An autopsy case of Fabry disease with neuropathological investigation of the pathogenesis of associated dementia

Abstract

The pathogenesis of dementia associated with Fabry disease was examined neuropathologically in an autopsy case. The patient was a 47-year-old computer programmer who developed renal failure at the age of 36, necessitating peritoneal dialysis, and thereafter suffered in succession episodic pulmonary congestion, bradyacusia, heart failure, and dementia, before dying of acute myocardial infarction. MRI of the brain demonstrated leuko-araiosis. The CNS parenchyma showed widespread segmental hydropic swelling of axons in the bilateral cerebral and cerebellar deep white matter in addition to neuronal ballooning due to glycolipid storage in a few restricted nuclei and multiple tiny lacunae. Hydropic axonal swelling was also sparsely distributed in the pyramidal tract, pedunculus cerebellaris superior and brachium colliculi inferioris, but wallerian degeneration of these tracts was absent. Additional features included angiopathy of the subarachnoidal arteries due to Fabry disease, such as medial thickening resulting from glycolipid deposition in smooth muscle cells (SMCs) and adventitial fibrosis with lymphocytic infiltration, together with widespread subtotal or total replacement of medial SMCs by fibrosis, associated with prominent intimal fibrous thickening and undulation of the internal elastic membrane of medium-sized (1000-100 microm diameter) arteries. The findings in this case suggest that axonopathic leukoencephalopathy due to multisegmental hydropic swelling of axons in the bilateral cerebral deep white matter is responsible for the dementia associated with Fabry disease, and may be caused by ischemia resulting from widespread narrowing and stiffening of medium-sized subarachnoidal arteries and progressive heart failure.