Proton MR spectroscopy in connatal Pelizaeus-Merzbacher disease

Background. Pelizaeus-Merzbacher disease (PMD) is a rare dysmyelinating dis order characterised by early pendular nystagmus, often rotatory and muscula r hypotonia with subsequent ataxia, spasticity and mental retardation. Vari ous point mutations or duplications in the PLP gene on the X chromosome are responsible for PMD in the majority of patients. Autosomal recessive inher itance, particularly in the connatal form, cannot be excluded. Three differ ent forms of the disease have been identified based on their onset, progres sion and severity of myelin pathology indicated by MRI features. Objective. To determine if MR spectroscopy is useful in the diagnosis of th e connatal form of PMD. Materials and methods. Proton MR spectroscopy was p erformed on two children with connatal PMD. Results. Our patients showed a markedly decreased peak of Cho. This alteration is well represented by quan titative analysis of the NAA-to-Cho ratio, which is the most important rati o affected. A significant decrease of the Cho-to-Cr ratio is also present. In the connatal form of PMD, global lack of myelination may be relevant, as demonstrated by a significant Cho peak reduction. Conclusions. Proton MR spectroscopy may be of diagnostic value in metabolic and destructive disorders of the brain. A greater number of patients with connatal PMD is needed in order to elucidate the significance of reduction of the Cho peak.