Cockayne Syndrome: A Diffusion Tensor Imaging and Volumetric Study
Résumé
OBJECTIVES: Cockayne syndrome (CS) is a rare disorder characterized by severe brain atrophy, white matter hypomyelination, and basal ganglia calcifications. This study aimed to quantify atrophy and white matter abnormalities using diffusion tensor imaging (DTI) and volumetric analysis, to evaluate possible differences between CS subtypes, and to determine if DTI findings may correspond to a hypomyelinating disorder. METHODS: Fourteen CS patients and 14 controls underwent brain MRI including DTI and a volumetric 3D T1-weighted sequence. DTI analysis was made through ROIs within the whole brain to obtain fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values, and in the left centrum semiovale to obtain DTI eigenvalues. A Student's t-test was used to compare patients and controls, and CS subtypes. Given the small number of CS patients, they were pooled in two groups: moderate (CS1/CS3) and severe (CS2/COFS (cerebro-oculo-facio-skeletal syndrome)). RESULTS: Total brain volume in CS was reduced by 57%, predominantly in the infratentorial area (68%) (p \textless0.001). Total brain volume reduction was greater in the severe group, but there was no difference in the degree of infratentorial atrophy in the two groups (p = 0.7). Mean FA values were lower, whereas ADC was higher in most of the white matter in CS patients (p \textless0.05). ADC in the splenium of the corpus callosum and the posterior limb of the internal capsule, and FA in the cerebral peduncles were significantly different between the two groups (p \textless0.05). Mean ADC values corresponded to a hypomyelinating disorder. All DTI eigenvalues were higher in CS patients, mainly for transverse diffusivity (+51%) (p \textless0.001). CONCLUSIONS: DTI and volumetric analysis provide quantitative information for the characterization of CS, and may be particularly useful for evaluating therapeutic intervention. ADVANCES IN KNOWLEDGE: DTI combined with volumetric analysis provides additional informations useful not only for characterization of Cockayne syndrome and distinction of clinical subtypes but also to monitor therapeutic interventions.