• Binswanger's disease,
  • chronic progressive subcortical encephalopathy,
  • subcortical arteriosclerotic encephalopathy,
  • periventricular leucoencephalopathy.

The number of alternative titles reflects the confusion between the clinical, radiological, and pathological literature. It is probably best to think first in terms of a radiological appearance, which can, and now should, be uniformly described and graded. On CT there is more-or-less symmetrical but irregular periventricular hypodensity, with or without ventricular dilatation and focal white matter hypodensities.

This is better seen as high signal on T2-weighted MR images. In the absence of other causes, such as multiple sclerosis or irradiation, this periventricular radiological appearance is due to demyelination, axonal loss, and gliosis, probably as a consequence of diffuse rather than focal ischaemia in the distribution of the long perforating arteries from the pial surface of the brain. These vessels are rendered sclerotic, it is assumed, by chronic hypertension, and the ischaemia is perhaps exacerbated by periods of hypotension as a result of cardiac failure, brief perturbations in perfusion pressure, and impaired cerebral autoregulation. Vascular occlusion has not been seen (Caplan 1995a; Pantoni and Garcia 1997).

This radiological appearance is frequent in the normal elderly but particularly so in patients who are demented, have had ischaemic or haemorrhagic strokes, or who are unsteady. It is more frequent in hypertensive patients and in those with other vascular risk factors, but not with increasing carotid stenosis severity (Bogousslavsky et al. 1987; van Swieten et al. 1991; Leys et al. 1992; Bots et al. 1993; Adachi et al. 1997; Tell et al. 1998).

It may be, therefore, that the association with stroke is because hypertension causes leukoaraiosis as well as lacunar and atherothrombotic ischaemic stroke in the same individuals. It is not the cause of the stroke clinical syndrome. The most important differential diagnosis, because it may be treatable, is normal-pressure hydrocephalus.