Dissecting and fusiform aneurysms of vertebro-basilar systems. MR imaging

3D phase-sensitive inversion recovery sequence for intracranial vertebrobasilar artery dissection

BACKGROUND

T1-weighted 3D turbo spin echo (T1W-3D-TSE) sequences with variable refocusing flip angle are commonly used to diagnose intracranial vertebrobasilar artery dissection (iVAD). However, magnetic susceptibility artifacts of the cavernous sinus may cause loss of the basilar and vertebral arteries. This study investigated the effectiveness of a 3D phase-sensitive inversion recovery (3D-PSIR) sequence in reducing magnetic susceptibility artifacts in the cavernous sinus, and its imaging findings for iVAD.

METHODS

Twelve volunteers and eleven patients with iVAD were included. Magnetic resonance imaging (MRI) was performed using a 3.0-T MRI system. 3D-PSIR and T1W-3D-TSE sequences were used. Vessel wall defects and contrast-to-noise ratio (CNR) were evaluated. The MRI findings were visually evaluated.

RESULTS

In the 3D-PSIR images, one volunteer (8 %) had vessel wall defects, and five (42 %) had vessel wall defects (p = 0.046) in the T1W-3D-TSE images. CNR was higher in 3D-PSIR images for vessel wall-to-lumen, whereas it was higher in T1W-3D-TSE images for vessel wall-to-CSF (p < 0.001). Visual evaluation revealed similar MRI findings between the two sequences.

CONCLUSIONS

The 3D-PSIR sequence may be able to improve the vessel wall defects and achieve MRI findings comparable to those of the T1W-3D-TSE sequence in iVAD. The 3D-PSIR sequence can be a useful tool for the imaging-based diagnosis of iVAD.

Quantitative evaluation for intravascular structures of vertebral artery dissection with a novel zoomed high-resolution black-blood MR imaging

BACKGROUND

Although non-stroke vertebral artery dissection (VAD) is diagnosed using MRI, detecting the subtle intravascular structure remains challenging. This study aimed to evaluate the validity of quantitative intravascular scanning based on novel zoomed high-resolution black blood (Z-HB) MRI for distinguishing VAD from other vessel pathologies.

METHODS

Twenty-one patients with non-stroke VAD and 18 with symptomatic atherosclerotic plaques in their vertebral artery underwent Z-HB MRI and subsequent profile curve processing. Axial Z-HB imaging was obtained from dissected and normal segments in patients with VAD and atherosclerotic plaque in patients with ischemia. We investigated the qualitative categorization of the scanning patterns of the intravascular signals. We also evaluated the quantitative ability of each profile curve to discriminate multiple vessel pathologies by analyzing the receiver operating characteristics curves.

RESULTS

Profile curve processing of 140 Z-HB images categorized the intravascular signal patterns into luminal, asymmetrical, and omega types. The asymmetrical type included both dissecting and atherosclerotic vessels, and the omega type included dissecting and normal vessels. In the asymmetrical type, quantitative evaluation successfully distinguished intramural hematomas of VAD from atherosclerotic plaque with an area under the curve of 0.80. The intimal flap of the VAD was distinguished from the blood flow artifact of the normal vessel with an area under the curve of 0.93 in the omega type.

CONCLUSIONS

A combination of novel Z-HB MRI and profile curve processing provided an ultra-high-resolution analysis of the intravascular structure of non-stroke VAD and successfully distinguished VAD from normal vessels or atherosclerotic plaques.

Imaging features of vertebrobasilar dolichoectasia combined with posterior circulation ischemic stroke: A vessel wall magnetic resonance imaging study

PURPOSE

To elucidate the vessel wall changes of vertebrobasilar dolichoectasia (VBD) with ischemic stroke, using vessel wall magnetic resonance imaging (VW-MRI).

METHOD

Thirty-four patients with VBD (22 with stroke and 12 without stroke) who underwent VW-MRI were recruited. Forty-one patients without VBD who underwent VW-MRI were also recruited if they had a recent stroke due to atherosclerosis in the basilar artery or the intracranial vertebral artery. The vessel wall features of VBD were compared between stroke and non-stroke groups. The plaque characteristics were compared between VBD and non-VBD stroke patients.

RESULTS

The frequency of plaques was higher (54.5% vs. 8.3%, P = 0.011) in VBD patients with stroke than that in non-stroke patients, while the frequencies of aneurysm, dissection, intraluminal thrombus, and diffuse/concentric wall enhancement did not differ. When the plaque features were compared between plaque-positive stroke patients with and without VBD, the degree of stenosis (31.0% ± 26.8% vs. 71.5% ± 19.0%, P < 0.001), normalized wall index (NWI) (0.7 ± 0.1 vs. 0.9 ± 0.1, P < 0.001), and remodeling index (RI) (1.0 ± 0.4 vs. 1.3 ± 0.4, P = 0.023) were lower in the VBD group, while intraplaque hemorrhage, and enhancement ratio showed no difference.

CONCLUSIONS

This preliminary study suggests that atherosclerosis may be an important cause of stroke in VBD patients. Symptomatic plaques in VBD patients have a lower degree of stenosis, NWI, and RI than that in non-VBD patients. VW-MRI may help to assess stroke mechanisms and identify VBD patients at high risk.

MR Imaging for Intracranial Vessel Wall Imaging: Pearls and Pitfalls

Conventional vascular imaging methods have primarily focused on evaluating the vascular lumen. However, these techniques are not intended to evaluate vessel wall abnormalities where many cerebrovascular pathologies reside. With increased interest for the visualization and study of the vessel wall, high-resolution vessel wall imaging (VWI) has gained traction.Over the past two decades, there has been a rapid increase in number of VWI publications with improvements in imaging techniques and expansion on clinical applications. With increasing utility and interest in VWI, application of proper protocols and understanding imaging characteristics of vasculopathies are important for the interpreting radiologists to understand.

A review of the top 100 most influential articles on basilar artery aneurysms

Basilar artery aneurysms account for approximately 5% of all intracranial aneurysms. This bibliometric analysis summarizes the most-cited articles on basilar artery aneurysms and highlights the contributing articles to today's evidence-based practice. In the execution of this bibliometric-based review article, the Scopus database was used to perform a title-specific, keyword-based search for all publications until August 2022. The keyword "basilar artery aneurysm" or "basilar aneurysm" was used. Our results were arranged in descending order based on the article's citation count. The 100 most cited articles were selected for analysis. Parameters included the following: title, citation count, citations per year, authors, specialty of first author, institution, country of origin, publishing journal, Source Normalized Impact Per Paper (SNIP), and Hirsch index. The keyword-based search showed that 699 articles were published between 1888 and 2022. The top 100 articles were published between 1961 and 2019. The top 100 most cited articles collected a total of 8869 citations with an average of 89 citations per paper. The rate of self-citations accounted for an average of 4.85% of the total number of citations. The bibliometric analysis provides a quantitative overview of how medical topics and interventions are analyzed in academic medicine. In the present study, we evaluated the global trends in basilar artery aneurysms by finding the top 100 most cited papers.

Predictors of improvement for patients with CNS vasculitis stenoses: A high-resolution vessel wall MRI follow-up study

PURPOSE

To investigate the predictors of the improvement for patients with isolated intracranial vasculitis stenoses using high-resolution vessel wall magnetic resonance imaging (HR VW-MRI).

METHODS

We retrospectively reviewed data from consecutive patients with confirmed intracranial vasculitis under the same conventional conservative treatment based on a prospectively established HR VW-MRI database between December 2016 and December 2020. According to the changes between the degree of stenosis at baseline compared to follow-up MR angiography, the patients were divided into an improvement group and a non-improvement group. A multivariate analysis was performed to identify the predictive factors associated with the improvement of stenoses secondary to intracranial vasculitis.

RESULTS

Overall, 41 patients (mean age 32.0 ± 10.1 years, 16 females) with isolated intracranial vasculitis stenoses were included (41.5 % [17/41] in the improvement group, and 58.5 % [24/41] were in the non-improvement group). The degree of wall enhancement on follow-up imaging was significantly reduced compared with that on the baseline imaging in the improvement group (P = 0.004). The multivariate analysis showed that the degree of enhancement (OR, 0.219, 95 % CI, 0.054 to 0.881; P = 0.033) at baseline was an independent predictive factor associated with the improvement in the intracranial vasculitis stenoses.

CONCLUSIONS

In patients with isolated intracranial vasculitis stenoses, the less enhancement the vessel wall was, the more likely the degree of stenosis would be reduced by conventional conservative therapy.

Bilateral Fusiform Aneurysms of the Internal Carotid Arteries Presenting with Subarachnoid Hemorrhage

Fusiform aneurysms of cerebral arteries are less prevalent than saccular aneurysms and are rarely associated with subarachnoid hemorrhage (SAH). In this article, we report SAH due to a rare case of bilateral fusiform aneurysm of the supraclinoid segment of the internal carotid arteries (ICAs) (C4 segment of the ICA).

Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology

Intracranial vessel wall MR imaging is an adjunct to conventional angiographic imaging with CTA, MRA, or DSA. The technique has multiple potential uses in the context of ischemic stroke and intracranial hemorrhage. There remain gaps in our understanding of intracranial vessel wall MR imaging findings and research is ongoing, but the technique is already used on a clinical basis at many centers. This article, on behalf of the Vessel Wall Imaging Study Group of the American Society of Neuroradiology, provides expert consensus recommendations for current clinical practice.

State-of-art in surgical treatment of dissecting posterior circulation intracranial aneurysms

Vertebrobasilar (VB) intracranial dissecting aneurysms (IDAs) pose difficult therapeutic issues and are especially among the most difficult to manage surgically. There are, however, some cases where selective aneurysm obliteration by endovascular approach is impossible or is associated with an unacceptable risk of morbidity. This is particularly true when the aneurysm is dissecting, giant, or has a large neck. In such cases, surgical treatment may be the only alternative. Optimal management of these lesions is therefore challenging and treatment decisions have to be made on a case-by-case basis. Ideal treatment should be a complete surgical excision of the lesion; however, this procedure might only be possible after distal and proximal vessel wall occlusion which might not be tolerated by the patient depending on the location of the aneurysm. Therefore, formulation of recommendations concerning the surgical strategy remains still difficult due to inconsistency of surgical outcomes. The literature describing surgical strategy of VB IDAs is varying in quality and content, and many studies deal with only a few patients. In the presented review, the authors summarize the current knowledge on the incidence, pathogenesis, clinical presentation, and diagnostic procedures with special emphasis on surgical treatment of IDAs in posterior circulation.

Dolichoectasia of the vertebral basilar and internal carotid arteries: A case report and literature review

Background:

Dolichoectasia is a rare disorder of the cerebral vasculature consisting of vascular elongation, widening, and tortuosity, usually involving the vertebral and basilar arteries. Its neurological symptoms and signs are highly variable.

Case Description:

We present a case of dolichoectasia of the vertebrobasilar system in a patient with a long standing history of multiple falls. Repeat neuroimaging revealed an increase in size of the dolichoectatic segment. In addition, a new fusiform dilatation of the contralateral petrous segment of the internal carotid artery and isolated ventriculomegaly had developed.

Conclusion:

Vertebrobasilar dolichoectasia can cause multiple clinical manifestations, with hydrocephalus being less common. In addition, having dolichoectasia of both posterior and anterior circulation is extremely rare.

Evaluation of luminal and vessel wall abnormalities in subacute and other stages of intracranial vertebrobasilar artery dissections using the volume isotropic turbo-spin-echo acquisition (VISTA) sequence: a preliminary study

OBJECTIVE

To evaluate the utility of 3D variable refocusing flip-angle volume isotropic turbo-spin-echo acquisition (VISTA) imaging, using a 1.5-T MRI unit, which can minimize flow artifacts, due to its sequence-endogenous flow-void capability, in the diagnosis of intracranial vertebrobasilar artery dissection (VAD).

MATERIAL AND METHODS

The presence of intimal flaps, intramural hematomas, vessel dilatations and abnormal vessel enhancements were evaluated on T1-weighted VISTA images from 18 VAD patients with 20 dissected arteries (15 subacute and five at other stages). Additional gadolinium-enhanced T1VISTA images were available for 13 patients. The frequency of flow artifacts on T1VISTA imaging in 70 non-dissected arteries in VAD patients and 12 control subjects was also evaluated. Furthermore, in 13 and eight patients, contrast-enhanced three-dimensional (CE3D) imaging with spoiled gradient-recalled (SPGR) acquisition in steady state and electrocardiographically gated black-blood (BB) T1-weighted imaging (T1WI) were evaluated to compare visualization of false lumens.

RESULTS

Intimal flaps, intramural hematomas and dilatations were identified on T1VISTA images in 65% (13/20), 55% (11/20) and 90% (18/20) of VADs, respectively. Abnormal vessel enhancement was recognized in 100% (15/15) of VADs on contrast-enhanced T1VISTA images. Only four normal arteries showed small, thin, linear artifacts. Compared with CE3D-SPGR imaging, T1VISTA imaging depicted false lumens more conspicuously in seven VADs (P=0.02). T1VISTA also revealed intimal flaps and hematomas as did BB T1WI.

CONCLUSION

T1VISTA imaging may be useful for diagnosing VAD at subacute stages, as it can reveal vessel wall and lumen abnormalities with a minimum of flow artifacts.

Large Basilar Aneurysm with Posterior Inferior Cerebellar Artery Stroke and Consequential Fatal Subarachnoid Hemorrhage

Basilar artery aneurysm presenting a stroke is rare, and we present a case of this along with a discussion of the management options available.

The challenge of managing fusiform basilar artery aneurysms: from acute ischemic stroke to a massive subarachnoid hemorrhage

We present the case of a patient with acute brain stem ischemic stroke who was found to have a fusiform basilar aneurysm with a thrombus within the dilated vessel. Three days after the ischemic stroke, the patient had a massive subarachnoid hemorrhage and died. This case illustrates the difficulties in the acute management of ischemic events in patients with basilar fusiform aneurysms, because the natural history of this disease encompasses both bleeding and thrombosis.

Cervical arterial dissection: current concepts

The increasing use and safety of noninvasive imaging in recent years has revealed the surprising frequency of dissection of the carotid and vertebral arteries (cervical arterial dissection [CAD]) as a cause of ischemic and hemorrhagic stroke. This review is an overview of current concepts and practice of patients with CAD, but our ideas are constantly evolving with new discoveries from neurovascular imaging and medical and surgical management in this area.

Three-dimensional visualization of vertebrobasilar system aneurysms in a vertigo patient

Cerebral artery fenestration refers to a division in the lumen of an artery leading to two distinct endothelium-lined channels. At the site of turbulent flow, fenestration may predispose to an aneurysm formation. In this study, a 45-year-old woman suffered an acute vertiginous attack after cervical manipulation. The MRI scan demonstrated basilar artery duplication and tortuous left distal vertebral artery impinging on the cisternal segment of the cochleovestibular nerve. Subsequent three-dimensional (3D) reconstruction by MR imaging showed vertebrobasilar artery fenestrations with aneurysms. Unfortunately, subarachnoid hemorrhage occurred 6 days later, and the patient became comatose one year after presentation. In summary, subarachnoid hemorrhage caused by vertebrobasilar system aneurysms is a life-threatening event. Delineating the configuration by 3D-reconstruction of MR images allows more accurate diagnosis and more effective management.

Trunkal intracranial aneurysms: dissecting and fusiform aneurysms

Aneurysms arising along the arterial trunk are uncommon and not well-characterized lesions in contrast to saccular aneurysms. According to pathological studies, most of spontaneous trunkal aneurysms are related to dissecting phenomena. On the basis of clinical presentation, dissecting aneurysms can be separated into acute or chronic lesions. Understanding of the underlying pathological mechanisms associated with these aneurysms is useful for planning appropriate treatment. This article reviews the etiopathogenesis, the angiographic aspects, and the endovascular treatment of dissecting aneurysms. Fusiform aneurysms and aneurysms in atherosclerotic disease also are discussed briefly.

Intracranial vertebral artery dissection mimicking acute peripheral vertigo

When diagnosing and treating patients with acute vertigo, the clinician must differentiate brain lesions from benign peripheral disorders. We here report a rare case of acute vertigo caused by intracranial vertebral artery dissection mimicking peripheral disease. A 67-year-old man presented with spontaneous nystagmus and moderate ataxia preceded by neck pain. No other neurological signs were observed, suggesting acute peripheral vertigo. However, magnetic resonance imaging (MRI) demonstrated a cerebellar infarction. Simultaneous magnetic resonance angiography (MRA) showed no flow void of the left vertebral artery and contrast-enhanced MRA demonstrated a double lumen sign, suggesting that vertebral artery dissection was a cause of infarction. The clinical course was favorable without anticoagulation drugs, which are sometimes contraindicated because of the potential risk of subarachnoid hemorrhage. Vertebral artery dissection can cause cerebellar infarction in patients without vascular risk factors mimicking acute peripheral vertigo. Careful history regarding the neck pain is important and MRA in combination with MRI can replace angiography in diagnosing this disorder.

Enlarging vertebrobasilar nonsaccular intracranial aneurysms: frequency, predictors, and clinical outcome of growth

Object. Vertebrobasilar nonsaccular intracranial aneurysms (NIAs) are characterized by elongation, dilation, and tortuosity of the vertebrobasilar arteries. The goal of this study was to define the frequency, predictors, and clinical outcome of the enlargement of vertebrobasilar NIAs.

Methods. Patients with vertebrobasilar fusiform or dolichoectatic aneurysms demonstrated on imaging studies between 1989 and 2001 were identified. In particular, patients who had undergone serial imaging were included in this study and their medical records were retrospectively reviewed. Prospective information was collected from medical records or death certificates when available. Both initial and serial imaging studies were reviewed. The authors defined NIA enlargement as a change in lesion diameter greater than 2 mm or noted on the neuroradiologist's report. A Cox proportional hazards regression was used to model time from diagnosis of the vertebrobasilar NIA to the first documented enlargement as a function of various predictors. The Kaplan-Meier method was used to study patient death as a function of aneurysm growth.

Of the 159 patients with a diagnosis of vertebrobasilar NIA, 52 had undergone serial imaging studies including 25 patients with aneurysm enlargement. Lesion growth significantly correlated with symptomatic compression at the initial diagnosis (p = 0.0028), lesion type (p < 0.001), and the initial maximal lesion diameter (median 15 mm in patients whose aneurysm enlarged compared with median 8 mm in patients whose aneurysm did not enlarge; p < 0.001). The mortality rate was 5.7 times higher in patients with aneurysm growth than in those with no enlargement after adjustment for patient age (p = 0.002).

Conclusions. Forty-eight percent of vertebrobasilar NIAs demonstrated on serial imaging enlarged, and this growth was associated with significant morbidity and death. Significant risk factors for aneurysm enlargement included symptomatic compression at the initial diagnosis, transitional or fusiform vertebrobasilar NIAs, and initial lesion diameter. Further studies are necessary to determine appropriate treatments of this disease entity once enlargement has been predicted or occurs.

Magnetic Resonance Imaging of Suspected Cervicocranial Arterial Dissections

The authors propose that the optimal screening protocol for evaluation of suspected cervicocranial arterial dissections is magnetic resonance imaging (MRI) that includes three components: 1) contrast-enhanced three-dimensional time-of-flight magnetic resonance angiography (MRA) through the superior mediastinum, neck, and skull base; 2) three-dimensional multiple overlapping thin-section acquisition MRA of the skull base and Circle of Willis region; and 3) axial non-contrast, non-fat-suppressed T1-weighted, fat-suppressed T1-weighted, and T2-weighted spin-echo MRI from the level of the aortic arch through the level of the circle of Willis. MRA permits visualization of vascular luminal narrowing or obliteration, which can suggest vascular dissection but can also be caused by congenital variation, dysplasia, intraluminal thrombus, vasospasm, or extramural compression by tumor. By directly visualizing the blood vessel wall, axial T1-weighted and T2-weighted spin-echo MRI can identify the intramural hemorrhage of vascular dissection. This protocol is designed to maximize the sensitivity of a noninvasive technique and may eliminate the need for conventional endovascular angiography.

Primary end-to-end anastomosis of anterior cerebral artery dissecting aneurysm: technical case report and review of literature

OBJECTIVE AND IMPORTANCE:

Subarachnoid hemorrhage caused by an isolated dissection of the anterior cerebral artery (ACA) is an extremely rare problem. The optimal treatment for patients with this clinical scenario varies and is controversial in the literature. We report a patient with a hemorrhage from a distal ACA dissecting aneurysm at presentation 2 years after an arteriovenous malformation resection, who was treated effectively with excision of the diseased segment and direct revascularization of the ACA. We report this as the first case of delayed hemorrhagic arterial dissection after arteriovenous malformation resection treated with early revascularization. We review this rare topic and present our perspective on the method of treatment of ACA dissection.

CLINICAL PRESENTATION:

A 32-year-old woman was transferred to the University of Texas Southwestern Medical Center and admitted with subarachnoid and intraventricular hemorrhage. Angiography revealed the source of the hemorrhage to be a dissecting aneurysm of the pericallosal artery.

INTERVENTION:

The patient underwent surgery on the third day after hemorrhage for excision of the dissecting aneurysm and in situ primary anastomosis of the pericallosal artery. Exposure and anastomosis of the pericallosal artery was facilitated by partial resection of the genu of the corpus callosum.

CONCLUSION:

On the basis of our experience and review of the literature regarding this topic, an optimal treatment for a dissecting aneurysm with hemorrhage involving the pericallosal portion of the ACA at presentation is excision of the diseased segment followed by revascularization. This treatment should prevent rehemorrhage from the aneurysm and avoid iatrogenic ischemic complications to the ACA territory that would be likely with trapping of the aneurysm without revascularization.

MR angiography of the extracranial circulation

In this article, the authors present a brief history of MR angiography (MRA) of the neck with emphasis on the techniques developed, particularly recent ones, to improve image quality. The goal of MRA is to eventually replace catheter angiography. The use of MRA, particularly contrast enhanced MRA with regards to pathology (atherosclerotic disease/plaque formation, dissection and post-traumatic aneurysm) involving the extra-cranial carotid and vertebral arteries is addressed. The authors also comment on computed tomographic angiography and sonography and how they compare with contrast enhanced MRA when pertinent.

Isolated dissections and dissecting aneurysms of the posterior inferior cerebellar artery: topic and literature review

Isolated dissections of the posterior inferior cerebellar artery (PICA) are rare. Thus, no large series of cases have been reported in the literature. Due to limited knowledge regarding the natural history of these lesions and the lack of high-quality evidence supporting various treatment options, management is controversial and practice parameters are ill defined. In order to offer a comprehensive reference for the diagnosis and management of isolated PICA dissections, the authors reviewed the National Library of Medicine from 1966 to October 2001. Twenty-seven patients averaging 43.6 years of age and including 14 males and 13 females were reported. Subarachnoid hemorrhage occurred in 20 patients, and two died. Dissections were located in the proximal PICA in 22 patients and were three times more common on the left side (left:right=3:1). Six patients were managed conservatively, and four with endovascular techniques. Seventeen had open surgery: five underwent resection, two went through trapping, and two had proximal clipping. Wrapping with muscle was performed in two patients, encasement with Sundt clips in two, and four had occipital artery (OA)-PICA bypass surgery. A meticulous analysis of reported cases with regard to clinical and pathological features, management strategies, and outcomes is presented.

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.

Trapping and revascularization for a dissecting aneurysm of the proximal posteroinferior cerebellar artery: technical case report and review of the literature

OBJECTIVE AND IMPORTANCE

Subarachnoid hemorrhage caused by an isolated dissection of the proximal portion of the posteroinferior cerebellar artery (PICA) is a rare problem. The optimal treatment to use for patients presenting with this clinical scenario varies and therefore is controversial in the literature. We report a patient in whom this problem was treated effectively with trapping of the diseased segment and revascularization of the PICA. We report this case to review this rare topic and to present our perspective on the indications for and the effectiveness of trapping and revascularization for proximal PICA dissections that cause hemorrhage.

CLINICAL PRESENTATION

A 55-year-old man was transferred to our institution and admitted for Hunt and Hess Grade IV subarachnoid hemorrhage, which improved to Hunt and Hess Grade III after ventricular drainage. Imaging revealed the source of the hemorrhage to be a pseudoaneurysm related to the dissection of the proximal portion of the PICA.

INTERVENTION

Three days after the initial bleeding episode, we operated on the patient. After the occipital artery was prepared for bypass, the diseased segment was trapped. The occipital artery-to-PICA anastomosis was then immediately performed distal to the trapped segment.

CONCLUSION

On the basis of our experience, the literature regarding this topic, and the anatomy of the perforators of the PICA, we think that the best treatment for a pseudoaneurysm located within the first three segments of the PICA is trapping of the diseased segment followed by revascularization distal to the trapped segment. This approach should prevent rehemorrhage and should avoid iatrogenic ischemic complications of the brainstem.

Dissecting aneurysms of intracranial carotid circulation

BACKGROUND AND PURPOSE

Clinical features of nontraumatic dissecting aneurysms of intracranial carotid circulation remain unclear because investigation of this disease has been limited to case reports. The aim of this study was to investigate the clinical features of this disease through the use of cooperatively collected cases.

METHODS

The cases diagnosed as dissecting aneurysms of intracranial carotid circulation on the basis of clinical signs and neuroradiological findings in 46 stroke centers from 1995 through 1999 were collected, and their clinical features were analyzed.

RESULTS

Forty-nine cases of dissecting aneurysms of intracranial carotid circulation were collected. Thirty-two patients presented with subarachnoid hemorrhage (SAH), and 17 presented with cerebral ischemia. The ratio of this disease to all intracranial dissecting aneurysms treated in the same institutes for the same period was 19.1%, and the ratio of SAH resulting from this disease to SAH of unverified origin treated in the same institutes for the same period was 6.2%. The predominant site of lesion was the internal carotid artery in 18 of 32 patients (56%) with SAH and the anterior cerebral artery in 13 of 17 patients (76%) with cerebral ischemia. The predominant angiographic findings were that stenosis with dilatation occurred in 20 of 32 patients (63%) with SAH and stenosis without dilatation was seen in 11 of 17 patients (65%) with cerebral ischemia. Poor prognosis was seen in 21 of 32 patients (66%) with SAH, which was due largely to rebleeding seen preoperatively, during operation, and even postoperatively when clipping or wrapping of the aneurysmal bulge was performed.

CONCLUSIONS

Nontraumatic dissecting aneurysm of intracranial carotid circulation is not as rare as expected. It seems to be one of the important causes of SAH of unverified origin.

Vertebral artery dissection: spectrum of imaging findings with emphasis on angiography and correlation with clinical presentation

A study was performed to evaluate the relationship between the imaging features and clinical presentation of vertebral artery (VA) dissection. Twenty-two patients with 24 VA dissections at angiography and clinical evaluation also underwent computed tomography and magnetic resonance imaging. The angiographic patterns of VA dissection were categorized as aneurysmal (n = 10) or steno-occlusive (n = 14). All 10 patients (10 lesions) with the aneurysmal pattern had dissection in the V4 (intradural) segment and presented with headache (n = 5), neurologic deficit (n = 2), dizziness (n = 2), or altered mentality (n = 1). However, the 12 patients (14 lesions) with the steno-occlusive pattern had dissection from the V1 segment to the V4 segment and presented with neurologic deficits caused by infarction of an embolic nature. Overall, the most frequent VA dissection site was the V4 segment. The distribution of the dissection sites and the clinical presentation tended to differ according to the angiographic patterns of aneurysm or stenosis-occlusion.

Transcranial bypass for spontaneous intracranial carotid artery dissection--a case report

A case of spontaneous intracranial artery dissection (IAD) of the anterior circulation is reported. A 32-year-old man developed left hemiparesis with headache. Angiographies (AGs) showed progressive occlusion of the distal end of the right internal carotid artery. He underwent a superficial temporal artery-middle cerebral artery anastomosis 20 days after his initial symptoms. He improved gradually after operation. The prognosis and treatment of IAD are discussed. The authors conclude that cases with IADs of the anterior circulation should be followed up by cerebral AG or magnetic resonance angiography and that early bypass surgery should be considered to prevent massive cerebral infarction in some cases.

Clinicopathological study of intracranial fusiform and dolichoectatic aneurysms : insight on the mechanism of growth

BACKGROUND AND PURPOSE

Intracranial fusiform aneurysms can be divided into 2 clinically different subtypes: acute dissecting aneurysms and chronic fusiform or dolichoectatic aneurysms. Of these 2, the natural history and growth mechanism of chronic fusiform aneurysms remains unknown.

METHODS

A consecutive series of 16 patients with chronic fusiform aneurysms was studied retrospectively to clarify patient clinical and neuroradiological features. Aneurysm tissues were obtained from 8 cases and were examined to identify histological features that could correspond to the radiological findings.

RESULTS

Four histological features were found: (1) fragmentation of internal elastic lamina (IEL), (2) neoangiogenesis within the thickened intima, (3) intramural hemorrhage (IMH) and thrombus formation, and (4) repetitive intramural hemorrhages from the newly formed vessels within thrombus. IEL fragmentation was found in all cases, which suggests that this change may be one of the earliest processes of aneurysm formation. MRI or CT detected IMH, and marked contrast enhancement of the inside of the aneurysm wall (CEI) on MRI corresponded well with intimal thickening. Eight of 9 symptomatic cases but none of 7 asymptomatic cases presented with both radiological features.

CONCLUSIONS

Data suggest that chronic fusiform aneurysms are progressive lesions that start with IEL fragmentation. Formation of IMH seems to be a critical event necessary for lesions to become symptomatic and progress, and this can be monitored on MRI. Knowledge of this possible mechanism of progression and corresponding MRI characteristics could help determine timing of surgical intervention.

Clinical and neuroradiological features of intracranial vertebrobasilar artery dissection

BACKGROUND AND PURPOSE

We sought to determine the clinical and neuroradiological features of intracranial vertebrobasilar artery dissection.

METHODS

The clinical features and MR findings of 31 patients (20 men and 11 women) with intracranial vertebrobasilar artery dissections confirmed by vertebral angiography were analyzed retrospectively. The vertebral angiography revealed the double lumen sign in 11 patients (13 arteries) and the pearl and string sign in 20 patients (28 arteries).

RESULTS

The patients ranged in age from 25 to 82 years (mean, 54.8 years). Clinical symptoms due to ischemic cerebellar and/or brain stem lesions were common, but in 3 cases the dissections were discovered incidentally while an unrelated disorder was investigated. Headache, which has been emphasized as the only specific clinical sign of vertebrobasilar artery dissection, was found in 55% of the patients. Intramural hematoma on T1-weighted images has been emphasized as a specific MR finding. The positive rate of intramural hematoma was 32%. Double lumen on 3-dimensional (3-D) spoiled gradient-recalled acquisition (SPGR) images after the injection of contrast medium was identified in 87% of the patients. The 3-D SPGR imaging method is considered useful for the screening of vertebrobasilar artery dissection.

CONCLUSIONS

Intracranial vertebrobasilar artery dissection is probably much more frequent than previously considered. Such patients may present no or only minor symptoms. Neuroradiological screening for posterior circulation requires MR examinations, including contrast-enhanced 3-D SPGR. Angiography may be necessary for the definite diagnosis of intracranial vertebrobasilar artery dissection because the sensitivity of the finding of intramural hematoma is not satisfactory.

Risk factors and precipitating neck movements causing vertebrobasilar artery dissection after cervical trauma and spinal manipulation

STUDY DESIGN

Potential precipitating events and risk factors for vertebrobasilar artery dissection were reviewed in an analysis of the English language literature published before 1993.

OBJECTIVES

To assess the literature pertaining to precipitating neck movements and risk factors for vertebrobasilar artery dissection in an attempt to determine whether the incidence of these complications can be minimized.

SUMMARY OF BACKGROUND DATA

Vertebrobasilar artery dissection and occlusion leading to brain stem and cerebellar ischemia and infarction are rare but often devastating complications of cervical, manipulation and neck trauma. Although various investigators have suggested potential risk factors and precipitating events, the basis for these suggestions remains unclear.

METHODS

A detailed search of the literature using three computerized bibliographic databases was performed to identify English language articles from 1966 to 1993. Literature before 1966 was identified through a hand search of Index Medicus. References of articles obtained by database search were reviewed to identify additional relevant articles. Data presented in all articles meeting the inclusion criteria were summarized.

RESULTS

The 367 case reports included in this study describe 160 cases of spontaneous onset, 115 cases of onset after spinal manipulation, 58 cases associated with trivial trauma, and 37 cases caused by major trauma (3 cases were classified in two categories). The nature of the precipitating trauma, neck movement, or type of manipulation that was performed was poorly defined in the literature, and it was not possible to identify a specific neck movement or trauma that would be considered the offending activity in the majority of cases. There were 208 (57%) men and 158 (43%) women (gender data not reported in one case) with an average age of 39.3 +/- 12.9 years. There was an overall prevalence of 13.4% hypertension, 6.5% migraines, 18% use of oral contraception (percent of female patients), and 4.9% smoking. In only isolated cases was specific vascular disease such as fibromuscular hyperplasia noted.

CONCLUSIONS

The literature does not assist in the identification of the offending mechanical trauma, neck movement, or type of manipulation precipitating vertebrobasilar artery dissection or the identification of the patient at risk. Thus, given the current status of the literature, it is impossible to advise patients or physicians about how to avoid vertebrobasilar artery dissection when considering cervical manipulation or about specific sports or exercises that result in neck movement or trauma.

Magnetic resonance angiographic and clinical features of extracranial vertebral artery dissection

OBJECTIVES

Clinical data and neuroradiological findings of 19 patients with 20 vertebral artery dissections were analysed to describe the features of time of flight magnetic resonance angiography (MRA) for the diagnosis and follow up of this vascular disorder.

METHODS

All patients underwent a combined MRI and MRA protocol with 1.5 T scanners, using a three dimensional flow compensated gradient echo sequence for MRA. Duplex sonography was performed on all patients and selective angiography was available from 17 vertebral artery dissections.

RESULTS

MRI showed ischaemic lesions of the brain in 18 of 19 patients (95%). In the acute and subacute stage, MRA detected signal abnormalities within the dissected vertebral artery in 94% (16/17) and MRI was specific for a dissection in 29% (5/17). Sensitivity of selective angiography was 100% and specificity was 35% (6/17). Combination of the results of both methods increased the specificity to 50%. Duplex sonography was sensitive in 79% (15/19), but lacked specific results. Follow up magnetic resonance in 16 patients showed recanalisation of the dissected vessel in 10 (63%), persistent occlusion in five (31%), and a dissecting aneurysm in one (6%) patient.

CONCLUSIONS

Magnetic resonance improves the triage for selective angiography and discloses complementary information for the diagnosis of vertebral artery dissection. If magnetic resonance identifies a double lumen or a mural haematoma with a stenosis or aneurysmal dilatation, invasive procedures can be omitted.

Posterior circulation infarcts in patients with vertebrobasilar dolichoectasia

BACKGROUND AND PURPOSE

Vertebrobasilar dolichoectasia (VBD) may produce symptoms by direct compression of cranial nerves or the brain stem, by obstructive hydrocephalus, or by ischemia in the vertebrobasilar arterial territory. This study was undertaken to examine and characterize clinical and imaging findings in patients with stroke associated with VBD and compare these data with those for patients with VBD who did not have a stroke.

METHODS

We studied 40 consecutive stroke patients with associated VBD. All were evaluated by CT scan (n=9), MRI (n=6), or both (n=25). The diameter of the basilar artery (BA), height of bifurcation, and transverse position were evaluated. Clinical and imaging findings were compared with those found in a group of 40 VBD patients without stroke.

RESULTS

More than half of the patients (24 of 40) had infratentorial infarcts, located mainly in the midpons. Sixteen patients had supratentorial lesions localized in the thalamus (n=8) or in the superficial arterial territory of the posterior cerebral artery (PCA; n=8). The diameter and height of the bifurcation of the BA were correlated with the location of the lesion (PCA territory versus BA territory), in that severe ectasia and vertical elongation of the BA were significantly more often observed in patients with infarcts in PCA territory than in patients with infarcts in territories supplied by branches of the BA. Comparison of VBD patients with and without stroke showed that the incidence of arterial hypertension and the degree of ectasia and lateral displacement of the BA were not significantly different in the two groups. Patients with stroke more often had atherosclerotic changes of the posterior circulation (P=.0006) and a higher degree of vertical elongation of the BA (P=.025).

CONCLUSIONS

In patients with VBD, superimposed atheromatous changes of the posterior circulation may have an important role in precipitating ischemia. However, other factors related to the severity of the dolichoectasia also favor ischemia and in some cases are the only factors responsible.

Follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation by using gadolinium-enhanced magnetic resonance imaging

The authors assessed the reliability of magnetic resonance (MR) imaging contrast enhancement for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation. Twenty consecutively admitted patients who underwent both gadolinium-enhanced MR imaging and conventional angiography were reviewed. Enhancement of the dissecting aneurysm was seen in all but one of the 20 patients, including 10 (71%) of 14 patients examined in the chronic phases, when the T1-hyperintensity signal that corresponded to the intramural hematoma was unrecognizable. The enhanced area corresponded to the "pearl sign" or aneurysm dilation noted on the comparable angiogram. On follow-up MR studies enhancement had spontaneously disappeared in four patients at a time when comparable vertebral angiograms revealed disappearance of the aneurysm dilation. The enhancement persisted in five of nine patients examined more than 24 weeks after symptom onset; in all five patients the aneurysm dilation remained on comparable angiograms. Dynamic MR studies showed rapid and remarkable enhancements with their peaks during the immediate dynamic phase after injection of the contrast material. The authors conclude that gadolinium-enhanced MR imaging is useful for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation.

Unruptured intracranial vertebral artery dissection. Clinical course and serial radiographic imagings

BACKGROUND AND PURPOSE

Intracranial vertebral artery dissection is an increasingly recognized cause of stroke. However, little is known about its natural history and clinical manifestations, and appropriate management protocol has not yet been established. This study was performed to clarify its clinical course and determine the best management protocol.

METHODS

This study is a retrospective clinical and radiographic review of 11 patients with 13 lesions who presented between 1990 and 1996. Patients with a history of trauma and those who presented with subarachnoid hemorrhage were excluded. The 11 patients comprised seven men and four women, who ranged in age from 34 to 71 years, with a mean age of 47 years. Ten patients presented with ischemic symptoms.

RESULTS

Although recurrent ischemic attacks were observed in two patients, most (90%) subsequently made a good recovery and returned to their previous lifestyle. Five arteries showed the typical "string sign" or "pearl and string sign" on initial angiography. They changed in the follow-up examinations, which demonstrated either resolution of the stenosis or progression to complete occlusion. In contrast, the angiographic signs of complete occlusion (three arteries) or aneurysmal dilatation without luminal stenosis (four arteries) remained unchanged during the observation period of 5 months to 2.5 years. MRI was a sensitive tool for diagnosing intracranial vertebral artery dissection; intramural thrombus and intimal flap were the two major findings. MR angiography was also useful for demonstrating abnormalities of the arterial signal column such as pseudolumen or aneurysmal dilatation.

CONCLUSIONS

The natural history of unruptured intracranial vertebral artery dissection seems relatively benign, with a high probability (62%) of spontaneous angiographic cure. Some persistent aneurysmal dilatation may be amenable to intravascular coil embolization.

Proximal balloon occlusion for dissecting vertebral aneurysms accompanied by subarachnoid hemorrhage

Five patients with spontaneous dissecting vertebral aneurysms presenting with subarachnoid hemorrhage were treated with endovascular proximal balloon occlusion after a successful balloon Matas' test. Occlusion was performed in the extracranial portion of the vertebral artery after the potentially dangerous period of cerebral vasospasm. Two patients rebled preoperatively during the waiting period. Although angiograms demonstrated residual aneurysmal dilatation for four of the five patients, postoperative hemorrhages or progression of the dissection were not observed during the 19- to 48-month follow-up period. Only one patient experienced transient postoperative ischemic complication. Although the timing of the procedure and the site of occlusion remain controversial, proximal balloon occlusion of the vertebral artery appears to be a safe and effective therapy for patients with dissecting vertebral aneurysms presenting with subarachnoid hemorrhages. This method provides an important, less invasive alternative for this condition.

Vertebrobasilar infarcts in patients with dolichoectatic basilar artery

We reported 18 patients who had stroke in the posterior circulation with dolichoectatic basilar artery. TIAs preceded posterior circulation infarct in 5 patients. Strokes involved medulla oblongata (3), pons (4), cerebellum (4), mesencephalon (4), thalamus or occipital lobe (3). Dolichoectatic basilar artery also produced hydrocephalus in one patient. The mechanism of stroke may be due to penetrating artery occlusion, basilar artery thrombosis or an embolism from the abnormal basilar artery. Short-term prognosis was poor seeing that 4 patients died within 12 days of stroke.

Magnetic resonance imaging study of intracranial vertebrobasilar artery dissections

BACKGROUND AND PURPOSE

The purpose of this study is to demonstrate the magnetic resonance features of intracranial vertebrobasilar artery dissections and to determine the potential and limitations of magnetic resonance imaging in their diagnosis.

METHODS

We studied five consecutive patients with angiographically verified intracranial vertebrobasilar artery dissection with magnetic resonance imaging (0.5 T) in regard to the shapes of the intramural hematoma and the chronological change of its signal intensity. We also estimated the sensitivity of magnetic resonance imaging for diagnosing dissection.

RESULTS

We observed intramural hematoma in four patients on the first magnetic resonance scan and in all five patients during the course of the study. The shapes of the intramural hematomas were curvilinear, crescentic, "bamboo-cut," "band-like," and spotty. The intensity of the intramural hematoma varied according to its age. On the T1-weighted and the proton images, the intramural hematomas appeared isointense to slightly hyperintense in the first few days and became hyperintense thereafter. The intramural hematomas became isointense or unrecognizable 2 months after onset. The T1-weighted image and the proton images were superior to the T2-weighted image in demonstrating the intramural hematomas.

CONCLUSIONS

Magnetic resonance imaging is a sensitive tool for diagnosing intracranial vertebrobasilar artery dissection, particularly in the subacute to early chronic stage. Magnetic resonance imaging is complementary to angiography in that it can directly visualize intramural hematomas.

Management of dissecting aneurysms of the posterior circulation

We analysed the clinical presentation, treatment and outcome of our own 36 cases of posterior circulation dissecting aneurysms (DA) and discussed the surgical indications and procedures regarding posterior fossa DA. Twenty one cases were male, 15 cases were female. Their mean age was 54 +/- 14 years. Clinical manifestations were subarachnoid haemorrhage (SAH) in 14 cases (39%) and ischaemic attacks in 22 cases (61%). Three of 14 SAH cases had rebleeding in the acute stage. Angiographic findings were aneurysmal dilatation in 16 cases, retention of contrast medium in 12 cases, string sign in 9 cases, double lumen in 4 cases, pearl and string sign in 3 cases, and occlusion of parent artery in 2 cases. Surgical treatment was performed on nineteen cases (53%). The operation was carried out in the acute stage on the SAH group; in the subacute or chronic stage on the ischaemic group. The surgical procedure was the proximal ligation, trapping and removal of DA with or without revascularization of the parent artery. 84% of the surgically managed patients and 71% of the nonsurgical cases had a favourable outcome (good recovery or moderate disability). Poor prognosis was revealed from the rebleeding and primary neurological stage. We recommend surgical treatment in the acute stage on the SAH group. On the ischaemic group surgical treatment in the subacute or chronic stage is recommended, if the DA has the risk of rupture or progression of the dissection.

Unusual angiographic changes in a dissecting aneurysm of the basilar artery: case report

A patient with unusual angiographic changes of a dissecting aneurysm of the basilar artery is presented. Initial angiography and magnetic resonance imaging revealed a typical dissecting aneurysm. However, a follow-up study demonstrated a saccular aneurysmal dilatation of the proximal part of the dissection. The importance of the follow-up study, particularly in regard to the usefulness of magnetic resonance imaging and the pathogenesis of this change are discussed.

Dissecting aneurysm of the posterior inferior cerebellar artery

Dissecting aneurysms of the posterior inferior cerebellar artery are an uncommon cause of stroke in the vertebrobasilar system, but they may also present with subarachnoid bleeding into the posterior fossa in 70% of the cases. Neither magnetic resonance imaging nor vertebral angiography show specific signs. Treatment should be neurosurgical to prevent rebleeding, although few cases have been reported. The authors report a tenth case and the literature is reviewed.

Ultrasound findings in spontaneous extracranial vertebral artery dissection

BACKGROUND AND PURPOSE

In this study we analyzed the value of ultrasound examination for diagnosis of vertebral artery dissection.

METHODS

The vertebrobasilar arterial system was assessed in 14 patients using transcranial and extracranial pulsed-wave Doppler and duplex sonography.

RESULTS

The dissections were verified by angiography (in 1 patient), magnetic resonance imaging (in 5), or both (in 8). The dissected segments were atlantoaxial (V-3) in 6, V-3 and intertransverse (V-2) in 3, V-3 and intracranial (V-4) in 3, and V-2 in 2 patients. Extracranial and transcranial Doppler examination of the atlas loop, involved in 12 patients, showed absent flow signal in 5, low bidirectional flow signal in 1, and poststenotic low blood flow velocities in 3 patients. Seven of these patients had high-grade stenosis or occlusion. The stenotic segment with increased flow signal could be identified directly in 2 patients. Duplex examination of the intertransverse segment confirmed absent flow in 4 patients, making technically insufficient examination unlikely. In the 2 patients with directly detected stenosis, duplex examination showed low flow velocities before the stenosis. The combined use of extracranial and transcranial Doppler and duplex sonography increases the diagnostic yield to detect vertebral artery pathology. If any abnormal sonographic finding was considered, the yield was 86%; relying only on definitively abnormal findings (absent flow signal, severely reduced vertebral artery blood flow velocities, no diastolic flow, bidirectional flow, and a stenosis signal), the yield was 64%.

CONCLUSIONS

In most cases, there is no pathognomonic ultrasound finding for vertebral artery dissection. However, if a patient presents with suggestive symptoms, ultrasound may corroborate the clinical suspicion and aid in the decision regarding early anticoagulant treatment. A definite diagnosis can be made noninvasively when magnetic resonance imaging demonstrates hematoma in the vessel wall. Angiography yields additional information such as nature of underlying vascular disease, site and extent of dissection, intracranial extension, and presence of pseudoaneurysm.

Dissecting aneurysm of the posterior inferior cerebellar artery: case report

A patient with a dissecting aneurysm of a posterior inferior cerebellar artery who presented with Wallenberg's syndrome is reported. A 31-year-old man suddenly experienced an occipital headache, vertigo, and vomiting, followed by dysphagia. A neurological examination revealed partial Wallenberg's syndrome. Vertebral angiography revealed aneurysmal dilatation at the origin of the left posterior inferior cerebellar artery, with distal luminal narrowing. T1-weighted magnetic resonance imaging demonstrated an area of high-signal intensity, indicating an intramural hemorrhage in the arterial wall of the narrowed lumen. The dissecting aneurysm with a typical intramural hematoma of the posterior inferior cerebellar artery was entrapped with clips after an anastomosis of the left occipital artery to the distal posterior inferior cerebellar artery. The diagnosis and the treatment of dissecting aneurysms of the posterior inferior cerebellar artery are discussed.