MRI findings of Pelizaeus-Merzbacher disease correlated with phenotypes and genetic mutation

Abstract

Objective To investigate the correlation of MRI features and phenotypes and genetic mutations in Pelizaeus-Merzbacher disease.Methods Sixteen boys with clinical diagnosis of PelizaeusMerzbacher disease (PMD) were included in this study.Their ages ranged from 22 months to 9 years.They were examined by pediatric neurologists,and clinical classification was made according to the symptoms and physical signs.An experienced radiologist reviewed the cranial MRI images and analyzed the brain involvement,including pallidus globus,pyramidal tract,corpus callosum,cerebellar white matter,semiovale centrum,brain atrophy and ‘ tigroid sign’.Results There were 8 patients with classic form,7 patients with transitional form and one patient with connatal form.They all showed diffuse delayed myelination in the white matter,with involvement of pallidus globus in 13 cases,pyramidal tract in 7 cases,corpus callosum in 11 cases,cerebellar white matter in 7 cases,semiovale centrum in 12 cases.Cerebral atrophy was found in 5 patients and eerebellar atrophy was found in one patient.Five cases depicted ' tigroid sign'.In patients with PLP1 gene point mutation,pyramidal tract and cerebellar white matter involvement showed a high incidence.Cerebellar white matter lesions were relatively frequent in children with transitional form and connatal form.In contrast,‘ tigroid sign' was often related to classic form,which indicated a better myelination and outcome.Conclusion PMD patients show distinct imaging features in their brains,which may be correlated with the phenotype and genetic mutation. Key words: Leukoencephalopathy; progressive multifocal; Magnetic resonance imaging; DNA mutational analysis