01/09/2024
ISCHEMIC INFARCT OR SIMPLY INFARCT?
The terminology ‘ischemic infarct’ has been increasingly used in the veterinary literature. This terminology appears to be lacking in the human stroke or neuroimaging literature. So, is it correct to talk about ischemic infarct or should we just refer to infarct?
Let’s go back to the actual pathophysiology. The term cerebrovascular disease designates any abnormality of the brain resulting from a pathological process of its blood vessels. Cerebrovascular diseases are the underlying causes of cerebrovascular accidents (CVA). The latter, also called stroke, is the most common clinical presentation of cerebrovascular disease. CVA can be caused by an abrupt disruption of blood flow to the brain due to blockage of an artery, thus depriving the brain of oxygen and glucose to maintain ionic pump function (ischemic stroke), or to rupture of a blood vessel, which results in hemorrhage into or around the brain (haemorrhagic stroke).
The pathophysiology of ischemic stroke begins with insufficient blood supply to a focal area of brain tissue. Within minutes, the central core of tissue in this affected area progresses toward irreversible damage, known as the area of infarction. The surrounding tissue, referred to as the penumbra, does not experience immediate cell death and has the potential for recovery if early reperfusion is achieved. The ischemic penumbra is the area surrounding the core which shows a more moderate decrease in cerebral blood flow and can tolerate longer duration of ischemic stress. The neurons within the penumbra are still viable but are at risk of becoming irreversibly injured. The penumbra is the ischemic tissue potentially destined for infarction but not yet irreversibly injured and that can potentially be salvaged by timely intervention such as thrombolytic therapy in man. The relative volume of these two pathological regions changes with time. Infarction is therefore the aggravation of the process leading to ischemia and which results in cellular death. Referring to ischemic infarct is therefore incorrect and not necessary since infarction is the process of tissue death (necrosis) due to prolonged ischemia. In some cases, infarct can undergo secondary hemorrhagic transformation and can be referred as ‘red’ infarct or hemorrhagic infarct. It occurs as a result of preserved collateral perfusion or from reperfusion of infarcted tissues which have weakened vessels. Differentiating between hemorrhagic infarct and parenchymal intracerebral hemorrhage can be challenging on imaging but the main clue to the presence of hemorrhagic infarct is the topographic distribution!
Laurent Garosi
Ines Carrera
Simon Platt
