Tractography reveals diffuse white matter abnormalities in Myotonic Dystrophy Type 1

Abstract

Cerebral involvement in Myotonic Dystrophy Type 1 (DM1) is well-established but not well characterized. This study applied new Diffusion Tensor Imaging (DTI) tractography to characterize white matter disturbance in adults with DM1. Forty-five participants with DM1 and 44 control participants had MRIs on a Siemens 3T TIM Trio scanner. Data were processed with TRActs Constrained by UnderLying Anatomy (TRACULA) and 7 tracts were evaluated. Bilateral disturbances in white matter integrity were seen in all tracts in participants with DM1 compared to controls. There were no right-left hemisphere differences. The resulting DTI metrics were correlated with cognitive functioning, particularly working memory and processing speed. Motor speed was not significantly correlated with white matter microstructural integrity and, thus, was not the core explanation for the working memory and processing speed findings. White matter integrity was correlated with important clinical variables including the muscular impairment rating scale (MIRS). CTG repeat length was moderately associated with white matter status in corticospinal tract and cingulum. Sleepiness (Epworth Sleepiness Scale) was moderately associated with white matter status in the superior longitudinal fasciculus and cingulum. Overall, the results add to an emerging literature showing widespread white matter disturbances in both early-onset and adult-onset DM1. Results suggest that further investigation of white matter pathology is warranted in DM1 and that non-invasive measures such as DTI have a potentially important clinical value in characterizing the status of individuals with DM1.

Keywords: Brain; Diffusion Tensor Imaging; MRI; Myotonic Dystrophy; Neuropsychology; White matter.

Figure 1

Illustration of white matter tracts from TRACULA (purple = corticospinal tract; red = forceps major & forceps minor; teal= cingulum bundle {cingulum gyrus component}; light green = cingulum bundle {angular gyrus component}; light blue = superior longitudinal fasciculus {temporal component}; orange = inferior longitudinal fasciculus; medium blue = uncinated fasciculus; yellow = thalamic radiations {not examined}.