Abstract
Five adult siblings from a sibship of ten suffering from an external ophthalmoplegia with a spastic paraplegia are reported. In addition, optic nerve atrophy was present in three of the patients and dementia in two; extrapyramidal signs and cerebellar ataxia were found only in one patient. Contrary to earlier studies of patients with comparable neurological signs the pattern of inheritance was autosomal recessive. Neuropathological investigation of the index case, who had never shown ataxia, nevertheless showed demyelination of the spinocerebellar and the olivocerebellar pathways, and also a severe loss of Purkinje cells, of cells in Clarke's column and in the inferior olives. The dentate nucleus was severely gliotic but showed no cell loss. Earlier neuropathological investigations of this disorder, but with an autosomal dominant heredity, were incomplete. It is concluded that the five siblings of this family have a unique autosomal recessive disorder, which should be considered a distinct entity.