Bilateral paramedian thalamic infarctions are usually associated with impaired consciousness, oculomotor disturbances and neuropsychological changes. A 44-year-old healthy woman presented with amaurosis fugax of the right eye immediately after a Valsalva maneuver. Neurological examination, in particular visual acuity, vigilance and ocular movements, was normal. Blood pressure, ECG and angio-CT of the neck and head vessels were normal, but MRI/DWI and T2 sequences showed recent bi-thalamic ischemic lesions in the paramedian territories. Doppler sonography and transesophageal echocardiography showed a large right-to-left shunt due to an atrial communication, with septum aneurysm. Twenty-four-hours cardiac monitoring was normal but prior to an eventual closure of the cardiac defect she underwent an ambulatory 7-day ECG monitoring which revealed several paroxystic short lasting passages into atrial fibrillation, unnoticed by the patient. The interest in this case is threefold: (1) bilateral paramedian thalamic infarction which usually presents with a devastating clinical picture may occur clinically silent; (2) monocular amaurosis fugax which is usually associated with ipsilateral carotid disease may be the consequence of cardiac embolism, and (3) atrial fibrillation is never completely ruled out, here it was caught only in a 7-days ambulatory R-test, and consequently prevented closure of a possibly asymptomatic patent foramen ovale.