Predictors of ischemic events in patients with unilateral extracranial vertebral artery dissection: A single-center exploratory study

Abstract

Objective: Extracranial vertebral artery dissection (EVAD) is one of the main causes of stroke in young and middle-aged patients. However, the diagnosis is challenging. This study aimed to identify the characteristics of EVAD on color duplex ultrasonography (CDU) and high-resolution magnetic resonance imaging (hrMRI), hoping to improve the accuracy and determine the relative contribution of vessel findings and clinical factors to acute ischemic events.

Methods: Patients with unilateral EVAD were recruited and divided into ischemia and non-ischemia groups. Clinical features of patients and the lesion location; a variety of signs which indicate dissection, including the presence of an intimal flap, double lumen, intramural hematoma, dissecting aneurysm, intraluminal thrombus, and irregular lumen; and other quantitative parameters of each dissected segment on CDU and hrMRI were reviewed, respectively. Multiple logistic regression was performed to explore the association between clinical, imaging characteristics, and ischemic events in patients with unilateral EVAD.

Results: Ninety-six patients with unilateral EVAD who met the inclusion criteria were enrolled during a six-year period. Overall, 41 cases (42.7%) were confirmed as ischemic stroke (n = 40) or transient ischemic attack (n = 1) during the 48 h after the onset of symptoms. Men, infections during the last week, and smoking were more common in the ischemia group. Intraluminal thrombus and occlusion on CDU were more prevalent in patients with cerebral ischemia than in those without (36.6 vs. 5.5%; p < 0.001, and 39.0 vs. 9.1%; p = 0.001, respectively). On hrMRI, intraluminal thrombus and occlusion were also more frequent in the ischemia group than in the non-ischemia group (34.1 vs. 5.5%; p < 0.001, and 34.1 vs. 9.1%; p = 0.003, respectively). In addition, lesion length on hrMRI was significantly longer for patients with ischemia (81.5 ± 41.7 vs. 64.7 ± 30.8 mm; p = 0.025). In multivariable logistic regression analysis, male gender, infections during the last week, and the presence of intraluminal thrombus on CDU and hrMRI were independently associated with acute ischemic events.

Conclusion: Male sex, infections during the last week, and the presence of intraluminal thrombus due to dissection are associated with an increased risk of ischemic events in patients with unilateral EVAD.

Keywords: color duplex ultrasonography; high resolution magnetic resonance imaging; intraluminal thrombus; stroke; vertebral artery dissection.

Figure 1

Characteristics of the extracranial vertebral artery dissection on color duplex ultrasonography (CDU) and its corresponding, pathognomonic high-resolution magnetic resonance imaging signs. The (A–D) four columns represent four patients (Patients # 1, 2, 3, and 4), respectively, and each column from top to bottom is CDU, fat-suppressed T2-weighted (FS-T2W), magnified view of FS-T2W, and 3D time-of-flight magnetic resonance angiography (TOF) imaging.

Figure 2

Ultrasonographic imaging for one case (Patient # 5) with left vertebral artery dissection. The 40-year-old man who had a history of falling down from a freight car 1 day ago presented with sudden syncope on admission. (A) Gray scale ultrasound examination reveals heterogeneous echo in the lumen, indicating intraluminal thrombus formation, which occupies the entire lumen of the V2 segment. (B) A homogenous echo in the V1 segment is suggestive of intramural hematoma. (C,D) No blood flow signal was detected, suggesting occlusion of the left VA.

Figure 3

Magnetic resonance imaging studies for the same case (Patient # 5). (A) 3D proton density-weighted volumetric isotropic tse acquisition (PDW) shows the homogeneous hyperintensity within the lumen suggestive of intramural hematoma. (B) PDW demonstrates intraluminal thrombus formation with heterogeneous signals downstream of intramural hematoma. (C) Fat-suppressed T₂-weighted axial sequence clearly shows the dilated lumen of the left VA fulfilling with heterogeneous hyperintensity, which symbolizes the formation of intraluminal thrombus as a donut sign, while a normal flow void is evident on the right VA. (D) 3D time of flight magnetic resonance angiography showing the lumen of left VA tapers gradually ending in total occlusion, which is indicative of a dissection. (E–H) Diffusion-weighted imaging demonstrates multiple, scattered, acute infarcts in posterior circulation territory suggestive of artery-to-artery embolization.