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Frederic Nicot, Alain Bron, Catherine Creuzot-Garcher, Francis Renault; Flash Electroretinogram In Children With Mitochondrial Diseases. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5730.
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Retinopathy due to systemic diseases with mitochondrial defect usually does not produce severe visual deficiency. It can be diagnosed using fundoscopic examination and electroretinogram (ERG). We report the results of flash ERG recordings in a series of 17 children.
Monocular ERG was performed at ages from 4 months to 13 years. ERG was recorded using disposable contact lens electrodes in the conscious child with eyes open, after topical anesthesia but without sedation. Stimulus was a white flash (color temperature 5600°K, energy at source 0.3J) applied in mesopic conditions (background light: 0.55lux). Analysis focused on a- and b- waves amplitudes and latencies, and the a/b amplitude ratio.
Patients showed various clinical features including generalized muscle weakness with ophthalmoplegia (n = 2) or without (n = 9) and combined neuromuscular symptoms with ophthalmoplegia (n = 1) or without (n = 5). Fundoscopic examination was normal in 15 patients and showed typical salt and pepper retina in the two others. Various biochemical defects were diagnosed: carnitine palmitoyl transferase deficiency (n = 2) ; defects of β-oxydation (n = 8) ; respiratory chain complex I deficiency (n = 4) and complex IV deficiency (n = 3). ERG was normal in three patients including one with salt and pepper retina. It was extinguished in one patient with normal fundus. Thirteen patients showed various ERG changes. Global amplitude was increased in 7 patients, associated with increased a/b ratio in 2 of them. In 6 patients, the a/b ratio was increased with normal or decreased global amplitude. Latencies were always normal. We did not find any specific correlation between ERG results and biochemical data.
ERG changes are early signs of mitochondrial diseases even in the absence of fundoscopic signs of retinal degeneration.
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