A Chinese girl with Leigh syndrome: effect of botulinum toxin on dystonia.

Leigh syndrome is a form of neurodegenerative disease which is associated with intracranial infarcts. The diagnosis is made by finding hyperlactacidaemia together with cerebral infarcts on neuroimaging. We report a 4-year-old Chinese girl with Leigh syndrome who had several atypical features. She presented with generalized dystonia and developmental regression. In addition, she suffered from an unusual feature of bladder dystonia. This patient appeared to be suffering from respiratory chain complex I deficiency from studies on cultured skin fibroblasts. Assays for respiratory chain enzymes as well as mitochondrial DNA point mutations and major deletions in muscle were normal. Dystonia persisted despite treatments with muscle relaxants and a ketogenic diet. Intramuscular botulinum toxin resulted in significant relief of dystonia.