Spontaneous Subarachnoid Hemorrhage Induced by Warfarin Use

Introduction: The most frequent cause of spontaneous subarachnoid hemorrhage (SAH) is the rupture of a brain aneurysm. Approximately 5% of cases of spontaneous SAH did not show changes on magnetic resonance imaging (MRI) or angiography that explain such bleeding. The objective of this study was to report a case of spontaneous SAH induced by warfarin, where there was no evidence of any vascular malformation. Case Report: A 59 year-old male patient developed a sudden onset severe headache while in the shower. The patient had a history of mitral valve disease and valve replacement 23 years before and hypertension monitored by a cardiologist with 5 mg warfarin sodium daily. Computed tomography (CT) scan revealed a SAH. Laboratory tests showed an International Normalized Ratio (INR) of 2.22 (normal: 1 to 1.2). Cerebral angiography and neuraxis MRI were performed and  showed no aneurysms or other vascular malformations. Conclusion: The occurrence of hemorrhageassociated with warfarin treatment is a well-documented event in the literature. However, the isolated occurrence of SAH in these patients is a rare event. To prove that SAH is indeed attributed to anticoagulation, it is necessary to excludethe presence of aneurysms and other vascular diseases by imaging techniques.