International Stroke Conference
February 19–21, 2020

Kat Dakay, DO

Deciding how to manage unruptured intracranial aneurysms is a common challenge in neuroendovascular surgery, as many of these aneurysms are incidentally found on imaging performed for other reasons. The classic dogma of the ISUIA study stratifies rupture risk based on size and location; however, this is an oversimplified picture. In this ISC session, the speakers discussed complex anatomical features, neuroimaging findings, and lifestyle counseling for patients with unruptured intracranial aneurysms.

Dr. Juhana Frösen discussed the influence of wall structure on rupture risk; the wall structure of aneurysms is very heterogenous. This may explain why some small aneurysms can rupture. Macrophages and inflammation can lead to aneurysm wall growth, which increases the stress on the aneurysm and can increase the risk of rupture. Future targets for drug research may include reducing inflammation and reducing wall growth.

Dr. Waleed Brinjikji discussed how MRI vessel wall imaging is sometimes used to guide treatment decision making. Black blood imaging showing enhancement in the vessel wall has been postulated to correlate with an increased rupture risk; however, it is not clear whether the enhancement represents true inflammation or if it is due to stasis within the dome of the aneurysm. He also showed several examples of larger, dysplastic appearing aneurysms that did not demonstrate enhancement on MRI vessel wall imaging as a counterpoint that vessel wall imaging can be misleading in some cases and that it is of limited use in guiding management at this time. Dr. Michael Levitt commented that he sometimes uses vessel wall imaging when a patient with a diffuse subarachnoid hemorrhage has a nonspecific bleeding pattern and multiple aneurysms; vessel wall imaging may show one avidly enhancing aneurysm among them that may suggest that it is the culprit aneurysm. 

Next, Dr. Sepideh Amin-Hanjani spoke about various morphologic features that can be measured from the 3-D spin of the aneurysm, and how these may correlate with rupture risk. These include nonsphericity, bottleneck factor, height to width ratio, among others. However, many of these studies were limited because they were cross-sectional (i.e., whether a given aneurysm ruptured or not) and not longitudinal (not predicting risk of future rupture). The use of these various measurements is limited at this time. 

And lastly, Dr. Mervyn Vergouwen spoke about counseling patients on unruptured aneurysms. Avoid using fear-inducing statements like “ticking time bomb” to describe aneurysms, but do counsel patients on the importance of smoking cessation, controlling blood pressure, and avoiding recreational substances such as cocaine or other sympathomimetics that can acutely raise blood pressure. The PHASES score is a helpful starting point, though limited, for assessing aneurysm rupture risk based on several patient and aneurysm-specific features. 

In all, the symposium outlined the many risk factors for aneurysm rupture, but also the limitations of relying on any one single modality to predict which aneurysms should be treated. Current scoring systems are helpful in providing a reasonable estimate of aneurysm risk; however, additional patient-specific factors and morphologic characteristics often play a role in this very nuanced decision-making process.