Identification the Cause of Silent Cerebral infarctiON in Healthy Subjects (ICONS)

Inclusion Criteria: Healthy subjects

• Subjects with age over 20 years

• Subjects who consecutively visited a health promotion center for a health screeningexamination that included routine laboratory test, cardiac work-ups (12-leadelectrocardiography and/or echocardiography), and brain magnetic resonance image (MRI)and MR angiography (MRA)

• Subjects who showed silent brain infarction (SCI) which was defined as a focalhyperintensity lesion 3 mm or large in diameter in the fluid-attenuation inversionrecovery (FLAIR) images without a history of a corresponding stroke or transientischemic attack (TIA)

• Subjects who performed agitated saline transcranial Doppler (TCD) monitoring Patients with acute stroke (both cryptogenic embolic stroke and conventional strokemechanisms)

• Patients with age over 20 year

• Patients with focal neurologic deficits presented within 7 days of symptom onset

• Patients with acute ischemic lesions on diffusion-weighted image (DWI)

• Patients who performed agitated saline TCD monitoring

Exclusion Criteria: Healthy subjects

• Subjects with the presence of previous history of stroke or TIA

• Subjects with the presence of dementia on history taking or mini-mental statusexamination

• Subjects with the presence of proximal source of embolism, including atrialfibrillation or significant (≥50%) stenosis on cervicocerebral artery on MRA orcarotid Duplex

• Subjects who had SCI restricted within perforator territory (basal ganglia or pons)suggesting that microangiopathy rather than embolism could be the main mechanism ofSCI

• Subjects in whom agitated saline TCD monitoring was not performed or those who hadpoor temporal windows Patients with acute stroke (both cryptogenic embolic stroke and conventional strokemechanisms)

• Patients in whom agitated saline TCD monitoring was not performed or those who hadpoor temporal windows