KEYWORDS Cervical artery dissection; Ultrasound; Spontaneous Summary Spontaneous cervical artery dissection is caused by a hematoma in the arterial wall. Recent research revealed that the most likely pathophysiological key mechanism is rupture of a vas vasorum resulting in a bleeding into the medio-adventitial borderzone [1] . The expansion of the hematoma into the arterial lumen can secondarily lead to a rupture of the tunica intima with a high risk of thrombus formation and embolic cerebral

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... farction [2] . Moreover the expansion of the hematoma causes an arterial stenosis or arterial occlusion with the risk of hemodynamic impairment. The risk of an ischemic stroke in the course of a dissection is thought to be about 70% for dissections of the internal carotid artery (ICA) [3] and about 80% for dissections of the vertebral artery (VA) [4] . The annual incidence of dissections of the ICA has been estimated to be 2.5-3/100,000 and for the VA 0.97-1.5/100,000 [5, 6] . Although dissections as such are rare they are a frequent etiology of stroke in children and young adults. Approximately 25% of the strokes in patients younger than 50 are caused by dissections with a peak age between 40 and 45 years [7-16]. (R. Dittrich). dissections of the ICA has been estimated to be 2.5-3/100,000 and for the VA 0.97-1.5/100,000 [5, 6] . Although dissections as such are rare they are a frequent etiology of stroke in children and young adults. Approximately 25% of the strokes in patients younger than 50 are caused by dissections with a peak age between 40 and 45 years [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] . Due to the technical improvement of the ultrasound devices the investigation of the brain supplying arteries is nowadays an established and indispensable diagnostic tool in the detection and monitoring of spontaneous dissection. Ultrasound in spontaneous dissection of the internal carotid artery The ultrasound investigation should include the complete anterior circulation, i.e. both common carotid arteries (CCA), both external carotid arteries (ECA) and both ICA. Moreover, the flow velocities and flow properties of the intracranial portion of the ICA, the anterior (ACA), and 2211-968X