Depressive episode with catatonic features in a case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).

Three months previously, a 17-year-old girl had complained of right-hand side hemiparesis, and her brain magnetic resonance imaging (MRI) showed a signal change in the left temporoparietooccipital area. The 3243A>G mutation was found in mitochondrial DNA. She was diagnosed with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and was prescribed dichloroacetic acid to treat lactic acidosis. Her health improved. Two months later, she developed drowsiness and generalized weakness. A New lesion was not found on brain MRI, and electrodiagnostic findings were compatible with acute motor sensory axonal neuropathy. Her negative symptoms, such as depressed mood, loss of interest in activities, psychomotor retardation, and hypersomnia, were aggravated. She was prescribed antidepressants and psychostimulants by a psychiatrist after diagnosis of severe depression episode with catatonic features. One month later, her catatonic condition had improved with medication. Our experience shows that psychiatric diagnostic evaluation of abruptly regressed neurologic and clinical features is important, even in a patient with devastating underlying disease.