ABSTRACT
Despite these similarities, there are major differences between the cerebral vessels and the coronary arteries or other muscular arteries. The cerebral vessels are histologically different: they have no external elastic lamina and they have a thinner tunica media and trivial adventitia; this makes these vessels quite fragile. They also differ from the coronary arteries in being partly (i.e., the petrous and cavernous carotids) surrounded by bone or rigid and fibrous tissue (i.e., the dura mater). Combined with significant tortuosity in their proximal segments, this makes the navigation of endovascular devices to the intracranial vessels extremely difficult, if not impossible at times, which greatly increases the risk of vessel injury and perforation during endovascular therapy. The most tortuous and rigid segments of artery are the petrous and cavernous segments of the ICA. As a consequence, access to the MCA may be difficult. This makes the endovascular AIS approach problematic because approximately 80% of large-vessel AISs involve the MCA.
