There is evidence of subarachnoid blood: location by sulcus anatomic site.

There is evidence of intra ventricular blood products.

There is evidence of parenchymal blood products or hematoma.

There is evidence of SAH in relationship to cortical vein(s) consistent with cortical vein thrombosis.

There is evidence of SAH near falx (possibly post traumatic).

There is evidence of vertex sulcal blood (possibly vasoconstrictive vasc. disorders or vasculitis or coagulopathy source).

There is evidence of thrombosed major arterial vessel.

There is evidence of thrombosed vascular malformation simulating acute SAH.

There is evidence of acute or subacute intercurrent stroke (with or without hemorrhage, or completed stroke with chronic blood products following coagulative necrosis.

There is evidence of acute cytogenic edema consistent with acute hemorrhagic or nonhemorrhagic stroke.

There is evidence of completed stroke: subacute, chronic with completed encephalomalacia.

There is evidence of an atherosclerotic sacculo-fusiform aneurysm with or without internal thrombus.

There is evidence of giant aneurysm with or without internal thrombus.

There is evidence of mycotic aneurysm with or without internal thrombus or even abscess.

There is evidence of arteriosclerotic dolichoectasia.

There is evidence of meningoangiomatosis, of any non shunting vascular malformations simulating parenchymal hemorrhage.

There is evidence of hemorrhagic met, or other tumor as basis for SAH.

There is evidence of multicentric bleeding sites for coagulopathy as cause for bleeding.

There is evidence of hydrocephalus or pial siderosis from prior SAH.

There is evidence of intercurrent hydrocephalus or herniation syndromes.

Other abnormalities.