Dissection of the extracranial vertebral artery. Color flow ultrasound findings in 20 patients

Aim: To assess the diagnostic potential of duplex color-flow imaging in the evaluation of extracranial vertebral artery dissection. In 15 of 20 patients (75%), the dissection was related to trauma. Method: Over the last six years, we evaluated 20 consecutive patients aged 18 to 59 years with 24 extracranial vertebral artery dissections (four occurring bilaterally). The examinations were performed with a color Doppler imaging system using a 7 MHz transducer. Angiography was done in 18 patients, confirming the diagnosis. Results: In 15 patients, the diagnosis was primarily established with ultrasonography. Six vertebral arteries were dissected at the origin or in the proximal V1 segment, one in the distal V2 segment and one at the atlas loop. Most dissections occurred in the region between the V1 and V2 segments (n = 16), most often at the entrance of the artery into the transverse foramen of the C6 vertebra (n = 11). Typical ultrasonographic findings were irregular stenosis, dissecting membrane with true and false lumen, localized increase in diameter of the artery, pseudoaneurysm, intramural hematoma and tapering stenosis with distal occlusion. The diagnosis of dissection in the V3 segment was based on indirect signs such as high resistance flow pattern and decreased diastolic flow velocity. In follow-up examinations, marked resolution of pathological findings was found in 17 cases (70.8%). Two occlusions were completely recanalized. Conclusion: Duplex color-flow imaging is a valuable noninvasive method for early diagnosis of extracranial vertebral artery dissection and for follow-up examinations.