Expanding cerebellar lacunes due to dilatation of the perivascular space associated with Binswanger's subcortical arteriosclerotic encephalopathy.

An 80-year-old hypertensive woman developed right hemiplegia and died 24 hours after admission. Neuropathologic examination revealed multiple cerebral infarcts of various ages and diffuse subcortical arteriosclerotic encephalopathy. Clusters of asymptomatic "expanding" lacunes, due to dilatation of the perivascular spaces, were found in both dentate nuclei. These cavities, which presented as space-occupying lesions, were surrounded by a single layer of flattened cells and contained 1 or more sections of normal-looking arterioles. Such a topographic grouping of lacunes in the dentate nucleus has not been described previously. The mechanism of widening of the perivascular compartment remains unclear; its occurrence in a hypertensive patient and its association with typical Binswanger's subcortical arteriosclerotic encephalopathy and severe atherosclerosis with multiple infarcts suggest a common pathophysiologic mechanism possibly including an alteration of the blood-brain barrier.