Childhood-Onset Progressive Dystonia With Mitochondrial DNA G14459A Mutation: Efficacy of Long-Term Sodium Succinate Treatment

This article reports the case of an 11-year-old boy with progressive dystonia caused by the homoplasmic G14459A mitochondrial DNA mutation. The patient presented with focal dystonia in the right upper limb at 3 years of age, which progressed over 4 years to exhibit dystonia in both the upper and lower limbs. At 7 years of age, high signal intensity lesions in the bilateral striata and the midbrain were observed on fluid-attenuated inversion recovery images. It was observed on diffusion-weighted images that with time, these high signal intensity lesions migrated from the putamen to the caudate nuclei, which closely correlated with disease progression. Because his symptoms and abnormal magnetic resonance imaging findings progressed despite treatment with coenzyme Q10 and l-carnitine, at 7 years of age he was then started on sodium succinate, hoping to improve his complex I deficiency. After treatment, progression of MRI abnormalities appeared to have been suppressed for 4 years, although no improvement was observed in dystonia.