Figure 6.

Dissecting aneurysmal vasculopathies: Whereas in "classic" dissecting aneurysms a transmural dissection leads to an acute SAH, partially thrombosed aneurysms are characterized by recurrent subacute and non-transmural dissections that result in repeated subadventitial bleeding and progressive enlargement of the aneurysm. If SAH in these types of aneurysms was present, the neck of the aneurysm is most often involved, presumably due to a transmural dissection at this site. Arterial dissection might therefore generate a wide range of intracranial arterial aneurysms depending on the impact of extrinsic factors (inflammation, hemodynamic forces, etc.), the vessel wall integrity and the intrinsic repair systems.