The pathogenic mechanism of deep small infarction in middle cerebral artery stenosis

Objective To investigate the morbidity rate and pathogenic mechanism of deep small infarction in patients with middle cerebral artery stenosis (MCAS). Methods A total of 86 symptomatic MCAS patients (onset within 1 week) were diagnosed through transcranial Doppler ultrasonography, color ultrasonography, magnetic resonance angiography (MRA) and function MRI. The patients with internal carotid disease, cardiac emboli and nonartherosclerotic stenosis were excluded through neck vascular color ultrasonography and MRA. Then, the morphological characteristics of deep small infarction on DWI were studied. Results Thirty seven cases (43.02%) of deep small infarction were found by DWI in symptomatic MCAS patients, including striatocapsular infarction and macrolacuna (n=18, 20.93%) and smaller diameter lacunar infarction (n=19, 22.09%). Most patients with deep small infarction ( 15 mm) characterized as single lesion and only a few patients showed multiple lesions on DWI. Patients of deep small infarction with middle cerebral artery stenosis were unfavourable prognosis. All small deep infarctions were associated with middle cerebral artery (MCA) truncal stenosis and the size of infarction was correlated with MCA atherosclerosis stenosis degree. Most cases of striatocapsular infarction were found in patients with more severe MCA truncal stenosis. Conclusion About 50 percent of MCAS patients have deep small infarction and the pathogenic mechanism is associated with the occlusion of lenticulostriate artery origin by thrombosis and/or artherosclerotic plaque, thus the treatment of deep small infarction with MCAS is different from that of classical lacunar cerebral infarction.