The single largest cause of adult disability in the developed world is ischemic stroke, in which blood flow in or to the brain is blocked. It precipitates immense amounts of social and financial costs. Currently, therapies for stroke focus on prevention or acute phase treatments that arrest the stroke while it is happening. But many patients are not fortunate enough to get acute phase treatment and suffer neurological damage that leads to functional and cognitive impairment. Until now, there have been almost no options for such patients. But last February, a company called ReNeuron received approval to begin a clinical trial of neural stem cell therapy for disabled stroke patients . Two patients have been treated thus far and the therapy appears to be safe.
In January 2007, a meta-analysis published in the journal Neurology determined updated rates of the most common neurological disorders . The review found that 183 out of every 100,000 people suffer a stroke each year. Most studies included in the analysis attributed 80% or more of all strokes to ischemia (meaning a localized deficiency of blood caused by a clot obstructing arterial flow). In contrast, the incidence of a hemorrhagic stroke (meaning bleeding in the brain) is much more rare and is associated with higher mortality rates. Indeed, a study of stroke incidence rates and case fatality in 15,792 middle-aged adults found that hemorrhagic strokes were 4.5 times as fatal as ischemic strokes .