Silent cerebral ischaemia: hidden fingerprints of invasive medical procedures.

Cardiovascular and cerebrovascular disorders are the main cause of death and permanent disability worldwide. Improved diagnostic and therapeutic options for these diseases have led to increasing numbers of invasive procedures such as angiography, stent placement, and operations exceeding 4 million each year in the USA. Although clinical examinations suggest a relatively low risk for ischaemic complications affecting the brain, new magnetic resonance techniques have led to the awareness of much higher numbers of clinically silent ischaemic brain lesions. Diffusion-weighted MRI (DWI) has shown new ischaemic lesions in a substantial number of patients undergoing cardiac or carotid-artery surgery, and coronary or cerebral-angiographic interventions. The clinical impact of these "silent" ischaemic lesions within brain areas without primary motor, sensory, or linguistic function ("non-eloquent" brain areas) is debated. There is increasing evidence, however, that cumulative burden of ischaemic brain injury causes neuropsychological deficits or aggravates vascular dementia. Thus, DWI emerges as a valuable diagnostic method for the monitoring of periprocedural ischaemic events in the brain, and could be a surrogate parameter for optimising diagnostic and therapeutic vascular procedures in the future.