© American Society of Neuroradiology The Reflection of Histology in MR Imaging of Pelizaeus-Merzbacher Disease

Pelizaeus-Merzbacher disease is a rare disease of infants and young children in which there is an arrest of myelination of the eNS. The cause of the disorder is unknown. Three cases are reported, representing the con natal and classical forms of the disease. The MR images obtained of these children are compared with histologic findings as reported in the literature. In the connatal form a complete absence of myelin in the brain is demonstrated. In the classical form an arrest of myelination in an early stage of development is shown in combination with progressive abnormalities of the unmyeli-nated white maHer and possibly a slow degradation of some myelin. MR imaging appears to be a unique diagnostic method for assessing the degree of hypomyelination, the core of Pelizaeus-Merzbacher disease, and for contributing to the understanding of the underlying pathology of this disorder. Pelizaeus-Merzbacher disease (PMD) is a rare neurologic disorder affecting the myelination of the eNS in young children. The disease can be categorized into three types; classical, connatal, and transitional. These types differ in their time of onset and clinical severity [1]