A fatal, chronically growing basilar artery: a new type of dissecting aneurysm

Outcomes of reconstructive endovascular treatment of vertebrobasilar dissecting aneurysms with intramural hematoma

Background

Vertebrobasilar dissecting aneurysms (VBDAs) with an intramural hematoma (IMH) usually cause symptoms because of mass effect and grow in size over time. Clinical outcomes are generally poor.

Objective

This study aimed to examine outcomes of reconstructive endovascular treatment (EVT) in patients with VBDAs with IMH. Safety and effectiveness were compared between flow diverters (FDs) and conventional stents.

Methods

We retrospectively analyzed the clinical and radiological data of 36 VBDAs with IMH in 36 patients who underwent EVT with either FDs or conventional stents from January 2012 to December 2020 at our institution.

Results

Among the 36 study patients, 20 were treated with FDs and 16 with conventional stents. Incidence of procedure-related complications did not significantly differ between the two stents. IMH growth occurred after EVT in a significantly higher proportion of conventional stent group aneurysms (zero vs. 31.3% [5/16]; p = 0.012). Among the five aneurysms with IMHs that grew, all recurred. Change in IMH size after EVT was significantly lower in the FD group (−2.7 vs. +8.1%, p = 0.036). However, after the recurrent aneurysms were removed from the conventional stent group, change in IMH size did not significantly differ between the two groups (−2.7 vs. +1.0%, p = 0.332). The proportion of patients who experienced an improvement in mRS score after EVT was significantly higher in the FD group (60 vs. 25%, p = 0.036).

Conclusion

IMHs in VBDAs stop growing after successful reconstructive EVT. Although both FD and conventional stent treatment are effective, FD treatment may be superior based on clinical outcomes and effect on IMH size.

Aneurysms Arising from Persistent Arteries in the Vertebrobasilar Paramedian Longitudinal Axis: Two Case Reports

A 50-year-old man and a 69-year-old woman with consciousness disturbance were diagnosed to have suffered from subarachnoid hemorrhage (SAH) involving the posterior fossa. In both cases, the initial 3D CT angiogram failed to reveal the SAH source in the vertebrobasilar system. Delayed 3D rotational angiography revealed aneurysms on unfamiliar aberrant arteries. One was a dissecting aneurysm located between the proximal part of the posterior inferior cerebellar artery and the distal part of the intracranial vertebral artery. It was trapped and resected; the patient subsequently presented with lateral medullary symptoms. The other aneurysm was between the distal posterior and the distal anterior inferior cerebellar artery. It was successfully embolized; there were no complications. We think that the aberrant aneurysm-harboring vessels encountered in these two patients were primitive arteries on or adjacent to the vertebrobasilar paramedian longitudinal axis and that they persisted past the embryologic stage. Such aneurysms arising from unfamiliar persistent arteries beside the brainstem are extremely rare but must be considered when the SAH source is not detected in the trunk of the vertebrobasilar system.

Microsurgical Treatment Strategy of Vertebral Artery Fusiform Aneurysm-From the Standpoint of Hemodynamic Integrity and Perforator Preservation

During treatment of vertebral artery (VA) fusiform aneurysms, it is critical to preserve peripheral perforators and anterograde blood flow of the VA and to reduce hemodynamic load to the contralateral VA. Even in the era of endovascular treatment, there are still many benefits to using microsurgical treatments with appropriate clip application and preservation of the perforators around the aneurysm, in conjunction with various bypass techniques. The ideal microsurgical technique involves reconstructive clipping that obliterates the aneurysm but preserves anterograde blood flow of the VA, followed by isolation of the aneurysm and VA reconstruction. If these two methods are unavailable, proximal clipping of the aneurysm combined with flow-augmentation bypass to the distal branch can be considered as an alternative surgical management. We discuss the microsurgical treatment of unruptured VA fusiform aneurysms in our surgical cases on the basis of a review of the current literature.

Basilar artery dissection with rupture 6 years after accidental detection: A case report

Background:

Chronic basilar artery dissection (BAD) is a rare pathology, and only a few reports have been mentioned in the literature. The imaging features of chronic BAD, especially those that develop into a subarachnoid hemorrhage (SAH), are unknown.

Case Description:

We report a unique case of a chronic BAD with a split intimal flap that developed into an SAH. A 74-year-old man was diagnosed with BAD. After considering all treatment options, conservative treatment was selected for the patient. We continued imaging follow-up of the patient in our outpatient clinic once a year. The BA gradually dilated and the internal flap split. The patient and his family refused surgical treatment; therefore, conservative treatment was continued. Six years and 2 months from the first diagnosis, he developed a massive SAH and died.

Conclusion:

In the case of this patient, the weakened condition of the internal elastic lamina may have caused dissection of the intimal flap between the intima and media. Furthermore, the dissection may have developed and connected the true lumen to the pseudolumen and induced BA rupture. Thereby, split of the internal flap could be a risk factor for rupture in chronic BAD.

Unfavorable Outcomes Related to Endovascular Treatment of Giant Vertebrobasilar Aneurysms

Background: Giant vertebrobasilar aneurysms (GVBAs) have an unfavorable natural history if left untreated and often pose a sizeable challenge to endovascular treatment. The aim of this study was to analyze the angiographic and clinical outcomes of GVBAs treated by various endovascular procedures. Methods: Between January 2010 and September 2018, 27 patients with 27 GVBAs treated endovascularly were enrolled in this consecutive study. The clinical and angiographic features, treatment modalities, and outcomes were analyzed. Results: The patient cohort comprised 21 men (77.8%) and 6 women (22.2%) of mean age 42.7 ± 18.9 years (range, 6-65 years). The most common presenting symptom was compressive symptoms, present in 15 patients (55.6%). None of the GVBAs was ruptured. Of the 27 GVBAs, 23 aneurysms were dissecting aneurysm with intramural hematoma and 4 aneurysms were saccular. Regarding treatment approach, internal trapping was used in 5 aneurysms, stent-assisted coil embolization in 10, sole stenting in 4, and flow diverters in 8. Overall, 12 patients (44.4%) had an unfavorable angiographic or clinical outcome: 3 patients presented with post-operative complications and subsequent death, and 9 with poor prognosis during follow-up. Conclusions: Patients with GVBAs may not benefit from endovascular treatment. Newer-generation devices are necessary to provide more optimal therapy for the management of these complex lesions.

Practical value of three-dimensional high resolution magnetic resonance Vessel Wall imaging in identifying suspicious intracranial vertebrobasilar dissecting aneurysms

Background

Direct evidence of intimal flaps, double lumen and intramural haematomas (IMH) is difficult to detect on conventional angiography in most intracranial vertebrobasilar dissecting aneurysms (VBDAs). Our purpose was to assess the value of three-dimensional high-resolution magnetic resonance vessel wall imaging (3D HRMR VWI) for identifying VBDAs.

Methods

Between August 2013 and January 2016, consecutive patients with suspicious VBDAs were prospectively enrolled to undergo catheter angiography and VWI (pre- and post-contrast). The lesion was diagnosed as definite VBDA when presenting direct signs of dissection; as possible when only presenting indirect signs; and as segmental ectasia when there was local dilation and wall thickness similar to adjacent normal artery’s without mural thrombosis.

Results

Twenty-one patients with 27 lesions suspicious for VBDAs were finally included. Based on findings of VWI and catheter angiography, definite VBDA was diagnosed in 25 and 7 lesions (92.6%, vs 25.9%, p <  0.001), respectively; possible VBDA in 0 and 20 (0 vs 74.1%), respectively; and segmental ectasia in 2 and 0 (7.4% vs 0%), respectively. On VWI and catheter angiography, intimal flap was detected in 21 and 7 lesions (77.8% vs 25.9%, p = 0.001), respectively; double lumen sign in 18 and 7 (66.7% vs 25.9%, p = 0.003), respectively; and IMH sign in 14 and 0 (51.9% vs 0), respectively.

Conclusions

3D HRMR VWI could detect direct dissection signs more frequently than catheter angiography. This may help obtain definite diagnosis of intracranial VBDAs, and allow accurate differentiation between dissecting aneurysm and segmental ectasia as well. Further prospective study with larger sample was required to investigate the superiority of HRMR VWI for definite diagnosis of intracranial VBDAs than catheter angiography.

[Successful combination treatment of giant bicameral fusiform partially thrombosed vertebral artery aneurysm at 12-year-old patient (practical case and literature review)]

Giant cerebral aneurysms are diagnosed more often in children than in adults. Treatment of giant aneurysms is carried out both by endovascular and microsurgical methods. Literature information on combination of microsurgical and endovascular operations of cerebral aneurysms at children is little. A clinical case of the combined treatment of a giant bicameral fusiform partially thrombosed aneurysm of the right vertebral artery at a 12-year-old patient and a literature review on this topic are presented. The patient underwent several complex neurosurgical interventions during two operations: 1) microsurgery including revascularization of the right posterior lower cerebellar artery, thrombectomy and trapping of the larger chamber of fusiform aneurysm of the right vertebral artery, and 2) endovascular, which consists in the installation of redirecting stent from the left vertebral artery to main artery. The uniqueness of the case which we presented lies in the fact that the tactics of stage combined treatment for a complex aneurysm at child was originally planned and successfully implemented. The treatment allowed to ensure a complete shutdown of aneurysm and to exclude postoperative cerebral complications.

Qualitative Assessment and Reporting Quality of Intracranial Vessel Wall MR Imaging Studies: A Systematic Review

BACKGROUND

Over the last quarter-century, the number of publications using vessel wall MR imaging has increased. Although many narrative reviews offer insight into technique and diagnostic applications, a systematic review of publication trends and reporting quality has not been conducted to identify unmet needs and future directions.

PURPOSE

We aimed to identify which intracranial vasculopathies need more data and to highlight areas of strengths and weaknesses in reporting.

DATA SOURCES

PubMed, EMBASE, and MEDLINE databases were searched up to September 2018 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA ANALYSIS

Two independent reviewers screened and extracted data from 128 articles. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used to assess the reporting quality of analytic observational studies.

DATA SYNTHESIS

There has been an exponentially increasing trend in the number of vessel wall MR imaging publications during the past 24 years (P < .0001). Intracranial atherosclerosis is the most commonly studied intracranial vasculopathy (49%), followed by dissections (13%), aneurysms (8%), and vasculitis (5%). Analytic observational study designs composed 48% of the studies. Transcontinental collaborations showed nonsignificantly higher reporting quality compared with work originating from single continents (P = .20).

LIMITATIONS

A limitation is the heterogeneity in study designs.

CONCLUSIONS

Investigations on the diagnostic utility of vessel wall MR imaging in less commonly studied intracranial vasculopathies such as dissections, aneurysms, and vasculitis are warranted. More consistent adherence to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines should improve transparency and maximize effective synthesis for clinical translation. Diverse collaborative teams are encouraged to advance the understanding of intracranial vasculopathies using vessel wall MR imaging.

Inflammation promotes progression of thrombi in intracranial thrombotic aneurysms

Advances in the understanding of the pathogenesis of arteriosclerosis, abdominal aorta aneurysms and dissections, and carotid artery plaques have focused on chronic inflammation. In this study, we report that inflammatory changes of thrombi contribute to the enlargement and growth of giant intracranial thrombotic aneurysms. Surgical and postmortem samples were collected from 12 cases of large or giant intracranial thrombotic aneurysms diagnosed via pathological investigations. Degeneration of the aneurysmal wall and the infiltration of inflammatory cells in the thrombi were assessed. The number of blood cells and immunohistochemical stain-positive cells was enumerated, and the inflammation and neovascularization in the thrombi were assessed. In all cases, the appearance of inflammatory cells (CD68⁺ cells, CD206⁺ cells, lymphocytes, and neutrophils) was apparent in the thrombi. The number of CD34⁺ cells was moderately correlated with the number of CD68⁺ cells, and CD34⁺ cells significantly and strongly correlated with the number of CD206⁺ cells. Based on the number of neutrophils per CD68⁺ cells, we classified the cases into 2 groups: a macrophage inflammation-dominant group and a neutrophilic inflammation-dominant group. The neutrophilic inflammation-dominant group had significantly more cases with previous treatments and neurological symptoms due to mass effect than the macrophage inflammation-dominant group. Chronic inflammation due to macrophages in thrombi is a fundamental mechanism in the enlargement of an intracranial thrombotic aneurysm, and neutrophilic inflammation can accelerate this process. Microvascularization in thrombi is linked to inflammation and might promote thickening of the intima and repeated intimal microbleeds.

Quantitative Analysis of Intracranial Vertebrobasilar Dissecting Aneurysm with Intramural Hematoma After Endovascular Treatment Using 3-T High-Resolution Magnetic Resonance Imaging

OBJECTIVE

Quantitative measurements of intracranial vessel walls are reliable in 3-T high-resolution magnetic resonance imaging (HR-MRI). However, few reports have assessed the arterial wall after endovascular treatment (EVT) by 3-T HR-MRI. This study aimed to quantitatively analyze vessel walls in vertebrobasilar artery dissecting aneurysms after EVT.

METHODS

From May 2012 to December 2015, a total of 21 patients with 21 intracranial vertebrobasilar dissecting aneurysms (VBDAs) were enrolled in this consecutive study. All the VBDAs were characterized by intramural hematomas (IMHs ≥5 mm) and treated with reconstructive EVT. Images of preoperative and follow-up 3-T HR-MRI were used to evaluate the arterial wall. The relative signal intensity (RSI) of IMHs was quantified on T1-weighted imaging (T1WI) and magnetization-prepared rapid acquisition gradient-echo (MPRAGE).

RESULTS

Angiographic follow-up was performed for a mean of 9.19 ± 3.22 months. According to angiographic results at follow-up, 21 patients were divided into 2 groups (progressive group, n = 6; stable group, n = 15). In the progressive group, RSI of IMHs was significantly increased on MPRAGE of follow-up 3-T HR-MRI compared with that before treatment (P < 0.05), and the difference was not significant on T1WI. However, in the stable group, RSI of IMHs was significantly reduced after treatment (P < 0.05).

CONCLUSIONS

Persistent high signal intensity of IMHs in VBDAs after reconstructive EVT may be associated with the progression of VBDAs. It may also indicate an unsteady state of the aneurysm, which suggests that reconstruction of the parent artery is not satisfactory.

Clinical and Imaging Characteristics of Diffuse Intracranial Dolichoectasia

BACKGROUND AND PURPOSE

Among patients with vertebrobasilar dolichoectasia is a subset of patients with disease affecting the anterior circulation as well. We hypothesized that multivessel intracranial dolichoectasia may represent a distinct phenotype from single-territory vertebrobasilar dolichoectasia. The purpose of this study was to characterize clinical characteristics and angiographic features of this proposed distinct phenotype termed "diffuse intracranial dolichoectasia" and compare them with those in patients with isolated vertebrobasilar dolichoectasia.

MATERIALS AND METHODS

We retrospectively reviewed a consecutive series of patients with diffuse intracranial dolichoectasia and compared their demographics, vascular risk factors, additional aneurysm prevalence, and clinical outcomes with a group of patients with vertebrobasilar dolichoectasia. "Diffuse intracranial dolichoectasia" was defined as aneurysmal dilation of entire vascular segments involving ≥2 intracranial vascular beds. Categoric and continuous variables were compared by using χ² and Student t tests, respectively.

RESULTS

Twenty-five patients had diffuse intracranial dolichoectasia, and 139 had vertebrobasilar dolichoectasia. Patients with diffuse intracranial dolichoectasia were older than those with vertebrobasilar dolichoectasia (70.9 ± 14.2 years versus 60.4 ± 12.5 years, P = .0002) and had a higher prevalence of abdominal aortic aneurysms (62.5% versus 14.3%, P = .01), other visceral aneurysms (25.0% versus 0%, P < .0001), and smoking (68.0% versus 15.9%, P < .0001). Patients with diffuse intracranial dolichoectasia were more likely to have aneurysm growth (46.2% versus 21.5%, P = .09) and rupture (20% versus 3.5%, P = .007) at follow-up. Patients with diffuse intracranial dolichoectasia were less likely to have good neurologic function at follow-up (24.0% versus 57.6%, P = .004) and were more likely to have aneurysm-related death (24.0% versus 7.2%, P = .02).

CONCLUSIONS

The natural history of patients with diffuse intracranial dolichoectasia is significantly worse than that in those with isolated vertebrobasilar dolichoectasia. Many patients with diffuse intracranial dolichoectasia had additional saccular and abdominal aortic aneurysms. These findings suggest that diffuse intracranial dolichoectasia may be a distinct vascular phenotype secondary to a systemic arteriopathy affecting multiple vascular beds.

Effect of Headache on the Pathologic Findings of Unruptured Cerebral Saccular Aneurysms

BACKGROUND

Some patients with aneurysm exhibit warning headaches without minor bleeding, and this could be caused by stretching of the aneurysm wall. Recently, our pathologic study observed subintimal fibrin deposition in a majority of the ruptured aneurysms. However, these findings also were observed in some unruptured aneurysms. In this report, 2 unruptured aneurysms exhibited subintimal fibrin, and interestingly, one of the patients experienced severe headache within 1 month before neuroimaging.

OBJECTIVE

We performed pathologic analysis of unruptured aneurysms and collected their various clinical variables, including severe headache, to clarify the clinical characteristics of "dangerous" unruptured aneurysms.

METHODS

This study included unruptured saccular aneurysm samples (n = 17) that were resected after clipping. We compared the differences in clinical variables, including warning headache, between aneurysms with and without fibrin deposition.

RESULTS

Fibrin deposition was present in the subintimal layer in 4 patients and in the periouter membrane in 4 patients. Three of the 4 former patients experienced warning headaches, and one presented aneurysm growth. Of the latter 4 patients, one exhibited aneurysm growth, whereas the others presented with relatively large aneurysms. In the remaining 9 aneurysms without fibrin deposition, monocyte infiltration was observed in one, all aneurysms were small, and no patients experienced warning headaches or aneurysm growth.

CONCLUSIONS

Subintimal fibrin deposition is observed frequently in patients with aneurysm with warning headaches. These pathologic findings are clinically inspiring and may suggest that these aneurysms exhibit rapid stretching by newly formed aneurysms, which can result in rupture at an early stage.

A case of intracranial arterial dolichoectasia with 4 repeated cerebral infarctions in 6 months and enlargement of basilar artery

A 78-year-old man was admitted to our hospital because of sudden right hemiparesis and dysarthria. His cranial MRI showed an area of hyperintensity in left pons on DWI and MRA revealed dilated, elongated and tortuous intracranial artery. We diagnosed as acute phase ischemic stroke and intracranial arterial dolichoectasia (IADE). Intravenous infusion of rt-PA was performed 157 minutes after the onset of symptoms, and his hemiparesis improved. However, he subsequently suffered from cerebral infarction 4 times in 6 months, and we treated him twice with thrombolytic therapy. Although thrombolytic therapy was effective in the short term and antithrombotic therapy was continued, he had bilateral hemiplegia and severe dysphagia because of repeated cerebral infarctions. Hence basilar artery was dilated with intramural hemorrhage over 6 months, and we discontinued antithrombolytic therapy. It is possible that antithrombolytic therapy affects enlargement of IADE. Antithrombolytic therapy for IADE should be done carefully.

Brain Stem Infarction Due to Basilar Artery Dissection in a Patient with Moyamoya Disease Four Years after Successful Bilateral Revascularization Surgeries

Moyamoya disease (MMD) is a rare cerebrovascular disease with an unknown etiology and is characterized by intrinsic fragility in the intracranial vascular walls such as the affected internal elastic lamina and thinning medial layer. The association of MMD with intracranial arterial dissection is extremely rare, whereas that with basilar artery dissection (BAD) has not been reported previously. A 46-year-old woman developed brain stem infarction due to BAD 4 years after successful bilateral superficial temporal artery-middle cerebral artery anastomosis with indirect pial synangiosis for ischemic-onset MMD. She presented with sudden occipitalgia and subsequently developed transient dysarthria and mild hemiparesis. Although a transient ischemic attack was initially suspected, her condition deteriorated in a manner that was consistent with left hemiplegia with severe dysarthria. Magnetic resonance (MR) imaging revealed brain stem infarction, and MR angiography delineated a double-lumen sign in the basilar artery, indicating BAD. She was treated conservatively and brain stem infarction did not expand. One year after the onset of brain stem infarction, her activity of daily living is still dependent (modified Rankin Scale of 4), and there were no morphological changes associated with BAD or recurrent cerebrovascular events during the follow-up period. The association of MMD with BAD is extremely rare. While considering the common underlying pathology such as an affected internal elastic lamina and fragile medial layer, the occurrence of BAD in a patient with MMD in a stable hemodynamic state is apparently unique.

[Giant partially thrombosed aneurysm of the vertebral artery: a case report and literature review]

INTRODUCTION

Giant partially thrombosed aneurysms of the vertebral artery are recalcitrant to treatment by microsurgical trapping and thrombectomy. Application of endovascular interventions is limited due to substantial brainstem compression and cranial nerve neuropathy. Combined endovascular exclusion and microsurgical excision provides an approach to treatment of these lesions.

CLINICAL CASE

A 48-year-old female patient presented with progressive complaints of ataxia, diplopia in left lateral gaze, and dysphagia. Imaging studies (CT, MRI, angiography) revealed a giant partially thrombosed aneurysm of the right vertebral artery and pronounced brainstem compression.

TREATMENT

The initial phase of treatment involved endovascular occlusion of the vertebral artery and aneurysm trapping that did not lead to changes in the postoperative patient's neurological status. MRI demonstrated complete aneurysm thrombosis and a weak TOF signal in the vertebral artery near the proximal aneurysm neck region. Because of persistent brainstem compression, the patient underwent right suboccipital craniectomy and hemilaminectomy of the CI arch for aneurysm excision one week after endovascular occlusion. After isolating the aneurysmal sac, the vertebral artery was transected, and two small branches extending from the aneurysm neck to the brainstem were also coagulated and transected, followed by aneurysm excision. Numerous vasa vasorum in the wall of the proximal vertebral artery and aneurysm neck were coagulated to stop bleeding. After surgery, the patient developed neurological symptoms (right leg ataxia and dysphagia worsening) due to lateral medullary infarction (confirmed by MRI) that presumably resulted from coagulation of two small perforating branches coming from the aneurysm neck to the brainstem. Recovery of the patient's neurological functions was observed during conservative treatment. The patient was discharged with mild right leg ataxia and preoperative left-sided abducens paresis.

CONCLUSION

Medulla oblongata compression associated with a giant thrombosed aneurysm of the vertebral artery can be eliminated by endovascular trapping followed by surgical excision of the aneurysm. Preserving the vasa vasorum feeding the brainstem is crucial for prevention of ischemic complications.

High-Resolution Magnetic Resonance Imaging of Intracranial Vertebral Artery Dissecting Aneurysm for Planning of Endovascular Treatment

The equipment and techniques associated with magnetic resonance imaging (MRI) have rapidly evolved. The development of 3.0 Tesla MRI has enabled high-resolution imaging of the intracranial vessel wall. High-resolution MRI (HRMRI) can yield excellent visualization of both the arterial wall and lumen, thus facilitating the detection of the primary and secondary features of intracranial arterial dissection. In the present report, we describe the manner in which HRMRI affected our endovascular treatment planning strategy in 2 cases with unruptured intracranial vertebral artery dissection aneurysm. HRMRI provides further information about the vessel wall and the lumen of the unruptured intracranial vertebral artery dissecting aneurysm, which was treated by an endovascular approach in the 2 current cases.

Epidemiology, pathophysiology, diagnosis, and management of intracranial artery dissection

Spontaneous intracranial artery dissection is an uncommon and probably underdiagnosed cause of stroke that is defined by the occurrence of a haematoma in the wall of an intracranial artery. Patients can present with headache, ischaemic stroke, subarachnoid haemorrhage, or symptoms associated with mass effect, mostly on the brainstem. Although intracranial artery dissection is less common than cervical artery dissection in adults of European ethnic origin, intracranial artery dissection is reportedly more common in children and in Asian populations. Risk factors and mechanisms are poorly understood, and diagnosis is challenging because characteristic imaging features can be difficult to detect in view of the small size of intracranial arteries. Therefore, multimodal follow-up imaging is often needed to confirm the diagnosis. Treatment of intracranial artery dissections is empirical in the absence of data from randomised controlled trials. Most patients with subarachnoid haemorrhage undergo surgical or endovascular treatment to prevent rebleeding, whereas patients with intracranial artery dissection and cerebral ischaemia are treated with antithrombotics. Prognosis seems worse in patients with subarachnoid haemorrhage than in those without.

Pathological findings of saccular cerebral aneurysms-impact of subintimal fibrin deposition on aneurysm rupture

Although several studies have suggested that aneurysmal wall inflammation and laminar thrombus are associated with the rupture of saccular aneurysms, the mechanisms leading to the rupture remain obscure. We performed full exposure of aneurysms before clip application and attempted to keep the fibrin cap on the rupture point. Using these specimens in a nearly original state before surgery, we conducted a pathological analysis and studied the differences between ruptured and unruptured aneurysms to clarify the mechanism of aneurysmal wall degeneration. This study included ruptured (n = 28) and unruptured (n = 12) saccular aneurysms resected after clipping. All of the ruptured aneurysms were obtained within 24 h of onset. Immunostainings for markers of inflammatory cells (CD68) and classical histological staining techniques were performed. Clinical variables and pathological findings from ruptured and unruptured aneurysms were compared. Patients with ruptured or unruptured aneurysms did not differ by age, gender, size, location, and risk factors, such as hypertension, smoking, and hyperlipidemia. The absence or fragmentation of the internal elastica lamina, the myointimal hyperplasia, and the thinning of the aneurysmal wall were generally observed in both aneurysms. The existence of subintimal fibrin deposition, organized laminar thrombus, intramural hemorrhage, neovascularization, and monocyte infiltration are more frequently observed in ruptured aneurysms. Multivariate logistic regression analysis showed that ruptured aneurysm was associated with presence of subintimal fibrin deposition and monocyte infiltration. These findings suggest that subintimal fibrin deposition and chronic inflammation have a strong impact on degeneration of the aneurysmal wall leading to their rupture, and this finding may be caused by endothelial dysfunction.

Partially thrombosed vertebral artery dissecting aneurysm presenting as delayed bulbar compression after lateral medullary infarction

A 48-year-old man experienced lateral medullary infarction resulting from spontaneous vertebral artery (VA) dissection. Minimal fusiform dilatation was noted on basi-parallel anatomic scanning-magnetic resonance imaging; therefore, the patient was treated conservatively. Eight months later, he experienced deterioration of dysphagia and the onset of gait ataxia. Repeated imaging studies showed enlargement of the VA aneurysm with bulbar compression. Parent artery occlusion on the proximal side of the VA affected by the dissection relieved the patient's symptoms. Although the majority of dissected lesions stabilize within a few months, studies with longer observation periods and more frequent neuroimaging examinations are required.

Reconstructive Endovascular Treatment of Spontaneous Symptomatic Large or Giant Vertebrobasilar Dissecting Aneurysms: Clinical and Angiographic Outcomes

PURPOSE

To investigate the clinical and angiographic outcomes of spontaneous symptomatic large or giant vertebrobasilar dissecting aneurysms (VBDAs) following reconstructive endovascular treatment (EVT) with stent(s).

METHODS

We retrospectively identified 21 patients with spontaneous symptomatic large or giant VBDAs who had been treated with reconstructive EVT between September 2009 and September 2013 in our department. There were 20 men and 1 woman, with a mean age of 46.5 years (range: 17-67 years). Clinical and angiographic data were reviewed and evaluated.

RESULTS

Reconstructive EVT with sole stenting (SS, 10 cases) or stent-assisted coiling (SAC, 11 cases) technique was technically feasible in all cases. Angiographic follow-up results confirmed delayed thrombosis of the aneurysm sac in only two of the eight cases after SS, and recurrence of the aneurysm sac in six of the nine cases after SAC. Postoperative complications or poor neurologic outcomes occurred in seven cases (33.3 %). Three patients died after SS, including postoperative subarachnoid hemorrhage in one case and pulmonary embolism in one case. The other patient died soon after SAC, without radiologic result to confirm the causes of death. Other adverse events after treatment include ischemic complication in two cases, intramural hemorrhage in one case, aggravation of initial mass effect in one case. As to the other 14 cases, the post-procedural processes were uneventful and no complication was observed. The condition of them was improved in seven cases (33.3 %), and unchanged in seven cases (33.3 %) during follow-up.

CONCLUSIONS

Reconstructive EVT with traditional intracranial stent(s) for the treatment of large and giant VBDAs carries a high failure rate and substantial risk of complications. The outcome of treating these difficult lesions with traditional intracranial stenting seems questionable and unpredictable.

Pathological examination of a ruptured fusiform aneurysm of the middle cerebral artery

BACKGROUND

Little is known about the pathogenesis and clinical course of fusiform compared with saccular aneurysms. The case of a ruptured fusiform aneurysm accompanied by dissection at the M2 portion of the middle cerebral artery (MCA) is reported, along with pathological findings.

CASE DESCRIPTION

A 41-year-old female presenting with subarachnoid hemorrhage was revealed to have a ruptured fusiform aneurysm at the M2 portion of the right MCA on angiography. She was treated with superficial temporal artery-MCA anastomosis and trapping of the aneurysm. The aneurysm consisted of a whitish fusiform dilatation with a thickened wall of the MCA and two red protrusions on it. Pathological examinations revealed disruption and fragmentation of the internal elastic lamina and intimal thickening in the fusiform lesion. There were two aneurysmal protrusions on the main fusiform dilatation. In one protruded lesion, a dissection of the intima was observed.

CONCLUSION

We propose that a dissection and saccular aneurysm additionally developed on the wall of a preexisting segmental ectasia of the MCA in our case. In this report, we discuss the etiology of fusiform aneurysms of the MCA.

Growing dissecting aneurysm of basilar trunk treated with stent-assisted coiling

Growing basilar dissecting aneurysm is a scarce but increasingly recognized entity, accounting for a significant risk of death and disability. Controversy exists regarding the optimal management. A 61-year-old man presented with dysarthria and left hemiparesis attributable to a basilar trunk dissecting aneurysm. Antiplatelet therapy was instituted, and the patient's clinical condition markedly improved. However, he developed severe headache, dysarthria, and left hemiparesis 35 days later. Angiography revealed significant enlargement of the aneurysm, and stent-assisted coiling was then uneventfully performed. The patient remained clinically stable with only mild left-sided hemiparesis at the 2-year clinical follow-up.

Giant vertebral artery aneurysm in a child treated with endovascular parent artery occlusion and coil embolization

Background:

Intracranial giant vertebral artery aneurysms are extremely rare in the pediatric population and are associated with significant morbidity and mortality. The present report describes a case of a pediatric patient with giant vertebral artery aneurysm who presented with intracranial mass effect. This patient was successfully treated with endovascular parent artery occlusion and coil embolization.

Case Description:

A 7-year-old girl presented with tetraparesis, ataxia, dysphagia, and dysphonia. Cerebral angiography revealed intracranial giant aneurysm arising from the right vertebral artery. The patient underwent endovascular parent artery occlusion alone to facilitate aneurysmal thrombosis as an initial treatment. This was done to avoid a coil mass effect to the brainstem. However, incomplete thrombosis occurred in the vicinity of the vertebral artery union. Therefore, additional coil embolization for residual aneurysm was performed. Two additional coil embolization procedures were performed in response to recurrence. Mass effect and clinical symptoms gradually improved, and the patient had no associated morbidity or recurrence at 2 years after the last fourth coil embolization.

Conclusion:

Intracranial giant vertebral artery aneurysms are rare and challenging in pediatric patients. Staged endovascular strategy can be a safe and effective treatment option.

Imaging investigation of intracranial arterial dissecting aneurysms by using 3 T high-resolution MRI and DSA: from the interventional neuroradiologists' view

OBJECTIVES

The purpose of this study was to investigate vessel wall imaging features combined with the luminal shapes of intracranial dissecting aneurysms (IDAs) by using 3 Tesla (3T) high-resolution magnetic resonance imaging (MRI) and digital subtraction angiography (DSA).

METHODS

Sixty-seven patients with 76 IDAs were consecutively enrolled in the study from December 2011 to May 2013. DSA was performed to diagnose an IDA and to categorize its angiography patterns into either aneurysmal dilation, steno-occlusive, combined, or unclassifiable. Images of 3T high-resolution MRI were used to evaluate arterial wall imaging features of each lesion. Chi-squared tests were used for statistical analyses.

RESULTS

Aneurysmal dilation (51 of 76, [67%]) was the most common angiography pattern of IDAs, followed by the combined pattern (20 of 76, [26%]). Seven percent (five of 76) of IDAs showed steno-occlusive (n = 3) and unclassifiable (n = 2) angiography patterns, in which intramural hematomas were detected in the arterial wall without luminal connection. Intimal flaps (32 of 76, [42%]), double-lumen sign (38 of 76, [50%]) and intramural hematomas (46 of 76, [61%]) were recognized as the characteristic features of dissection by high-resolution MRI. Intramural hematomas occurred more frequently in the combined patterns group (16 of 20, [80 %]) than in the aneurysmal dilation group (25 of 51, [49%]) (P = .017), while the occurrence of intimal flaps and double-lumen sign did not differ between angiographic patterns (P > .05).

CONCLUSIONS

3T high-resolution MRI combined with DSA offered clear visualization of vessel wall features and accurate assessment of the vessel lumen in IDAs. This combined approach would be highly useful for understanding the underlying pathological status of IDAs and in guiding treatment choices.

Usefulness of V3-radial artery graft-V4 bypass in bilateral fusiform aneurysms of vertebral artery: case report

A 55-year-old woman with bilateral vertebral artery (VA) aneurysms was transferred to our hospital. She suffered from a minor stroke. Magnetic resonance imaging (MRI) for the stroke incidentally revealed bilateral VA aneurysms. Due to its size, more observation was recommended, and the patient was found eager to be treated. Both side surgeries were found inappropriate because of severe lower cranial nerve disturbances. The right aneurysm involved the posterior inferior cerebellar artery (PICA) and the V4 segment was deviated to the right side. Therefore, the smaller right aneurysm was treated first with an occipital artery (OA)-PICA bypass and a V3-radial artery graft (RAG)-V4 bypass followed by proximal clipping of the PICA and the right VA. The right VA was successfully remade by RAG and the right aneurysm was not revealed on postoperative examination. By doing so, the opposite aneurysm was able to be eliminated by the parent artery occlusion even by using an interventional radiology (IVR). The V3-RAG-V4 bypass is a useful method for treating bilateral VA aneurysms. This is a new bypass which has not been reported so far to the best of our knowledge.

Research progress on vertebrobasilar dolichoectasia

Vertebrobasilar dolichoectasia (VBD) is a rare disease characterized by significant expansion, elongation, and tortuosity of the vertebrobasilar arteries. Current data regarding VBD are very limited. Here we systematically review VBD incidence, etiology, characteristics, clinical manifestations, treatment strategies, and prognosis. The exact incidence rate of VBD remains unclear, but is estimated to be 1.3% of the population. The occurrence of VBD is thought to be due to the cooperation of multiple factors, including congenital factors, infections and immune status, and degenerative diseases. The VBD clinical manifestations are complex with ischemic stroke as the most common, followed by progressive compression of cranial nerves and the brain stem, cerebral hemorrhage, and hydrocephalus. Treatment of VBD remains difficult. Currently, there are no precise and effective treatments, and available treatments mainly target the complications of VBD. With the development of stent technology, however, it may become an effective treatment for VBD.

Vertebral and/or basilar dolichoectasia in human adult cadavers

BACKGROUND

Intracranial arterial dolichoectasia is a condition in which arteries demonstrate an increase in length and diameter, with the vertebrobasilar system being the most commonly affected segment. Because the criteria for and degree of vertebrobasilar dolichoectasia are usually established on three-dimensional time-of-flight MR angiography, we presented the results of an anatomic study of vertebrobasilar dolichoectasia cadaveric specimens.

METHOD

Examination was carried out on the brains of human adult cadavers, routinely dissected at the Institute of Forensic Medicine. Measurement of the outer diameter and length of vertebral and/or basilar arteries was performed using the ImageJ processing program.

RESULTS

There were 14 cases (14/216) of vertebral and/or basilar (dolicho)ectasia. Their classification into special (sub)types is made according to the basilar and/or vertebral diameter. The basilar length ranged from 32.91-59.37 mm, and the basilar outer diameter ranged from 3.51-8.92 mm in relation to the corresponding point of its measurement. The outer diameter of the vertebral arteries ranged from 0.67-5.91 mm. The Games-Howell post hoc test additionally showed that a basilar outer diameter of grade III and IV was significantly larger than in grade II (p < 0.05).

CONCLUSIONS

We noted a predisposition of males older than 40 years to arterial dolichoectasia in the vertebrobasilar system, independently from population group, as well as its asymptomatic appearance, independently from the presence of atherosclerotic plaques.

Multiple non-branching dissecting aneurysms of the mid-basilar trunk presenting with sequential subarachnoid hemorrhages

OBJECTIVE

We describe a rare case of a patient with subarachnoid hemorrhage (SAH) due to a ventral dissecting mid-basilar aneurysm that was treated surgically. One week after surgery, the patient experienced sudden deterioration due to a new SAH caused by the development of a new aneurysm of the basilar trunk distinct from the previously clipped aneurysm.

CASE DESCRIPTION

A 54-year-old woman with acute subarachnoid hemorrhage was found to have a small, broad-based aneurysm arising from the ventral aspect of the mid-basilar artery. This complicated lesion was treated with a microsurgical clipping via a translabyrinthine pre-sigmoidal sub-temporal approach. One week postoperatively, the patient suffered a new SAH and was found to have developed a distinct basilar artery aneurysm. The patient was returned to the Operating Room for microsurgical clipping via the previous craniotomy. After surgery, the patient made a slow, but steady, recovery. She underwent repeated angiographic imaging, demonstrating a stable appearance. Two years post surgery, the patient had returned to work and had no obvious neurological deficit, with the exception of unilateral iatrogenic hearing loss.

CONCLUSION

We describe a rare case of multiple aneurysms originating in relation to a mid-basilar dissection, resulting in multiple episodes of SAH. These are difficult and dangerous lesions that can be treated with open microsurgical reconstruction or possibly via an endovascular approach. The intricate location of the lesions poses a particular challenge to neurosurgeons attempting to directly treat mid-basilar lesions.

Natural course of intracranial arterial dissections

Object

Noninvasive neuroimaging techniques are increasingly identifying unruptured intracranial arterial dissections (IADs) at examination for headache or ischemic symptoms. Approximately 3% of cases of aneurysmal subarachnoid hemorrhage (SAH) are caused by IADs in Japan, but the natural history of unruptured IADs is not known.

Methods

Clinical data obtained in 190 patients with 206 IADs were retrospectively analyzed on the basis of long-time follow-up of geometry and clinical event. The IADs were divided into an unruptured group and SAH group depending on the patient's clinical status at the initial diagnosis. Day 0 was defined as the day preceding diagnosis of IAD—that is, the day of symptom onset. This was retrospectively determined from the clinical history.

Results

The 206 IADs included 98 unruptured lesions and 108 SAH. In both groups, the vertebral artery was the most frequent site. In the unruptured group, 93 IADs were followed for a mean of 3.44 years. The mean interval between symptom onset (Day 0) and neuroimaging diagnosis was 9.8 days. Subsequent geometry change was seen in 78 (83.9%) of 93 IADs. Major change was almost completed within 2 months, and complete normalization was seen on neuroimaging in 17 (18.3%) of 93 IADs, with the earliest on Day 15. Rupture of the IAD in the unruptured group occurred in only 1 patient on Day 11.

In the SAH group, 84 of the 108 patients complained of preceding headache before onset of SAH. In 81 (96.4%) of the 84 patients, SAH occurred on Day 0–3 with the latest on Day 11. In all patients in the unruptured and SAH groups, the latest day of SAH from the onset of preceding headache was Day 11.

Conclusions

Most IADs causing SAH bleed within a few days of occurrence. Most IADs that are unruptured already have little risk for bleeding at diagnosis because of the repair process. Intracranial arterial dissections may be much more common than previously thought, and the majority may occur and heal without symptom manifestation.

Reconstructive endovascular treatment of intracranial fusiform aneurysms: a 1-stage procedure with stent and balloon

BACKGROUND AND PURPOSE

Intracranial fusiform aneurysms, which incorporate the branch vessel and require salvaging of the parent vessel, are difficult to manage. The goal of this study was to evaluate the efficacy of reconstructive endovascular treatment of intracranial fusiform aneurysms by using a 1-stage procedure with a stent and balloon.

MATERIALS AND METHODS

During a 3-year period, 20 patients with 20 intracranial fusiform aneurysms were treated by using a 1-stage procedure involving a balloon and stent. Subarachnoid hemorrhage was present in 15 patients. Five aneurysms were located in the anterior circulation and 15, in the posterior circulation. Clinical outcomes and periprocedural complications were evaluated in all patients. The extent of coil packing was evaluated by control angiography after embolization and classified as either complete occlusion or partial occlusion. Angiography was performed 6, 12, and 24 months after embolization to evaluate stent patency and coil packing.

RESULTS

The 1-stage procedure by using a combination of balloon and stent was technically successful in all patients. There were no complications related to the procedure, complete occlusion was obtained in 16 patients, and partial occlusion, in 4 patients. All patients recovered well except for 2 who died due to causes unrelated to the procedure. Clinical follow-up was performed in all surviving patients at a mean of 12.3 months (range, 7-24 months), and angiography showed that the patent parent arteries were free of aneurysm recanalization or in-stent stenosis.

CONCLUSIONS

This 1-stage procedure may provide a feasible and safe treatment strategy for the management of intracranial fusiform aneurysms that are not amenable to deconstructive embolization.

In vivo assessment of rapid cerebrovascular morphological adaptation following acute blood flow increase

OBJECT

Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model.

METHODS

Rabbits were subjected to sham surgery (3 animals), unilateral CCA ligation (3 animals), or bilateral CCA ligation (5 animals). Transcranial Doppler ultrasonography and rotational angiography were used to compute BA flow, diameter, wall shear stress (WSS), and a tortuosity index on Days 0, 1, 4, 7, 14, 28, 56, and 84. Basilar artery tissues were stained and analyzed at Day 84. Statistical analysis was performed using orthogonal contrast analysis, repeated measures analysis of variance, or mixed regression analysis of repeated measures. Statistical significance was defined as a probability value < 0.05.

RESULTS

Basilar artery flow and diameter increased significantly after the procedure in both ligation groups, but only the bilateral CCA ligation group demonstrated significant differences between groups. Wall shear stress significantly increased only in animals in the bilateral CCA ligation group and returned to baseline by Day 28, with 52% of WSS correction occurring by Day 7. Only the bilateral CCA ligation group developed significant BA tortuosity, occurring within 7 days postligation. Unlike the animals in the sham and unilateral CCA ligation groups, the animals in the bilateral CCA ligation group had histological staining results showing a substantial internal elastic lamina fragmentation.

CONCLUSIONS

Increased BA flow results in adaptive BA remodeling until WSS returns to physiological baseline levels. Morphological changes occur rapidly following flow alteration and do not require chronic insult to affect substantial and significant structural transformation. Additionally, it appears that there exists a flow-increase threshold that, when surpassed, results in significant tortuosity.

Internal trapping following proximal clipping for a ruptured partially thrombosed giant aneurysm of the vertebral artery--case report

A 52-year-old woman presented with a partially thrombosed giant aneurysm of the vertebral artery (VA) manifesting as a 3-month history of left hemiparesis. She developed subarachnoid hemorrhage during hospitalization and underwent emergency surgery for surgical proximal clipping and ventricular drainage with decompressive suboccipital craniectomy. She underwent additional surgery for endovascular coil embolization of the aneurysm and the affected distal VA on the 7th postoperative day. Although she suffered transient lower cranial nerve pareses and respiratory failure, her neurological condition improved gradually and she returned home with only slight ataxia and hoarseness 3 months after surgery. Magnetic resonance imaging obtained 28 months postoperatively revealed a remarkable decrease in the size of the aneurysm as well as reduction of the mass effect on the brainstem. Combined proximal clipping and internal trapping can solve the problems associated with treatment of giant aneurysms of VA by either direct surgery or endovascular surgery, and should be considered as a therapeutic option for giant aneurysms of the VA.

Dissecting aneurysms limited to the basilar artery: report of two cases and review of the literature

Spontaneous dissecting aneurysms limited to the basilar artery are rare. We describe two patients who presented to our institution with different clinical problems, one with brain stem infarction and the other with subarachnoid hemorrhage. We describe the clinical and imaging features in these patients, their treatment, and outcome. We also reviewed the literature concerning this entity, and we have identified 32 patients (including our two patients) with angiographically confirmed dissecting aneurysms limited to the basilar artery. Of these, 40.6% presented with brain stem infarction, 50.0% presented with subarachnoid hemorrhage, and 9.4% presented with both infarction and subarachnoid hemorrhage. Patients who presented with basilar artery dissecting aneurysms and brain stem infarction tended to be younger (mean age, 38 +/- 7 years) than those who presented with subarachnoid hemorrhage (48 +/- 12 years) and were more likely to be male. We discuss the natural history of this entity and suggest an approach to clinical management for these patients.

Clinical analysis of vertebrobasilar dissection

BACKGROUND

The natural history of vertebrobasilar artery dissection (VAD) is not fully known. The purpose of this study was to review the clinical outcome of the patients with VAD, then to propose an appropriate management strategy for VAD.

METHOD

From 1992 to 2004, 35 VAD patients admitted to our institutes were retrospectively reviewed. There were 28 men and 7 women, whose age ranged from 4 to 67 years with a mean age of 44 years. Angiography was assessed to document the shape, and location of the dissecting aneurysm with respect to the posterior inferior cerebellar artery (PICA). A modified Rankin score was assigned for functional outcome. The functional outcome scores were analyzed according to the patient's age, gender, hypertension history, the pattern of initial manifestation, angiographic shape of VAD, angiographic location of VAD, treatment modality.

FINDINGS

There was no statistically significant difference between the functional outcome with age, gender, trauma history and past medical history of hypertension. Of 35 patients, 22 presented with SAH, 11 with ischemic symptoms and 2 were incidentally detected. The patients without SAH had a better functional outcome than those with SAH (p = 0.029). There was statistical significance between Hunt-Hess (H-H) grade and clinical outcome (p = 0.032). The shape and location of VAD was not significantly related to the functional outcome (p = 0.294, 0.840). But all the cases of rebleeding and mortality (except one case with initially poor H-H grade) developed exclusively in patients with aneurysms. There was no statistically significant correlation between the treatment modality and the outcome (p = 0.691).

CONCLUSION

The VAD patients with SAH would be recommended to be managed by either surgical or endovascular treatment, but those without SAH, could be managed conservatively with antiplatelet therapy and/or anticoagulation.

Late morphological progression of a dissecting basilar artery aneurysm after staged bilateral vertebral artery occlusion: case report

BACKGROUND

The authors present a patient who experienced late (5-year follow-up) morphological progression of a dissecting aneurysm of the distal basilar artery after treatment with a combined microsurgical and neuroendovascular Hunterian strategy. In addition to postulating about the possible reasons underlying the evolution of this lesion, the role of stenting is discussed.

CASE DESCRIPTION

The patient was 37 years old when she suffered a subarachnoid hemorrhage from spontaneous basilar artery dissection. At the time of the hemorrhage, minimal aneurysmal enlargement was noted angiographically, and she was therefore treated nonoperatively. On reimaging 5 months later, massive enlargement of the aneurysm was noted. The patient was treated with staged bilateral vertebral artery sacrifice using a combination of microsurgical and neuroendovascular techniques. The dominant vertebral artery was clip-ligated distal to the posteroinferior cerebellar artery, whereas the contralateral vertebral artery was coil-occluded cervically 1 week later.

CONCLUSIONS

Despite the patient remaining asymptomatic, follow-up angiography 5 years after the initial hemorrhage revealed further enlargement of the aneurysm as well as a newly discovered inferiorly projecting daughter sac measuring 5 mm in diameter. Clearly, certain aneurysms exist for which indirect approaches involving hemodynamic attenuation fail to prevent progression. With greater refinements in stent technology, such lesions may be more effectively treated.

Basilar artery dissection

Object. Little is understood about the clinical manifestations of basilar artery (BA) dissections, which can present with subarachnoid hemorrhage (SAH), brainstem compression, or ischemia. In any instance, the prognosis seems poorer than that for vertebral artery (VA) dissection. The authors analyzed clinical presentations and radiological features of BA dissection with and without rupture.

Methods. Between 1998 and 2003, the authors treated 10 patients (eight men and two women, ranging in age from 32–78 years; mean age 54 years) with BA dissection. Diagnosis was based on clinical and radiological findings, including those from magnetic resonance imaging and cerebral angiography studies.

Of the 10 patients, five had impaired consciousness at disease onset. Among four patients presenting with SAH, two were treated conservatively and had fair outcomes without recurrent hemorrhage. The other two patients with SAH were treated using unilateral endovascular VA occlusion, but one of them subsequently suffered fatal rebleeding. A fifth patient presented with progressive signs of a mass involving the brainstem, whereas the remaining five patients showed brainstem ischemia; all were treated conservatively. Four patients could not return to their previous daily activities.

Conclusions. Basilar artery dissections are rare lesions associated with significant morbidity and death. The natural course of and the treatment options for BA dissection differ considerably from those for VA dissections. Management of these lesions is controversial and difficult, and requires particular care.

Progressive Growth of a Giant Dolichoectatic Vertebrobasilar Artery Aneurysm after Complete Hunterian Occlusion of the Posterior Circulation: Case Report

OBJECTIVE AND IMPORTANCE:

Dolichoectatic vertebrobasilar artery aneurysms are often extremely difficult, if not impossible, to treat with microneurosurgical clip reconstruction. As such, a Hunterian strategy via vertebral or basilar artery sacrifice is often used. We have encountered a patient in whom deliberate bilateral vertebral artery sacrifice was insufficient to avoid progressive expansion of a giant dolichoectatic vertebrobasilar artery aneurysm. On the basis of a review of the literature, we are unaware of another reported case.

CLINICAL PRESENTATION:

A 60-year-old man presented with signs and symptoms of brainstem compression from a large fusiform aneurysm involving the distal dominant vertebral and proximal basilar arteries. Results of angiographic evaluation were highly characteristic of underlying dolichoectasia.

INTERVENTION:

The patient was treated initially with staged bilateral vertebral artery occlusion and adjunctive posterior circulation revascularization. After this therapy failed, he underwent a trapping procedure and aneurysm deflation.

CONCLUSION:

Unclippable aneurysms of the vertebrobasilar system are formidable lesions. They are not uniformly treatable by direct surgical reconstruction, and their growth is not consistently stabilized by the implementation of a complete Hunterian strategy. Future developments related to the use of endovascular stent technology may offer a more successful treatment approach for patients with these complex cerebrovascular lesions.

Progressive cervicocranial arteriopathy with dilatations and stenoses: case report

We report the case of a 36 year-old woman who presented occlusion of a basilar artery fusiform aneurysm (FA) associated with pontine infarction, and two episodes of subarachnoid hemorrhage possibly due to arterial dissection. She also had asymptomatic FAs in the right middle cerebral and left internal carotid arteries. Over 5 years, lesions suggestive of fibromuscular dysplasia in the right vertebral artery and occlusion of the left vertebral artery were observed. This combination of lesions emphasizes the possibility of a common pathogenetic mechanism causing different degrees of media disruption in cervicocranial arteries.

Successful treatment of a ruptured dissecting basilar artery aneurysm

✓ Dissecting basilar artery (BA) aneurysms in patients presenting with subarachnoid hemorrhage are life threatening, especially in those who experience subsequent bleeding or progressive dissection, and immediate surgical or endovascular intervention may be necessary. The authors report on a 52-year-old woman whose dissecting BA aneurysm was treated successfully with proximal occlusion and flow reversal. Clipping of the proximal BA above the level of the anterior inferior cerebellar arteries facilitated retrograde flow from a radial artery graft placed between the left vertebral artery and the left posterior cerebral artery, thereby providing continuous perfusion of the BA and its branches. Postoperative angiograms obtained 1 year later revealed good retrograde flow through the BA and dilation of the radial arterial graft. There were no episodes of recurrent hemorrhage.

Healing process for cerebral dissecting aneurysms presenting with subarachnoid hemorrhage

OBJECTIVE

This was a pathological study to investigate the healing process for cerebral dissecting aneurysms presenting with subarachnoid hemorrhage (SAH).

METHODS

Thirteen dissecting aneurysms that presented with SAH were obtained from 13 patients. Nine aneurysms arose from the vertebral artery, two arose from the anterior cerebral artery, one arose from the internal carotid artery, and one arose from the superior cerebellar artery. Eight aneurysm specimens were collected during autopsy and five were resected during surgery (trapping with or without bypass). The period between the onset of SAH and the time of specimen collection ranged from 6 hours to 35 days. All 13 aneurysms were pathologically examined with immunohistochemical staining, with a focus on the chronological healing process after SAH.

RESULTS

All dissecting aneurysms were generated with sudden widespread disruption of the internal elastic lamina and media. The healing process occurred with neointimal proliferation. The neointima, consisting mainly of newly synthesized smooth muscle cells and collagen fibers, extended from the disrupted ends of the media proper forward to the ruptured portion.

CONCLUSION

It is assumed that the healing process, with neointimal proliferation, begins after 1 week and may not be complete even after 1 month, depending on the extent of the wall injury.

A case of segmental mediolytic arteriopathy involving both intracranial and intraabdominal arteries

Segmental mediolytic arteriopathy (SMA) is an uncommon nonatherosclerotic and nonvasculitic arteriopathy. This disease is characterized by lytic degeneration of the arterial media, intramural dissection and thrombosed or ruptured aneurysm. SMA mainly involves the intraabdominal arterial system, resulting in intraabdominal and retroperitoneal hemorrhage. However, only a few cases of SMA with involvement of intracranial arteries have been reported. Here, we present a case of SMA developing subarachnoid hemorrhage due to dissection of the internal carotid and vertebral arteries. This patient was a 48-year-old male who died 13 days after admission for sudden loss of consciousness. Computed tomography showed subarachnoid hemorrhage. At autopsy, the affected vessels included the right vertebral, left internal carotid, superior mesenteric, bilateral renal and left external iliac arteries. Histopathologically, the arteries showed segmental lytic degeneration and disappearance of medial smooth muscle cells, medial dissection and formation of pseudo-aneurysms, the wall of which consisted of a thin membrane of the adventitia. These histopathological features mimicked an entire wall dissection type of intracranial dissecting aneurysm, which exclusively affects the vertebro-basilar system. Thus, SMA should be considered a possible underlying disease in patients with spontaneous dissection of intracranial arteries.

Development of a pontine cyst after endovascular coil occlusion of a basilar artery trunk aneurysm: case report

OBJECTIVE AND IMPORTANCE

Cyst formation within the brain parenchyma after endovascular coil occlusion of an intracranial aneurysm is a previously undescribed occurrence. We describe a 70-year-old woman who presented with a symptomatic pontine cyst 1 year after uncomplicated stenting and Guglielmi detachable coil occlusion of an unruptured basilar artery trunk aneurysm.

CLINICAL PRESENTATION

A 70-year-old woman presented with an episode of transient dysequilibrium and gait difficulty. Magnetic resonance imaging and cerebral angiography demonstrated a 15-mm distal basilar artery trunk aneurysm. Endovascular stenting and coil occlusion of the aneurysm were performed without technical complications. One year after the initial treatment, the patient developed progressive dysarthria, dysphagia, diplopia, and left hemiparesis. A large pontomesencephalic cyst adjacent to the coiled basilar aneurysm was identified on magnetic resonance imaging scans.

INTERVENTION

A subtemporal craniotomy and decompression of the pontomesencephalic cyst were performed. The patient's symptoms of brainstem dysfunction improved temporarily but recurred within 2 months, necessitating reoperation for cyst drainage and placement of a cyst-peritoneal shunt.

CONCLUSION

Intra-axial cyst formation after stenting and endovascular occlusion of an intracranial aneurysm is an unusual occurrence and should be considered in the differential diagnosis of new neurological deficits after endovascular treatment. The pathophysiological mechanism of cyst formation in this case is not known.

Vertebrobasilar artery dissection presenting with simultaneous subarachnoid hemorrhage and brain stem infarction: case report

BACKGROUND

Intracranial dissecting aneurysms have been associated with subarachnoid hemorrhage (SAH) or cerebral ischemia. We encountered a patient presenting with simultaneous subarachnoid hemorrhage and brainstem infarction caused by a dissecting aneurysm of the vertebrobasilar artery, which was diagnosed by magnetic resonance imaging (MRI) but did not show abnormal findings on cerebral angiography.

CASE DESCRIPTION

A 55-year-old man had sudden onset of headache and left abducens palsy. Computed tomography revealed a subarachnoid hemorrhage localized in the left prepontine cistern and the left cerebellomedullary fissure. Cerebral angiography showed neither a saccular aneurysm nor fusiform dilatation causing the subarachnoid hemorrhage. MRI demonstrated a small infarction in the left dorsal pons, and an intramural hematoma of the left vertebral artery and lower basilar artery.

CONCLUSION

This is a rare case of a vertebrobasilar dissecting aneurysm that simultaneously caused both SAH and brain stem infarction. MRI should be performed in the acute phase of SAH of unknown origin to determine the possible coexistence of a dissecting aneurysm, as occurred in this case.

Fusiform aneurysm of the vertebral artery presenting hemifacial spasm treated by intravascular embolization: case report

BACKGROUND

A rare case of fusiform vertebral artery aneurysm causing hemifacial spasm was successfully treated by intravascular embolization.

CASE DESCRIPTION

A 53-year-old man presented with left hemifacial spasm persisting for 2 years. No other clinical symptoms were observed. Vertebral angiography revealed a fusiform aneurysm of the left vertebral artery, and thin-slice spoiled gradient-recalled acquisition magnetic resonance imaging demonstrated the aneurysm compressing the root exit zone of the left facial nerve. The parent artery was occluded together with the aneurysm by intravascular embolization with Guglielmi detachable coils (GDCs). The patient is free of left hemifacial spasm without any complication.

CONCLUSION

Hemifacial spasm caused by aneurysms, especially fusiform aneurysms, is quite rare but can be treated by parent artery occlusion and coiling the aneurysm with GDCs.

Different roles of arteriosclerosis in the rupture of intracranial dissecting aneurysms

AIMS

Although intracranial dissecting aneurysm (IDA) is a newly described variant of the brain aneurysms that affects mainly the vertebrobasilar arterial system, its pathogenesis remains obscure. We aimed to clarify the role of arteriosclerosis in the pathogenesis of IDA based on histopathological findings in seven autopsy cases of IDA.

METHODS AND RESULTS

All cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited subarachnoid haemorrhage. Two types of dissection were recognized in the vertebral artery. Six of seven IDA cases showed a widespread disruption of the entire thickness of the arterial wall with the formation of a dilated pseudoaneurysm, which consisted of thin adventitia (arterial wall disruption type). Medial disruption of the arterial wall and subadventitial dissecting haemorrhage were also found, resulting in the formation of a false lumen and stenosis of the 'true' lumen of the artery. However, these lesions were connected to the site of rupture of the entire arterial wall. Within 1 day after onset of IDA, the autopsy cases showed formation of fibrin thrombus, marked leucocyte infiltration and necrosis of the arterial wall at the site of the lesion. Cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration in the lesions. These cases showed no atherosclerotic plaque, but non-atherosclerotic fibrocellular intima. The thickness of intima and media was significantly less in the vertebral artery of IDA patients than that of non-IDA patients with systemic hypertension. On the other hand, the remaining case showed severe atherosclerosis with haemorrhage into the lipid core without connection to the arterial lumen (intra-atheromatous plaque haemorrhage type). However, unusual arterioles and neovascularization of the intra-and peri-arterial walls were observed.

CONCLUSIONS

Our results suggest that disruption of the entire arterial wall may be a critical event in the development of IDA and result in the medial disruption and subadventitial haemorrhage. Non-atheromatous intima might function as a protective factor in arterial wall disruption. On the other hand, atherosclerosis may predispose to intra-atheromatous plaque haemorrhage type of IDA through intramural haemorrhage originating from the newly formed vessels.