Types of Brain Aneurysms

There are several types of brain aneurysms classified by shape. These are saccular (also known as berry aneurysms), which are by far the most common. The less common fusiform and dissecting types. Brain aneurysms may also be classified by size (small, large, and giant), by their location, or by the cause such as a mycotic aneurysm (caused by an infection).  Most aneurysms occur where an artery branches, often at the base of the brain. The treatment options vary, depending on the type of aneurysm, its size, and its location.

Brain viewed from bottom showing brain stem, cerebellum, and arteries. Closeup of brain with two connected arteries on surface showing saccular aneurysm with neck ballooning out from artery wall where two arteries connect. Closeup of artery with fusiform aneurysm bulging out from all sides of artery. Fusiform aneurysm rarely has neck. Closeup of artery with giant aneurysm over 2.5 centimeters wide. Giant aneurysm can involve more than one artery. Closeup of mycotic aneurysm caused by infected artery wall. Mycotic aneurysm fairly rare.