Correlation between the hemodynamic parameters of extracranial vertebral artery and the severity and location of intracranial vertebral artery stenosis

Objective To analyze the effects of the degree and location of intracranial vertebral artery(VA) lesions on the hemodynamic parameters of extracranial VA. Methods A total of 275 consecutive patients who were diagnosed as posterior circulation ischemic stroke or transient ischemic attack (TIA) with unilateral intracranial VA stenosis or occlusion in the Department of Neurology and Neurosurgery of Capital Medical University Xuanwu Hospital from January 2015 to December 2017 were enrolled. All patients were examined by head and neck vascular ultrasound, CT angiography (CTA) and/or digital subtraction angiography (DSA) within one week. According to the results of DSA or CTA, the patients were divided into mild stenosis group(53 patients), moderate stenosis group(62 patients), severe stenosis group(58 patients) and occlusion group(102 patients). The inner diameter (D), peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) of the extracranial segment (V2 segment) of the VA were recorded and analyzed. Results The PSV and EDV in the severe stenosis group and the occlusion group were significantly lower than those in the mild stenosis group and the moderate stenosis group (P=0.000), and the PSV and EDV in the occlusion group were significantly lower than those in the severe stenosis group[ (31±10) cm/s vs (46±12)cm/s, (5±4)cm/s vs (15±7)cm/s; all P=0.000], RI was significantly higher than the other three groups (0.85±0.12, 0.70±0.10, 0.66±0.07, 0.64±0.06, respectively; all P=0.000); RI in the severe stenosis group were not significantly different from those in the mild to moderate stenosis groups (P=0.044, 0.223). There were no significant differences in the inner diameter, PSV, EDV and RI between the subgroups in the severe stenosis group before or after the PICA (posterior inferior cerebellar artery)(P=0.130, 0.322, 0.865, 0.227). However, the EDV decreased and RI increased in the occlusive subgroup before the PICA when compared the subgroup after the PICA (all P=0.000). Conclusions The location and degree of intracranial VA lesions directly affect the changes of blood flow velocity and vascular resistance of extracranial VA, and the changes of low-speed and high-resistance hemodynamics of extracranial VA may indicate the existence of occlusive lesions in intracranial VA. Key words: Ultrasonography; Vertebral artery stenosis; Occlusive diseases; Hemodynamics; Extracranial segment; Intracranial segment