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[A case with MELAS associated with epilepsia partialis continua]
1Department of Pediatrics, School of Medicine, University of Tokushima.
Abstract:
We report a 14-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) who presented repeated episodes of abdominal pain and vomiting since the age of 8 years. In addition, he developed strokelike episodes with myoclonic seizures and transient hemiplegia on three occasions. At the age of 14-1/12-years, he also developed epilepsia partialis continua persisting for 10 days, which was associated with myoclonic seizures synchronized with spike discharges at the right central area. Laboratory examination disclosed increased levels of lactate and pyruvate in serum and CSF and low density areas in the bilateral temporal regions on CT scan. Muscle biopsy showed scattered ragged-red fibers. The enzyme activities (pyruvate dehydrogenase complex, pyruvate carboxylase, phosphoenol pyruvate carboxykinase, and cytochrome c oxidase) and the rates of decarboxylation of [3-14C]pyruvate in cultured skin fibroblasts were within normal ranges.
Insights
This study details a 14-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Despite typical MELAS symptoms, key enzyme activities were normal, suggesting atypical disease mechanisms.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Diseases
Background:
- Mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) is a maternally inherited disorder.
- MELAS typically presents with stroke-like episodes, seizures, and mitochondrial myopathy.
Observation:
- A 14-year-old boy experienced recurrent abdominal pain, vomiting, stroke-like episodes with hemiplegia, and epilepsia partialis continua.
- Laboratory findings included elevated serum and CSF lactate and pyruvate levels.
- Brain CT revealed low-density areas in bilateral temporal regions, and muscle biopsy showed ragged-red fibers.
Findings:
- Despite classic MELAS clinical and pathological features, all tested enzyme activities (pyruvate dehydrogenase complex, pyruvate carboxylase, phosphoenol pyruvate carboxykinase, cytochrome c oxidase) and pyruvate decarboxylation rates in fibroblasts were normal.
- This suggests a potential genetic mutation affecting mitochondrial function not detectable by standard enzyme assays.
Implications:
- The findings challenge the typical understanding of MELAS pathophysiology, indicating that normal enzyme activity does not exclude the diagnosis.
- Further genetic investigation is warranted to identify novel mutations responsible for this atypical MELAS presentation.
- This case highlights the importance of considering MELAS in pediatric patients with recurrent neurological events and metabolic derangements, even with normal enzyme assays.