| Ischemic cerebrovascular disease is one of the common diseases in neurological department,which has a high incidence rate, high mutilation rate, high mortality and high recurrence rate,threating seriously to human life and health.While,early discovery, diagnosis and prevention are key measures to reduce the mortality, disability rate and improve the life quality of the patients.Ischemic cerebral vascular disease has many risk factors,one of which the internal carotid artery stenosis is an important and independent risk factor, that some researches report about20%-30%of ischemic stroke or transient ischemic attack is due to internal carotid artery disease. We often find some patients with chronic internal carotid artery stenosis without obvious symptoms clinically,which related to the degree of stenosis and collateral circulation.Generally,only when the degree of internal carotid artery stenosis achieves to a certain or collateral compensative deficiency,causing cerebral low perfusion and neuronal dysfunction,cerebral infarction or transient cerebral ischemia attack happens.Thus,it is important to evaluate the perfusion and function of brain tissue in patients with the internal carotid artery stenosis.With the development of nerve electrophysiological and nerve imaging techniques, multi slice CT perfusion imaging,electroencephalogram,transcranial magnetic stimu--lation and somatosensory evoked potentials have been widely used in the treatment of ischemic cerebrovascular disease.The CT perfusion imaging could in early detect the position and range of acute cerebral infarction,and observe the changes of cerebral perfusion sensitively and timely,which is an important examination method of thrombolysis for acute ischemic disease.Now many domestic and foreign researches showed that multi slice CT perfusion imaging can effectively evaluate cerebral low perfusion after internal carotid artery stenosis.At the same time,a foreign Meta analysis showed that comparing with the others monitoring indicators such as transcranial Doppler ultrasound (TCD) and evoked potential (EP) in carotid endarterectomy, quantitative EEG should be the best index to evaluate cerebral ischemia.EEG could reflect sensitively the function and the damage extent of brain cell,and evaluate objectively the changes of cellular electrophysiology.Quantitative EEG could turn the basic elements of EEG spectral power (frequency, rhythm, amplitude, waveform) quantitative number through the computer, and can greatly improve the objectivity and sensitivity to observer the brain function after internal carotid artery stenosis.Some studies showed that in carotid endarterectomy EEG together with perfusion can reflect changes and dysfunction of cellular electrophysiology, and directly reflect cellular function, played an important role in observing the brain function and condition change.But the researches about CT perfusion combined with quantitative EEG in patients with chronic unilateral internal carotid artery stenosis have no reported in domestic and foreign.The aim of this study was to explore the changes of quantitative EEG and CT perfusion imaging parameters in different brain perfusion and carotid artery stenosis,clear the correlations between EEG and vascular stenosis or cerebral perfusion parameters, and investigate the superiority of quantitative EEG combined with quantitative EEG in patients with chronic unilateral internal carotid artery stenosis.Computed tomography perfusion(CTP) is a kind of functional imaging to reflect the cerebral hemodynamic state,which can detect abnormalities of cerebral perfusion prior to the occurrence of organic brain parenchymal damage.256slices CT perfusion imaging is a sensitive index to react perfusion after vascular stenosis or occlusion,that can also detect sensitively the compensation of collateral circulation, the main parameters of which are cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP).We can reflect local perfusion through quantitative measurement of CBF, CBV, MTT and TTP value, while many studies showed that the relative perfusion parameters of CT perfusion imaging affected less by external factors, which could reflect the change of cerebral perfusion more accuratelyEEG is an important index to evaluate the neuronal function, that might be sensitive to detect the change of neuronal function. Studies have reported that EEG had high sensitivity and specificity on cerebral ischemia, and the changes of EEG often occur simultaneously with the clinical symptoms in patients with cerebral ischemia.It has better timeliness compared to other clinical assistant examination.Quantitative EEG through the fast FFT method let the original EEG brain waves amplitude variation with time into brain electrical power with frequency by using a technique of computer spectrum analysis on EEG power, which can directly observe the distribution and changes of alpha, beta, and delta theta band.Quantitative EEG in foreign countries had already applied to observe cerebral ischemia in carotid endarterectomy.The studies have shown that quantitative EEG increased significantly in unilateral carotid artery stenosis or occlusion, and decreased when cerebral blood flow perfusion recovery,which had higher sensitivity to observe cerebral blood perfusion compared with traditional EEG.This study,based on cerebrovascular digital subtraction angiography,is to observe the changes of quantitative EEG and CT perfusion imaging parameters in different degree of unilateral internal carotid artery stenosis,the correlation between the quantitative EEG and cerebral perfusion parameters, so as to explore the change of brain tissue perfusion and neuronal function after unilateral internal carotid artery stenosis.Part1The characteristics of quantitative EEG indexes in patients with chronic unilateral internal carotid artery stenosisContents and methods:To explore the characteristics of quantitative electroencephalogram at hyperventilation test and quiet breathing in patients with chronic unilateral internal carotid artery stenosis.66cases with unilateral internal carotid artery stenosis confirmed by cerebrovascular DSA were included.According to the result of cerebral vascular DSA,all cases were divided into3groups:mild stenosis (≤29%)23cases, moderate stenosis (30%-69%)23cases,severe stenosis (70%-99%)20cases.3-5days after cerebral vascular DSA,an16normal EEG was done in all cases,then by the Matlab software we calculate the spatial symmetry index(sBSI), temporal spatial symmetry index (tBSI), Delta and theta/alpha+beta ratio (DTABR) and95%spectral edge frequency (95%SEF),and compare quantitative EEG indexes during three groups.Result:1.Comparison of the general data between subjects:66patients with carotid artery stenosis underwent DSA:mild stenosis group (23cases), moderate stenosis group (23 patients), severe stenosis group (20cases), male42cases, female24cases, mean age64.29±11.26years old (mean±SD years).all patients were collected the risk factors such as hypertension, hyperlipidemia, diabetes, smoking, drinking, heart disease and clinical symptoms.The age and gender strictures of patients in three groups had no statistical significance (P>0.05), the risk factors but diabetes had no difference (P=0.034), clinical symptoms that whether they have acute infarction had statistical significance (P=0.023).2.Comparison of the quantitative EEG parameters during the three groups at quiet breathing:The spatial symmetry index (sBSI), temporal spatial brain symmetry index (tBSI) and Delta and theta/alpha+beta ratio (DTABR) of three groups had difference significance (F=54.808, P=0.000; F=148.517,P=0.000;F=12.805, P=0.000);95%spectral edge frequency (95%SEF) of three groups no difference significance (F=0.412,P=0.664); Among the three groups, the spatial symmetry index (sBSI) and delta and theta/alpha+beta ratio (DTABR) between moderate and severe stenosis group had no significant difference (P=0.419; P=0.720), and the temporal spatial brain symmetry index (tBSI) there was a significant difference in comparison between the three groups (P<0.05).3.Comparison of the quantitative EEG parameters during the three groups at quiet breathing and hyperventilation test:The spatial symmetry index (sBSI), temporal spatial symmetry index (tBSI) and Delta and theta/alpha+beta ratio (DTABR) of three groups at hyperventilation test and quiet breathing had difference significance (P<0.05); The spatial symmetry index (sBSI) and delta and theta/alpha+beta ratio (DTABR) between moderate and severe stenosis group had no significant difference at quiet breathing (>0.05), while at hyperventilation test there was statistical significance and hyperventilation is difference (P<0.05);The temporal spatial symmetry index (tBSI) there was a significant difference in comparison between the three groups at quiet breathing and hyperventilation test (P<0.05).4.Analysis of correlation between the quantitative EEG indexes and degree of vascular stenosis:The spatial symmetry index (sBSI), temporal spatial symmetry index (tBSI) and Delta and theta/alpha+beta ratio (DTABR) at hyperventilation test and quiet breathing were positively correlated to the degree of stenosis (P<0.05), But Compared with quiet breathing,the quantitative EEG index at hyperventilation test correlation is stronger.95%spectral edge frequency(95%SEF) had no significant correlation with the degree of stenosis (r=0.024,P=0.846).Summary:1.The spatial symmetry index (sBSI), temporal spatial symmetry index (tBSI) and Delta+theta/alpha+beta ratio (DTABR) in chronic unilateral internal carotid artery stenosis to diagnosis of cerebral ischemia have certain significance, especially in the severe stenosis. And the95%spectral edge frequency (95%SEF) has no meaning.2.The spatial symmetry index (sBSI), temporal spatial symmetry index (tBSI) and Delta+theta/alpha+beta ratio (DTABR) at hyperventilation compared with quiet breathing in uin chronic unilateral internal carotid artery stenosis have more meaningful, and more relevant to the degree of stenosis.3.The temporal spatial symmetry index (tBSI) was the strongest correlation with the degree of carotid stenosis, more sensitive to determine cerebral ischemia caused by the internal carotid artery stenosis.Part2Application of CT perfusion imaging combining with quantitative EEG in patients with unilateral chronic internal carotid artery stenosisContents and methods:To explore CT perfusion imaging parameters and its correlation with quantitative EEG in patients with different unilateral chronic internal carotid artery stenosis.66cases with unilateral internal carotid artery stenosis confirmed by cerebrovascular DS A from Part1were included.According to the result of cerebral vascular DSA,all cases were divided into3groups:mild stenosis (≤29%)23cases, moderate stenosis (30%-69%)23cases,severe stenosis (70%---99%)20cases.3-5days after cerebral vascular DSA, an16normal EEG and CT perfusion imaging were done in all cases.The relative perfusion parameters (rCBV, rCBF, rMTT, rTTP)of CT perfusion were compared during three groups,and then we defined wether the spatial brain symmetry index and temporal spatial brain symmetry index and CT perfusion had correlation.Result:1.General data analysis the same with the first part.2.Comparison of CT perfusion imaging in three groups:(1)Comparison of pseudo color map:There were no significant difference during three groups on both sides of the brain tissue CBF and CBV map; The MTT and TTP map of the two sides in all the severe stenosis group and11patients with moderate stenosis group have differences; No significant differences in both sides of the TTP and MTT diagram were found in all patients with mild stenosis group.(2) Comparison of CT perfusion imaging parameters in three groups:①The temporal region:There was no significant difference between the rCBF between rCBV during three groups(F=1.298, P=0.283; F=2.539, P=0.087); While there was statistical significance in rMTT and rTTP (F=52.784, P=0.000F=9.245, P=0.000);②The basal ganglia:There was no significant difference between the rCBF between rCBV during three groups (F=1.787, P=0.176; F=2.168, P=0.123); While there was statistical significance in rMTT and rTTP (F=35.158, P=0.000; F=26.544, P=0.000); (3)Comparison of CT perfusion imaging between three groups:①The temporal region:rCBV:The comparisons between mild and moderate, mild and severe, moderate and severe groups were not statistically significant (P=0.635, P=0.121, P=0.270); rCBF:The comparisons between mild and severe stenosis group have differences (P=0.032), but mild and moderate, moderate and severe stenosis group had no difference (P=0.136; P=0.465); rMTT:The differences in comparing between mild and moderate, moderate and severe, mild and severe stenosis group were statistically significant (P=0.003, P=0.000, P=0.000); rTTP:There were no significant differences between the mild and moderate stenosis group (P=0.178), while statistically significant in moderate and severe, mild and severe stenosis group(P=0.000, P=0.000).②The basal ganglia:rCBV:The differences compared between mild and moderate, mild and severe, moderate and severe groups were not statistically significant (P=0.312, P=0.064; P=0.369);rCBF:The comparisons between mild and moderate, moderate and severe groups were not statistically significant (P=0.602, P=0.135), but mild and severe stenosis group different (P=0.048); rMTT:The differences compared between mild and moderate, moderate and severe, mild and severe stenosis group were statistically significant (P=0.028, P=0.000, P=0.000); rTTP:There were no significant differences between the mild and moderate stenosis group (P=0.216), while statistically significant between moderate and severe, mild and severe stenosis group.(P=0.000, P=0.000).(4)The correlation between CT perfusion imaging and degree of vascular stenosis:All the relative perfusion parameters in temporal lobe and basal ganglia were correlated with degree of vascular stenosis.There was a negative correlation between rCBV and rCBF and the degree of stenosis, while a positive correlation between rMTT and rTTP and the degree of stenosis. ①The temporal region:There was a negative correlation augring rCBV and rCBF with the degree of stenosis (r=-0.304, P=0.001; r=-0.385, P=0.013); and rMTT and rTTP with the degree of stenosis was positively correlated (r=0.713, P=0.000; r=0.616,P=0.000).②The basal ganglia:There was a negative correlation augring rCBV and rCBF with the degree of stenosis (r=-0.355,P=0.003; r=-0.308,P=0.012); and rMTT and rTTP with the degree of stenosis was positively correlated (r=0.609,P=0.000; r=0.420,P=0.000).3.The correlation between perfusion parameters and spatial brain symmetry index:①The temporal region:There was no significant correlation between the spatial brain symmetry index and rCBV and rCBF (r=-0.037, P=0.765; r=-0.184, P=0.139), but positive relation to rMTT and rTTP (r=0.394, P=0.004; r=0.351, P=0.004); The temporary symmetry index was not obviously correlated with rCBV (r=-0.153, P=0.219), but negatively correlated with rCBF (r=-0.283, P=0.021), positively correlate with rMTT and rTTP.(r=0.547, P=0.000; r=0.467, P=0.000).②The basal ganglia:The spatial symmetry index had no significant correlation to rCBV, rCBF, rMTT and rTTP (r=-0.241, P=0.052, r=-0.159, P=0.203; r=0.230, P=0.063; r=0.098, P=0.436); The temporary symmetry index had no correlation to rCBV, rCBF and rTTP (r=-0.225, P=0.069; r=-0.201, P=0.106; r=0.214, P=0.084),but positive relation to rMTT (r=0.417, P=0.000).Summary:1.The rTTP and rMTT are sensitive indexes to reflect cerebral ischemia in internal carotid artery stenosis, have certain correlation with the degree of stenosis and quantitative EEG.And the rMTT is more sensitive;2.The relation between quantitative EEG indexes and temporal rMTT was strongest, which indicate quantitative EEG could sensitively reflect the cerebral cortex ischemia;3.CT perfusion imaging combined with quantitative EEG evaluate changes of neuronal function and perfusion caused by cerebral ischemia after internal carotid artery stenosis.Conclusion:1.The spatial symmetry index (sBSI), temporal spatial symmetry index (tBSI), Delta and theta/alpha+beta ratio (DTABR) have certain significance to detect cerebral ischemia in unilateral chronic internal carotid artery stenosis.The temporal spatial symmetry index (tBSI) have the strongest correlation with the degree of internal carotid artery stenosis, more sensitive to determine cerebral ischemia caused by the internal carotid artery stenosis.2.Compared with quiet breathing,the difference of quantitative EEG indexes during three groups at hyperventilation test was more obvious,and the correlation to the degree of stenosis is stronger,.Thus hyperventilation test to monitor cerebral function in internal carotid artery stenosis more meaningful.3.CT perfusion imaging and quantitative EEG have consistency in the evaluation of cerebral ischemia after carotid artery stenosis,and the combination of the two evaluate changes of neuronal function and perfusion caused by cerebral ischemia after ion internal carotid artery stenosis more better. |
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