An Investigation Between Abnormality Of The Blood Vessel And Hemodynamics In Posterior Circulation Ischemia

PartⅠAn Investigation of the Correlation between the Abnor- mality of the Blood Vessels and Posterior Circulation IschemiaObjective To identify the occurrence of abnormal blood vessels in the posterior circulation ischemia cases and to analyze factors influencing artery stenosis degree. Methods 120 patients with diagnosed posterior circulation ischemia syndrome and a control group of 68 healthy subjects for outpatient treatment are sampled with detailed information on clinical symptoms and signs recorded, a holistic neurological examination conducted and the stroke risk factors proposed. Then the artery stenosis and variation distribution are observed by 64-slice spiral CT angiography (CTA) with artery stenosis degree and its contributing factors analyzed by multiple linear regression; a contrastive analysis is then made with the investigation of blood vessels of the infarction group, TIA group .Results 1. The Diffusion Weighted Imaging of head MRI reveals 83 patients with posterior circulation infarction and 37 with transient ischemia attach. 2. CTA results show that 85 out of 120 subjects (70.83%) with posterior circulation ischemia have abnormal blood vessels, a significant increase compared to the control group(χ2=24.32, P<0.01) in which only 23 examples(33.83%) of abnormal blood vessels are found. 3. Of the 85 cases of abnormal blood vessels, 56(65.88%) suffer from artery stenosis, left vertebral artery stenosis 17(20%), 22(25.88%) heteroplasia and 7 (8.24%)aneurysm, osteophyma or sandwich. Among 35 patients with normal posterior circulation, 20 are found with abnormal anterior circulation. 4. Angiostegnosis degree of posterior circulation has high negative correlation with high density lipoprotein cholesterol(HDL-C)(R2=0.266,P<0.05), and positive correlation with glycosylated hemoglobin A1c (GHbA1c)level(R2=0.187, P<0.01), while age, smoking, gender, BMI, hypertension, LDL-C, homocysteic acid and FIB do not constitute triggering factors of Angiostegnosis. 5. The anomalous vascular distribution has no statistical difference between infarction group and TIA group (χ2=0.638, P>0.05).Conclusions Angiostegnosis and heteroplasia are the primary causes of posterior circulation ischemia. Besides, the abnormality of anterior circulation artery also has a role to play in triggering the ischemia. Most cases of stenosis are attributable to atherosclerotic while the stenosis degree is correlative with HDL-C, GHbA1c. It is suggested that TIA group with posterior circulation has the highest potential to develop posterior circulation ischemia and thus should be given most attention.PartⅡAnalysis on the Correlation between Hemodynamic Changes and Risk Factors in Posterior Circulation IschemiaObjective To analyze the hemodynamic changes in patients with posterior circulation ischemia(PCI), and to identify the possible risk factors affecting hemodynamics.Methods In the current study, a sample of 120 patients with diagnosed posterior circulation ischemia and a control group of 68 healthy subjects for outpatient treatment are subject to a composite examination of vertebral artery, basilar artery and intracranial artery by using transcranial Doppler sonography. Their vertebral artery and anterior circulation stenosis were observed by 64-slice spiral CT angiography (CTA). The hemodynamic parameters of the posterior circulation ischemia group are then recorded and compared with that of normal control group. Risk stratification is conducted based on ABCD2 score and a contrastive analysis is made in accordance with the changes of hemodynamic parameters at different levels. Afterwards, the hemodynamic parameters of hypoplastic VA and the normal VA of 22 vertebral artery hypoplasia patients are examined. The same parameters of 43 patients with the anterior circulation arterial stenosis and 77 stenosis-free subjects are also contrastively analyzed.Results 1. Significant deviation (P<0.05) is observed between the hemodynamic parameter of posterior circulation ischemia group and that of normal control group. 2. Based on risk stratification, when the risk score is up to 6-7, the hemodynamic parameters of vertebral artery and basilar artery abnormality demonstrates statistically significant deviation from other scores (P<0.01). 3. Vertebral artery hypoplasia were discovered by CTA. The peak systolic velocity (Vs) of hypoplastic VA are lower than those of normal VA in vertebral artery hypoplasia patients (P<0.01) with an increased resistant index(RI) (P<0.05). The Vs of anterior circulation stenosis are lower than those of normal anterior circulation(P<0.05)while RI show no statistically significant difference(P>0.05).Conclusions Our study suggests that hemodynamic change of vertebrobasilar artery is one of the important methods in evaluating posterior circulation ischemia. Age, hypertension, diabetes, and clinical duration of symptoms all exert influence of some degree to the hemodynamics of posterior circulation ischemia. The hemodynamic parameters are statistically consistency with the evaluative score of the risk factors in question. The higher the score, the more obvious the hemodynamic changes. Vertebral artety heteroplasia and anterior circulation stenosis can also result in hemodynamic abnormality, which will further leads to posterior circulation ischemia.