Patterns of Brain Lesions in Adult-Onset Myotonic Dystrophy Type 1: A Quantitative MRI Study

Background: Myotonic dystrophy type 1 (DM1) is a multisystemic disorder caused by CTG repeat expansion in the DMPK gene. Brain involvement in DM1 has been reported, but quantitative imaging data is limited. This study aimed to characterize and quantify brain structural abnormalities in DM1 using MRI and DUIH-Image software.Methods: Sixteen patients with classic DM1 (10 male, 6 female; age range 17–68 years) underwent genetic testing, neuropsychologic assessment, and brain MRI. FLAIR images were analyzed using DUIH-Image software to quantify brain lesions and create probabilistic lesion maps.Results: FLAIR imaging revealed hyperintensities predominantly in periventricular and subcortical white matter. Probabilistic lesion maps highlighted the subcortical white matter near the anterior horn as the most affected site, with additional involvement of the posterior horn, frontal, insular, parietal, and temporal cortices. Neuropsychological testing identified frontal lobe dysfunction as the most common deficit, correlating with brain involvement. No significant correlations were found between lesion load, CTG repeat number, and disease duration.Conclusions: This study demonstrates significant periventricular and subcortical white matter involvement in DM1, with the anterior subcortical white matter being the most affected site. Frontal lobe dysfunction was a frequent finding. Brain involvement did not correlate with CTG repeat number or disease duration, suggesting complex pathophysiology in DM1-related brain abnormalities.