MELAS and L-arginine therapy: pathophysiology of stroke-like episodes.

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a maternally inherited multisystem mitochondrial disorder. Although many molecular and cellular mechanisms have been discovered leading to mitochondrial cytopathy, the pathogenic mechanism of stroke-like episodes seen in MELAS has not been clarified yet. According to the muscle and brain pathology and vascular physiology, mitochondrial angiopathy, or endothelial dysfunction, were proposed to play an important role for developing stroke-like episodes. Based on a hypothesis of mitochondrial angiopathy theory, we use L-arginine in MELAS patients and report its usefulness. This review aims to give a general idea on the actual knowledge about the possible pathogenic mechanism of stroke-like episodes, including clinical symptoms that lead to stroke-like episodes, muscle, or brain pathology, molecular cellular functions, neuroimagings including MRI, MRS, and SPECT, and the proposed site of action of L-arginine therapy on MELAS patients. Currently, L-arginine therapy may be the most promising for the treatment of stroke-like episodes in MELAS.