Lateral medullary infarction extending to the lower pons.

A case of lateral ponto-medullary infarction was studied pathologically using serial sections of the involved region. The infarct involved 4 mm of the lower pons and 10 mm of the upper medulla. The feeding arteries of most of the infarct were traced back to form one small artery 350 micron in diameter which arose from an artery 2 mm in diameter identified as the posterior inferior cerebellar artery. The latter was occluded by a recent thrombus or embolus which blocked the mouth of the branch to ponto-medullary region.