Intracranial aneurysms associated with arteriovenous malformations

Neuromonitoring in Children with Cerebrovascular Disorders

BACKGROUND

Cerebrovascular disorders are an important cause of morbidity and mortality in children. The acute care of a child with an ischemic or hemorrhagic stroke or cerebral sinus venous thrombosis focuses on stabilizing the patient, determining the cause of the insult, and preventing secondary injury. Here, we review the use of both invasive and noninvasive neuromonitoring modalities in the care of pediatric patients with arterial ischemic stroke, nontraumatic intracranial hemorrhage, and cerebral sinus venous thrombosis.

METHODS

Narrative review of the literature on neuromonitoring in children with cerebrovascular disorders.

RESULTS

Neuroimaging, near-infrared spectroscopy, transcranial Doppler ultrasonography, continuous and quantitative electroencephalography, invasive intracranial pressure monitoring, and multimodal neuromonitoring may augment the acute care of children with cerebrovascular disorders. Neuromonitoring can play an essential role in the early identification of evolving injury in the aftermath of arterial ischemic stroke, intracranial hemorrhage, or sinus venous thrombosis, including recurrent infarction or infarct expansion, new or recurrent hemorrhage, vasospasm and delayed cerebral ischemia, status epilepticus, and intracranial hypertension, among others, and this, is turn, can facilitate real-time adjustments to treatment plans.

CONCLUSIONS

Our understanding of pediatric cerebrovascular disorders has increased dramatically over the past several years, in part due to advances in the neuromonitoring modalities that allow us to better understand these conditions. We are now poised, as a field, to take advantage of advances in neuromonitoring capabilities to determine how best to manage and treat acute cerebrovascular disorders in children.

Cerebral Digital Subtraction Angiography in Acute Intracranial Hemorrhage: Considerations in Critically Ill Children

Cerebrovascular disorders are an important cause of morbidity and mortality in children. Although minimally invasive, cerebral digital subtraction angiography (DSA) has been shown to be safe in children and is a valuable, and perhaps underutilized, technique for the diagnosis and management of pediatric cerebrovascular disorders in the critical care setting. Through a case-based approach, we explore the utility of DSA in critically ill children with acute intracranial hemorrhage (ICH). We discuss the use of DSA in the acute management of aneurysm and arteriovenous malformation rupture as well as cerebral vasospasm. Those caring for critically ill children with acute ICH should consider cerebral DSA as part of a comprehensive approach to the diagnosis and management of these conditions.

The Effect of Flow-Related Aneurysms on Hemorrhagic Risk of Intracranial Arteriovenous Malformations

BACKGROUND

Previous reports indicated an association between hemorrhagic presentation and flow-related aneurysms in arteriovenous malformation (AVM) patients. However, it remains unclear whether these flow-related aneurysms result in the hemorrhage of AVM.

OBJECTIVE

To characterize this hemorrhage risk using our institutional experience over 25 yr.

METHODS

We retrospectively reviewed records of patients at our institution diagnosed with AVM from 1990 to 2015. Patients without associated aneurysms (AVM only) and those with flow-related aneurysms (AVM-FA) were compared. Those with intranidal or unrelated aneurysms were excluded. Annual risk of AVM-related hemorrhage was calculated using the birth-to-treatment approach and compared using Poisson rate ratio test.

RESULTS

Among 526 patients, there were 457 AVM only patients and 69 with flow-related aneurysms. AVM-FA patients were older (P = .005). AVMs with flow-related aneurysms were more likely located in the cerebellar vermis and hemispheres (P = .023 and .001, respectively). Presence of flow-related aneurysms increased the risk of presentation with subarachnoid hemorrhage (P < .001). Interestingly, no significant differences in presenting hemorrhage due to AVM rupture were found (P > .356). The majority of aneurysms were untreated (69.5%), and only 8 (9.8%) had ruptured presentation. At follow-up (mean = 5.3 yr), patients with flow-related aneurysms were less likely to develop seizures (P = .004). The annual risk of AVM hemorrhage was 1.33% and 1.05% for AVM only patients and AVM-FA patients, respectively (P = .248).

CONCLUSION

Despite increased risk of subarachnoid hemorrhage at presentation, there was no increased likelihood of rupture in AVMs with flow-related aneurysms. More studies are warranted, as clarifying the competing risks of AVM vs aneurysm rupture may be critical in determining optimal treatment strategy.

The "focus on aneurysm" principle: Classification and surgical principles of management of concurrent arterial aneurysm with arteriovenous malformation causing intracranial hemorrhage

Context:

Concurrent arterial aneurysms (AAs) occurring in 2.7-16.7% patients harboring an arteriovenous malformation (AVM) aggravate the risk of intracranial hemorrhage.

Aim:

We evaluate the variations of aneurysms simultaneously coexisting with AVMs. A classification-based management strategy and an abbreviated nomenclature that describes their radiological features is also proposed.

Setting:

Tertiary care academic institute.

Statistics:

Test of significance applied to determine the factors causing rebleeding in the groups of patients with concurrent AVM and aneurysm and those with only AVMs.

Subjects and Methods:

Sixteen patients (5 with subarachnoid hemorrhage and 11 with intracerebral/intraventricular hemorrhage; 10 with low flow [LF] and 6 with high flow [HF] AVMs) underwent radiological assessment of Spetzler Martin (SM) grading and flow status of AA + AVM. Their modified Rankin's score (mRS) at admission was compared with their follow-up (F/U) score.

Results:

Pre-operative mRS was 0 in 5, 2 in 6, 3 in 1, 4 in 3 and 5 in 1; and, SM grade I in 5, II in 3, III in 3, IV in 4 and V in 1 patients, respectively. AA associated AVMs were classified as: (I) Flow-related proximal (n = 2); (II) flow-related distal (n = 3); (III) intranidal (n = 5); (IV) extra-intranidal (n = 2); (V) remote major ipsilateral (n = 1); (VI) remote major contralateral (n = 1); (VII) deep perforator related (n = 1); (VIII) superficial (n = 1); and (IX) distal (n = 0). Their treatment strategy included: Flow related AA, SM I-III LF AVM: aneurysm clipping with AVM excision; nidal-extranidal AA, SM I-III LF AVM: Excision or embolization of both AA + AVM; nidal-extranidal and perforator-related AA, SM IV-V HF AVM: Only endovascular embolization or radiosurgery. Surgical decision-making for remote AA took into account their ipsilateral/contralateral filling status and vessel dominance; and, for AA associated with SM III HF AVM, it varied in each patient based on diffuseness of AVM nidus, flow across arteriovenous fistula and eloquence of cortex. Follow up (F/U) (23.29 months; range: 1.5-69 months) mRS scores were 0 in 12, 2 in 2, 3 in 1 and 6 in 1 patients, respectively.

Conclusions:

Patients with intracranial AVMs should be screened for concurrent AAs. Further grading, management protocols and prognostication should particularly “focus on the aneurysm.”

Acute rupture of a feeding artery aneurysm after embolization of a brain arteriovenous malformation

BACKGROUND

Staged endovascular embolization of large arteriovenous malformations (AVMs) is frequently performed to gradually reduce flow and prevent abrupt hemodynamic changes. While feeding artery aneurysms have been associated with increased risk of hemorrhage in the setting of AVMs, decisions regarding if and when to treat these aneurysms vary. Acute, fatal rupture of a feeding artery aneurysm following embolization of a large, unruptured AVM has been infrequently reported in the literature.

CASE DESCRIPTION

A 69-year-old female presented with headache and mild left hemiparesis referable to a 5 cm right fronto-parieto-temporal AVM with surrounding vasogenic edema. The AVM was associated with numerous bilateral feeding artery aneurysms (the largest was a 2 cm right middle cerebral artery (MCA) bifurcation aneurysm). There was also a large, partially thrombosed venous varix. Staged embolization of the AVM was performed. Several hours after the third stage of her embolization, she became obtunded, with a fixed and dilated right pupil. Head computed tomography (CT) showed a large intraparenchymal hemorrhage with midline shift in the right sylvian fissure, remote from the AVM nidus. She was taken to surgery for a decompressive craniectomy and hematoma evacuation. The MCA aneurysm was confirmed to be the source of hemorrhage and it was clipped. Despite aggressive medical and surgical treatments, the patient died.

CONCLUSIONS

An increase in AVM feeding artery pressure following endovascular embolization may contribute to the rupture of a feeding artery aneurysm. For this reason, treatment of large arterial aneurysms on feeding pedicles should be considered prior to embolization of the AVM nidus.

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.

A case of ruptured peripheral aneurysm of the anterior inferior cerebellar artery associated with an arteriovenous malformation : a less invasive image-guided transcortical approach

A 47-year-old man presented with a subarachnoid hemorrhage (SAH) and right cerebellar hematoma was referred for evaluation. Cerebral angiography revealed a distal anterior inferior cerebellar artery (AICA) aneurysm associated with an arteriovenous malformation (AVM). Successful obliteration and complete removal of the aneurysm and AVM were obtained using transcortical approach under the guidance of neuronavigation system. The association of a peripheral AICA aneurysm and a cerebellar AVM by the same artery is unique. The reported cases of conventional surgery for this disease complex are not common and their results are variable. Less invasive surgery using image-guided neuronavigation system would be helpful and feasible for a peripheral aneurysm combining an AVM of the posterior fossa in selective cases.

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.

Risk factors for the association of intracranial and aortic aneurysms

This study investigated the association of intracranial aneurysms and abdominal aortic aneurysms to elucidate the incidence and independent risk factors for this association. Ultrasonography of the abdominal aorta was performed in 181 patients with 224 intracranial aneurysms. Six patients had suffered subarachnoid haemorrhage and the others had chronic disease or no symptoms. Magnetic resonance angiography was performed for confirmation if abdominal aortic aneurysm was identified by ultrasonography. Thirteen patients (7.2%) with 23 intracranial aneurysms had abdominal aortic aneurysms. Univariate analysis demonstrated that age (p < 0.01), size of intracranial aneurysms (p < 0.001), male sex (p < 0.01), multiplicity of intracranial aneurysms (p < 0.001), history of cerebrovascular diseases (p < 0.05), and current smoking (p < 0.0001) were significantly different between patients with and without this association. Multiple logistic analysis indicated that age (odds ratio [OR] 1.27, 95% confidence interval 1.08-1.48, p < 0.01), multiplicity (OR 22.1, 95% confidence interval 1.83-266.3, p = 0.01), size of intracranial aneurysms (OR 1.30, 95% confidence interval 1.10-0.54, p < 0.01), and current smoking (OR 33.3, 95% confidence interval 2.43-456.7, p = 0.01) were independent risk factors for the association. Patients with intracranial aneurysms who are older males with multiple or large intracranial aneurysms, and current smokers should be examined for abdominal aortic aneurysms using ultrasonography.

Neurologie des malformations artérioveineuses cérébrales

INTRODUCTION

Brain arteriovenous malformations (AVMs) constitute a neurovascular disorder that comes to clinical attention mainly in young adults in their mid thirties. Associated symptoms often require neurological treatment for symptomatic seizures (focal or generalized), headaches (episodic or chronic), progressive neurological deficits, or spontaneous AVM rupture leading to intracerebral, intraventricular, and/or subarachnoid hemorrhage.

STATE OF ART

Little data exist in the medical literature regarding the natural history risk of the disease and no controlled studies are available on the risk of invasive AVM treatment (endovascular, neurosurgery, radiotherapy).

PERSPECTIVES

This review focuses on all aspects of neurological brain AVM management and discusses possible predictors of the natural history risk as well as the benefit and risk of invasive treatment.

CONCLUSIONS

AVM patient management is ideally based on a trans-disciplinary approach via a neurovascular team of neurologists, neuroradiologists, neurosurgeons, and radiotherapists. A newly diagnosed AVM does not necessarily represent an a priori indication for interventional treatment. The decision in favor or against therapy mainly depends on clinical criteria (ruptured versus unruptured AVM, neurological exam, patient age and co-morbidity, etc.) and the angioarchitecture of the malformation. The ARUBA study is going to be the first randomized clinical trial comparing the risk of invasive treatment versus non-invasive management.

Reprint of: SYMPOSIUM ON CEREBROVASCULAR DISEASES. Pathogenesis, Natural History, and Treatment of Unruptured Intracranial Aneurysms

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Pathogenesis, natural history, and treatment of unruptured intracranial aneurysms

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Update on the management of unruptured intracranial aneurysms

Over the past decade, several factors have led to a dramatic change in the manner in which patients with unruptured intracranial aneurysms are diagnosed and treated. These factors include the increased use of noninvasive imaging modalities for the diagnosis of intracranial aneurysms, publication of new natural history data detailing the hemorrhage risks associated with unruptured intracranial aneurysms, and the broad application of endovascular therapy for their treatment. With these new technologies and new natural history data has come considerable uncertainty about the optimal treatment strategy for patients with unruptured intracranial aneurysms. In this light, it seems prudent to review periodically and examine critically all recent data pertaining to the natural history and treatment of unruptured intracranial aneurysms, in an effort to provide a scientific update on which management recommendations can be based. This review article represents the authors' attempt at such an update, and it is their hope that members of the community of neurovascular surgeons might find this information helpful during their continuing efforts to provide optimal care for their patients with unruptured intracranial aneurysms.

Distal posterior inferior cerebellar artery aneurysms: clinical features and management

OBJECT

Aneurysms located on the distal portion of the posterior inferior cerebellar artery (PICA) are uncommon, and their underlying pathology, natural history, and clinical management are poorly understood. To clarify these lesions more fully, the authors undertook a retrospective analysis of the clinical features and management results of 22 distal PICA aneurysms in 20 consecutive patients treated at one institution by the same surgeon during the past decade.

METHODS

The series included 10 men and 10 women (mean age at presentation 51 years). Nine patients presented with only subarachnoid and/or intraventricular hemorrhage (median Hunt and Hess Grade II). In seven patients intracerebellar hemorrhage was also found; two patients presented with pressure effects and two hemorrhages were incidentally discovered. Prominent comorbidities included cigarette smoking (50%) and hypertension (50%). The 13 saccular and nine fusiform distal PICA aneurysms were distributed on the following segments of the PICA: lateral medullary (seven lesions), tonsillomedullary (five lesions), telovelotonsillar (five lesions), and cortical (five lesions). Six oases were associated with cerebellar arteriovenous malformations. Skull-base and far-lateral transcondylar surgical approaches were used to secure the aneurysms in 86% of cases, either by direct clipping (13 lesions), vessel sacrifice (four lesions), or vessel sacrifice plus bypass (two lesions). Two aneurysms were treated using endovascular PICA ablation. Overall outcome at hospital discharge was excellent or good in 70% of cases. At long-term follow up (100% of patients, mean 123 days), an excellent or good outcome had been achieved in 85% of cases.

CONCLUSIONS

Depending on the PICA segment that was affected, variations in clipping strategies and surgical exposures aimed at the PICA branch and main trunk preservation were major contributors to good long-term results.

Concurrent arterial aneurysms in brain arteriovenous malformations with haemorrhagic presentation

OBJECTIVE

To assess the effect of concurrent arterial aneurysms on the risk of incident haemorrhage from brain arteriovenous malformations (AVMs).

METHODS

In a cross sectional study, 463 consecutive, prospectively enrolled patients from the Columbia AVM Databank were analysed. Concurrent arterial aneurysms on brain angiography were classified as feeding artery aneurysms, intranidal aneurysms, and aneurysms unrelated to blood flow to the AVM. Clinical presentation (diagnostic event) was categorised as intracranial haemorrhage proved by imaging or non-haemorrhagic presentation. Univariate and multivariate statistical models were applied to test the effect of age, sex, AVM size, venous drainage pattern, and the three types of aneurysms on the risk of AVM haemorrhage at initial presentation.

RESULTS

Arterial aneurysms were found in 117 (25%) patients with AVM (54 had feeding artery aneurysms, 21 had intranidal aneurysms, 18 had unrelated aneurysms, and 24 had more than one aneurysm type). Intracranial haemorrhage was the presenting symptom in 204 (44%) patients with AVM. In the univariate model, the relative risk for haemorrhagic AVM presentation was 2.28 (95% confidence interval (CI) 1.12 to 4.64) for patients with intranidal aneurysms and 1.88 (95% CI 1.14 to 3.08) for those with feeding artery aneurysms. In the multivariate model an independent effect of feeding artery aneurysms (odds ratio 2.11, 95% CI 1.18 to 3.78) on haemorrhagic AVM presentation was found. No significant effect was seen for intranidal and unrelated aneurysms. The attributable risk of feeding artery aneurysms for incident haemorrhage in patients with AVM was 6% (95% CI 1% to 11%).

CONCLUSIONS

The findings suggest that feeding artery aneurysms are an independent determinant for increased risk of incident AVM haemorrhage.

Characteristics of brain arteriovenous malformations with coexisting aneurysms: a comparison of two referral centers

BACKGROUND

Patients harboring a brain arteriovenous malformation (BAVM) often have coexisting arterial aneurysms. Experts have argued about the clinical significance of these aneurysms, which may be important for risk stratification in patient management and clinical trials. We studied the association between coexisting aneurysms and initial presentation with intracranial hemorrhage (ICH) in patients with BAVM evaluated at two tertiary-care centers.

METHODS

Demographic and clinical data were collected from a prospective series of patients evaluated for BAVM at the University of California, San Francisco (UCSF; n=82), and Columbia-Presbyterian Medical Center, New York (CPMC; n=254). Using multivariate logistic regression, we examined the independent association between ICH presentation and the presence of a coexisting aneurysm, and compared the association at the two hospitals.

RESULTS

Aneurysms were associated with 28 BAVMs at UCSF (34%) and 74 at CPMC (29%; P=0.39). Initial presentation with ICH was associated with the presence of a coexisting aneurysm at CPMC (odds ratio 1.8, 95% confidence interval 1.0 to 3.0, P=0.044). The opposite trend was observed at UCSF (odds ratio 0.4, 95% confidence interval 0.2 to 1.1, P=0.085). We observed an interaction by site involving the association between ICH presentation and aneurysm (P=0.016).

CONCLUSION

Although many BAVM characteristics were similar at the referral centers studied, the association between initial presentation with ICH and coexisting aneurysms was not. This heterogeneity between populations undermines the validity of inferences on the role of aneurysms from any single referral series, and emphasizes the complexity in creating BAVM risk-stratification models that incorporate aneurysms.

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.

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.

Arterial aneurysms associated with cerebral arteriovenous malformations: classification, incidence, and risk of hemorrhage

OBJECT

The goal of this study was to develop a classification system for aneurysms associated with arteriovenous malformations (AVMs) based on their anatomical and pathophysiological relationships and to determine the incidence and bleeding rates for these aneurysms as well as the effects of AVM treatment on their natural history.

METHODS

Of 632 patients with AVMs, intranidal aneurysms were found in 35 (5.5%) and flow-related aneurysms in 71 (11.2%). Patients with intranidal aneurysms presented more frequently with hemorrhage (72% compared with 40%, p < 0.001) and had a 9.8% per year risk rate of bleeding during follow-up review. Twelve (17%) of the patients with flow-related aneurysms associated with an AVM presented with hemorrhage from an aneurysm, whereas 15 (21%) bled from their AVM. Seventeen patients underwent angiography after AVM treatment (mean 2.25 years). Of 23 proximal aneurysms, 18 (78.3%) were unchanged, four (17.4%) were smaller, and one (4.3%) had disappeared, whereas four (80%) of five distal aneurysms regressed completely and one was unchanged. Sixteen patients underwent angiography after partial AVM treatment (mean 3.8 years). In cases with less than a 50% reduction in the AVM, no aneurysms regressed, although two enlarged and bled. In cases with greater than a 50% reduction in the AVM, two of three distal aneurysms disappeared and five proximal aneurysms were unchanged.

CONCLUSIONS

Arterial aneurysms associated with cerebral AVMs may be classified as intranidal, flow-related, or unrelated to the AVM nidus. Intranidal aneurysms have a high correlation with hemorrhagic clinical presentation and a risk of bleeding during the follow-up period that considerably exceeds that which would be expected in their absence. Patients with flow-related aneurysms in association with an AVM may present with hemorrhage from either lesion. Aneurysms that arise on distal feeding arteries near the nidus have a high probability of regressing with substantial or curative AVM therapy.

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.

Cerebral arteriovenous malformation feeding artery aneurysms: a theoretical model of intravascular pressure changes after treatment

OBJECTIVE

A quantitative model may be used to estimate the magnitude of expected pressure changes along the vascular tree with shunt ablation and may provide information to assess the hemodynamic risk of arteriovenous malformation (AVM) treatment.

METHODS

A computer model of the cerebral circulation was applied to estimate the changes in intravascular pressure, velocity, biomechanical stress, and shear stress that might be expected from either endovascular or surgical ablation of AVMs. Two AVM sizes and two feeding artery constellations were simulated. The effect of different shunt flows on vascular pressure was modeled. In each simulation, AVMs were occluded in a stepwise fashion. The effects of systemic hypertension and hypotension in various vascular zones were also simulated.

RESULTS

As large (1000 ml/min) AVMs were occluded, the mean feeding arterial pressure increased from 18 to 68 mm Hg; the percent-occlusion at half-maximal pressure increase was 92%. For medium (500 ml/min) AVMs, feeding arterial pressure increased from 37 to 66 mm Hg; the percent-occlusion at half-maximal pressure increase was 71%. During manipulation of systemic pressure, hemodynamic changes in the circulation close to the nidus were proportionally less than changes in systemic pressure; the degree of proportionality depended on the magnitude of AVM shunt flow.

CONCLUSION

In this simulation, shunt obliteration increased pressure in the nidus and feeding arteries with little effect on the proximal circulation. The shunt provided a "buffering" effect, i.e., higher flow fistulas were exposed to smaller variations in intravascular pressure in feeding artery and nidal pressures during manipulation of systemic pressure.

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.

'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.

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.

Complications of surgery for arteriovenous malformations of the brain

A series of 112 patients undergoing complete surgical resection of arteriovenous malformations (AVM's) of the brain between 1974 and 1990 were analyzed for complications and 12-month outcomes. The cohort consisted of 44 patients with small AVM's (< 2 cm in diameter), 43 patients with medium-sized AVM's (2 to 4 cm in diameter), and 25 patients with large AVM's (> 4 cm in diameter). There was a 3.6% series mortality rate and an 18% morbidity rate. One of the four deaths was caused by normal perfusion pressure breakthrough. Analysis of logistic regression found that the most important factor influencing the occurrence of complications in this series was AVM size (p = 0.005) and that the occurrence of complications (p < 0.001) and the neurological grade at the time of surgery (p < 0.004) both significantly contributed to the outcome at 12 months. This study stresses the importance of defining complications in terms of rigid criteria when analyzing AVM series in order to allow for a correct evaluation of the risk:benefit ratio of surgery. Furthermore, it emphasizes the need for a separate analysis of the importance of complications upon outcome.

Arteriovenous aneurysm of the occipital artery

We report an unique case of a giant aneurysm of the occipital artery, with a venous connection to the transverse sinus via an emissary vein. Because of this connection, the term arteriovenous aneurysm is used.

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.

Arteriovenous malformations of the posterior fossa

AVMs of the posterior fossa are reviewed on the basis of personal experience of 47 cases including 2 venous angiomas, 7 cavernous angiomas, 5 arteriovenous fistulas and 33 true arteriovenous malformations and of the few series reported in the literature. MRI is now an indispensable tool to define the exact localization of any malformation. Combined with angiography, it permits one to choose the most adequate therapeutic strategy and the best surgical approach. Radical cure is to be contemplated in most cases considering the often dramatic consequences of bleeding at the infratentorial level. Deep AVMs and moreover cavernous angiomas, even those located in highly functional structures such as the brain stem, can now be discussed for treatment. Encouraging results have already been obtained using, alone or in association, the recently advanced modalities of treatment: interventional neuroradiology, radiosurgery, and microsurgery.

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.

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.

Association of cerebral arteriovenous malformation and cerebral aneurysm. Diagnosis and management

Between 1979 and 1989, 7 patients were admitted, with cerebral arteriovenous malformations (AVM) and associated aneurysms (7% of the AVM patients and 2% of the aneurysm patients admitted during the same period). 6 of these patients were admitted because of an intracranial haemorrhage (in 3 of them the AVM, angiographically occult, was discovered at surgery). The last patient was referred for seizures. Preoperatively it was supposed that the haemorrhage was related to the aneurysm in 3 cases, and to the AVM in 3 cases. But surgery allowed one to correct this supposition. Haemorrhage was due to AVM rupture in all 6 cases, and no aneurysm had ruptured. Overall three situations were demonstrated in this series: aneurysm and occult AVM (3 cases); AVM and independent aneurysm in the same area (2 cases); large AVM and aneurysm on a feeding artery (2 cases). All 6 patients admitted for haemorrhage were operated upon, at one operation in 5 of them. Both the malformations were excluded in these six patients. For the patient admitted for seizure, intra-vascular embolization of the AVM was performed, the aneurysm was not treated. The pathogenesis of the association AVM-aneurysm is discussed. In the authors' opinion, haemodynamic relationship should be considered in two cases (large AVM and aneurysm on a feeding vessel). For the other 5 cases, both the AVM and the coexisting aneurysm may be the end-result of a common congenital vascular malformation syndrome.

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.

Hemodynamic analysis of associated extracranial atraumatic vertebral artery aneurysm and arteriovenous fistula. Case report

A case of atraumatic arteriovenous (AV) fistula of the extracranial vertebral artery associated with an atraumatic aneurysm of the contralateral extracranial vertebral artery is reported. The fistulous lesion was excised after distal and proximal ligation of the vessel. Subsequently, the contralateral aneurysm underwent spontaneous dissolution. Seven cases of extracranial vertebral AV fistulae associated with ipsilateral vertebral artery aneurysms (four traumatic and three as part of vascular dysplastic syndromes) have been reported previously.

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.