[The early hemiparesis of stroke in evolution of basilar artery--case report].

In basilar artery thrombosis, hemiparesis without obvious brainstem signs may precede the tetraplegia with coma or a locked-in state. This premonitory hemiparesis was called as "herald hemiparesis" by Fisher (1988). Its early detection is important because immediate anticoagulant therapy may prevent its evolution. We reported two patients with such hemiparesis. The first case was a 71-year-old diabetic and hypertensive man who was admitted because of right hemiparesis, dysarthria and decreased spontaneous speech. Initially, his symptoms looked like those of a left cerebral lesion. CT scans revealed no fresh cerebrovascular lesion. A few hours later, a myoclonic movement appeared in his left lower limb, and right MLF syndrome developed. We thought he had basilar artery thrombosis and we started intravenous administration of heparin. But he developed tetraplegia with locked-in state. The second case was a 76-year-old diabetic and hypertensive man with a confusional state, right hemiparesis, dysarthria and conjugate gaze deviation to left. After admission, he rapidly became comatose and developed respiratory arrest. CT scans revealed low density areas in the brainstem, cerebellum and the occipital lobe. He died ten days later. Early detection of herald hemiparesis is by no means easy. However, severe dysarthria and myoclonic jerks in a patient with hemiparesis should be considered as warning signs to indicate the herald hemiparesis with subsequent severe brainstem infarction.