The Collateral Circulation And The Affecting Factors In Patients With Severe Stenosis Or Occlusion Of Middle Cerebral Artery

Cerebral artery stenosis is an important factor causing ischemic cerebrovascular disease. Among them, the middle cerebral artery (MCA) has the highest incidence of stenosis. However, we often see that there is no absolute parallel relationship between the cerebral vascular supply areas and actual areas of cerebral infarction after a vascular stenosis or occlusion, in Clinically.This is because the existence of extensive collateral anastomosis of the cerebral artery. Rich collateral circulation can exert protective effects to the ischemic tissue of brain. At present, the awareness on the collateral circulation o f the middle cerebral artery is still limited and controversy both at home and abroad.Objective:The purpose of our study are to explore the relationship between the degree of middle cerebral artery stenosis and the frequency and type of collateral circulation compensatory; analysis the factors that affect the set up of collateral circulation of middle cerebral artery.Methods:Retrospective analyze 78 cases of patients with MCA stenosis confirmed by the DSA and the degree of stenosis≥50% who attended at the Neurology department of the First Hospital of Jilin University during October 2007~October 2008. We collect the stroke risk factors (hypertension, hyperlipidemia, diabetes) and cerebro-vascular examination results of the selected patients, and the datas were statistically analyzed.Results: 1. The various forms of collateral circulation of MCA stenosis or occlusion in accordance with the incidence are followed by the soft membrane anastomosis of anterior cerebral artery and the soft membrane anastomosis of posterior cerebral artery (73.3%), neovascularization (13.3%), anterior and posterior communicating artery(8.9%), vertebrobasilar and dural artery compensatory (2.2%)2. There exist significant difference between the different degree of MCA stenosis and availability of collateral circulation (T=12.811, P=0.002<0.01); There was a significant difference between the different degree of stenosis and its collateral circulation type(T = 284.50, P = 0.024 <0.05)3. There is a very significant statistical significance (t=2.85, p=0.005<0.01) in RVaca between MCA stenosis group (1.29±0.51) and the control group(1.05±0.30); There is a very significant statistical significance (t=3.61, p=0.000<0.01) in RVpca between MCA stenosis group(1.35±0.64) and the control group(1.01±0.23). There is no statistical significance(t=1.24, p=0.22>0.05) in Vaca/Vmca in MCA stenosis group(1.29±0.51), Compared with the control group (0.84±0.17).4. Vaca / Vmca was no significant difference (H = 2.938, P=0.401>0.05) in different degree of MCA stenosis;RVaca is different (H=8.537, p=0.036<0.05) in different degree of MCA stenosis, there is significant difference (H=7.218, P=0.007<0.0083) only between the occlusion group and the normal group for further comparison;RVpca is significantly different (H=14.389, p=0.002<0.01) in different degree of MCA stenosis .For further comparison, there is significant difference (H=8.498, P=0.004<0.0083) between the occlusion group and the normal group; the severe degree of MCA stenosis group and the normal group were significantly different (H=10.532, P=0.001<0.0083).5. The difference of collateral circulation between patients with hypertension and patients without hypertension was no statistical significance (x2=1.461, P=0.227>0.05);The difference of collateral circulation between patients with hyperlipidemia and patients without hyperlipidemia was no statistical significance (x2=0.014, P=0.905>0.05);The difference of collateral circulation between patients with diabetes and patients without diabetes has a very significant statistical significance (x2=6.798, P=0.009<0.01).6. The independent variables impacting the establishment of collateral circulation were degree of stenosis (OR = 4.147, P=0.003<0.01) and lipids (OR=7.526, P=0.015<0.05).Conclusions:1. The leptomeningeal anastomosis play a major role in the collateral compensatory after MCA stenosis or occlusion, particularly the collateral circulation between ACA and MCA.2. The higher degree of Middle cerebral artery stenosis, the higher the frequency of collateral circulation compensatory and the higher level of the collateral circulation opening up.3. Compared with dVaca/nVmca, RVaca and RVpca can be a valuable target observing the changes of intracranial hemodynamics,the functional status and the effectiveness of the collateral circulation pathways the leptomeningeal anastomosis, after MCA stenosis or occlusion.4. Diabetes is not conducive to the seting up of the secondary collateral circulation after MCA stenosis. Hyperlipidemia and the degree of MCA stenosis play a promotive role for the establishment of the secondary collateral circulation. There is no relationship between hypertention and the seting up of collateral circulation.