Cutaneous Signs of Vascular Disorders: Carotid–Cavernous Sinus Fistula

Redness, irritation, and diplopia developedover 2 to 3 weeks in a 55-yearoldman's left eye (A). The injectionworsened and was unresponsive toeye drops. Ptosis, mild proptosis, andelevated intraocular pressure developed.A bruit was auscultated overthe affected eye.Contrast-enhanced CT scans (Band C) demonstrated an enlarged,bulging, convex-bordered, enhancingleft cavernous sinus; mild left proptosis;and dilated left posterior ciliaryand superior ophthalmic veins.The diagnosis is an arteriovenousfistula--in this case either aninternal carotid artery (ICA) cavernoussinus fistula or a dural sinusfistula. The distinction between thesefistulas depends on which arterialvessel is abnormally communicatingwith the cavernous sinus (ie, thelarger intracavernous ICA or a smallermeningeal branch that suppliesthe dural walls of the cavernoussinus). The definitive diagnosis canbe made with either conventional an- giography or magnetic resonance angiography(MRA).Figure D, the collapsed imagefrom a flow-sensitive 2-dimensionaltime-of-flight MRA, depicts flowingblood in large intracerebral vessels asareas of high (white) signal. Extravasatedblood is seen outside the lumenof the left intracavernous ICA(L); whereas in the right cavernoussinus, the blood is flowing within theintracavernous ICA (R). The basilarartery is seen in the center.A carotid cavernous sinus fistulacan be congenital, may occur aftersevere head trauma, or can developspontaneously. Spontaneous developmentmay be attributable to a rupturedintracavernous aneurysm. Thiscan be lifesaving, because morbidityand mortality from a ruptured aneurysminto the subarachnoid space isfar worse than bleeding and fistulaformation to the venous space of thecavernous sinus. A history of severehead trauma--with or without a confirmeddiagnosis of skull base fracture--may be elicited. Arterial hypertensionand atherosclerosis also predisposeto carotid cavernous sinusfistula.Dural sinus fistulas may closespontaneously. They involve less arteriovenousshunting and thereforecause fewer symptoms than ICA cavernoussinus fistulas. Because of theirhigher pressure/flow, the latter lesionsoften require embolization toprevent ischemic injury to the eyeand complications of exposure fromproptosis.This patient underwent intravascularclosure of the fistula. His conditionimproved dramatically withindays of the procedure.