Reversible brain dysfunction in MELAS: MEG, and 1H MRS analysis

Abstract

This case report describes a follow up investigation of a patient with impaired word discrimination due to mitochondrial encephalopathy with lactic acidosis and stroke-like syndrome (MELAS) using proton magnetic resonance spectroscopy (1H MRS) and auditory evoked magnetic fields (AEFs). The initial 1H MRS showed no N-acetyl aspartate (NAA) and marked accumulation of lactate (Lac) in the stroke-like lesion of MELAS, which was silent in neural activity according to AEFs. The follow up investigations, however, demonstrated that NAA reappeared, that the formerly increased Lac signal was significandy reduced, and that the magnitude of AEFs of the lesion was markedly increased. Metabolic and functional changes in 1H MRS and AEFs reflected the neurological recovery very well. The stroke-like lesion was shown, using AEFs and 1H MRS, to be able to function properly, although brain tissue of the lesion initially had severe damage due to mitochondrial dysfunction.