Central nervous system lesion in myotonic dystrophy--demonstrated by X-ray computed tomography and magnetic resonance imaging]

We made an attempt to detect organic brain lesions in eight patients with myotonic dystrophy (MyD) using X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The patients comprised seven men and one woman with ages ranging from 41 to 58 years (average 47 +/- 5.3 years). Seven patients had intellectual impairment assessed using an intelligence quotient test (WAIS-R < 70). CT scans were obtained in the axial plane with a slice thickness of 10 mm, and MRI scans were performed on a 1.5 tesla system in the axial and coronal sections with a slice thickness of 8 mm. CT scans displayed both marked sulcal and prominent ventricular enlargement in 6 of the 8 patients, indicating the presence of brain atrophy, and 3 cases had a few paraventricular low density area in the cerebral hemispheres. In contrast to CT, MRI study revealed more widespread brain parenchymatous lesions in all the 8 cases, showing the multiple foci of high signal intensity with varying size in the white matter on T2-weighted images and proton density-weighted images. No visible changes were detected on CT or MRI in the brain stem and cerebellum. The present study demonstrated that there exist organic cerebral lesions, predominantly located in the white matter in patients with MyD, regardless of focal neurological symptoms. The parenchymatous lesions in the brain can be detected with MRI, and lesser extent with CT, and are considered to be intimately correlated with intellectual deterioration commonly seen in patients with MyD.