Cryptogenic stroke accounts for 40% of patients with ischemic stroke and it is considered that in which after conducting a thorough investigation, a cause cannot be determined. For several years there has been a close association between cryptogenic stroke and paradoxical embolism through right-to-left shunt, which occurred specially in patients with patent foramen ovale (PFO), whose prevalence is significantly higher in patients with cryptogenic stroke than in patients with stroke of a definite cause. The study of this type of cardiac abnormalities has been strengthened today with the advent of new technologies including transesophageal echocardiography (TEE) which remains the gold standard in the diagnosis of PFO, however, there are increasing reports of the usefulness of transcraneal doppler in the evaluation of these patients in a way that makes its recommendation comparable to TEE. This review is intended to expand the knowledge available on this specific procedure according to the current existing evidence.
