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Prevalence of small cerebral bleeds in patients with progressive supranuclear palsy: a neuropathological study with 7.0-Tesla magnetic resonance imaging correlates.

INTRODUCTION
Progressive supranuclear palsy (PSP) is a degenerative disease affecting mainly the brain stem, basal ganglia and cerebellum. Associated cerebrovascular lesions, mainly small cerebral bleeds, are frequently observed in some neurodegenerative diseases such as Alzheimer dementia and rare in others such as frontotemporal lobar degeneration. The present post-mortem study investigates the prevalence and distribution of small cerebral bleeds in PSP brains.


MATERIAL AND METHODS
Nineteen brains of PSP patients were compared to 12 age-matched controls. The prevalence and distribution of mini-bleeds were investigated on a coronal section of a cerebral hemisphere at the level of the mamillary bodies and on a horizontal section through the pons and cerebellum. In addition, out of these series T2*-weighted gradient-echo 7.0-Tesla magnetic resonance imaging (MRI) of 3 coronal sections of a cerebral hemisphere and of a brain stem and cerebellum was performed in 14 PSP and 11 control brains.


RESULTS
Although the total number of mini-bleeds was the same on neuropathological examination of both groups, they prevailed around the dentate nucleus of the cerebellum (p = 0.05) and in the tegmentum pontis (p = 0.05) of the PSP brains. On MRI the small bleeds were also more frequent around the dentate nucleus of the cerebellum (p = 0.02) and in the pons (p = 0.04) of PSP brains.


DISCUSSION
In PSP brains, mini-bleeds only prevail in the regions affected by the neurodegenerative process, similarly to what happens in frontotemporal lobar degeneration. They should be considered as the result of increased angiogenesis and microglial activation, leading to associated disturbances of the blood-brain barrier in the most affected regions of PSP. They are not indicative of cerebrovascular disease.