Asymptomatic Middle Cerebral Artery Stenosis Research Articles

Increasing severity of cardiovascular risk factors with increasing middle cerebral artery stenotic involvement in type 2 diabetic Chinese patients with asymptomatic cerebrovascular disease.

To identify determinants associated with increasing severity of middle cerebral artery (MCA) stenosis in asymptomatic Chinese type 2 diabetic patients with and without MCA stenosis determined using transcranial Doppler. Conventional risk factors contribute to the pathogenesis of ischemic stroke, and differences in the pattern of these may explain the heterogeneity of disease presentation in different populations. In Chinese patients, MCA stenosis is the most commonly identified intracranial vascular lesion. Anthropometric and fasting biochemical parameters were compared between type 2 diabetic patients with MCA stenosis in one (n = 185) or both (n = 200) vessels and 1,492 type 2 diabetic patients without evidence of stenosis. Increasing MCA stenotic vascular involvement was associated with significantly increasing age, duration of diabetes, systolic blood pressure, and LDL cholesterol, but with lower glucose levels. There was also an increased prevalence of hypertension, dyslipidemia, and use of blood pressure-and glucose-lowering agents in the patients with MCA stenosis. Concomitant significant increases in the prevalence of peripheral vascular disease and retinopathy were also observed in the patients with MCA stenosis. Transcranial Doppler examination identified stenosis in one or both MCAs in over one-fifth of the Chinese type 2 diabetic subjects without symptoms of cerebrovascular disease. A number of conventional cardiovascular risk factors were closely associated with MCA stenosis. This technique may allow the identification of a particularly high-risk group, and further studies are required to determine whether asymptomatic MCA stenosis is predictive of primary cerebrovascular events and whether intensive treatment of risk factors would reduce the risk.

Asymptomatic middle cerebral artery stenosis diagnosed by magnetic resonance angiography.

We reviewed 1440 MRA studies to identify patients with middle cerebral artery stenosis (MCAS). We identified 99 cases, and after reviewing the clinical records, classified 28 as asymptomatic MCAS (AMCAS), a prevalence of 2%. Suspected stroke was the most frequent indication for MRA. Follow-up was available for 21, mean 46.7 months (range 2.4-75.6 months). One stroke occurred in the AMCAS territory (5%), other strokes in five patients (24%). There were five deaths in patients with MCAS; age > 69 (P = 0.045) was the only associated risk factor. This study suggests that patients in whom MRA is performed and shows AMCAS may be at increased risk of strokes in any vascular distribution or of death.

A pilot study of microembolic signals in patients with middle cerebral artery stenosis.

There has been limited data on the frequency of microembolic signals in patients with middle cerebral artery (MCA) stenosis, especially during the acute phase of stroke. Using transcranial Doppler, the authors prospectively monitored the MCA segments distal to stenosis in 4 groups of patients for 30 minutes: (1) symptomatic patients with acute ischemic stroke and MCA stenosis, (2) asymptomatic group patients with asymptomatic MCA stenosis, (3) control patients with acute ischemic stroke of undetermined etiology, and (4) normal people. A total of 60 patients completed the study. There were no microembolic signals in the asymptomatic, control, and normal groups. Among 20 patients in the symptomatic group, microembolic signals were detected in 3 patients (15%). The number of emboli ranged from 1 to 6 per 30 minutes. This is the first report of the presence of microembolic signals in acute stroke patients with MCA stenosis.

Detection of microembolic signals in patients with middle cerebral artery stenosis by means of a bigate probe. A pilot study.

Middle cerebral artery (MCA) stenosis is a relatively rare occlusive disease with an annual stroke risk of approximately 7% to 8%. However, the frequent coincidence of cardiac or ipsilateral carotid artery disease may lead to difficulties in identifying the relevant embolizing source in symptomatic patients. We undertook this study to evaluate the prevalence of microembolic signals (MES) as well as the potential and limitations of bigate monitoring in patients with MCA stenosis. Fourteen patients aged 33 to 87 years with angiographically demonstrated symptomatic (acute, n = 2; chronic, n = 8) or asymptomatic (n = 4) MCA stenosis were examined. Six patients (43%) had additional cardiac (n = 3) or carotid artery (n = 3) disease. By means of a bigate probe, simultaneous insonation of prestenotic and poststenotic vessel segments was attempted. In 10 patients (71%), MES detection could be performed sufficiently at target vessel sites. In the remaining patients, either prestenotic (n = 3) or poststenotic (n = 1) monitoring was not satisfactory due to insufficient transtemporal bone window or the great length or extent of MCA stenosis. Poststenotic MES were detectable in 2 acutely symptomatic and 1 asymptomatic patient (prevalence, 21%). In the latter case, the sequential appearance of MES in both prestenotic and poststenotic channels excluded MCA stenosis but strongly favored coexisting carotid artery stenosis as the active embolic source. MES are detectable in patients with MCA stenosis. Bigate monitoring in this setting is feasible and allows identification of the active source among "competing" embolizing conditions.