neurologic disorders
Overview of Stroke
Introduction
Strokes are a heterogeneous group of disorders involving sudden, focal interruption of cerebral blood flow that causes neurologic deficit. Strokes can be Ischemic Stroke (80%), typically resulting from thrombosis or embolism Hemorrhagic (20%), resulting from vascular rupture (eg, Subarachnoid Hemorrhage (SAH) , 1 hour) without evidence of acute cerebral infarction (based on diffusion-weighted MRI) are termed a Transient Ischemic Attack (TIA) (TIA). In the US, stroke is the 5th most common cause of death and the most common cause of neurologic disability in adults. Strokes involve the arteries of the brain (see figure), either the anterior circulation (branches of the internal carotid artery) or the posterior circulation (branches of the vertebral and basilar arteries). The anterior cerebral artery supplies the medial portions of the frontal and parietal lobes and corpus callosum. The middle cerebral artery supplies large portions of the lateral surfaces of frontal, parietal, and temporal lobes. Branches of the anterior and middle cerebral arteries (lenticulostriate arteries) supply the basal ganglia and anterior limb of the internal capsule. The vertebral and basilar arteries supply the brain stem, cerebellum, posterior cerebral cortex, and medial temporal lobe. The posterior cerebral arteries bifurcate from the basilar artery to supply the medial temporal (including the hippocampus) and occipital lobes, thalamus, and mammillary and geniculate bodies. Anterior circulation and posterior circulation communicate in the circle of Willis via the posterior communicating artery. 