Prevalence of asymptomatic intracranial atherosclerosis in high-risk patients.

We used transcranial Doppler to screen 3,057 patients who had at least one vascular risk factor of hypertension, diabetes, or hyperlipidemia and found 385 (12.6%) had middle cerebral artery stenosis. Elderly, hypertension, diabetes, and hyperlipidemia were associated factors. The prevalence escalated quadratically with increasing number of associated factors: from 7.2% for one, to 29.6% for four associated factors. Asymptomatic middle cerebral artery stenosis is common in patients with vascular risk factors.