[Leukoaraiosis. Clinical importance and prognosis].

Advance in the health care systems, in medical knowledge and improvements in quality of life have contributed to the fact that life expectancy of the persons in developed countries exceeds 80 years of age. This has made it possible to observe the increase in frequency of common diseases of the elderly, one of the most relevant of which is dementia. The two most frequent etiologies of dementia are the degenerative one, with Alzheimer's disease (AD) as the main cause, and those of vascular etiology or vascular dementia, within which subcortical arteriosclerotic encephalopaty or Binswanger's disease (BD) are found with low prevalence. Since, on one hand, diagnosis of the dementias is not enough or definitive by clinical means, and on the other hand, the pathological diagnosis does not modify the evolution of disease, emphasis is presently placed on diagnosis by neuroimaging studies. In recent years, with the coming of the computerized tomography (CT) and the magnetic resonance (MR), it has been possible to observe lesions in the white matter of the brain hemisphere in patients with these two etiologic groups of dementias, that is, degenerative and vascular, as well as in elderly patient without cognitive deterioration, with or without vascular risk factors.