The 'herald hemiparesis' of basilar artery occlusion.

In thrombosis of the basilar artery, not infrequently a hemiparesis is present at an early stage, when brain-stem signs may be absent or few, slight or equivocal. It is natural to suspect that such a hemiparesis signifies localization in a cerebral hemisphere, but unexpectedly in a few hours bilateral hemiplegia appears associated with coma or a locked-in syndrome, indicating basilar artery occlusion. I would term this disarming hemiparesis the "herald hemiparesis" of basilar artery occlusion. If the true nature of the condition is recognized early, the use of heparin and other measures may forestall disaster.