneurysm Registry is a multicenter observational trial exclusively focusing on giant intracranial aneurysms (GIA). As no data exist on the interobserver variability in the radiological description of GIA, there is some uncertainty concerning the reliability of the GIA characteristics included in the registry. We have therefore designed a study to test the interobserver variability in the description of the specific GIA characteristics that are examined in the GIA registry.

METHODS

Six different raters analyzed imaging of five GIA concerning GIA location, GIA size, GIA shape, GIA thrombosis, and the presence of perianeurysmal edema. Interobserver variability was examined using intraclass correlation and Fleiss' kappa analysis.

RESULTS

The intraclass correlation coefficient was 0.99 (95 % CI 0.97-1.0) for the largest GIA diameter and 0.98 (95 % CI 0.94-1.0) for the largest GIA diameter in an axial imaging slice. We found perfect interobserver agreement (Fleiss' kappa 1.00) in the characterization of GIA location and the presence of perianeurysmal edema and almost perfect interobserver agreement for GIA thrombosis (Fleiss' kappa 0.86, 95 % CI 0.63-1.00). Only moderate interobserver agreement was found in the description of GIA shape (Fleiss' kappa 0.50, 95 % CI 0.27-0.73).

CONCLUSIONS

While GIA size, location, thrombosis, and the presence of perianeurysmal edema showed excellent interobserver agreement, the description of GIA shape was achieved with only moderate agreement. Data on GIA shape in multicenter studies, like the GIA registry, should therefore be discussed with caution and potentially reassessed in a centralized fashion.

Changes in volume of giant intracranial aneurysms treated by surgical strategies other than direct clipping

BACKGROUND

Giant intracranial aneurysms (GIA) are often not eligible for direct clip occlusion. Surgical alternatives include partial clip occlusion or the placement of a cerebrovascular bypass or the combination of both. These alternative indirect strategies are expected to lead to a decrease in GIA volume over time rather than instantaneously. To examine whether this is the case, we analyzed follow-up imaging results 1 year after surgery.

METHODS

We retrospectively screened the prospective GIA Registry's imaging database for anterior circulation GIA treated by surgical strategies other than direct clipping. We measured pre- and 1-year post-treatment GIA volume, lateral ventricle volume (LVV), and mid-line shift (MLS) in 19 cases.

RESULTS

After a mean follow-up of 466 days (standard deviation ±171) GIA volumes decreased from 9.6 cm(3) (interquartile range (IQR) 6.1-14.1) to 4.3 cm(3) (IQR 2.9-5.7; p < 0.01). Ipsilateral LVV increased from 8.6 cm(3) (IQR 6.4-24.9) to 16.0 cm(3) (IQR 9.1-27.2; p < 0.01) while contralateral LVV increased from 10.3 cm(3) (IQR 7.3-20.1) to 11.7 cm(3) (IQR 8.2-19.4; p = 0.02). MLS changed from 0.1 mm (IQR -1.9 to 2.0) to -0.9 mm (IQR -1.8 to 0.4; p = 0.03). The decrease in GIA volume correlated with the increase in ipsilateral LVV (rs = 0.60; p = 0.01) but not with the changes in MLS (rs = 0.41; p = 0.08).

CONCLUSIONS

In our patient cohort, surgical strategies other that direct clipping for the treatment of anterior circulation GIA lead to a significant decrease in GIA volume over time. The resulting decrease in mass effect was more sensitively monitored by the measurement of changes in ipsilateral LVV than changes in MLS.

CLINICAL TRIAL REGISTRATION-URL

http://www.clinicaltrials.gov . Unique identifier: NCT02066493.

Perianeurysmal edema in giant intracranial aneurysms in relation to aneurysm location, size, and partial thrombosis

OBJECT

The underlying mechanisms causing intracranial perianeurysmal edema (PAE) are still poorly understood. Since PAE is most frequently observed in giant intracranial aneurysms (GIAs), the authors designed a study to examine the occurrence of PAE in relation to the location, size, and partial thrombosis (PT) of GIAs along with the clinical impact of PAE.

METHODS

Magnetic resonance imaging data for patients with a diagnosis of unruptured GIA from the international multicenter Giant Intracranial Aneurysm Registry were retrospectively analyzed with regard to location and size of the GIA, PAE volume, and the presence of PT. The occurrence of PAE was correlated to clinical findings.

RESULTS

Imaging data for 69 GIAs were eligible for inclusion in this study. Perianeurysmal edema was observed in 33.3% of all cases, with the highest frequency in GIAs of the middle cerebral artery (MCA; 68.8%) and the lowest frequency in GIAs of the cavernous internal carotid artery (ICA; 0.0%). Independent predictors of PAE formation were GIA volume (OR 1.13, p = 0.02) and the occurrence of PT (OR 9.84, p = 0.04). Giant intracranial aneurysm location did not predict PAE occurrence. Giant aneurysms with PAE were larger than GIAs without PAE (p < 0.01), and GIA volume correlated with PAE volume (rs = 0.51, p = 0.01). Perianeurysmal edema had no influence on the modified Rankin Scale score (p = 0.30 or the occurrence of aphasia (p = 0.61) or hemiparesis (p = 0.82).

CONCLUSIONS

Perianeurysmal edema was associated with GIA size and the presence of PT. As no PAE was observed in cavernous ICA aneurysms, even though they exerted mass effect on the brain and also displayed PT, the dura mater may serve as a barrier protecting the brain from PAE formation.

Characteristics and outcomes of varied treatment modalities for partially thrombosed intracranial aneurysms: a review of 35 cases

OBJECTIVE

The purpose of this study was to analyze the characteristics of partially thrombosed intracranial aneurysms (PTIAs) in terms of location, shape, size, and symptoms, and to assess outcome according to the type of treatment.

METHODS

We reviewed the radiological and clinical findings of 35 cases of PTIAs followed in our institution between 2006 and 2011. We divided all treatment modalities into two groups. Patients in group A (n = 15) were treated by blood flow blockage from the lesion of the pathogenic segment of the parent where the PTIAs originated, and patients in group B (n = 20) were only treated with obliteration of the remnant perfused aneurysmal sac. Radiological and clinical outcomes of treatment were compared between the two groups.

RESULTS

Group A showed complete occlusion in 15 cases (100 %) compared to six cases (30.0 %) in group B (p < 0.001). No cases required retreatment in group A, while six cases (30.0 %) underwent retreatment in group B (p = 0.027). In terms of clinical outcome, 12 cases (80.0 %) showed symptomatic improvement in group A compared to eight cases (40.0 %) in group B (p = 0.037). Nine cases (60.0 %) showed improvement in postoperative GOS at six months compared to initial preoperative GOS in group A versus four (20.0 %) in group B (p = 0.032).

CONCLUSION

PTIAs should be treated by preventing blood flow from the lesion of the pathogenic segment of the parent artery where PTIAs originate. This treatment approach is associated with better clinical and radiological outcomes.

The Y-shaped double-barrel bypass in the treatment of large and giant anterior communicating artery aneurysms

Large and giant anterior communicating artery (ACoA) aneurysms usually show partial thrombosis and incorporate both the A1 and A2 segments and crucial perforating vessels. Therefore, direct clip placement or endovascular strategies often fail, leaving cerebral bypass surgery as a relevant therapeutic option. The authors present 3 cases in which a giant or large ACoA aneurysm was successfully occluded using a new technique that applies a double-barrel radial artery bypass. A radial artery graft is modified into a Y-shaped double-barrel conduit. After both pterional and parasagittal craniotomies are carried out, the graft is tunneled between both sites and anastomosed in an end-to-side fashion proximally to either a superficial temporal artery (STA) or M2 branch and distally to bilateral A3 branches. Aneurysm occlusion is then conducted through the pterional or parasagittal craniotomy. In one case, a 42-year-old patient in whom an endovascular approach had failed, the authors performed an STA-A3-A3 bypass and proximal aneurysm occlusion. In two others, a 49-year-old man in whom coiling had failed and a 56-year-old man in whom a giant ACoA aneurysm was partially thrombosed, the authors performed an M2-A3-A3 double-barrel bypass followed by either proximal or distal aneurysm occlusion. Complete aneurysm occlusion with excellent bypass perfusion was documented in the first two cases. In the third case, the authors observed good bypass perfusion with persistent antegrade aneurysm filling, and thus endovascular coil embolization was added to completely occlude the aneurysm.

The Y-shaped double-barrel bypass using a radial artery graft allows for safe and effective occlusion of large and giant ACoA aneurysms that cannot be treated by direct clip application.

Intracranial aneurysms: midterm outcome of pipeline embolization device--a prospective study in 143 patients with 178 aneurysms

PURPOSE

To evaluate the midterm clinical and angiographic outcomes after pipeline embolization device (PED) placement for treatment of intracranial aneurysms.

MATERIALS AND METHODS

This prospective nonrandomized multicenter study was approved by the review boards of all involved centers; informed consent was obtained. Patients (143 patients, 178 aneurysms) with unruptured saccular or fusiform aneurysms or recurrent aneurysms after previous treatment were included and observed angiographically for up to 18 months and clinically for up to 3 years. Study endpoints included complete aneurysm occlusion; neurologic complications within 30 days and up to 3 years; clinical outcome of cranial nerve palsy after PED placement; angiographic evidence of occlusion or stenosis of parent artery and that of occlusion of covered side branches at 6, 12, and 18 months; and clinical and computed tomographic evidence of perforator infarction.

RESULTS

There were five (3.5%) cases of periprocedural death or major stroke (modified Rankin Scale [mRS] > 3) (95% confidence interval [CI]: 1.3%, 8.4%), including two posttreatment delayed ruptures, two intracerebral hemorrhages, and one thromboembolism. Five (3.5%) patients had minor neurologic complications within 30 days (mRS = 1) (95% CI: 1.3%, 8.4%), including transient ischemic attack (n = 2), small cerebral infarction (n = 2), and cranial nerve palsy (n = 1). Beyond 30 days, there was one fatal intracerebral hemorrhage and one transient ischemic attack. Ten of 13 patients (95% CI: 46%, 93.8%) completely recovered from symptoms of cranial nerve palsy within a median of 3.5 months. Angiographic results at 18 months revealed a complete aneurysm occlusion rate of 84% (49 of 58; 95% CI: 72.1%, 92.2%), with no cases of parent artery occlusion, parent artery stenosis (<50%) in three patients, and occlusion of a covered side branch in two cases (posterior communicating arteries). Perforator infarction did not occur.

CONCLUSION

PED placement is a reasonably safe and effective treatment for intracranial aneurysms. The treatment is promising for aneurysms of unfavorable morphologic features, such as wide neck, large size, fusiform morphology, incorporation of side branches, and posttreatment recanalization, and should be considered a first choice for treating unruptured aneurysms and recurrent aneurysms after previous treatments.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120422/-/DC1.

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.

The rationale and design of the Giant Intracranial Aneurysm Registry: a retrospective and prospective study

AIMS AND HYPOTHESIS

Giant intracranial aneurysms have a poor prognosis mainly due to their high risk of rupture. Because their incidence is low, clinical trial evidence for adequate treatment is lacking. The Giant Intracranial Aneurysm Registry is designed to document current treatment strategies in giant aneurysm care and to monitor the course of the disease over five-years. It aims to evaluate the hypothesis that all three possible branches of therapy (conservative/endovascular/surgical) lead to equal rupture rates.

DESIGN

The Giant Intracranial Aneurysm Registry is an interdisciplinary multicenter observational study. Each center recruits patients diagnosed with a giant intracranial aneurysm both prospectively and retrospectively. Primary outcome will be the aneurysm rupture rate at five-years of follow-up.

STUDY OUTCOME

Patient enrollment has begun at 20 neurovascular centers throughout Germany, with 19 further centers applying for local ethics approval to take part in the study. The first nine months are designed as a pilot phase followed by the integration of study centers throughout the EU and the initiation of separate sub-studies.

DISCUSSION

Giant intracranial aneurysms have often been ignored or marginalized due to their low incidence. The Giant Intracranial Aneurysm Registry aims to lead to a better understanding of these complex lesions and to serve as a basis for the development of future clinical studies.

Partially thrombosed intracranial aneurysms: symptoms, evolution, and therapeutic management

BACKGROUND

Partially thrombosed intracranial aneurysms (PTIAs) are different from saccular or nonthrombosed giant or large aneurysms, as they are characterized by multiple intramural thrombotic phenomena related to recurrent vessel wall dissections.

METHODS

We retrospectively reviewed clinical and radiological files of 23 consecutive patients with PTIAs (mean age 49.3 years). Twenty-two lesions were studied by magnetic resonance imaging (MRI). Patients were managed by endovascular treatments, medically with steroids, or conservatively.

RESULTS

Thirteen patients presented with progressive neurological symptoms. Subarachnoid hemorrhage was suspected but not proven in three. At MRI, 90.9% of PTIAs caused mass effect; perilesional T2 hypersignal compatible with edema was evident in 13.6%. Aneurysmal wall enhancement was detectable in 63.2% of the PTIAs and considered a marker of inflammatory processes. Parent artery occlusion was performed in seven patients with clinical improvement in six. Selective coiling was proposed in three patients (one improved, one remained stable, and one experienced symptoms progression). Three patients were treated with steroids and improved. Ten patients were managed conservatively: eight because spontaneous thrombosis of the lesion had been diagnosed and two because of clinical and radiological stability.

CONCLUSIONS

The natural history of PTIAs is different from other aneurysms. They most commonly present with progressive neurological symptoms due to mass effect. MRI properly diagnoses PTIAs and allows precise follow-up, more accurately than angiography because it detects prominent "abluminal" features indicating inflammation and neovascularization. Spontaneous thrombosis is part of the natural history of PTIAs and it should be taken in consideration when discussing the therapeutic management.

Circulatory arrest and deep hypothermia for the treatment of complex intracranial aneurysms--results from a single European center

BACKGROUND

Vascular neurosurgery faces the controversial discussion about the need for deep hypothermia and circulatory arrest (dh/ca) for the treatment of complex cerebral aneurysms. In this retrospective analysis, we present our experience in the treatment of 26 giant and large cerebral aneurysms under profound hypothermia and circulatory arrest.

METHODS

All patients were treated surgically under dh/ca. Seventeen patients had aneurysms of the anterior circulation, and nine patients had aneurysms of the posterior circulation. Thrombosis or calcification was found in ten patients. Eleven patients presented with subarachnoid hemorrhage. The seven patients with the longest circulation arrest time were analyzed in detail.

RESULTS

Subarachnoid hemorrhage led to hospital admission in 42% (n = 11) of cases. The overall mortality was 11.5%, and the overall morbidity was 15%. Ten patients deteriorated transiently but fully recovered. The mean age, Glasgow Coma Score, Fisher, and Hunt and Hess Score correlated significantly with the long-term outcome. Circulation arrest time correlated significantly to the neurological outcome on discharge. All patients with prolonged circulation arrest times had wide aneurysmal necks, and four had adjacent vessels to the dome or the parent vessel included in the neck. We observed a significant increase of neurological deficits immediately postoperatively, but this neurological deterioration resolved over time.

CONCLUSIONS

We observed neurological deterioration immediately postoperatively in 13 patients, but all patients fully recovered within 6 months except for four patients. A long cardiac arrest time reflected complex pathoanatomical conditions. We conclude that the clipping procedure under deep hypothermia and circulatory arrest remains a pivotal armament in complex vascular neurosurgery.