Résumé :
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Myotonic dystrophy type 1 (DM1) is an autosomal dominant inherited neuromuscular condition caused by an abnormal CTG triplet expansion within the 3' untranslated region of the myotonic dystrophy protein kinase (DMPK) gene on chromosome 19q35The childhood-onset form of DM1 is characterised by slowness, fatigue, hypersomnia, learning disabilities and cognitive impairment (intellectual impairment, attentional deficit, visuospatial deficit), while neuromuscular symptoms are rather mild or sometimes even absent. In the literature, neuroimaging findings of some isolated case of patients with congenital form were reported, showed a cerebral atrophy or a ventricular dilatation. In the other hand, conventional MRI studies in adults have documented cortical atrophy more prominent in the frontal and temporal lobes and white matter hyperintense lesions (WML) usually diffuse in both hemispheres. Some correlations between WML and neuropsychological data or duration of the disease are suggested. Voxel-based morphometry (VBM) has been used by several authors to map cortical and subcortical grey matter atrophy in DM1 even where there were no or minimal abnormalities on traditional MRI studies. These studies confirm that regional neuronal loss occurs in the parietal and frontal lobes and demonstrate that atrophy extends to the superior and middle temporal gyrus and the occipital lobes. In the childhood-onset form of DM1 neuroimaging informations are absent. So, in order to:- identify the neuroradiologic features of childhood-onset of DM1- compare them to those of the congenital or adult form of the disease- try to correlate neuroradiologic features with learning disabilities or cognitive impairmentWe perform a MRI study in nine infantile DM1 patients (6 men, 17.9 ± 4.8 years) who also received a clinical examination and neuropsychological evaluation and 18 normal controls (9 men, 14.6 ± 4.8 years). They underwent structural MRI on a 1.5 T scanner using a T1-weighted spoiled gradient echo sequence. MRI scan were preprocessed with SPM8 using the Gaser's Voxel-Based Morphometry toolbox. Results will be presented at the conference.
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