[Two cases of thrombosis of an aneurysm in the acute stage].

Thrombus formation within aneurysm is common and has generally been proved to be a slowly progressive phenomenon. We report two cases of acute completely thrombosis of aneurysms. The initial angiogram failed to reveal aneurysm and other etiology of subarachnoid hemorrhage. CT revealed diffuse cisternal blood and acute hydrocephalus. We decided to operate on these patients in the acute stage because of the generally-known strict correlation between the amount of cisternal high density on CT and the subsequent development of vasospasm and ischemic event. Case 1. A 68 year-old female was admitted on Day 1 with neurological deterioration of Grade 3 (H & K). Complete angiographic study was done, including the basal view and stereotechnique, but failed to reveal aneurysm. On Day 2 we operated on this patient and discovered a thrombosed aneurysm of the anterior communicating artery (3 X 7 mm in size). Case 2. A 51 year-old male suffering from subarachnoid hemorrhage was transferred to our hospital on Day 0. Emergency angiography gave no information, but the pattern of cisternal clots on CT was suggested the existence of an aneurysm of the right internal carotid artery. The next day we performed angiography once more, at that time 2 X 5 mm internal carotid bifurcated aneurysm was revealed. Shortly thereafter we operated and found the intra-aneurysmal clot. Through consideration of these we have reached the following conclusions. When CT findings in a patient with subarachnoid hemorrhage show the diffuse cisternal clots due to rupture of aneurysm, we should consider immediate surgery even if the angiogram is negative in order to lessen the risk of delayed vasospasm.(ABSTRACT TRUNCATED AT 250 WORDS)