Poor outcome after lateral medullary infarcts.

In two patients, lateral medullary infarcts were followed by repeated brainstem ischemia. One patient had posturally sensitive vertebrobasilar TIAs, and the other had TIAs followed by quadriparesis. Both had angiographic evidence of intracranial vertebral artery occlusion on one side and severe stenosis of the contralateral vertebral artery. Propagation or embolization of clot from the occluded vertebral artery or decreased blood flow caused by stenosis of the contralateral vertebral artery can cause a bad outcome.