Spontaneous downbeat nystagmus in two sisters with sudanophilic leukodystrophy

Two sisters who manifested downbeat nystagmus at the early stage of leukodystrophy are reported. The younger sister whose onset was at the age of 20, deteriorated rapidly to the vegetative state, and died of acute pneumonia 7 years after. Her downbeat nystagmus was observed only during the early 2 years of the course of her disease. The histopathological study on her brain enabled a diagnosis of sudanophilic leukodystrophy which demonstrated overall gliosis of white matter in the cerebrum and severe depopulation of Purkinje cells in the cerebellum, particularly in the vermis. The elder sister's onset was at the age of 29 and deteriorated rapidly to akinetic mutism. Her downbeat nystagmus was observed only during the first year of the course of her disease. For over 10 years she has been at the vegetative state. CT-scan of her brain demonstrates low density areas in the white matter of the cerebrum and in the vermis of the cerebellum. These two cases showed similar clinical signs and courses of their diseases, which were spontaneous nystagmus, early changes of personality and intelligence, and extra-pyramidal sign and later rapid deterioration of the stage of akinetic mutism. Histopathologically these cases are suspected as having an identical hereditary etiology of sudanophilic leukodystrophy. In these cases it is noted that downbeat nystagmus was the early sign of the disease.