Ultrasound findings in spontaneous extracranial vertebral artery dissection.

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Abstract
In this study we analyzed the value of ultrasound examination for diagnosis of vertebral artery dissection. The vertebrobasilar arterial system was assessed in 14 patients using transcranial and extracranial pulsed-wave Doppler and duplex sonography. The dissections were verified by angiography (in 1 patient), magnetic resonance imaging (in 5), or both (in 8). The dissected segments were atlantoaxial (V-3) in 6, V-3 and intertransverse (V-2) in 3, V-3 and intracranial (V-4) in 3, and V-2 in 2 patients. Extracranial and transcranial Doppler examination of the atlas loop, involved in 12 patients, showed absent flow signal in 5, low bidirectional flow signal in 1, and poststenotic low blood flow velocities in 3 patients. Seven of these patients had high-grade stenosis or occlusion. The stenotic segment with increased flow signal could be identified directly in 2 patients. Duplex examination of the intertransverse segment confirmed absent flow in 4 patients, making technically insufficient examination unlikely. In the 2 patients with directly detected stenosis, duplex examination showed low flow velocities before the stenosis. The combined use of extracranial and transcranial Doppler and duplex sonography increases the diagnostic yield to detect vertebral artery pathology. If any abnormal sonographic finding was considered, the yield was 86%; relying only on definitively abnormal findings (absent flow signal, severely reduced vertebral artery blood flow velocities, no diastolic flow, bidirectional flow, and a stenosis signal), the yield was 64%. In most cases, there is no pathognomonic ultrasound finding for vertebral artery dissection. However, if a patient presents with suggestive symptoms, ultrasound may corroborate the clinical suspicion and aid in the decision regarding early anticoagulant treatment. A definite diagnosis can be made noninvasively when magnetic resonance imaging demonstrates hematoma in the vessel wall. Angiography yields additional information such as nature of underlying vascular disease, site and extent of dissection, intracranial extension, and presence of pseudoaneurysm.

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