Background: Even though ruptured intracranial aneurysm is a major cause of non-traumatic subarachnoid hemorrhage (SAH), non-aneurysmal SAH has a good prognosis with few neurologic complications. The gold standard for detecting the vascular pathology is digital subtraction cerebral angiography (DSA).
Objective: The primary objective of the present study was to clarify cerebral angiographic findings in patients with nontraumatic subarachnoid hemorrhage (SAH); to define the incidence of nonaneurysmal SAH. The secondary aim was to review the clinical data of all of the patients diagnosed with non-traumatic SAH in order to determine the associated etiology.
Material and Method: This retrospective, descriptive study, was conducted at Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, between January 2005 and November 2010. The authors reviewed the medical records, cranial computed tomography (CT) and DSA of patients with non-traumatic SAH. The DSA findings were assessed and the correlation with clinical data and CT pattern determined.
Results: The author included and analyzed the records of 118 non-traumatic SAH patients (66 females, 52 males). The DSA discovered vascular lesions in 62.6% of cases (57.6% aneurysm, 4.2% arteriovenous malformation (AVM) and 0.8% Moyamoya disease). A total of 76 aneurysms were found in 68 cases. The location of the aneurysms included: 35.5% anterior communicating artery, 17.1% posterior communicating artery, 15.7% middle cerebral artery, 11.8% internal carotid artery, 2.6% basilar artery, 1.3% vertebrobasillar junction and 10.5% others. The prevalence of nonaneurysmal SAH was 42.4% (50/118). In the multivariate analysis, hypertension was the factor most strongly associated with aneurysmal SAH on the DSA (p = 0.029). The location of SAH on Sylvian fissure was most frequently associated with the cause of aneurysms. In another way, tentorial cerebelli SAH was most commonly associated with a non-aneurysm cause.
Conclusion: The present study revealed that the major cause of non-traumatic SAH is cerebral aneurysm. The factors associated with aneurysmal SAH included: hypertension and Sylvian fissure SAH. Tentorial cerebelli SAH was most commonly associated with a non-aneurysm cause.

Keywords: Cerebral angiographic finding, Non-traumatic subarachnoid hemorrhage, Associated factors