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Metabolism in MELAS: Case Report

Taisuke Otsuki, MD, PhD; Tomoyuki Kanamatsu, PhD; Yasuzo Tsukada, MD, PhD; Yuichi Goto, MD, PhD; Kazuya Okamoto, BS; Hidehiro Watanabe, PhD

Arch Neurol. 2005;62:485-487.

Background  Carbon 13–labeled magnetic resonance spectroscopy (¹³C-MRS) with [^1-13C]-glucose administration, the ¹³C atom that behaves as a radio inactive tracer in the brain, can differentiate aerobic and anaerobic glucose metabolism by detecting [^4-13C]-glutamate (Glu C4) and [^3-13C]-lactate (Lac C3).

Objective  To investigate the cerebral metabolic derangement resulting from mitochondrial dysfunction in mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS).

Design  Application of a new ¹³C-MRS technique to a patient with MELAS compared with control subjects (n = 7).

Patient  A 19-year-old woman with an A3243G mitochondrial mutation who underwent ¹³C-MRS for 30 minutes after oral administration of [^1-13C]-glucose (0.75 g/kg).

Result  Decreased Glu C4–labeling (P<.001) and increased Lac C3 synthesis (>2 SDs) compared with controls were demonstrated in the patient with MELAS.

Conclusions  This first report on ¹³C-MRS observation of cerebral glucose metabolism in a patient with MELAS demonstrated the presence of low glutamate production via the tricarboxylic acid cycle compared with high lactate synthesis by glycolysis. The present findings suggest that the clinical use of ¹³C-MRS can be extended to diagnose mitochondrial dysfunction and monitor cerebral glucose metabolism in a variety of mitochondrial disorders.

Author Affiliations: Department of Neurosurgery, National Center Hospital for Mental, Nervous, and Muscular Disorders, National Center of Neurology and Psychiatry (Dr Otsuki), Institute of Life Science, Soka University (Drs Kanamatsu and Tsukada), and Mental Retardation and Birth Defect Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (Dr Goto), Tokyo, Japan; and Medical Systems Research and Development, Toshiba Corporation, Tochigi, Japan (Messers Okamoto and Dr Watanabe).