MRI Findings in 77 Children with Non-Syndromic Autistic Disorder

International audienceBACKGROUND: The clinical relevance of MR scanning in children with autism is still an open question and must be considered in light of the evolution of this technology. MRI was judged to be of insufficient value to be included in the standard clinical evaluation of autism according to the guidelines of the American Academy of Neurology and Child Neurology Society in 2000. However, this statement was based on results obtained from small samples of patients and, more importantly, included mostly insufficient MRI sequences. Our main objective was to evaluate the prevalence of brain abnormalities in a large group of children with a non-syndromic autistic disorder (AD) using T1, T2 and FLAIR MRI sequences. METHODOLOGY: MRI inspection of 77 children and adolescents with non-syndromic AD (mean age 7.4+/-3.6) was performed. All met the DSM-IV and ADI -R criteria for autism. Based on recommended clinical and biological screenings, we excluded patients with infectious, metabolic or genetic diseases, seizures or any other neurological symptoms. Identical MRI inspections of 77 children (mean age 7.0+/-4.2) without AD, developmental or neurological disorders were also performed. All MRIs were acquired with a 1.5-T Signa GE (3-D T1-FSPGR, T2, FLAIR coronal and axial sequences). Two neuroradiologists independently inspected cortical and sub-cortical regions. MRIs were reported to be normal, abnormal or uninterpretable. PRINCIPAL FINDINGS: MRIs were judged as uninterpretable in 10% (8/77) of the cases. In 48% of the children (33/69 patients), abnormalities were reported. Three predominant abnormalities were observed, including white matter signal abnormalities (19/69), major dilated Virchow-Robin spaces (12/69) and temporal lobe abnormalities (20/69). In all, 52% of the MRIs were interpreted as normal (36/69 patients). CONCLUSIONS: An unexpectedly high rate of MRI abnormalities was found in the first large series of clinical MRI investigations in non-syndromic autism. These results could contribute to further etiopathogenetic research into autism

Impairment of cerebello-thalamo-frontal pathway in Rab-GDI mutated patients with pure mental deficiency

International audienceBackground: Rab-GDI mutations are responsible for "pure" mental deficiency, without any specific clinical features or brain malformation. Therefore, screening for mutations in mentally retarded patients is not available on a routine basis. Moreover, neuronal networks involved in mental deficiency still remain largely unknown.Methods: We performed a fine neuropsychological and imaging study in five patients from two unrelated families, affected with mental deficiency due to a mutation in the Rab-GDI gene. High resolution 3D brain MRI of the five mentally retarded adult males (mean age 33 years) were compared to MRI of 14 healthy males (mean age 35 years) using a Voxel-Based Morphometric analysis (VBM).Results: All patients had isolated moderate mental retardation (WAIS-III IQ range, 41-50; mean 45) without specific morphological or behavioural features. No obvious brain abnormality was observed on visual inspection of individual scans. Using VBM analysis, Rab-GDI mutated patients' MRIs exhibited significant brain changes compared to normal subjects (p < 0.05, corrected for multiple comparisons): increased grey matter density in left cerebellum and in left angular gyrus, decreased grey matter volume in thalami, decreased white matter density in prefrontal lobes, right fusiform occipito-temporal gyrus, and decreased white matter volume in cerebellar peduncles.Conclusions: These morphological changes observed in Rab-GDI mutated patients, mainly localized in the cerebello-thalamo-prefrontal pathway, are consistent with the hypothesis that the cerebellum is one of the critical components of a global learning network. Our results open new avenues in the diagnosis of non-specific mental deficiency using gene-specific "brain maps" as endophenotypes. (C) 2008 Elsevier Masson SAS. All rights reserved

Clinical and sociodemographic characteristics of children with AD related to normal and abnormal MRIs.

<p>Clinical and sociodemographic characteristics of children with AD related to normal and abnormal MRIs.</p

Dilated Virchow-Robin spaces in autism.

<p>Virchow-Robin (VR) spaces are fluid-containing dilatations of the perivascular space that surrounds penetrating arteries in the brain (white arrow). We defined abnormal VR spaces when the spaces were >3 mm using the classification system developed by Heier et al <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004415#pone.0004415-Heier1" target="_blank">[11]</a>.</p

Results of Brain MRI abnormalities in patients with non-syndromic Autism Spectrum Disorder.

<p>Results of Brain MRI abnormalities in patients with non-syndromic Autism Spectrum Disorder.</p

Temporal pole abnormalities in a child with autism.

<p>Example of a typical sub-cortical hyperintensities on T2-weighted coronal images localized in the temporal poles observed in children with autism (red arrows) and a normal image of a control child without autism.</p

Clinical characteristics of the group of 77 children with autistic disorder.

<p>ADI-R = Autism Diagnosis Interview – Revised</p>*<p>Scores obtained in 42 children with sufficient verbal capacities</p

Presentation and long term follow-up of refractory celiac disease : comparison of type I with type II.

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