This didactic work will be an opportunity to present the various acquired white matter abnormalities in children, and to describe the clinical and radiological specificities.

Demyelination of white matter is a physiological situation in the newborn and the infant, ending around the age of 2 years. Two types of pathology can reach the white matter in children: congenital pathologies or "leukodystrophies", and acquired white matter abnormalities. In this work, we will be interested in acquired pathologies that can affect white matter in children, that are real diagnostic and therapeutic emergencies.

There are several groups of pathologies that may be responsible for an exclusive or predominant involvement of the white matter. Their imaging presentation is nonspecific The clinical context has a strong orientative value in pathologies acquired white matter : neonatal suffering, history of infection or vaccination, exposure to a toxic,chemotherapy ... The combination of clinical symptoms with MRI abnormalities is often characteristic, leading to early diagnosis and early therapy. I- A reminder of the anatomyof the white matter : The white matter accounts for about...

Acquired abnormalities of white matter in children are common. MRI is the most effective test for studying myelination and for diagnosis of white matter diseases.

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