Visualizing Recovery of Cognitive Function in Stroke

Hippocrates (460-377 BC) first described stroke over 2400 years ago. Stroke is the 4 leading cause of death in Canada (3 in the USA) and the primary cause of permanent motor and cognitive disability. The majority of strokes are ischemic. The extent of cerebral dysfunction and thus the severity of stroke are based on the location, severity and duration of ischemia. Stroke management and prognosis encompass early recognition of the onset of stroke and post-stroke determination of the extent of brain injury aided by clinical stroke scores and diffusion-weighted imaging. Cognitive domains most likely to be affected following stroke are memory, orientation, language, attention and executive function. While the vast majority of functional recovery occurs within the first 3 months post-stroke, the neural mechanisms promoting recovery are not well understood. Investigations into the neural plasticity of brain areas after a lesion demonstrate that the adult brain can be shaped by environmental inputs, such as rehabilitation techniques. Many rehabilitation techniques are actively being pursued, including brain-computer interfaces providing sophisticated methods for detecting rehabilitation-associated changes in cerebral physiology. The success of such strategies visualized with functional magnetic resonance imaging and positron emission tomography may provide an objective complement to clinical evaluations.