Clinical manifestations including the angiographic findings suggest that the spontaneous carotid-cavernous fistulae (CCF) are more likely considered etiologically to be one type of the dural arteriovenous fistulae in the cavernous region. This concept have been elaborated by Newton and Hoyt (1970) and also by us (1971) . However, this is not beyond working hypothesis. Recently we have encountered an autopsied case of spontaneous CCF. This 54-year-old female was expired from incidental apopletic complication two weeks after the selective external carotid ligation combined with embolization by polyurethane foam. At autopsy the sphenoid bone was removed including the sella turcica. After fixation, micropaque solution mixed with Evans blue was injected through the internal carotid artery. Blocks were cut in coronal section and stained with HE and Elastica van Gieson. Cavernous sinuses were divided into several sizes of small venous lakes, whose septa of connective tissues contained small arteries and veins. Injected dye not only was found in the arterioles in the septa, but also leaked out into the veins, connective tissues of the septa and also into the venous sinus. Walls of the arterioles running in the septa were partly thick and partly thin due to proliferation and interruption of the internal elastic lamina, and their lumina were irregularly narrowed and obstructed with concomitant organized thrombi. In addition, there were vessels which were hardly called either arteries or veins, and which had the appearance of venous or capillary angioma. Another interesting findings were observed in the thickened septa of the sinus wall, which are characterized by proliferation of elastica especially around the thrombosed small arteries. These histological features are reasonably considered to be that of arteriovenous malformation. Discussions were made from the histopathological standpoint on atherosclerosis, moya-moya disease, fibromuscular hyperplasia and Ehlers-Danlos syndrome.
From the clinical point of view, spontaneous CCF can be differentiated from the traumatic one. The former were commonly seen amongst the middle aged female and frequently accompanied by headache. Multiple feeders mostly of external carotid artery contribute to the fistula. Furthermore, except for a few cases, they were rarely cured with surgery but rather cured or improved either spontaneously or in the process of the angiographic examinations.
According to these clinical, angiographic and histological observations, it should be reasonably said that the spontaneous CCF is one type of dural arteriovenous fistula in nature and is the result of the rupture of the arteriovenous malformation of the dural vessels in the septa of the cavernous sinus directly into the cavernous sinus or via bleeding into the connective tissue of the septa.
