Posterior fossa arteriovenous malformations: Significance of higher incidence of bleeding and hydrocephalus

The incidence of infratentorial arteriovenous malformation-associated aneurysms: an institutional case series and systematic literature review

BACKGROUND

Arteriovenous malformation (AVM)-associated aneurysms represent a high-risk feature predisposing them to rupture. Infratentorial AVMs have been shown to have a greater incidence of associated aneurysms, however the existing data is outdated and biased. The aim of our research was to compare the incidence of supratentorial vs infratentorial AVM-associated aneurysms.

METHODS

Patients were identified from our institutional AVM registry, which includes all patients with an intracranial AVM diagnosis since 2000, regardless of treatment. Records were reviewed for clinical details, AVM characteristics, nidus location (supratentorial or infratentorial), and presence of associated aneurysms. Statistical comparisons were made using Fisher's exact or Wilcoxon rank sum tests as appropriate. Multivariable logistic regression analysis determined independent predictors of AVM-associated aneurysms. As a secondary analysis, a systematic literature review was performed, where studies documenting the incidence of AVM-associated aneurysms stratified by location were of interest.

RESULTS

From 2000-2024, 706 patients with 720 AVMs were identified, of which 152 (21.1%) were infratentorial. Intracranial hemorrhage was the most common AVM presentation (42.1%). The incidence of associated aneurysms was greater in infratentorial AVMs compared with supratentorial cases (45.4% vs 20.1%; P<0.0001). Multivariable logistic regression demonstrated that infratentorial nidus location was the singular predictor of an associated aneurysm, odds ratio: 2.9 (P<0.0001). Systematic literature review identified eight studies satisfying inclusion criteria. Aggregate analysis indicated infratentorial AVMs were more likely to harbor an associated aneurysm (OR 1.7) and present as ruptured (OR 3.9), P<0.0001.

CONCLUSIONS

In this modern consecutive patient series, infratentorial nidus location was a significant predictor of an associated aneurysm and hemorrhagic presentation.

Angiographic analysis on posterior fossa hemorrhages and vascular malformations beyond aneurysms by CT angiography and digital subtraction angiography

Background

Posterior fossa malformations are less common than supratentorial malformations, but hemorrhages in posterior fossa are more serious due to presence of vital structures within this region. Most common cause of bleed in posterior fossa apart from hypertension is aneurysms but other vascular malformations are also there which cause hemorrhage. Here we discuss other causes of posterior fossa bleed beyond aneurysms.

Results

A total of 80 patients were evaluated: 47 (58.8%) had aneurysms, 29 (36.3%) had arteriovenous malformations, one each had developmental venous anomaly and brainstem cavernoma. Thirty vascular malformations were detected, of which 18 (62.1%) were pial arteriovenous malformations (AVMs), 11 (37.9%) were dural arteriovenous fistulas (dAVF), and one had developmental venous anomaly (DVA). Six patients of AVM underwent both DSA and CTA, and CTA could correctly diagnose only 2 of 4 pial AVMs detected by DSA. Among two dAVFs detected by DSA, CTA could demonstrate dAVF only in one patient.

Conclusion

CTA could be used as alternative to DSA in diagnosis and characterizing aneurysms in posterior fossa but for AVMs, 3D-CTA cannot replace DSA; however potential of time-resolved CTA (TR-CTA) appears promising.

Hydrocephalus in children with ruptured cerebral arteriovenous malformation

OBJECTIVE

Hydrocephalus is a strong determinant of poor neurological outcome after intracerebral hemorrhage (ICH). In children, ruptured brain arteriovenous malformations (bAVMs) are the dominant cause of ICH. In a large prospective cohort of pediatric patients with ruptured bAVMs, the authors analyzed the rates and predictive factors of hydrocephalus requiring acute external ventricular drainage (EVD) or ventriculoperitoneal shunt (VPS).

METHODS

The authors performed a single-center retrospective analysis of the data from a prospectively maintained database of children admitted for a ruptured bAVM since 2002. Admission clinical and imaging predictors of EVD and VPS placement were analyzed using univariate and multivariate statistical models.

RESULTS

Among 114 patients (mean age 9.8 years) with 125 distinct ICHs due to ruptured bAVM, EVD and VPS were placed for 55/125 (44%) hemorrhagic events and 5/114 patients (4.4%), respectively. A multivariate nominal logistic regression model identified low initial Glasgow Coma Scale (iGCS) score, hydrocephalus on initial CT scan, the presence of intraventicular hemorrhage (IVH), and higher modified Graeb Scale (mGS) score as strongly associated with subsequent need for EVD (all p < 0.001). All children who needed a VPS had initial hydrocephalus requiring EVD and tended to have higher mGS scores.

CONCLUSIONS

In a large cohort of pediatric patients with ruptured bAVM, almost half of the patients required EVD and 4.4% required permanent VPS. Use of a low iGCS score and a semiquantitative mGS score as indicators of the IVH burden may be helpful for decision making in the emergency setting and thus improve treatment.

Single-session Curative Embolization of Unruptured Cerebellar Arteriovenous Malformation with Precipitating Hydrophobic Injectable Liquid

Microsurgery is the treatment of choice for cerebellar arteriovenous malformations (AVMs). Nevertheless, endovascular therapy aims to be an effective treatment since the introduction of new embolic agents. Cerebellar AVMs represent a subgroup of vascular lesions with a high rate of hemorrhagic presentation compared with their cerebral counterpart. Moreover, they have a higher incidence of flow-related aneurysms when diagnosed. With this in mind, prompt treatment must be performed to avoid rebleeding with devastating consequences. Herein, we present the case of an unruptured cerebellar AVM treated with precipitating hydrophobic injectable liquid (PHIL) with complete obliteration.

Cerebellar Arteriovenous Malformation Rupture Despite Apparent Angiographic Obliteration

BACKGROUND

Arteriovenous malformations (AVMs) can occur in all regions of the brain and spinal cord, with clinical consequences and risks varying by location. Delayed AVM rupture despite digital subtraction angiography-confirmed obliteration post-radiation is exceedingly rare.

CASE DESCRIPTION

To our knowledge, we present the first documented case of delayed hemorrhage associated with a cerebellar AVM 5 years after linear accelerator-based radiation in a man aged 31 years despite apparent angiographic obliteration.

CONCLUSIONS

Intracranial hemorrhage after radiosurgery in digital subtraction angiography-confirmed obliterated AVMs is rare, with limited understanding of risk factors, appropriate preventative management, and mechanisms of occurrence. This case serves to demonstrate the need for greater awareness of this rare complication, as well as the need for appropriate surveillance and management strategies.

Risk Assessment of Hemorrhage of Posterior Inferior Cerebellar Artery Aneurysms in Posterior Fossa Arteriovenous Malformations

BACKGROUND

Posterior fossa arteriovenous malformations (AVMs) are associated with increased risk of rupture and severe consequences from such rupture. The hemorrhagic risk of prenidal aneurysms (anr) on the posterior inferior cerebellar artery (PICA) may exceed that of the AVM in posterior fossa AVMs fed by PICA (PICA-AVM).

OBJECTIVE

To characterize the relative risks of aneurysm and AVM hemorrhage in patients with posterior fossa AVMs.

METHODS

We retrospectively reviewed patients diagnosed with AVM. Patients with posterior fossa AVMs were divided into 3 groups: PICA-AVM with prenidal aneurysm (PICA-AVM-anr group), PICA-AVM without prenidal aneurysm (PICA-AVM group), and AVMs without PICA feeder with/without aneurysm (AVM-only group). Patient and lesion characteristics and treatment outcomes were compared. ANOVA and chi squared tests were used for statistical analyses.

RESULTS

Our cohort included 85 patients. Mean age was 45.3 ± 18.1 yr, with 43(50.6%) female patients. Fifty-one patients (60.0%) had hemorrhagic presentation, and 27 (31.8%) experienced acute hydrocephalus. Patients in the PICA-AVM-anr group (n = 11) were more likely to present with aneurysmal subarachnoid hemorrhage (SAH; P = .005) and less likely to have AVM rupture (P &lt; .001). Ten (90.9%) patients presented with hemorrhage, 6 (60.0%) of which resulted from aneurysm rupture. Of these 6, 5 (83.3%) had acute hydrocephalus. No patients with AVM rupture had hydrocephalus. Eight (72.7%) received aneurysm treatment prior to AVM treatment. There were no significant differences in post-treatment outcomes dependent on treatment order.

CONCLUSION

In addition to relatively higher risk of AVM rupture from infratentorial location and prenidal aneurysm, a higher risk of aneurysm rupture rather than AVM rupture was observed in patients with PICA-AVM-anr complex.

Microsurgical Outcome of Cerebellar Arteriovenous Malformations: Single-Center Experience

OBJECTIVE

We aimed to describe our single-center experience in treating cerebellar arteriovenous malformations (AVMs) with microsurgical resection.

METHODS

During a 16-year period, 181 patients with cerebellar AVMs were surgically treated at the Department of Neurosurgery in Beijing Tiantan Hospital. Patient functional status was evaluated using modified Rankin Scale (mRS) scores both before treatment and at the last follow-up. The mRS scores at the last follow-up were dichotomized as good outcome (mRS <3) and poor outcome (mRS ≥3). The treatment modalities, post-treatment complications, obliteration rate, and follow-up outcomes were analyzed.

RESULTS

Of the 181 patients, 172 (95%) patients presented with initial hemorrhage and 62 (34%) patients experienced rehemorrhage before microsurgical treatment. Complete obliteration of the AVMs was achieved in 177 (97.8%) patients. Good functional outcome was achieved in 144 (80%) of the patients. The surgical mortality rate was 4.4% (8/181), and overall mortality rate was 6.6% (12/181). Poor outcome was significantly associated with increasing age (P = 0.035; odds ratio [OR], 1.030; 95% CI 1.002-1.060), presurgical mRS ≥3 (P = 0.029; OR, 2.563; 95% CI 1.101-5.968), eloquent AVM location (P = 0.015; OR, 3.058; 95% CI 1.244-7.516), and presurgical rehemorrhage (P = 0.008; OR, 3.266; 95% CI 1.358-7.858).

CONCLUSION

Good outcome can be achieved by microsurgical resection in most patients with cerebellar AVMs. Increasing age at surgery, poor presurgical functional status, eloquent AVM location, and presurgical rehemorrhage are independent predictors of poor outcomes after AVM resection. We recommend early surgical resection for all surgically accessible cerebellar AVMs to prevent subsequent hemorrhage and resultant poor neurologic outcomes.

Cerebellar Arteriovenous Malformations: Clinical Feature, Risk of Hemorrhage and Predictors of Posthemorrhage Outcome

OBJECTIVE

We aimed to summarize the clinical presentation, risk of hemorrhage, and predictors of posthemorrhage outcome in patients with cerebellar arteriovenous malformations (AVMs).

METHODS

We searched our AVM database at Beijing Tiantan Hospital and identified 225 patients with cerebellar AVMs between the year 2000 and 2015. The clinical presentation and hemorrhage risk were analyzed in all patients. Further analysis of predictors for immediate posthemorrhage outcome was performed in patients with ruptured AVMs. Posthemorrhage modified Rankin Scale (mRS) scores were dichotomized into nonsevere outcome (mRS ≤3) and severe outcome (mRS >3). Univariate and multivariate logistic regression analyses were applied to test the risk factors of hemorrhage and predictors of severe outcome.

RESULTS

Of the 225 patients, 197 (88%) presented with hemorrhage. Patients with initial hemorrhage were much younger than those with unruptured AVMs (univariate: P = 0.003; multivariate: P = 0.002). Single arterial supply (odds ratio [OR], 2.846; 95% confidence interval [CI], 1.022-7.922) and exclusively deep venous drainage (OR, 3.361; 95% CI, 1.045-10.813) were the other 2 independent risk factors for hemorrhagic presentation. Regarding the neurologic outcome immediately after hemorrhagic presentation, we used 3 models of multivariate logistic regression. Severe neurologic outcome (mRS >3) was associated with eloquent or deep AVM location, associated aneurysm, and the presence of intraventricular hemorrhage (all P < 0.05).

CONCLUSION

Cerebellar AVMs have an aggressive nature of hemorrhage. Younger age, single feeding artery, and exclusively deep venous drainage were independent risk factors for hemorrhagic presentation. Eloquent location, associated aneurysm, and presence of intraventricular hemorrhage may predict severe immediate posthemorrhage outcome.