The many faces of intracranial arterial dissections.

Intracranial arterial dissecting diseases are rare and challenging diseases with a high associated morbidity and mortality. Their common pathomechanic origin is related to blood entering the vessel wall via an endothelial and intimal tear. Depending on the fate of the thus established intramural hematoma, different symptoms may ensue including mass effect, subarachnoid hemorrhage or ischemia. If the mural hematoma ruptures all vascular layers of the intradural artery, a subarachnoid hemorrhagic will occur. If the intramural hematoma reopens distally into the parent vessel on the other hand, ischemic embolic events may happen following intramural clot formation. If the mural hematoma does neither open itself into the parent vessel nor into the subarachnoid space, the vessel wall may dilate leading to occlusion of perforator branches and local ischemia. Organization of the mural hematoma may result in a chronic dissecting process which may eventually lead to formation of a "giant partially thrombosed" aneurysm with thrombus of varying ages within the vessel wall, ingrowth of vasa vasorum and recurrent dissections with subsequent growth of the aneurysm from the periphery. Treatment strategies of these diseases should take the underlying pathomechanism into consideration and include, depending on the presentation medical treatment, parent vessel occlusion, flow reversal or diversion, surgical options or a combined treatment protocol.