Ultrasonography in Intracranial Dural Arteriovenous Fistula

Intracranial dural arteriovenous fistulas (AVFs) are abnormal arteriovenous shunts located in the intracranial dura mater. While invasiveness of conventional cerebral catheter angiography impedes regular investigation, more and more studies have attempted to use ultra-sonography to detect hemodynamic changes associated with dural AVFs. For example, the use of carotid duplex sonography in patients with dural AVFs has shown that these patients usually have a lower resistance index than normal subjects in the feeding arteries, including the external carotid artery and its branches. In addition, cerebral circulation time (CCT), which is the time delay between enhancement in the carotid artery and the contralateral internal jugular vein after injection of a sonographic enhancing agent, can be measured using carotid duplex sonography. CCT values were shown to be significantly lower in dural AVF patients than those in control subjects. Furthermore, transcranial color-coded sonography may show high flow velocity, reverse flow direction and abnormal Doppler waveforms in cerebral veins/sinus and in the superior ophthalmic veins of dural AVF patients. While early diagnosis with long-term follow-up is important in dural AVFs, ultrasonography could be a potential screening and follow-up tool in patients with dural AVFs, considering the convenience, noninvasiveness, low cost and reproducibility of results with this procedure.