The association of intracranial aneurysms and arteriovenous malformation of the brain. Case report

The Exceedingly Rapid Development of an Intracranial Aneurysm

Despite significant diagnostic and technical progress in managing intracranial aneurysms, there are still open questions in understanding their pathophysiology: how fast can they form and grow? We had the chance to observe the "de novo" genesis and rupture of an aneurysm of a left MCA posterior trunk M3 branch within 14 days in one of our patients. We were in the position to compare an initially inconspicuous vessel, assessed during a diagnostic cerebral angiogram with 3D acquisitions, performed as an elective follow-up to monitor the decade stability of a transitional aneurysm in the same vascular territory, and the same vessel only two weeks after, harboring a new small ruptured aneurysm. Several studies along the intracranial aneurysms' pathophysiology have been reported but primarily oriented toward identifying uncommon conditions such as inherent defects in collagen synthesis, genetic or familial factors, or basic anatomic variations or abnormalities in the cerebral vasculature. Suppose this case report does not pretend to provide a clear answer to these questions. However, it is up to date, the shortest time (14 days) reported in the literature for a well-documented "de novo" genesis and rupture of an intracranial aneurysm "in vivo" in humans. The purpose of this case report is not only to underscore the unpredictability of this vascular disease but, even more, to support the idea that further investigation, with more modern methodologies, is of paramount importance in determining the etiopathogenesis and behavior of this stealthy disease.

Endovascular treatment of cerebellar arteriovenous malformations: management of associated aneurysms first or later

The purpose of this study was to determine the safety and effectiveness of cerebellar arteriovenous malformations (AVMs) embolization and find out the suitable methods to manage associated aneurysms. Medical records of all patients between 1997 and 2014 with a diagnosis of cerebellar AVMs were retrospectively reviewed. Univariable and multivariable logistic analysis were used to assess AVMs characteristics to calculate for the risk of hemorrhage. Endovascular treatment was the main treatment measure to manage the AVMs and associated aneurysms. Of 142 patients, 115 (81.0 %) presented with hemorrhage and 42 (29.6 %) with associated aneurysms. A significant association with cerebellar AVMs hemorrhage was found for small size, prenidal aneurysms, and deep venous drainage in the univariable and multivariable analysis. Associated aneurysms were treated firstly in 41 patients except for 1 patient with 2 prenidal and 2 intranidal aneurysms. The special case was dealt with AVMs and 2 intranidal aneurysms first and angiography showed that the 2 prenidal associated aneurysms disappeared with time. Hemorrhage appeared in 13/142 patients (9.2 %) during the follow-up period, none of which was with associated aneurysms. Endovascular treatment can be a feasible way for treating cerebellar AVMs. Intranidal associated aneurysms should be treated first. Prenidal associated aneurysms can be treated later depending on the angioarchitecture of AVMs.

Frequency, risk of hemorrhage and treatment considerations for cerebral arteriovenous malformations with associated aneurysms

BACKGROUND

Data on arteriovenous malformations (AVMs) of the brain with AVM-associated aneurysms (AAA) are scarce. This study addresses the incidence, rate of hemorrhage, treatment strategies and stability during follow-up in a neurovascular center.

METHODS

We retrospectively reviewed patients harboring an AVM with at least one AAA treated at our neurovascular center between 2002 and 2013.

RESULTS

Of 216 patients, 59 (27.3%) had at least one AAA (n = 92 aneurysms total). Compared to patients without AAA, hemorrhagic presentation occurred more frequently (61.0% versus 43.9%, p = 0.025), and the rate of infratentorial AVMs was higher (37.3% versus 16.6%, p = 0.001). The aneurysm was the origin of the bleeding in most cases, most often categorized as a feeding artery aneurysm. Overall, the first and recurrent hemorrhage were associated with a high mortality and morbidity (15.3% and 39%, respectively). Aneurysms were treated by coiling (n = 21), surgery (n = 18), or embolizaton with liquid embolization agents (n = 11). All aneurysms treated by embolization and surgery remained occluded during follow-up (mean follow-up 39.0 ± 45.0 months). However, in incomplete AVM obliteration, significant recurrence of the treated aneurysm was noted after endovascular coiling (37.5%), which may be related to the persistence of pathological blood flow.

CONCLUSION

In our series, AAA was a significant risk factor for hemorrhage and was associated with a poor outcome. It seems worthwhile to consider whether the aneurysm itself is a risk factor or only an epiphenomenon of severely altered hemodynamics induced by these special AVMs and therefore only the most common site of rupture. As the complication rate was low for aneurysm occlusion, we recommend treating these aneurysms whenever possible. Furthermore, obliteration of the AVM should be strived for as this subtype may be associated with an increased risk of hemorrhage.

Re-growth of a posterior inferior cerebellar artery aneurysm after resection of the associated posterior fossa arteriovenous malformation

Arteriovenous malformation (AVM)-related aneurysms have been described in the literature. Their behavior varies based on their location in relation to and the activity of the shunting through the index AVM. The intuitive expectation supported by numerous reports is that these aneurysms should regress if the AVM is excluded from the circulation. We describe a case of 46-year-old man who presented with a posterior fossa AVM with an aneurysm on the posterior inferior cerebellar artery feeding the AVM. The nidus of the AVM was successfully excluded by glue embolization, with initial regression of the PICA aneurysm on serial imaging. Five years after the endovascular treatment, the aneurysm showed significant re-growth necessitating endovascular coiling. This case presents the re-growth of an AVM-related aneurysm and emphasizes the importance of long-term follow-up of such aneurysms even if the AVM is completely excluded.

Flow patterns and distributions of fluid velocity and wall shear stress in the human internal carotid and middle cerebral arteries

BACKGROUND

The aim of this study is to elucidate the relationship between the flow patterns and the preferred sites of the development of atherosclerotic lesions and cerebral aneurysms in the human ICA and MCA.

METHODS

Five isolated transparent arterial trees containing the ICA and MCA with a sufficient length of the carotid siphon were prepared from humans postmortem, and flow patterns and distributions of fluid velocity and wall shear stress in these vessels were studied in detail using flow visualization and high-speed cinemicrographic techniques.

RESULTS

In the carotid siphon that contained several acute bends, due to the impingement and deflection of the flow at the bends, a strong and complex helicoidal flow formed. As a result, the approaching velocity profile was flattened at the terminal bifurcation of the ICA, but it was sharpened at the first bifurcation of the MCA. Thus, at this latter bifurcation, fluid elements impinged on the vessel wall around the flow divider with much larger velocity than that at the preceding terminal bifurcation of the ICA. Throughout the entire arterial tree, atherosclerotic lesions were found almost exclusively in regions of low wall shear stress.

CONCLUSIONS

The carotid siphon provided a flattened approaching velocity profile at the terminal bifurcation of the ICA, making the hemodynamic stresses (pressure, tension, and shear stress) exerted on the vessel wall much lower than that at the bifurcation of the MCA where the approaching velocity profile was sharpened. This may account for the relatively low incidence of aneurysm formation at this site.

Multi-modality treatment for intracranial arteriovenous malformation associated with arterial aneurysm

OBJECTIVE

Intracranial arteriovenous malformation (AVM) associated with aneurysm has been infrequently encountered and the treatment for this malady is challenging. We report here on our clinical experience with AVMs associated with arterial aneurysms that were managed by multimodality treatments, including clipping of the aneurysm, microsurgery, Gamma-knife radiosurgery (GKS) and Guglielmi detachable coil (GDC) embolization.

METHODS

We reviewed the treatment plans, radiological findings and clinical courses of 21 patients who were treated with GKS for AVM associated with aneurysm.

RESULTS

Twenty-seven aneurysms in 21 patients with AVMs were enrolled in this study. Hemorrhage was the most frequent presenting symptom (17 patients : 80.9%). Bleeding was caused by an AVM nidus in 11 cases, aneurysm rupture in 5 and an undetermined origin in 1. Five patients were treated for associated aneurysm with clipping followed by GKS for the AVM and 11 patients were treated with GDC embolization combined with GKS for an AVM. Although 11 associated aneurysms remained untreated after GKS, none of them ruptured and 4 aneurysms regressed during the follow up period. Two aneurysms increased in size despite the disappearance of the AVM nidus after GKS and then these aneurysms were treated with GDC embolization.

CONCLUSION

If combined treatment using microsurgery, GKS and endovascular treatment can be adequately used for these patients, a better prognosis can be obtained. In particular, GKS and GDC embolization are considered to have significant roles to minimize neurologic injury.

Distal aneurysm of the rostral duplicate anterior inferior cerebellar artery feeding an associated dural arteriovenous malformation: case report and review of the literature

A rare case of a distal aneurysm of a rostral, duplicate anterior inferior cerebellar artery feeding an associated dural arteriovenous malformation is reported. The patient presented with severe nuchal rigidity after sexual intercourse; no neurological deficit was seen. The aneurysm causing the subarachnoid hemorrhage was wrapped but the arteriovenous malformation was inoperable. An analysis of the literature showed 51 cases of coexisting aneurysms and arteriovenous malformations in the posterior fossa; only three of them had a dural arteriovenous malformation. A 7:3 male predominance was recognized. The mean age at diagnosis was 48.5 years. Ninety-four per cent presented with hemorrhage and 6% with cranial nerve deficit only. The bleeding originated from the aneurysm in 73% and from the arteriovenous malformation in 15%; in 12% the origin of bleeding was not mentioned or could not be identified. Outcome was satisfactory in 76%, poor in 7% and 17% died. Treatment of both lesions should be performed in a one-stage operation if technically feasible. Additionally, radiosurgery to surgically unresectable arteriovenous malformations should be considered in cases where aneurysms are clipped or coiled.

Pathophysiology and treatment of stroke in sickle-cell disease: present and future

Sickle-cell anaemia is the most common cause of stroke in children, and stroke is one of the most devastating complications of sickle-cell disease. Overt strokes are typically due to large-artery vasculopathy affecting the intracranial internal carotid arteries and proximal middle cerebral arteries, whereas silent strokes typically occur in the territory of penetrating arteries. The sickled red blood cell can contribute to the pathogenesis of stroke via abnormal adherence to the vascular endothelium and by haemolysis, which results in endothelial cell activation, a hypercoaguable state, and alterations in vasomotor tone. Red-blood-cell transfusion, the most common preventive measure for stroke in sickle-cell disease, is associated with iron overload in chronic disease. Therefore, interventions directed towards the potential mechanisms that promote vasculopathy and occlusion in sickle-cell anaemia should be investigated. Here we review the epidemiology, clinical spectrum, and pathophysiology of stroke in sickle-cell disease to identify potential therapeutic targets.

Brain arteriovenous malformations in adults

Arteriovenous malformations of the brain (AMB) can cause stroke when they rupture. Epidemiological and imaging research has found that about 50% of patients with AMB present with haemorrhage, and the other 50% either present with non-focal symptoms, such as headache, seizure, or focal neurological deficit, or have no symptoms and the lesion is found during unrelated investigations. Treatment for arteriovenous malformations aims to prevent and resolve haemorrhage and is a growing interdisciplinary challenge. Although treatment uses enormous resources, there have been few studies on the risk-benefit ratios for treatment of unruptured AMB and the best approaches.

Intracranial arterial aneurysms associated with arteriovenous malformations: endovascular treatment

PURPOSE

To evaluate the results of endovascular treatment of patients having both arteriovenous malformations and aneurysms.

MATERIALS AND METHODS

Two hundred seventy consecutive patients underwent pretherapeutic selective and superselective angiography. In each patient, the following were recorded: demographic information; clinical symptoms; location of the arteriovenous malformation, including presence of aneurysms; therapeutic interventions and immediate anatomic results; and clinical and angiographic follow-up data. Every patient who had at least one angiographically confirmed arterial aneurysm at presentation was included in the study.

RESULTS

Arterial aneurysms were found in 30 (11%) of 270 patients in the population with arteriovenous malformations. Fifteen (50%) of 30 patients with aneurysms had a hemorrhage at presentation. Only 66 (27.5%) of 240 patients without aneurysms had a hemorrhage at presentation. The coexistence of arteriovenous malformations and aneurysms correlated significantly with intracranial hemorrhage at presentation (P <.05). When an aneurysm was believed to be responsible for a hemorrhage and whenever possible, it was treated before the arteriovenous malformation was treated. Treatments were protective against hemorrhage or recurrence of hemorrhage in all cases. Five of 30 patients had neurologic deficits as a result of endovascular treatment of both aneurysms and arteriovenous malformations.

CONCLUSION

Findings in this study highlight the importance of recognizing aneurysms in patients with arteriovenous malformations. A strategic focus on the circulatory exclusion of associated aneurysms, especially when such lesions have been responsible for a hemorrhagic episode, is recommended.

Clinical significance of pedicle aneurysms on feeding vessels, especially those located in infratentorial arteriovenous malformations

OBJECT

The diminishing threshold for the application of neuroimaging leads to an increasingly frequent diagnosis of previously asymptomatic arteriovenous malformations (AVMs). In such a context, it is warranted to define the criteria that make a lesion potentially hazardous so that neurosurgeons and patients reach a decision concerning how to manage the AVM. In addition to the proposed grading system for AVMs, which assesses the risk of an actual treatment procedure, several studies have been concerned with the evaluation of angioarchitectural features. The goal of the present study is to demonstrate the significance of feeding vessel pedicle aneurysms, especially those found in infratentorial AVMs.

METHODS

To determine the incidence of associated aneurysms, the authors reviewed an unselected cohort of 242 consecutive patients with AVMs managed between 1989 and 1999. Within this group were 240 patients who were treated by surgery, endovascular techniques, or a combination of both. Of these patients, 216 harbored a supratentorial and 24 an infratentorial AVM. Two additional patients with supratentorial AVMs underwent treatment of ruptured aneurysms without treatment of the AVMs. In six of the patients with supratentorial AVMs, proximal flow-related aneurysms were found on major feeding arteries, only one of which had caused hemorrhage. In only one patient were there additional distal feeding vessel pedicle aneurysms near the AVM, one of which had caused a major hemorrhage. In contrast, four of 24 patients with infratentorial AVMs had distal feeding artery pedicle aneurysms. Three of these aneurysms had caused hemorrhage.

CONCLUSIONS

Pedicle aneurysms on feeding vessels are frequently associated with hemorrhage (four of five cases in this series). In our cohort of 242 treated patients (240 treated for AVM and two for an aneurysm), feeding vessel pedicle aneurysms appear to occur more frequently in conjunction with infratentorial AVMs, which justifies aggressive management to prevent incidences of morbidity associated with rupture of the aneurysm.

Cerebral arteriovenous malformations associated with aneurysms--a report of 10 cases and literature review

We analysed 10 cases of arteriovenous malformations (AVMs) associated with aneurysms and reviewed the literature in order to confirm the clinical characteristics of AVMs associated with aneurysms. The mean incidence of aneurysms in our AVM population was 9.1% and the average age was 38 years. The ratio of male to female was 1.3 to 1. The aneurysms (40-96%) were often located on a feeding artery and seldom (23%) at an arterial bifurcation. The mortality rate was 0-26% in surgically managed patients and 38-60% in conservatively treated patients. The combination of intracranial vascular lesions is not rare. Most patients presented with symptoms referable to their AVMs. Treating both lesions in a single operation is the best option. The prognoses for most patients was good.

Cerebral arteriovenous malformations and associated aneurysms: analysis of 305 cases from a series of 662 patients

OBJECTIVE

Spontaneous intracranial hemorrhage is the primary danger for patients with cerebral arteriovenous malformations (AVMs). Associated aneurysms are considered weak points that increase the risk of intracranial hemorrhage. Aneurysms are classified as proximal aneurysms (PROXs) or intranidal aneurysms (INs).

METHODS

The present study was based on a series of 662 patients who presented with AVMs between 1985 and 1995. Its purpose was to evaluate prestated hypotheses using prospectively collected data. In 305 of these 662 patients, 372 INs and 313 PROXs were observed and analyzed with respect to their shapes, locations, and sizes. Partial targeted endovascular treatment with n-butylcyanoacrylate was performed for 450 of the 662 patients (68%) in this series, using a standard protocol. Of 450 treated patients, 181 (40%) had at least one IN and 138 (30.7%) had at least one PROX. Analysis of changes in the sizes of PROXs was based on the follow-up data for 83 treated patients, with a total of 149 PROXs. Changes in the sizes of PROXs in treated patients were analyzed with respect to PROX shapes, PROX locations, and treated AVM occlusion rates. Univariate and multivariate event data analyses were used to study factors influencing aneurysm shrinkage. False aneurysms were excluded from the series.

RESULTS

Presentation with intracranial hemorrhage was not correlated with any type of aneurysm. However, INs demonstrated a higher rebleeding rate (P < 0.002) before treatment. Among 181 patients, 92.2% of INs were occluded, together with the related portions of the AVM nidi. In cases of PROXs, embolization of the cerebral AVM compartment fed by the artery with the aneurysm was a priority. During follow-up monitoring of 83 treated patients with 149 PROXs, 100% shrinkage was observed for 12 PROXs and more than 50% shrinkage was observed for 33 PROXs. The median time required for more than 50% shrinkage was 3.5 years. The shrinkage of PROXs was influenced by the degree of AVM occlusion (P = 0.027) and occurred faster for PROXs on midline structures, such as the anterior cerebral artery and the circle of Willis, compared with arteries distal to the circle of Willis (P = 0.004). No rupture of untreated PROXs was observed after partial targeted treatment of AVMs.

CONCLUSION

PROXs are not primary treatment targets, compared with AVMs themselves. INs should be primary targets of endovascular therapy, because of their increased risk of rebleeding.

Stereotactic radiosurgery for tentorial dural arteriovenous fistulae draining into the vein of Galen: report of two cases

OBJECTIVE AND IMPORTANCE

Treatment of tentorial dural arteriovenous fistulae (DAVFs) primarily draining into the vein of Galen remains a therapeutic challenge. We present two cases of ruptured galenic DAVFs that were successfully treated with gamma knife radiosurgery.

CLINICAL PRESENTATION

Patient 1, a 66-year-old woman, experienced a sudden onset of headache and loss of consciousness. Neuroimaging studies revealed intraventricular hemorrhage and a DAVF with aneurysmal dilation of the vein of Galen. The DAVF was supplied by tentorial branches of the right meningohypophyseal artery and bilateral supracerebellar arteries, which drained directly into the vein of Galen. Patient 2, a 64-year-old woman, experienced subarachnoid hemorrhage. Cerebral angiography revealed a galenic DAVF at the falcotentorial junction, which was supplied by bilateral supracerebellar arteries. This patient had an aneurysm at the origin of the left supracerebellar artery.

INTERVENTION

Both patients were treated with gamma knife radiosurgery. In each case, the fistula was exclusively targeted and a dose of more than 20 Gy was delivered. Complete obliteration of the fistula was confirmed 27 and 29 months after radiosurgery for Patients 1 and 2, respectively, whereas the normal venous structures of the galenic system were preserved.

CONCLUSION

Gamma knife radiosurgery is an effective treatment modality for DAVFs primarily draining into the vein of Galen. Irradiation doses of more than 20 Gy, strictly limited to the fistulae, seem to be sufficient for successful obliteration of these high-risk vascular lesions, with minimal invasiveness.

The endovascular treatment of brain arteriovenous malformations

Advances in superselective microcatheterization techniques, which took place in the past decade, established superselective endovascular exploration as an integral and indispensable tool in the pretherapeutic evaluation of brain AVMs. The strict and routine application of superselective angiography furthered our knowledge on the angioarchitecture of brain AVMs, including vascular composition of the nidus, types of feeding arteries and types and patterns of venous drainage. In addition, various types of weak angioarchitectural elements, such as flow-related aneurysms, intranidal vascular cavities and varix formation proximal to high-grade stenosis of draining veins, could be identified as factors predisposing for AVM rupture. A wide spectrum of secondary angiomorphological changes induced by the arteriovenous shunt of the nidus and occurring up- and downstream of the nidus have been identified as manifestations of high-flow angiopathy. These data help to better predict the natural history, understand the widely variable clinical presentation and to define therapeutic targets of brain AVMs. Correlation of the topography of the AVM as demonstrated by MR with the angioarchitecture as demonstrated by superselective angiography provided a system for topographic-vascular classification of brain AVMs, which proved very useful for patient selection and definition of therapeutic goals. This study showed, that 40% of patients with brain AVMs can be cured by embolization alone with a severe morbidity of 1.3% and a mortality of 1.3%. Part of theses patients can, however, be cured equally effective by microsurgery or radiosurgery. Which modality will be chosen for a particular patient will mainly depend on the locally available expertise and experience, but also on the preference of the patient following its comprehensive information about the chances for cure and the risks associated with each of these therapeutic modalities. Embolization has a significant role in the multimodality treatment of brain AVMs, by either enabling or facilitating subsequent microsurgical or radiosurgical treatment. Appropriately targeted embolization in otherwise untreatable AVMs represents a reasonable form of palliative treatment of either ameliorating the clinical condition of the patient or reducing the potential risk of hemorrhage. Regarding the practical aspects of the endovascular treatment the following conclusions could be drawn from the experience obtained with this series of 387 patients with a brain AVM: (1) The goal of endovascular treatment should be defined prior to the procedure. This does not preclude a change in the goal, if additional information obtained during the procedure make this necessary. (2) The result of endovascular treatment of a brain AVM in terms of the degree of obliteration achieved and complication rate depends mainly on the endovascular strategy developed and the technique applied. These depend on the specific angioarchitecture and topography of the individual AVM, on the past history and clinical presentation of the patient and on the predefined goal of embolization. The strategy should include the definition of embolization targets, the selection of the most appropriate approach for endovascular navigation, the determination of the sequence of catheterization of individual feeding arteries, the selection of the type of catheters and microcatheters, the selection of the appropriate embolic materials as well as the site and mode of their delivery. Thereafter, every endovascular move should be, as in a chess game, the result of a logical plan. (3) Atraumatic superselective microcatheterization is a key point in the endovascular treatment of brain AVMs. It requires manual skills, knowledge of anatomy and respect for the vascular wall. (4) All locations of brain AVMs should be regarded as eloquent, and no distinction should be made between eloquent and non-eloquent areas of the brain when deciding on the execution of embolizatio

Posterior inferior cerebellar artery aneurysms associated with posterior fossa arteriovenous malformation: report of five cases and literature review

BACKGROUND

The association of posterior inferior cerebellar artery (PICA) aneurysms with posterior fossa arteriovenous malformation (AVM) is uncommon. Over the past 3 years, five patients with this condition were treated at this institution. A review of the clinical history of these and other reported cases has illuminated common threads in the presentation, treatment, and outcome of these lesions.

METHODS

The findings of 27 patients (5 from our institution and 22 from the medical literature) with PICA aneurysms associated with AVMs were reviewed.

RESULTS

Eighty-four percent of individuals presented with sub-arachnoid hemorrhage (SAH); 89% of these episodes resulted from aneurysm rupture documented by either intraoperative inspection or autopsy. All aneurysms were located on a feeding artery to the AVM, and 81% originated from distal portions of PICA. The majority of patients presented with Hunt & Hess grade I SAH; all patients who presented with hemorrhage were treated surgically. Surgical strategy was directed both to secure the aneurysm and to resect the AVM during the course of a single procedure. Although four individuals either died on admission or in the perioperative period, overall outcome was excellent or good in 82% of patients.

CONCLUSIONS

PICA aneurysms associated with AVMs most often involve the distal segments of the artery. Patients usually present with SAH secondary to aneurysmal rupture. Surgical clipping of the aneurysm and excision of the AVM is possible in a single procedure with minimal morbidity. Overall prognosis is favorable in 80% of the cases.

The management of patients with arteriovenous malformations and associated intracranial aneurysms

OBJECTIVE

Few published studies have focused specifically on the unique management issues encountered in treating patients with arteriovenous malformations (AVMs) and associated intracranial aneurysms. The primary objective of this study was to retrospectively review the clinical and radiographic features of these patients.

METHODS

Medical records of all patients seen at Stanford University Hospital between 1988 and 1996 with a diagnosis of AVMs were retrospectively reviewed. Aneurysms were identified by conventional angiography and characterized by size, number, and location relative to the AVMs. AVMs were graded according to the Spetzler-Martin scale. Odds ratios were calculated for the risk of intracranial hemorrhage. Variables included age, sex, number of aneurysms, and AVM grade.

RESULTS

Forty-five of 600 patients (7.5%) were identified as having coexisting intracranial aneurysms. All 45 patients had high-flow malformations, and 58% had AVMs of Spetzler-Martin Grade IV or higher. A majority of patients had multiple aneurysms. There was a statistically significant increase in AVM hemorrhage in female patients (odds ratio, 8.53 [1.87-38.98]; P < 0.005). There was no statistically significant correlation between the development of hemorrhage and either age, AVM grade, or the number of aneurysms. Twenty-three patients (51%) presented with intracranial hemorrhage: bleeding occurred from the AVMs in 15 and from ruptured aneurysms in 5, and the source of the bleeding could not be determined in 3. Overall, nine patients (20%) bled from ruptured aneurysms: five at presentation, two during or within 3 weeks of AVM treatment, and two from new aneurysms. Two of these nine patients died as a direct result of aneurysmal subarachnoid hemorrhage. Five patients (11%) developed new aneurysms.

CONCLUSION

Aneurysms associated with AVMs are at risk for rupture before, during, and immediately after treatment of the AVMs. New aneurysms may arise in patients with high-flow AVMs. The risk of intracranial hemorrhage from either source is higher in female patients. To reduce the complications of intracranial hemorrhage in these patients, we recommend a management protocol designed to treat the aneurysms by surgical or endovascular means before administering definitive therapy for the AVMs. Meticulous intraoperative blood pressure control and fluid management during aneurysm surgery is critical to avoid hemorrhage from the AVMs.

Experimental study of steady and pulsatile flows in cerebral aneurysm model of various sizes at branching site

Pulsatile and steady flow fields in cerebrovascular aneurysm models of various sizes are presented in terms of laser-Doppler velocimetry measurements and flow visualization. The bifurcation angle was 140 deg and volume flow rate ratio between the branches was 3:1. The mean, peak, and minimal Reynolds numbers based on the bulk average velocity and diameter of the parent vessel were 600, 800, and 280, respectively. It is found that among the tested sizes there exists a middle range of aneurysm sizes, above and below which the forced-vortex inside the aneurysmal model is weaker and lacking, respectively, whereas in the middle range of the tested sizes the forced vortex is stronger and the fluctuation level is higher near the dome. The present results also identify the major fluid dynamic factors of the aneurysmal promotion or rupture for the medium and larger aneurysms, respectively. Furthermore, the maximum fluctuation intensity is found to increase with aneurysm size. The locations of the maximum fluctuation intensity are found to occur in the bifurcation area or at the neck instead of intra-aneurysm.

Transient enlargement of an intracranial aneurysm during pregnancy: case report

BACKGROUND

The association of intracranial aneurysm and pregnancy is uncommon. Hemodynamic stress plays an important role in the growth of aneurysms.

METHODS

The authors report the case of an enlarging cavernous carotid aneurysm in a pregnant 15-year-old young woman.

RESULTS

The aneurysm was initially diagnosed prior to the patient's pregnancy by both cross-sectional imaging and cerebral angiography. Further imaging evaluation was required during pregnancy, which demonstrated significant enlargement of the aneurysm. Following delivery, the lesion decreased in size.

CONCLUSIONS

We review potential factors associated with pregnancy that may increase hemodynamic stress and influence aneurysm growth. Additionally, the management of pregnancy-related intracranial aneurysms is discussed.

Subarachnoid hemorrhage and aneurysms

Ruptured intracranial aneurysms are the usual cause of acute subarachnoid hemorrhage (SAH). Noncontrast CT is the primary imaging procedure of choice for establishing the diagnosis of SAH. Conventional contrast angiography is the gold standard for establishing the presence of intracranial aneurysms, but CT and MRI have supplementary roles. The pathogenesis, presentation, and imaging of SAH and intracranial aneurysms are discussed.

Large cerebral arteriovenous malformations: experience with 27 cases

BACKGROUND

The management of large cerebral arteriovenous malformations is difficult. Surgical excision is often attempted after embolization. Interventional neuro-radiology is available in only a few centers. If large AVMs can be safely excised without pre-operative embolizaton, then these lesions can be treated at many neurosurgical centers.

METHODS

Between January 1986 and June 1992, a total of 210 patients with cerebral AVMs were diagnosed by angiographic studies. Twenty-seven of them had large AVMs wider than 5 cm in the longest diameter. The case records of these patients were retrieved and studied.

RESULTS

Two patients were treated with Bragg peak proton beam therapy. Twelve patients were treated conservatively with no improvement. Thirteen patients underwent surgery and total AVM excision was achieved in 11. None of the patients who underwent surgery had any pre- or intra-operative embolization. All the patients had no neurological deterioration post-operatively.

CONCLUSIONS

Large cerebral AVMs can be treated by surgical excision alone with acceptable results.

'De novo' aneurysm formation: report of two cases

We report 2 cases of 'de novo' aneurysm formation in a vessel which appeared to be normal at a previous angiography. The first patient developed an anterior communicating artery aneurysm nine years after occlusion of the right internal carotid artery by Gianturco coils for the treatment of a giant intracavernous carotid aneurysm. In the second case a 'de novo' aneurysm of the internal angle A1-A2 segment of the left anterior cerebral artery developed 6 years after successful clipping of another aneurysm of the same location. De novo formation of an aneurysm in a vessel which was found to be normal in a previous angiographic study, may occur as result of hemodynamic changes, such as after internal carotid occlusion or in presence of an arteriovenous malformation or variations of the circle of Willis. However, definite hemodynamic changes may also be absent. We conclude that patients operated on for aneurysm clipping must be periodically explored by magnetic resonance angiography to evaluate the possibility of de novo appearance of another aneurysm.

In vitro study of haemodynamics in a giant saccular aneurysm model: influence of flow dynamics in the parent vessel and effects of coil embolisation

The purpose of this study was to investigate the influence of flow dynamics in the parent vessel and of intra-aneurysmal coil embolisation on flow pattern and pressure in an in vitro model of giant aneurysm. A pulsatile perfusion with a glycerol aqueous solution was installed in a silicone model of a lateral giant aneurysm. Flow visualization and pressure measurements were performed while modifying the flow rate, the pulsatility and the pulse rate in the parent vessel, and after partial coil embolisation. Vortices were formed during systole at the downstream lip of the aneurysm and circulated around the aneurysm. The centre and dome of the aneurysm were areas of fluid stagnation. Flow rate and pulsatility were the main factors which varied the pattern of flow within the aneurysm. Partial coil embolisation induced major flow disturbances in the aneurysm, in particular fluid stagnation at the dome. Pressure measurements were similar in the aneurysm and in the parent vessel. It was concluded that the pulsatility of flow is an important as the flow rate when considering the haemodynamics in a giant aneurysm. In the clinical context, this could explain the efficacy of vertebral artery occlusion in thrombosing giant vertebrobasilar aneurysms. Studies with intra-aneurysmal coil embolisation showed early fluid stagnation at the dome. This could result in embolic migration during endovascular treatment. Partial coil embolisation may prevent early rebleeding; however, it may induce additional mural stresses resulting from new haemodynamic forces and compliance mismatch.

Superior cerebellar artery aneurysms associated with infratentorial arteriovenous malformations

We describe three patients with aneurysms arising from the superior cerebellar artery feeding an arteriovenous malformation (AVM) in the posterior fossa. In one patient the aneurysms resolved following thrombosis of the AVM, suggesting that high flow through the feeding vessel is an etiological factor for aneurysm development. The usual presentation is subarachnoid hemorrhage but the outcome of surgical treatment of these lesions is often poor, suggesting an increasing role for interventional neuroradiology in the future.

Feeding artery pedicle aneurysms: association with parenchymal hemorrhage and arteriovenous malformation in the brain

The association between arteriovenous malformations (AVM's) and aneurysms is well documented in the literature. However, a specific type of aneurysm, termed a "pedicle" aneurysm, has received little attention despite its role as a primary source of hemorrhage. The authors report four recent cases of patients with cerebral AVM's who bled from aneurysms arising from the midportion of AVM-feeding artery pedicles. Angiography, computerized tomography, and magnetic resonance imaging confirmed the origin of the hemorrhage from the pedicle aneurysm in each case. Because pedicle aneurysms are at risk for recurrent rupture, they represent an important subclassification of aneurysms associated with AVM's. The authors have expanded the previous classification systems for aneurysms associated with AVM's to include pedicle aneurysms; this classification is based on the location of the aneurysm and its relationship to the malformation. Complete documentation of such aneurysms as the potential source of hemorrhage is recommended, and prompt intervention by embolization and/or surgical resection is indicated for this dangerous aneurysm associated with cerebral AVM's.

Spontaneous regression of intracranial arteriovenous malformation

Spontaneous regression of an arteriovenous malformation is rare. When complete or partial regression occurs, an associated factor is usually involved, such as intracranial hemorrhage, surgery, radiation therapy, or a new neurological deficit. Another case in which the resolution was totally spontaneous is presented here. We discuss the importance of transcranial doppler revealing the hemodynamic changes in the cerebral arteries in the presence of an AVM and when the latter is thrombosed. Several mechanisms for regression are considered, and we focus on the dissection of the afferent vessel, pointing out the role of such an event in the natural history of AVM.

The treatment of associated intracranial aneurysms and arteriovenous malformations

Cerebral arterial aneurysm associated with arteriovenous malformation (AVM) has been described with a variable incidence, averaging 10% of AVM cases. The present series includes 39 patients with this association, derived from a total of 400 patients with AVM's evaluated and treated since 1970. The aneurysms are classified into four major groups, each carrying particular therapeutic implications. Optimum treatment of these lesions is based in part on a knowledge of the hemodynamic alterations associated with the AVM's. In most of these cases, the symptomatic lesion was treated first; occasionally, when feasible, both lesions were treated during the same operation. All patients had some form of treatment, either surgical or endovascular, directed to at least one of the two types of lesions. All symptomatic lesions were treated and all ruptured aneurysms were obliterated. There were no deaths in this series.

Ruptured occult arteriovenous malformation associated with an unruptured intracranial aneurysm: report of three cases

Three patients who were admitted for intracranial hemorrhage are reported. Cerebral angiography demonstrated an aneurysm arising from the middle cerebral artery bifurcation. No other malformation was visible either on the computed tomographic scan or on angiography. The diagnosis was ruptured middle cerebral artery aneurysm with intracerebral hematoma. At surgery, there was no blood in the sylvian fissure and the aneurysm was not ruptured. Evacuation of the hematoma and thorough exploration of the cavity led to the discovery and resection of a small vascular anomaly typical of an arteriovenous malformation responsible for the hemorrhage. Occult vascular malformations and the association of aneurysm with arteriovenous malformations are discussed. In these 3 patients, the coexistence of these two malformations could be related to a common congenital abnormality.

Distal aneurysms of the superior cerebellar artery and posterior inferior cerebellar artery feeding an associated arteriovenous malformation: case report

The authors report a case of two distal aneurysms of the cerebellar arteries, one arising from the vermian branch of the posterior inferior cerebellar artery, the other arising from the hemispheric branch of the superior cerebellar artery, and both feeding an associated arteriovenous malformation (AVM). The aneurysm of the distal posterior inferior cerebellar artery was considered the source of a cerebellar hemorrhage because of the location of a hematoma in the cerebellar vermis. The life-threatening hematoma was evacuated in an emergency operation 6 hours after the acute onset of symptoms. The cerebellar aneurysms and the AVM were clipped or extirpated successfully after the patient's condition improved. The association of two rare types of aneurysms with an AVM strongly supports the theory that increased hemodynamic stress derived from the AVM plays an important role in aneurysm formation. The authors think that one should operate on the symptomatic lesion first or both the aneurysm and the AVM in the same operative procedure.

Embolization of arteriovenous malformations with peripheral aneurysms using ethylene vinyl alcohol copolymer. Report of three cases

The authors report three cases of arteriovenous malformations (AVM's) with aneurysms arising from the feeding artery; all were successfully treated with a new nonadhesive liquid embolic material, ethylene vinyl alcohol copolymer (EVAL). In two patients the AVM's were totally removed without difficulty, and in one the AVM was managed conservatively after embolization. No new neurological deficits appeared during or after embolization. After road-mapping techniques, EVAL was injected slowly until the feeding artery and aneurysm were completely obliterated. This embolic agent is easy to handle and is considered safe compared with other adhesive liquid embolic agents, such as isobutyl-2-cyanoacrylate or n-butyl cyanoacrylate. It is concluded that EVAL is an excellent agent for embolizing an AVM with a peripheral aneurysm on the feeding artery.

Aetiology of intracranial saccular aneurysms in childhood

Intracranial saccular aneurysms in childhood are rare neurosurgical lesions, occurring in 1-3% of large epidemiological aneurysm series. Analysis of previous reports indicates several distinct characteristics of this entity. First, there is a predominant male:female ratio approaching 2:1. Second, a disproportionately high number of these aneurysms arise at peripheral locations on the arterial tree. Third, approximately half of them are large or even giant aneurysms. These identifiable characteristics suggest that aneurysms in the younger age group may be a distinct pathophysiological entity from aneurysm in the adult population. In adults, epidemiological evidence indicates that 'acquired' factors such as hypertension, cigarette smoking, alcohol consumption, and oral contraceptive use together with 'intrinsic' or 'vascular' factors are causally related to the formation and rupture of cerebral aneurysms. Inherently, some of the 'acquired' factors must be of minor importance in aneurysm formation and rupture in childhood, whereas the 'intrinsic' factors may have a greater importance.

Unruptured intracranial aneurysms and arteriovenous malformations: frequency of intracranial hemorrhage and relationship of lesions

Among 91 patients with unruptured intracranial arteriovenous malformations (AVM's), 16 patients had 26 unruptured intracranial saccular aneurysms. An actuarial analysis showed the risk of intracranial hemorrhage among patients with coexisting aneurysm and AVM to be 7% per year at 5 years following diagnosis compared to 1.7% for patients with AVM alone. The difference in length of survival free of hemorrhage was significant (log-rank, p less than 0.0007). Several angiographic and clinical parameters were investigated to better understand the relationship of these lesions. The aneurysms occurred in similar percentages in patients with small, medium, and large AVM's. Twenty-five aneurysms were on arteries feeding the malformation system, almost equally distributed proximally and distally. Eleven aneurysms were atypical in location, and all arose from primary or secondary branch feeders to the malformation; 24 were on enlarged feeding arteries. Eleven (16%) of the 67 patients with high-flow AVM's had associated aneurysms, compared with five (21%) of the 24 patients with low-flow AVM's. Four (16%) of 25 low-shunt malformations and 12 (18%) of 65 high-shunt malformations had associated aneurysms. All five aneurysms associated with low-shunt malformations were on a direct arterial feeder of the malformation. These data suggest that the intracranial AVM's predispose to aneurysm formation within AVM feeding systems and that the mechanism is not simply based upon the high blood flow or high arteriovenous shunt in these systems.

General dysplasia of the cerebral arteries with persistent primitive acoustic artery and giant aneurysm

A case of cerebrovascular systemic dysplasia is presented. The anomalies were: persistent primitive acoustic artery, giant aneurysm of the left internal carotid artery, aneurysm of the basilar artery, and an arteriovenous fistula. A review of the literature shows that the association of multiple malformations of cerebral vessels with a persistent primitive acoustic artery has not previously been described. Impairment of embryonic development is suggested as the origin of the malformations.

Angiographic frequency of anterior circulation intracranial aneurysms

A retrospective angiographic analysis was designed to extrapolate the frequency of angiographically defined asymptomatic intracranial aneurysms in the anterior circulation from a relatively unbiased clinical series. A total of 9295 angiograms were reviewed from January, 1980, to January, 1987, and, based on these, 278 patients with minimal bias for the presence of an aneurysm were selected. Three patients were found to have incidental aneurysms; thus, the angiographic frequency of patients with asymptomatic aneurysms in this series was 1%. This patient population is skewed toward the older age groups and probably over-represents the incidence of these aneurysms in the population at large. Comparing current subarachnoid hemorrhage statistics and the low frequency of asymptomatic aneurysms suggests that a larger percentage of these aneurysms than was previously thought subsequently rupture. This study contrasts sharply with previous reports quoting a high incidence of aneurysms, and significantly alters the concept and treatment of this disease.

Cerebral arteriovenous malformations with associated arterial aneurysms: hemodynamic and therapeutic considerations

The common vascular anomalies of cerebral aneurysm and arteriovenous malformation may exist independently, or together as part of a closely related hemodynamic pairing. Resection or embolization of an AVM may be followed by a decrease in local blood flow, and lead to regression of a suitably situated proximal aneurysm. However, aneurysms located outside the angioarchitecture of the AVM, which remain flow-unrelated to the malformation, will likely not regress, and may in fact enlarge. Two cases are presented which demonstrate these vascular relationships, in order to better understand the regional hemodynamics of these anomalies prior to surgical or endovascular treatment planning.

Cerebral arteriovenous malformations (C. AVM) and associated arterial aneurysms (AA). Analysis of 101 C. AVM cases, with 37 AA in 23 patients

We report a series of 101 patients with cerebral arteriovenous malformations (CAVM), in which 23 cases presented with one or several arterial aneurysm(s) (AA). Each AA could be classified into distal intra-lesional, proximal or remote. Patients with CAVM + AA tend to be older and more frequently present with epilepsy, haemorrhage events and neurological deficits. Of these 23 patients, 16 had their AVM treated partially or totally by embolization. In our series, the endovascular treatment of the arteriovenous shunt with a proximal AA on the same vessel has resulted in at least a regression, and sometimes a disappearance of the arterial ectasia. Although partial treatment of the AVM does no erase the risk of haemorrhage from the malformation itself, it may diminish the chance of developing a flow-related AA or any other expression of the high-flow angiopathy.

Aneurysm recurrence associated with induced hypertension and hypervolemia

A case of angiographic recurrence of a previously clipped large distal basilar aneurysm associated with prolonged hypervolemic and hypertensive therapy for vasospasm is reported. Currently, the most effective therapy for reversing neurological deficits secondary to vasospasm and for augmenting cerebral blood flow is induced hypertension and hypervolemia. The complication of aneurysm enlargement with this therapeutic modality has been postulated but not previously demonstrated.

Multiple intracerebral arteriovenous malformations. A case report and literature review

The presence of multiple intracerebral arteriovenous malformations (AVMs) in a single patient has only been very rarely reported. We present a patient with three separate angiographically demonstrable intracerebral AVMs, all of which were radiologically demonstrated and surgically removed without residual neurological deficit. A literature survey was conducted and all the previously described cases of multiple intracerebral AVMs are discussed, along with the potential diagnostic and therapeutic implications.

Enlargement of a cerebral aneurysm associated with ruptured arteriovenous malformation

Enlargement of a small aneurysm during an eleven year period was encountered in a 32-year-old man who had experienced intracranial haemorrhage from a distally located AVM. Clipping of the feeding artery together with the aneurysmal neck was performed. It was very rare to observe the aneurysmal growth associated with the AVM. This case was considered worth reporting as supporting evidence that hemodynamic stress plays an important role in the development of an aneurysm.