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Mitochondrial encephalomyopathy presenting with clinical Leigh's disease: report of a case
1Department of Pediatrics, Veterans General Hospital-Taichung, Taiwan R.O.C.
Insights
Leigh disease, a mitochondrial disorder, presented in an infant with neurological symptoms. Despite extensive testing, the specific enzyme defect remained elusive, leading to respiratory failure.
Area of Science:
- Neurology
- Pediatrics
- Mitochondrial Diseases
Background:
- Leigh disease is a severe mitochondrial encephalomyopathy.
- Early diagnosis and treatment are crucial for managing mitochondrial disorders.
Observation:
- A 7-month-old infant developed episodic cranial nerve palsies, hypotonia, truncal ataxia, and myoclonus.
- Initial investigations including MRI and metabolic tests were inconclusive.
- Muscle biopsy revealed ragged red fibers and abnormal mitochondria.
Findings:
- Elevated lactic acid and abnormal brainstem evoked potentials were noted.
- Respiratory chain enzyme assays were normal, complicating diagnosis.
- The infant showed no improvement with Coenzyme Q, thiamine, or carnitine supplementation.
Implications:
- This case highlights diagnostic challenges in Leigh disease when standard enzyme tests are normal.
- Further research into novel diagnostic markers and therapeutic targets for mitochondrial encephalomyopathies is warranted.
- Understanding atypical presentations is vital for timely intervention in pediatric mitochondrial disorders.
Abstract:
Leigh's disease is one of the mitochondrial encephalomyopathies. This article presents a 7-month-old baby boy who had been well-being since birth until 6 months of age when episodic downward gaze of both eyes with limitation of horizontal eye movement were noted. This episode of cranial nerve palsies lasted about 4-5 days and subsided spontaneously. The second attack was noted one month later, to be associated with hypotonia and truncal ataxia. Episodic hyperventilation with resultant gasping and myoclonus was noted at the third attack but spontaneous respiration resumed soon with persistent ophthalmoplegia and truncal ataxia. Lumbar puncture, brain MRI, amino acid assay and cardiac echo all showed negative finding. The oral glucose lactate stimulation test revealed an elevation of lactic acid, brain stem evoked potential indicated bilateral obscure 4th and 5th waves, and muscle biopsy showed ragged red fibres with aggregation of structurally abnormal mitochondria noted under electron microscope. Coenzyme Q, thiamine and carnitine had been given before biochemical study; however, the neurological symptoms did not show any improvement. Biochemical study finally revealed normal respiratory chain enzymes including NADH-coenzyme Q reductase, succinate coenzyme Q reductase and cytochrome c oxidase while other enzymes were technically unavailable for study. Unfortunately the patient died at 18-month-old due to respiratory failure.