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

This case report describes a follow up investigation of a patient with impa ired word discrimination due to mitochondrial encephalopathy with lactic ac idosis and stroke-like syndrome (MELAS) using proton magnetic resonance spe ctroscopy (H-1 MRS) and auditory evoked magnetic fields (AEFs). The initial H-1 MRS showed no N-acetyl aspartate (NAA) and marked accumulation of lact ate (Lac) in the strokelike lesion of MELAS, which M as silent in neural ac tivity according to AEFs. The follow up investigations, however, demonstrat ed that NAA reappeared, that the formerly increased Lac signal was signific antly reduced, and that the magnitude of AEFs of the lesion was markedly in creased. Metabolic and functional changes in H-1 MRS and AEFs reflected the neurological recovery very well. The stroke-like lesion was shown, using A EFs and H-1 MRS, to be able to function properly, although brain tissue of the lesion initially had severe damage due to mitochondrial dysfunction.