The cerebral hemorrhage can have different patterns involving the cerebral parenchyma, the ventricular system, or the subarachnoid space in varying combinations and at different locations. The presence of bleeding can be diagnosed using CT or MR. More difficult is the diagnosis of its pathogenesis. In many cases, the angiography can clearly show the cause of the hemorrhage, but in other cases it does not.

As we have described previously (Chaps. 11, 12, 13, and 16), in cases of bleeding due to aneurysms, AVM, and DAVF, the malformation can easily be diagnosed with angiography. Angiography can also show the venous thrombosis responsible of the hemorrhagic ischemia. Hemorrhages occur in many cases of arteriopathies and arteritis described in Chap. 17. To this group belong also hemorrhages due to drug abuse such as sympathomimetic drugs, heroin, cocaine, LSD, as well as those linked to alcohol abuse. In all these cases the angiography shows nonspecific changes of the vessels characterized by narrowing, dilatations, and sometimes aneurysms involving commonly medium-sized arteries.

The angiography, however, fails to demonstrate some vascular malformations such as the cavernous angioma and the telangiectasia. In spite of this the angiogram can be useful, excluding the presence of other vascular malformations such as an AVM. Also in some cases of SAH, the suspected aneurysm cannot be demonstrated. This uncommon condition has been discussed in Sect. 11.​11.