[A computed tomography study of myotonic dystrophy]

Mental symptom is one of the characteristic features in myotonic dystrophy, but documentation of mental signs including pathological changes of the brain has been imprecise. An attempt to show the involvement of the central nervous system by CT scan and EEG has been done in our department. The material consists of 14 patients 10 males and 4 females, from 15 to 50 years of age. CT scan of the 14 patients showed diffuse enlargement of lateral and third ventricles without definite atrophy of cerebral cortex and brainstem. Measurements of various parts of the ventricles showed a difference and an increase with age of values compared with that obtained from 49 neurologically normal persons (P less than 0.01). Main findings of EEG taken from 7 patients were slowing and low voltage of background activity, and 4 patients showed monotonous alpha waves. Both asymmetry and paroxysmal waves were not found. There was no significant correlation between the degree of ventricular enlargement and the frequency of the alpha activity (P greater than 0.05). Our study reveals that the ventricular enlargement is more correlated with aging than the severity of muscle involvement or the degree of mental deterioration. This fact possibly reflects a progressive nature of the pathology of the brain, especially the white matter.