Response to the Letter to the Editor Regarding an Article “bilateral Striatal Necrosis Caused by a Founder Mitochondrial 14459G>A Mutation in Two Independent Japanese Families”

We thank Finsterer and a colleague for inquiries about our reports [ [1] Hirayanagi K. Okamoto Y. Takai E. Ishizawa K. Makioka K. Fujita Y. Kaneko Y. Tanaka M. Takashima H. Ikeda Y. Bilateral striatal necrosis caused by a founder mitochondrial 14459G>A mutation in two independent Japanese families. J. Neurol. Sci. 2017; 378: 177-181 Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar ]. Mitochondrial disorders including bilateral striatal necrosis (BSN) are characterized by multisystem involvement. Regarding multi-organ dysfunctions of three presented cases, our intensive investigations revealed that the affected organ is confined to the brain. As for the initial symptom of foot dragging in Patient A-1, we speculated it was due to dystonia occurred in lower limb muscles but not muscle weakness because manual muscle test on each muscles confirmed full scores without muscle atrophy. Tendon reflexes were normal in all limbs. Serum creatine kinase level was 122 IU/L (normal range: 62 to 287). Both the needle electromyogram and the nerve conduction studies in all limbs showed no pathological findings and each measurement was within normal limits, indicating complicating neuropathy and myopathy were unlikely. Based on clinical similarities between DOPA-responsive dystonia and Patient A-1, levodopa was administered to him with unsuccessful outcome.