Posterior circulation stroke and animal models.

The posterior circulation is part of the brain circulation that is subject to stroke. Strokes which involve the posterior circulation account for approximately 25% of all ischemic strokes, and about 10-20% of all hemorrhagic strokes. While the mortality rate from ischemic strokes in posterior circulation could be as low as 4%, the cerebellar and pontine hemorrhages carry a mortality rate close to 20% and 60%, respectively mainly due to brainstem compression secondary to edema or from direct parenchymal damage to vital cardio-respiratory centers. There are very few therapies geared towards neuroprotection or for reduction of edema in the posterior circulation. In fact, most treatments for anterior circulation stroke are commonly used for the posterior circulation, without an adequate study of the benefits and drawbacks. Since multiple neurovascular differences exist between these two circulations, this would imply that additional studies are needed to refine the clinical treatments in the posterior region. This review summarizes the existing animal models for posterior circulation stroke or vascular insufficiency, and discusses the anatomical, histological, neuronal, neurobehavioral and neurovascular differences at the hindbrain in comparison to the forebrain.