Aneurysms and Arteriovenous Malformations

Growth of Flow-Related Aneurysms Following Occlusion of Cerebral Arteriovenous Malformation

BACKGROUND

 Flow-related aneurysms (FRAs) associated with cerebral arteriovenous malformations (AVMs) pose a significant therapeutic challenge. Both their natural history and management strategy are still unclear and underreported. FRAs generally increase the risk of brain hemorrhage. However, following AVM obliteration these vascular lesions are expected to disappear or remain stable.

METHODS

We present two cases where growth of FRAs was detected following complete obliteration of an unruptured AVM.

RESULTS

 The first patient presented with proximal middle cerebral artery (MCA) aneurysm growth after spontaneous and asymptomatic thrombosis of the AVM. In our second case, a very small aneurysmal-like dilation located at the basilar apex enlarged to a saccular aneurysm following complete endovascular and radiosurgical obliteration of the AVM.

CONCLUSION

 The natural history of flow-related aneurysms is unpredictable. In the cases where these lesions are not managed first, there should be close follow-up. When aneurysm growth is evident, active management strategy seems mandatory.

Case Series for Gamma Knife Surgery for Arteriovenous Malformation Associated Intracranial Aneurysms

Objective The incidence of aneurysms coexisting with arteriovenous malformations (AVMs) ranges between 2.7% and 16.7%. The anatomical relationship between AVM and aneurysm is critical in deciding the best management.

Methods Between October 1994 and August 2017, gamma knife surgery (GKS) was performed in six patients with AVMs and associated aneurysms. The patients consisted of four men and two women with a mean age of 37.8 years (range, 18–57 years). The mean follow-up was 34.2 months (range, 13–84 months). The mean maximal dose was 35.9 Gy and the mean margin dose to AVM was 18 Gy. Coil embolization was performed in one of the aneurysms prior to GKS. In our study, GKS was performed in six AVM-associated aneurysms. Of the six aneurysms, four were intranidal and two were pedicular. The mean volume of AVMs was 3.6 cm3 (range, 1.6–6.5 cm3).

Results The locations of aneurysms are as follows: four on posterior cerebral artery (PCA), one on posterior inferior cerebellar artery (PICA), and one on middle cerebral artery (MCA). Sublocation sites were MCA M3 above, PCA P3 above, and PICA distal. There were no GKS-related complications. Complete obliteration of AVM and aneurysm was documented in all four patients with intranidal aneurysm-associated AVMs. Both the aneurysm and AVM were completely obliterated in the two patients with proximal pedicular aneurysms.

Conclusion GKS is a possible treatment for AVM with associated intranidal or pedicular aneurysms located above P3 or M3, etc., in which there is less turbulent flow and jet flow.

Periprocedural intracranial hemorrhage after embolization of cerebral arteriovenous malformations: a meta-analysis

OBJECTIVE

The primary goal of the treatment of cerebral arteriovenous malformations (AVMs) is angiographic occlusion to eliminate future hemorrhage risk. Although multimodal treatment is increasingly used for AVMs, periprocedural hemorrhage after transarterial embolization is a potential endovascular complication that is only partially understood and merits quantification.

METHODS

Searching the period between 1990 and 2019, the authors of this meta-analysis queried the PubMed and Embase databases for studies reporting periprocedural hemorrhage (within 30 days) after liquid embolization (using cyanoacrylate or ethylene vinyl alcohol copolymer) of AVMs. Random effects meta-analysis was used to evaluate the pooled rate of flow-related hemorrhage (those attributed to alterations in AVM dynamics), technical hemorrhage (those related to procedural complications), and total hemorrhage. Meta-regression was used to analyze the study-level predictors of hemorrhage, including patient age, Spetzler-Martin grade, hemorrhagic presentation, embolysate used, intent of treatment (adjuvant vs curative), associated aneurysms, endovascular angiographic obliteration, year of study publication, and years the procedures were performed.

RESULTS

A total of 98 studies with 8009 patients were included in this analysis, and the mean number of embolization sessions per patient was 1.9. The pooled flow-related and total periprocedural hemorrhage rates were 2.0% (95% CI 1.5%-2.4%) and 2.6% (95% CI 2.1%-3.0%) per procedure and 3.4% (95% CI 2.6%-4.2%) and 4.8% (95% CI 4.0%-5.6%) per patient, respectively. The mortality and morbidity rates associated with hemorrhage were 14.6% and 45.1%, respectively. Subgroup analyses revealed a pooled total hemorrhage rate per procedure of 1.8% (95% CI 1.0%-2.5%) for adjuvant (surgery or radiosurgery) and 4.6% (95% CI 2.8%-6.4%) for curative intent. The treatment of aneurysms (p = 0.04) and larger patient populations (p < 0.001) were significant predictors of a lower hemorrhage rate, whereas curative intent (p = 0.04), angiographic obliteration achieved endovascularly (p = 0.003), and a greater number of embolization sessions (p = 0.03) were significant predictors of a higher hemorrhage rate. There were no significant differences in periprocedural hemorrhage rates according to the years evaluated or the embolysate utilized.

CONCLUSIONS

In this study-level meta-analysis, periprocedural hemorrhage was seen after 2.6% of transarterial embolization procedures for cerebral AVMs. The adjuvant use of endovascular embolization, including in the treatment of associated aneurysms and in the presurgical or preradiosurgical setting, was a study-level predictor of significantly lower hemorrhage rates, whereas more aggressive embolization involving curative intent and endovascular angiographic obliteration was a predictor of a significantly higher total hemorrhage rate.

Targeted embolization reduces hemorrhage complications in partially embolized cerebral AVM combined with gamma knife surgery

This study investigated the effect and safety of targeted embolization in partially embolized cerebral arteriovenous malformation (AVM) followed by gamma knife surgery (GKS). We retrospectively analyzed 86 AVM patients who were targeted embolized by Onyx followed by GKS for residual nidus. Embolization-related complications were collected and the clinical effect was evaluated. During targeted embolization, intranidus or hemodynamic aneurysms and AVM-related fistula were evaluated and targeted embolized. Patients with AVM-related aneurysms and fistula were divided into a targeted embolization group and non-targeted embolization group based on the retrospectively determined treatment strategy. The effect of targeted embolization on hemorrhage risk was evaluated. The overall annual hemorrhage rate was 1.66% with 2.26% for ruptured AVMs and 1.08% for unruptured lesions. The annual mortality rate was 0.4%. Only one in 16 patients with embolization-related complications had permanent neurologic deficit. Twenty-four of 29 cases with intranidus aneurysms were targeted embolized, four of five cases with hemodynamic aneurysms were targeted embolized and eight of nine cases with arteriovenous fistula were targeted embolized. Chi square results showed the hemorrhage complications in the target embolization group were significantly lower than those in the non-target embolization group (p < 0.01). Targeted embolization combined with GKS treatment decreased the annual hemorrhage rate and improved clinical outcome with low permanent complications in partially embolized AVMs. This method could be proposed for the treatment of large brain AVMs when a single-technique treatment is not feasible.

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.

Management of intracranial aneurysms associated with arteriovenous malformations

Intracranial or brain arteriovenous malformations (BAVMs) are some of the most interesting and challenging lesions treated by the cerebrovascular neurosurgeon. It is generally believed that the combination of BAVMs and intracranial aneurysms (IAs) is associated with higher hemorrhage rates at presentation and higher rehemorrhage rates and thus with a more aggressive course and natural history. There is wide variation in the literature on the prevalence of BAVM-associated aneurysms (range 2.7%–58%), with 10%–20% being most often cited in the largest case series. The risk of intracranial hemorrhage in patients with unruptured BAVMs and coexisting IAs has been reported to be 7% annually, compared with 2%–4% annually for those with BAVM alone. Several different classification systems have been applied in an attempt to better understand the natural history of this combination of lesions and implications for treatment. Independent of the classification used, it is clear that a few subtypes of aneurysms have a direct hemodynamic correlation with the BAVM itself. This is exemplified by the fact that the presence of a distal flow-related or an intranidal aneurysm appears to be associated with an increased hemorrhage risk, when compared with an aneurysm located on a vessel with no direct supply to the BAVM nidus. Debate still exists regarding the etiology of the association between those two vascular lesions, the subsequent implications for patients’ risk of hemorrhagic stroke, and finally the determination of which patients warrant treatment and when. The ultimate goals of the treatment of a BAVM associated with an IA are to prevent hemorrhage, avoid stepwise neurological deterioration, and eliminate the mortality risk associated with recurrent hemorrhagic events. The treatment is only justifiable if the risks associated with an intervention are lower than or equivalent to the long-term risks of disability or mortality caused by the lesion itself. When faced with this difficult decision, a few questions need to be answered by the treating neu-rosurgeon: What is the mode of presentation? What is the symptomatic lesion? Which one of the lesions bled? What is the relationship between the BAVM and IA? Is it possible to safely treat both BAVM and IA? The objective of this review is to discuss the demographics, natural history, classification, and strategies for management of BAVMs associated with IAs.

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.

Gamma Knife surgery for intracranial aneurysms associated with arteriovenous malformations

✓The incidence of aneurysms coexisting with arteriovenous malformations (AVMs) ranges between 2.7 and 16.7%. The anatomical relationship between the AVM and the aneurysm is critical in deciding the best management. As a broad guide, this relationship can be classified as follows: 1) aneurysms unrelated to the AVM; or 2) aneurysms located on the feeding vessels to the nidus, which may be far away from the nidus or close to it or even within the nidus itself. Although radiosurgery has been widely accepted as a method of choice for AVM treatment, the role of radiosurgery for arterial aneurysms has not been adequately discussed.

Multiple anterior inferior cerebellar artery aneurysms associated with an arteriovenous malformation: case report

BACKGROUND

Multiple aneurysms of the proximal part of the anterior inferior cerebellar artery (AICA) associated with a distal arteriovenous malformation (AVM) are extremely rare lesions.

METHODS

A 52-year-old man was admitted because of sudden headache. Neurological examination revealed ataxia. Computed tomography scan showed a right cerebellar and subarachnoid hemorrhage. Vertebral angiograms demonstrated 3 small aneurysms at the proximal part of the AICA and distal AVM.

RESULTS

A right-sided lateral retromastoid suboccipital craniectomy was performed. We observed strangulation and obliteration at the AICA due to multiple clipping for aneurysms. Thus, aneurysms could not be clipped. At 11 years after bleeding, vertebral angiograms showed that 3 aneurysms had slightly enlarged but the AVM remained unchanged. To date, the patient is still doing well except for dizziness.

CONCLUSION

This association is very rare at the AICA level, and definitive treatment of this association is sometimes complex.

Comparison of MR angiography and conventional angiography in the investigation of intracranial arteriovenous malformations and aneurysms in children

BACKGROUND

Magnetic resonance angiography (MRA) is an attractive alternative to conventional catheter angiography (CCA) in children, especially for the detection of intracranial arteriovenous malformations (AVMs) or aneurysms in the out-of-hours setting, because it has fewer risks and complications. OBJECTIVE. To compare MRA with CCA for the detection of intracranial AVMs, aneurysms and arterial anatomy in children.

MATERIALS AND METHODS

Retrospective blinded review of MRAs and CCAs by two independent paediatric radiologists, in a group of 19 children already diagnosed with AVMs, aneurysms and subarachnoid haemorrhage (SAH) and who had undergone both imaging techniques.

RESULTS

Abnormalities were identified on MRA in 15 of 19 patients and by CCA in 11 of 19 patients. MRA showed one aneurysm, nine AVMs, three haemorrhages and two indeterminate lesions. CCA showed nine AVMs and two indeterminate lesions. The two modalities showed excellent correlation in the detection of AVMs in nine patients. Vascular supply to the AVMs correlated well in four cases. There was complete disagreement in the determination of vessel supply in one case, and in two cases CCA showed additional vessel supply compared to MRA, while in two further cases MRA showed an additional vessel supply compared to CCA. CCA was superior to MRA in demonstrating arterial anatomy, except with regard to the anterior and posterior communicating arteries where MRA was superior.

CONCLUSIONS

The high sensitivity of MRA in the detection of AVMs when compared to CCA and the low incidence of aneurysms support the use of MRA as the initial imaging modality when intracranial haemorrhage is diagnosed on CT, especially in the out-of-hours setting.

Arteriovenous malformations

Arteriovenous malformations of the brain are congenital vascular lesions that affect 0.01-0.50% of the population, and are generally present in patients aged 20-40 years. The usual clinical presentations are haemorrhage, seizures, progressive neurological deficit, or headache. Results of natural history studies have shown a yearly haemorrhage rate of 1-4%. Frequency of rebleeding has increased over the years, and several factors that increase risk of haemorrhage have been identified. Although substantial, the morbidity associated with haemorrhages could be less than previously thought. Over the past decade, great advances have been made in application of endovascular embolisation techniques, stereotactic radiosurgery, and microsurgery, allowing effective multidisciplinary treatment of arteriovenous malformations, including those previously deemed to be untreatable. Increasing attention has been paid to management of flow-related aneurysms associated with these malformations. Finally, many reports of recurrent arteriovenous malformations have coincided with new theories regarding the embryogenesis of these disorders and laboratory work suggesting their proliferative potential.

Aneurysm of the anterior inferior cerebellar artery (AICA) associated with high-flow lesion: report of two cases and review of literature

OBJECTIVE AND IMPORTANCE

Although aneurysms of the anterior inferior cerebellar artery (AICA) are rare lesions, their occurrence in combination with high-flow lesions in the same arterial territory is even more striking. Two cases of an AICA aneurysm in combination with a high -flow lesion are described.

CLINICAL PRESENTATION

In one case, a 52-year-old female presented with cerebellar syndrome as the result of a left-sided cerebellar tumor. Angiography revealed a highly vascularized tumor and a broad-based aneurysm at the offspring of the left AICA. In the second case, a 17-year-old female presented with a right-sided cerebellar hemorrhage. Angiography revealed a large peripheral AICA aneurysm and a distal arteriovenous malformation (AVM) fed by the AICA.

INTERVENTION

In the first case, a left lateral suboccipital craniotomy was performed and a highly vascularized tumor was removed. The AICA aneurysm could not be adequately clipped and was subsequently wrapped with muscle and reinforced with fibrin glue. Pathological examination of the tumor revealed a hemangioblastoma. Five years after surgery, the patient experienced a subarachnoid hemorrhage. Subsequent vertebral angiography revealed local enlargement of the known AICA aneurysm just at the superior aspect, but the patient refused further treatment. In the second case, the patient sustained a novel cerebellar rebleed while awaiting surgery. A right-sided lateral retromastoid suboccipital craniotomy was performed and the AICA aneurysm could be successfully clipped. More peripherally, the AVM with two draining veins could be totally removed. Postoperative angiography revealed no residual aneurysm or AVM.

CONCLUSION

Several aspects of these cases are discussed, such as the rare occurrence of AICA aneurysm and the contribution of high-flow lesions to the genesis of the AICA aneurysms.