Movement disorders in mitochondrial disease: a clinicopathological correlation.

PURPOSE OF REVIEW: The scope of this review is to give an updated account of movement disorders associated with mitochondrial disease, with a particular focus on recently discovered clinicopathological correlations. RECENT FINDINGS: Movement disorders are common clinical manifestations of mitochondrial diseases, in part because of the high vulnerability of neurons controlling motor circuits to mitochondrial respiratory dysfunction and energy failure. Intriguingly, the clinicopathological correlations of movement disorders in mitochondrial disease do not always conform to established neurophysiological knowledge. In particular, nearly complete substantia nigra degeneration and nigrostriatal denervation can occur without being accompanied by any of the clinical signs traditionally associated with parkinsonism. This apparent paradox, may be because of compensation by concomitant impairment of other motor circuits involving the cerebellum and thalamus. SUMMARY: Movement disorders commonly accompany mitochondrial disease and may show paradoxical clinical-anatomical correlations. Further research is warranted in order to elucidate the mechanisms underlying the phenotypic expression of movement disorders in mitochondrial disease. This knowledge will advance our understanding of the pathogenesis of movement disorders in a broader clinical and pathophysiological context.