Mini-infarct encephalopathy associated with uncommon microvessel convolute formation presenting with presenile dementia.

A female patient started to suffer from transient ischemic attacks when she was 47 years of age, followed by increasing predominantly left-side spastic tetraparesis, generalized seizures and progressive dementia over a period of 11 years. She died when she was 58 years of age. On gross examination the brain showed enlarged ventricles and arteriosclerotic changes of large extracerebral vessels of the circulus arteriosus. Microscopic examination of the atrophic brain showed innumerable incomplete microinfarcts in the white and gray matter throughout all parts of the brain. In the white matter these lesions were characterized by small foci of demyelination and loss of oligodendrocytes while occasionally some scavenger cells were seen. Axons seemed to be unaffected or displayed irregular axonal regeneratory growth. Any inflammatory reaction failed. In the cerebral cortex and subcortical nuclei the lesions showed loss of neurons and decrease in synaptophysin expression. Intracerebral arteries showed fibrosis or fibrohyalinosis of the entire intracerebral small-vessel network. In addition, numerous uncommon clusters of angioma-like telangiectatic vessels were observed. Medium-sized ischemic infarcts were found in the right putamen and adjacent internal capsule region, left-side dorsolateral brain stem and cerebellar hemisphere as well as a left-side pyramidal tract degeneration. Contralateral pseudohypertrophy of the inferior olivary nucleus was seen. The clinical and the neuropathologic observations made in this patient are compatible with small vessel disease characterized by a multicentric special and not yet described type of incomplete mini-infarcts in cerebral cortex and white matter accompanied by some larger ischemic infarcts of the common type in brain stem and cerebellum.