MRI in children with mental retardation.
BACKGROUND
In mental retardation (MR) an aetiological diagnosis is not always obtained despite a detailed history, physical examination and metabolic or genetic investigations. In some of these patients, MRI is recommended and may identify subtle abnormal brain findings.


OBJECTIVE
We reviewed the cerebral MRI of children with non-specific mental retardation in an attempt to establish a neuroanatomical picture of this disorder.


METHODS
Thirty children with non-specific MR were selected to undergo cerebral MRI. The examination included supratentorial axial slices, mid-sagittal images and posterior fossa coronal images. Brain malformations, midline and cerebellar abnormalities were studied.


RESULTS
In 27 of 30 patients, the neuroimaging evaluation revealed a relatively high incidence of cerebral and posterior fossa abnormalities. The most frequent were: dysplasia of the corpus callosum (46%; hypoplasia, short corpus callosum and vertical splenium), partially opened septum pellucidum and/or cavum vergae (33%), ventriculomegaly (33%), cerebral cortical dysplasia (23%), subarachnoid space enlargement (16.6%), vermian hypoplasia (33%), cerebellar and/or vermian disorganised folia (20%), and subarachnoid spaces enlargement in the posterior fossa (20%). Other anomalies were: enlarged Virchow-Robin spaces (10%), white matter anomalies (10%) and cerebellar or vermian atrophy.


CONCLUSIONS
MRI has shown a high incidence of subtle cerebral abnormalities and unexpected minor forms of cerebellar cortical dysplasia. Even if most of these abnormalities are considered as subtle markers of brain dysgenesis, their role in the pathogenesis of mental retardation needs further investigation.
Soto-Ares
Gustavo
G
Department of Neuroradiology, Hôpital Roger Salengro, CHRU Lille, 59037 Lille, France. gsotoares@chru-lille.fr
Joyes
Béatrice
B
Lemaître
Marie-Pierre
MP
Vallée
Louis
L
Pruvo
Jean-Pierre
JP
D000293:Adolescent; D001921:Brain / Q000473:pathology*; D002531:Cerebellum / Q000002:abnormalities; D002540:Cerebral Cortex / Q000002:abnormalities; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior / Q000002:abnormalities; D005260:Female; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male