Intracranial dural arteriovenous and carotid-cavernous fistulae and paragangliomas.

This chapter summarizes the diagnostic criteria and reliability of ultrasound detection of intracranial dural arteriovenous fistulae (DAVF), carotid-cavernous fistulae (CCF), and paragangliomas. In arteries feeding DAVF ultrasound shows increased blood flow, systolic and, especially, end-diastolic velocities causing a decreased resistance index (RI), and an increased diameter. The RI of the external carotid artery (ECA; cutoff: right, 0.72; left, 0.71) yielded a sensitivity of 74%, a specificity of 89%, a positive predictive value of 79%, and a negative predictive value of 86%, for detecting DAVF. Preliminary data suggest that contrastenhanced transtemporal color duplex sonography (CDS) may be useful for screening patients with clinical suspicion of DAVF of the transverse/sigmoid sinus. Most patients with CCF show a dilated superior ophthalmic vein with reversed blood flow direction. Decreased RI and increased blood flow and flow velocities are found in internal carotid arteries supplying the cavernous sinus directly through a fistula (type A CCF) at extracranial CDS, and sometimes in the cavernous sinus of CCF at transtemporal CDS. Definite diagnosis of DAVF and CCF is performed with catheter angiography. Typical CDS findings observed in paragangliomas of the head and neck include their solid, well-defined, and hypoechoic appearance, hypervascularity, intratumoral flow direction, displacement of the internal carotid artery (ICA) and ECA as well as the internal jugular vein. Whereas carotid body tumors can be visualized completely in most patients, other paragangliomas, for example, of the vagal nerve, are at best partially depicted due to their location in the upper neck. Confirmation of ultrasound suspicion of paraganglioma by magnetic resonance imaging or computed tomography of the neck is mandatory.