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Arterial aneurysms associated with cerebral arteriovenous malformations: classification, incidence, and risk of
G Redekop1, K TerBrugge, W Montanera
1Department of Surgery, The University of British Columbia, Vancouver, Canada.
Insights
A new classification system for aneurysms associated with arteriovenous malformations (AVMs) identifies intranidal and flow-related types. Intranidal aneurysms carry a high hemorrhage risk, while distal aneurysms may regress after AVM treatment.
Area of Science:
- Neurosurgery
- Vascular Neurology
- Radiology
Background:
- Arteriovenous malformations (AVMs) are complex vascular anomalies.
- Aneurysms can be associated with AVMs, posing significant clinical challenges.
- Understanding the classification and natural history of these aneurysms is crucial for patient management.
Purpose of the Study:
- To develop a classification system for aneurysms associated with AVMs.
- To determine the incidence and bleeding rates of these aneurysms.
- To evaluate the impact of AVM treatment on aneurysm behavior.
Main Methods:
- Retrospective analysis of 632 patients with AVMs.
- Classification of aneurysms into intranidal, flow-related, and unrelated types.
- Assessment of hemorrhage rates and follow-up angiography after AVM treatment.
Main Results:
- Intranidal aneurysms occurred in 5.5% and flow-related in 11.2% of patients.
- Intranidal aneurysms showed a significantly higher presentation with hemorrhage (72%) and a 9.8% annual bleeding risk.
- Distal aneurysms demonstrated a high probability of regression following substantial or curative AVM treatment.
Conclusions:
- Aneurysms associated with cerebral AVMs can be categorized as intranidal, flow-related, or unrelated.
- Intranidal aneurysms are strongly linked to hemorrhagic presentation and increased bleeding risk.
- Flow-related aneurysms may lead to hemorrhage from either the aneurysm or the AVM itself.
- Aneurysms on distal feeding arteries show regression potential with effective AVM therapy.
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.