Acute ischemic stroke

Stroke is considered one of the major public health problems and the third costliest health condition in developed countries. It is the most common cause of adult disability in developed countries, requiring long term costly rehabilitation and is the principle cause of 1 out of every 16 deaths. For example, in Australia, a country with a population of less than 25 million, every 10 min someone has a stroke, and every 40 min, someone dies from one, with the total economic costs of stroke have been estimated to exceed $4 billion a year. The majority of strokes are ischemic in nature with only about 15% being due to haemorrhagic events. In ischemic stroke, a core area of tissue dies due to under-perfusion and an area of surrounding hypo-perfused tissue with patent collateral vessels remains salvageable. This hypo-perfused tissue has been referred to as the “penumbra” which if revascularised in a timely manner can be saved. In a typical acute ischemic stroke, the brain loses 1.9 million neurons, 14 billion synapses, and 7.5 miles of myelinated nerve fibres every minute. Therefore, urgent recanalisation of the occluded artery and restoration of blood flow is considered the most important therapeutic step to reperfuse threatened brain parenchyma before an irreversible infarction is established, to reduce morbidity and mortality. Studies have estimated that there is a benefit of 1.8 days of added healthy life for each minute saved in terms of time to treatment, and a metanalysis has demonstrated that successful recanalisation increases the chance of a good functional outcome with an odds ratio of approximately 4.5, significantly reducing mortality at 3 months.