RESUMEN
Episodes of loss of consciousness are common, even in young, healthy people, and can sometimes represent a diagnostic challenge. The main diagnoses to consider are syncope and epileptic seizures, both of which may have similar symptomatology such as dizziness, loss of consciousness, falls, or "convulsive" phenomena. We present the case of a young male patient with a background of two venous thrombosis episodes (superior vena cava thrombosis and cerebral venous thrombosis), attributed to protein C and S deficiency and complicated by high intracranial pressure. A lumboperitoneal shunt was performed and anticoagulant therapy was initiated. He did not experience any medical problems until several years later, when he suddenly began to develop frequent, repetitive, transient episodes of dizziness, followed by loss of consciousness. Simultaneous video-EEG and ECG performed during these events showed a typical pattern normally observed during syncope. Due to the absence of changes in heart rate or blood pressure, and taking into account his medical history, intracranial hypertension was considered as a possible cause of cerebral hypoperfusion. Cerebral arteriography demonstrated chronic thrombosis of all the cerebral sinuses, and the lumbar puncture an intracranial pressure of 47 mm Hg. The lumboperitoneal shunt was replaced and the patient has since not presented with any episodes. The use of simultaneous video-EEG and ECG is a reliable and efficient approach to differentiate between syncope and seizure and in this case, was the key to finding the cause of these episodes. [Published with video sequences].