This entity was mentioned briefly in the discussion of the course and prognosis of atherothrombotic infarction and as a cause of dementia in Chaps. 20 and 38 but it has appeared in the literature with decreasing frequency. The term has come to denote a widespread degeneration of cerebral white matter having a vascular causation and observed in the context of hypertension, atherosclerosis of the small blood vessels, and multiple strokes. Hemiparesis, dysarthria, TIAs, and typical lacunar or cortical strokes are admixed in many cases. The process has been associated with a particular radiologic appearance that reflects confluent areas of white matter signal change. The term leukoaraiosis describes the imaging appearance of hypointense periventricular tissues, presumably damaged by chronic ischemia. It is likely that leukoaraiosis exist in a continuum with Binswanger disease and many elderly individuals who have these changes show cognitive impairment as discussed below. Whether multiple discrete lacunes in the deep white matter constitute Binswanger disease may be a semantic issue, but we adhere to the notion that the former is characterized by a more widespread ischemic and gliotic change in the deep white matter.
Dementia, a pseudobulbar state, and a gait disorder, alone or in combination, are the main features of Binswanger cases. They have been attributed to the cumulative effects of the ischemic changes producing white matter degeneration. It is likely that the pathologic basis of such a clinical entity is arteriolar sclerosis but surprisingly, as pointed out in Fisher’s review (1989), the lumens are open. Yet another problem is to distinguish such a state from deficits produced by the cumulative effect of numerous larger lacunes, which have for a century been known to cause the aforementioned syndromes of dementia, gait disturbance, and a pseudobulbar syndrome. From time to time, imaging studies of the brain disclose large regions of white matter change or the occurrence of multiple infarctions in the absence of hypertension, and it is not clear how such cases should be classified. Some prove to be areas of demyelination or metabolic dysmyelination; others are mitochondrial disorders, and perhaps some are related to the familial CADASIL syndrome or Susac syndrome discussed below. Fabry disease also enters into the differential diagnosis of multiple small infarctions in the cerebrum that may coalesce into areas of white matter damage. Readers may consult the reviews on the subject by Babikian and Ropper, by Caplan (1995), and the mentioned review by CM Fisher.
A process with an imaging appearance of large confluent cerebral white matter changes, somewhat similar to Binswanger leukoencephalopathy, has been identified as an autosomal dominant familial trait linked in several families to a missense mutation on chromosome 19. In the past, it had been described under a number of names, including hereditary multiinfarct dementia. The acronym CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is now applied. In these patients recurrent small strokes beginning in early adulthood culminate in a subcortical dementia (see Chap. 20). Migraine headaches, often with neurologic accompaniments, may precede the strokes by several years, and varied TIAs that are attributed, probably incorrectly, to the migraine. On the other hand, some individuals display few clinical changes while yet others are demented or have strokes that simulate lacunes. We are unable to comment on the encephalopathy and coma accompanied by fever described by Schon and colleagues that has been attributed to this condition.