Stroke echocardiography or ultrasound

Echocardiography
Echocardiography may be performed to determine the underlying etiology such as arrhythmias and the resultant clots in the heart that may spread to the brain vessels through the bloodstream.

Ultrasound/Doppler study
ultrasound/doppler study of the carotid arteries (to detect carotid stenosis) or dissection of the precerebral artieries