Introduction: The risk of de novo aneurysm formation is presumed to increase because of increased arterial flow in brain AVMs. Little evidence to-date has been presented regarding the risk of aneurysmal formation under the influence of a concurrent AVM. We aim to determine this risk using our institutional data.
Methods: Retrospective review of brain AVM patients evaluated at our institution from 1990-2015 was performed. Demographic and baseline characteristics were examined. De novo aneurysm was defined as new aneurysm diagnosis after initial angiographic characterization of AVM. Exposure intervals were censored until obliteration for treated patients and last follow-up for untreated patients. All de novo aneurysms detected during the censored interval were captured, and the annual rate of de novo aneurysm formation was calculated.
Results: A total of 672 AVM patients with complete information were included. Overall age was 37.3 years(44.5% male), and overall size of AVM was 3.1 cm. Six patients(0.9%) with 8 de novo aneurysms were found in this cohort. In these six patients, the average age was 46.9 years, with 50.0% males. The average AVM size was 4.1cm (range: 3-8cm). Two patients had presented with AVM hemorrhage, and the most common presenting symptom was seizure(50.0%). Most patients underwent radiosurgery(83.3%). Four(66.7%) patients were diagnosed with de novo aneurysms after first AVM treatment. Six aneurysms(75.0%) were prenidal in location. The average aneurysm size at detection was 4.66mm. Only one patient received treatment specifically for the aneurysm, which was surgically obliterated. The total non-obliterated interval for AVM was 3811.47 years, and the calculated annual rate of de novo aneurysm formation was 0.21%.
Conclusions: The annual risk of de novo aneurysm formation was relatively low at 0.21%, despite having concurrent AVMs. Most of these aneurysms were prenidal. Patients developing de novo aneurysms were older in general and more likely to have larger AVMs.
Patient Care: The rate of de novo aneurysm is characterized in this study, which will improve our understanding of disease progression to better target follow-up monitoring and treatment strategies for AVMs
Learning Objectives: By the conclusion of this session, participants should be able to:
1. Appreciate the risk of de novo aneurysm formation in patients with AVMs
2. Understand the baseline factors associated with de novo aneurysm formation
3. Appreciate characteristics of de novo aneurysms