Abstract
Myotonic dystrophy type 1 (DM1) is the most common of the muscular dystrophies. It is an autosomal dominant neuromuscular disorder with multisystem involvement, including the central nervous system. Two DNA-proven cases are presented. Patients reported are siblings showing features of DM1 on magnetic resonance imaging (MRI). These features include T2 and FLAIR hyperintensities in the periventricular, deep, and subcortical white matter, with frequent involvement of the anterior temporal lobe. Other features include general brain atrophy and enlarged Virchow-Robin spaces. Subcortical white matter lesions anterior in the temporal lobe are the most specific imaging finding, and a short differential diagnosis is discussed.