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MELAS: Clinical and pathologic correlations with MRI, xenon/CT, and MR spectroscopy
J M Clark1, M P Marks, E Adalsteinsson
1Stanford Stroke Center, Palo Alto, CA 94304-1705, USA.
Abstract:
We describe the clinical, imaging, and pathologic findings in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). The patient experienced her first stroke-like episode at age forty-four. Brain MRI, obtained at symptom onset, at 3 weeks, and at 1 year, revealed migrating T2-weighted hyperintensities in the temporal/parietal and occipital cortices and later revealed atrophy. Abnormal cerebrovascular reserve was evident on xenon/CT four days after the first MRI. MR spectroscopy at 1 year revealed increased lactate in both the occipital and temporal lobes. Histologic sections demonstrated spongy degeneration of the cortex that was most prominent at the crests of the gyri. Electron microscopy of the blood vessels showed increased numbers of abnormal mitochondria within the vascular smooth muscle and in endothelial cells. We hypothesize that the stroke-like episodes in MELAS may be due to impaired autoregulation secondary to the impaired metabolic activity of mitochondria in the endothelial and smooth muscle cells of blood vessels.
Insights
Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) can cause stroke-like brain lesions. Impaired mitochondrial function in blood vessels may underlie these events in MELAS patients.
Area of Science:
- Neurology
- Mitochondrial Diseases
- Neuroimaging
Background:
- Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a rare mitochondrial disorder.
- Characterized by stroke-like episodes, seizures, and developmental delay.
Observation:
- A patient with MELAS presented with recurrent stroke-like episodes.
- Brain MRI revealed migrating T2 hyperintensities and subsequent atrophy.
- Cerebrovascular reserve was abnormal, and MR spectroscopy showed increased lactate.
Findings:
- Histopathology showed spongy degeneration of the cortex.
- Electron microscopy identified abnormal mitochondria in vascular smooth muscle and endothelial cells.
- These findings suggest impaired autoregulation due to mitochondrial dysfunction in cerebral vasculature.
Implications:
- Hypothesizes that impaired mitochondrial metabolic activity in vascular cells contributes to stroke-like episodes in MELAS.
- Highlights the role of vascular pathology in MELAS pathogenesis.
- Suggests potential targets for therapeutic interventions in MELAS.