DISORDERS OF MOVEMENT IN LEIGH SYNDROME

Leigh syndrome (LS) is the clinical prototype of a genetically-determi ned mitochondrial encephalopathy. Twenty-two of 34 patients with LS ha d evidence of a movement disorder (MD). Dystonia, the most common MD, was present in 19 cases, rigidity in 4, tremor in 2, chorea in 2, hypo kinesia in 2, myoclonus in 1, and tics in 1. Dystonia was most commonl y multifocal at onset and showed progression in six patients. In half of the cases an enzymatic defect was detected, most commonly cytochrom e C oxidase. The neuroradiologic findings showed prominent basal gangl ia lesions in 20/21 patients. Putamen, caudate, substantia nigra and g lobus pallidus were involved in this order of frequency. This experien ce was reflected in a literature review encompassing 284 cases of LS. However, only 26.4 % had MD. Eleven patients, including one of our cas es, presented as the primary torsion dystonia phenotype. There are cli nical and pathological similarities between LS and other metabolic dis eases affecting the central nervous system. The enhanced vulnerability of the nervous system to metabolic stress and the resemblance in the distribution of the pathology of these diverse conditions suggests a c ommon pathogenetic mechanism. An excitotoxin-mediated mechanism is fav ored, one which might account for the frequent involvement of the basa l ganglia in LS.