Late onset cerebello-pontomesencephalic degeneration.

Two siblings are presented with late onset, rapidly progressive truncal ataxia, paralysis of down-gaze and loss of up-gaze saccades in association with other oculomotor dysfunctions as well as dementia. Electron microscopic muscle studies revealed abnormal distribution and form of the mitochondria, probably being the ultrastructural basis of the pathologic changes. A neurological syndrome as that described here has not been reported before.

Autosomal recessive ataxia, slow eye movements, dementia and extrapyramidal disturbances.

An Arab family with an autosomal recessive form of spinocerebellar degeneration with slow eye movements is reported. Hitherto all the reported cases were either sporadic or of autosomal dominant inheritance. Associated are progressive intellectual impairment and extrapyramidal dysfunction as well as peripheral neuropathy and skeletal abnormalities. Muscle biopsy revealed non-specific mitochondrial abnormalities. The spectrum of eye movement abnormalities is discussed and the literature is reviewed. It is concluded that the hallmark of this syndrome (slow or even absent saccades) is one of a group of oculomotor abnormalities, all being characterized by delayed initiation and slow velocity. The syndrome seems to be related to the olivopontocerebellar degenerations, but differs in that there is in addition selective degeneration of certain tracts and nuclei in the mesencephalon and probably more rostral structures.