NOS3 and Dilatation of the cerebral artery: In the last two decades, investigators across the world extensively explored relationship between eNOS polymorphisms and hemorrhagic cerebral vascular diseases, especially for intracranial aneurysm (IA) and its associated aneurysmal subarachnoid hemorrhage (aSAH), yet the relationship between eNOS polymorphisms and hemorrhagic cerebral vascular diseases is still controversial.