Vertebral artery occlusion in duplex color-coded ultrasonography

Background and Purpose - To establish the diagnostic criteria for the site of occlusion in the vertebral arteries (VAs) using duplex color-coded ultrasonography. Methods - In 128 consecutive patients who underwent conventional cerebral angiography, we prospectively measured the diameter, mean flow velocity (MV), peak systolic flow velocity, and end-diastolic flow velocity of both VAs. The diameter-ratio (diameter of contralateral VA divided by that of target VA) and MV-ratio (MV of contralateral VA divided by that of target VA) were determined. Based on the angiographic findings, we classified the VAs into 4 types (5 groups) as follows: (1) the origin of VA occlusion (Origin group: n = 9); (2) VA occlusion before branching into the posterior inferior cerebellar artery (PICA) (Before group: n = 10); (3A) symptomatic VA occlusion after branching into the PICA (After group: n = 12); (3B) asymptomatic or hypoplastic occlusive VA after branching into the PICA (PICA end group: n = 15); and (4) no significant occlusive lesions in the VA (Control group: n = 194). Results - No flow signals in the VAs apparently indicated the Origin group. Preserved peak systolic flow velocity but end-diastolic flow velocity of zero cm/s indicated the Before group. MV <18 cm/s and MV-ratio ≥1.4 indicated the PICA end group or After group. Furthermore, these groups could be distinguished as follows: a diameter-ratio <1.4 indicated the After group. A diameter-ratio greater than or equal to1.4 indicated the PICA end group. Either MV greater than or equal to18 cm/s or MV <18 cm/s in combination with MV-ratio <1.4 indicated the Control group. Conclusion - Duplex color-coded ultrasonography can accurately diagnose the site of VA occlusion.