Monday, March 8, 2010

Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-Like Episodes (MELAS)

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a rare disorder of intracellular energy production caused by mutations in mitochondrial DNA. Patients are usually normal at birth and during early infancy, then show delayed growth, episodic vomiting, seizures, and recurrent cerebral injuries resembling strokes that may cause hemiparesis, hemianopsia, hearing loss, or cortical blindness.

CT and MR imaging may show multiple cortical and subcortical infarct-like lesions that cross vascular boundaries, more commonly in the parieto-occipital region and basal ganglia. The lesions have a migrating pattern over time, with appearance, disappearance, and reappearance. Variable degrees of generalized cerebral and cerebellar atrophy may also be seen. Basal ganglia calcifications may also be seen.

CTA and MRA are usually normal, while conventional angiograms in the acute phase may show dilated cortical arteries with prominent capillary blush and no arterial occlusion.

The classic MRS finding is elevated lactate peak in the cerebrospinal fluid and normal brain.

Differential consideration for infarction in a young person:
  • Cardiac embolic disease: Valvular disease, left atrial myxoma.
  • Prothrombic disorder: Sickle cell disease, protein S or C deficiency, factor V-Leiden, lupus anticoagulant, polycythemia, leukemia.
  • Congenital vascular: CADASIL, neurocutaneous syndromes
  • Acquired vascular: Dissection, moya moya.
  • Drugs: Oral contraceptives, stimulants (methamphetamines, cocaine).

Based on the clinical characteristics of MELAS, some have suggested that Friedrich Nietzsche may have suffered from MELAS, and not syphilis as commonly thought.


  • Kim IO, Kim JH, Kim WS, Hwang YS, Yeon KM, Han MC. Mitochondrial myopathy-encephalopathy-lactic acidosis-and strokelike episodes (MELAS) syndrome: CT and MR findings in seven children. AJR Am J Roentgenol. 1996 Mar;166(3):641-5.
  • Koszka C. Friedrich Nietzsche (1844-1900): a classical case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome? J Med Biogr. 2009 Aug;17(3):161-4.
  • Osborn AG. MELAS. StatDx. 2006-09-11.

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