Neuroimaging studies in the evaluation of developmental delay/mental retardation

The employment of neuroimaging studies in the evaluation of individuals with developmental delay/mental retardation (DD/MR) is still highly debated. The Consensus Conference of the American College of Medical Genetics has suggested that "neuroimaging appears to have an especially important role in patients with microcephaly or macrocephaly, seizures, loss of psychomotor skills and neurologic signs," whereas the value of neuroimaging investigations "in the normocephalic patient without focal neurological signs is unclear" [Curry et al., 1997]. However, recent literature reports show how the latest neuroimaging techniques (in vivo proton magnetic resonance spectroscopy [H-MRS]) may prove to be useful in the diagnostic process of those individuals with DD/MR and no neurological signs/symptoms. The use of these techniques can, in addition, help in monitoring treatment in distinct metabolic disorders. This review will focus on the usefulness of neuroimaging studies in some of the newer metabolic disorders. This paper will also cover those recognizable patterns of human malformation where neuroimaging findings seem to be relevant both toward diagnosis and management, and add to our understanding of the related behavior phenotype. The essential role of magnetic resonance imaging (MRI) on the progress in the diagnostic recognition of malformations of cerebral cortical development is stressed.