'Herald hemiparesis' of basilar artery occlusion: early recognition by transcranial Doppler ultrasound.

A transient hemiparesis may be ocassionally present at an early stage of the thrombosis of the basilar artery (herald hemiparesis). We report on one of these cases and the valuable role of transcranial Doppler ultrasound (TCD) to the early detection of the stroke-in-evolution. TCD in the emergency room is a good tool to assess a basilar occlusion, searching for direct (absence of signal at the basilar artery) and indirect (reversal flow of the pre-communicating segment the of posterior cerebral artery through the posterior communicating artery) signs. Early recognition and treatment of this condition could avoid the development of the full syndrome of the basilar artery thrombosis.