Diffusion Tensor Imaging and Fiber Tractography Analysis in Patients with Pelizaeus-Merzbacher Disease.

INTRODUCTION

Pelizaeus-Merzbacher Disease (PMD) is a hypomyelinating disorder with X-linked recessive inheritance caused by mutations in the proteolipid protein 1 (PLP1) gene on chromosome Xq22. In the early stages of PMD, head tremor and pendular nystagmus are observed, while in the later stages, psychomotor developmental delay, choreoathetosis, ataxia, and spasticity are added to the clinical presentation. This study aimed to investigate the relationship between diffusion tensor imaging-fiber tractography (DTI-FT) findings, the clinical and pathogenetic features in PMD patients.

METHODS

Nineteen patients diagnosed with PMD between 1995-2006 and 19 healthy controls were included in our study. Both patient and control groups underwent 3 Tesla Magnetic Resonance Imaging (MRI), DTI, and FT examinations. By using DTI regions of interest (ROI) were drawn in the corticospinal tract, right inferior occipitofrontal fasciculus (RIOFF), middle cerebellar peduncle, and right cingulum. The mean fractional anisotropy (FA) values of the tractographies which obtained from the ROIs were calculated. Clinical and genetic features were compared with mean FA values.

RESULTS

Significant differences were found between the PMD and control groups in the FA values of the corticospinal tract (CST), corpus callosum, right inferior occipitofrontal fasciculus, middle cerebellar peduncle and right cingulum. This patient group had significantly higher FA values. Patients with severe disabilities showed marked reductions in anisotropy at the corticospinal tract level.

CONCLUSION

The significantly reduced FA values in the white matter regions in the patient group are sufficient to suggest predominantly white matter involvement in PMD. The markedly lower CST FA values in patients with severe disabilities indicate that CST may serve as an important localization for determining disease severity. Studies using DTI-FT in similar patient groups will non-invasively enhance our understanding of structural differences.