Infarcts In The Territory Of Middle Cerebral Artery Perforating Arteries: The Morphologic Characteristics And Mechanisms

OBIECTIVE:To analyze the morphologic characteristics of the infarcts in the territory of perforating arteries which arise from the middle cerebral artery(MCA),in order to investigate the pathologic mechanisms underlying this type of cerebral infarction.METHODS:We identified 55 patients with acute ischemic stroke who admitted to the department of Neurology in Peking Uninon Medical College Hospital(PUMCH), Beijing,China between January 1,2005 and December 31,2006.All of the patients had single acute infarction in the territory of the MCA perforating arteries revealed on diffusion weighted imaging(DWI) and magnetic resonance imaging(MRI). Transcranial Doppler(TCD) and magnetic resonance angiography(MRA) were performed for all patients.Patients with stenosis＞50%of proximal internal carotid artery and potential cardiac sources of embolism were excluded from the study. Patients were classified into two groups according to the presence of the atherosclerotic stenosis of the ipsilateral MCA:patients with MCA stenosis and patients without MCA stenosis.Size of the lesions was measured including the diameter,area and volume.The infarcts which diameter was＜2cm were classified as lacunar infarcts;other infarcts which diameter was＞2cm were classified as the striatocapsular infarcts.The position of the infarcts on DWI was classified into basal ganglia,the body of lateral ventricle and both of these places.The concomitance of subcortical multiple small old infarcts or leucoariosis between the two groups was assessed.RESULTS: Among these 55 patients,26%had a stenotic disease of the ipsilateral MCA and 74%had a normal MCA.No significant difference in the size of infarcts were found between the two groups(P＞0.05).In the group of MCA stenosis.71% patients were lacunar infarcts,as well as 66%patients were lacunar infarcts in the normal MCA group.There was no significant difference between the two groups(P=0.701).The involvement of the basal ganglia,the body of lateral ventricle and both of these places between the two groups was as follows:the normal MCA group 32%,17%,51%;the stenotic MCA group 36%,28%,36%.No significant difference was found(P=0.52).The number of patients with the concomitance of subcortical multiple small old infarcts or leucoariosis was 23 in the normal MCA group and 3 in the MCA stenosis group,and there was significant difference between the two groups(P=0.032).CONCLUSIONS:Different pathologic mechanisms are supposed to cause the infarction in the territory of MCA perforating arteries.Except small artery disease,large artery disease can also be the underlying cause.It is unable to distinguish the pathologic mechanisms according to the size,volume or distribution of the lesions.The concomitance of subcortical multiple small old infarcts or leucoariosis may demonstrate an extensive small artery disease.