Focal hyperperfusion in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. Case report.

A 28-year-old woman presented with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). The diagnosis was based on the results of molecular genetic analysis, which indicated a typical point mutation at the nucleotide pair 3243. Xenon computerized tomography scans obtained during the strokelike episodes revealed the lesion responsible for the symptoms to be an area of focal hyperperfusion, and scans obtained after the episodes revealed an area of hypoperfusion. Pathogenesis of the strokelike episodes appears to be metabolic dysfunction, although the involvement of a vascular event cannot be excluded.