Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
August 2019
Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-Like Episodes (MELAS)
- Background
- Defect in mitochondrial respiratory chain mechanism acquired by maternal inheritance.
- Increased local lactic acid production creates a neurotoxic microenvironment.
- Presents with stroke-like episodes in children and young adults.
- More than 90% are found before age of 40.
- Clinical Presentation
- Stroke-like episodes with seizure potential in young individuals without definite risk factors.
- Can acquire permanent dysfunction or have spontaneous resolution.
- Frequently presents clinically with elevated lactic acid levels.
- In the absence of stroke-like features, generalized encephalopathy, myopathy, and headaches are common.
- Key Diagnostic Features
- CT: Acute infarcts typically within the parieto-occipital and parieto-temporal regions. Appear as stroke-like cortical lesions with shifting spread that may cross multiple vascular territories. Demonstrates variable enhancement.
- MRI: FLAIR cortical hyperintensity with no evidence of hemorrhage. DWI positive ADC variable but typically normal/slightly decreased
- Angiography: Inconclusive in acute episodes with possible cerebral vessel vasodilation early in progression.
- MRS: Lac peak at 1.3 ppm may precede DWI changes in the early acute phase.
- Differential Diagnosis
- True ischemic stroke from embolism or dissection
- Myoclonic Epilepsy with Ragged-Red Fibers (MERRF)
- Leigh Disease
- Epilepsy
- Cerebral Vasculitis
- Treatment
- No definitive treatment. Supportive anticonvulsants and a variety of antioxidants/vitamins such as: CoQ10, L-arginine, B vitamins, and levocarnitine have shown varying efficacy in small trials.
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