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●診断：MELAS
Mitochondrial Encephalopathy with
Lactic Acidosis and Strokelike episodes
●Diagnostic Keys
・Clinical
・Intractable epilepsy
・Increased CSF lactate level
・Second decade of life
・Imaging
・peripheral white matter and deep gray matter
・Parietal and occipital lobes
・Different age of the lesions
Mitochondrial disorders
I. Exclusive or predominant muscle involvement
Fatal infantile myopathy, Benign infantile myopathy
II. Predominant brain involvement
Subacute necrotizing encephalomyelopathy (Leigh syndrome)
Alpers' disease, Myoclonic epilepsy with ragged-red fibers (MERRF)
Trichopoliodystrophy (Menkes' disease), Glutaric acidurias types
I and ll
Mitochondrial encephalopathy with lactic acidosis and strokelike
episodes (MELAS)
Familial mitochondrial encephalopathy with maorocephaly, cardiomyopathy,
and complex l deficiency
III. Other
Progressive external ophthalmoplegia
Isolated
With retinitis pigmentosa and other organ invdlvement (Kearns-Sayre
syn.)
Encephalomyopathy in adults
Myoneurogastrointestinal encephalopathy
MELAS
・Nausea, vomiting, strokelike events (hemianopsia, hemiparesis)
・Any age, commonly second decade
・Dysfunctional mitochondria in smooth muscle cells in the small
arteries causes strokelike episodes
Brain involvement in MELAS
・Vascular hypothesis
Metabolic damage of endothelium
→ small vessel occlusion
→ 2ndary neuronal death
・Defect in neuronal metabolism hypothesis
Mitochondrial dysfunction
→ anaerobic metabolism
→ neuronal death from acidosis
Imaging Findings of MELAS
・Increased water in the affected area
・Primarily parietal and occipital lobes and in the basal ganglia
・Subsequent resolution and reappearance
・Not restricted to a specific vascular area
・High lactate in affected area in MRS
・Markedly decreased metabolic rate and lower oxygen extraction
fraction in PET
References
・Barcovich AJ. Toxic and metabolic brain disorders. In Pediatric
Neuroimaging, 3rd ed. Philadelphia: Lippincott Williams and Wilkins,
2000: 71-156.
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