Angiogram-negative subarachnoid hemorrhage: Is it a correct definition?

Dear Editor,\r\nSpontaneous, nontraumatic subarachnoid hemorrhage (SAH)\r\nis a significant clinical problem thatmost commonly occurs as\r\na result of aneurysm rupture [4].\r\nIn approximately 15 % of cases, no aneurysm or other\r\nvascular malformation can be identified as the origin of the\r\nhemorrhage by cerebral angiography [4].\r\nIn the English literature, over time, several definitions\r\nhave been used to define these cases: idiopathic SAH or\r\nperimesencephalic nonaneurysmal subarachnoid hemorrhage\r\n(PN-SAH), angiogram-negative subarachnoid hemorrhage\r\n(AN-SAH), and nonaneurysmal SAH [2, 4].\r\nAN-SAH is nowadays the widely accepted term for such\r\nnosological entities [2].\r\nIn 1985, Van Gjin et al. named this type of subarachoid\r\nhemorrhage as perimesencephalic subarachnoid hemorrhage\r\nbecause of its anatomical blood distribution [8]. This definition\r\nwas insufficient to describe those cases in which the\r\nhemorrhage extended to the carotid cisterns, Sylvian fissure,\r\nand/or interhemispheric fissure [7]. For this reason, the\r\ndefinition of AN-SAH has been popularized by the relevant\r\nliterature. As a matter of fact, AN-SAH is definitely used as\r\nthe prevalent and widely accepted definition in the medical\r\nliterature [1].\r\nBut is it the best definition?\r\nWe report two cases in which spontaneous SAH revealed\r\nan aneurysmal malformation that was clearly not responsible\r\nfor the subarachnoid bleeding. Can these cases still be defined\r\nas AN-SAHs?