Decrease of neurons in the medullary arcuate nucleus in myotonic dystrophy

Respiratory insufficiency has been reported frequently in patients with myo tonic dystrophy (MyD). Recent data support the hypothesis that this respira tory failure results from a primary dysfunction of the central nervous syst em. The medullary arcuate nucleus (ARC) has been shown to be involved in th e regulation of respiration. We performed a quantitative study of neurons i n the ARC in eight MyD patients, ten control subjects with other neurologic al diseases (control group A) and eight control subjects without neurologic al diseases (control group B). Alveolar hypoventilation of the central type occurred in three of the MyD patients but not in the remaining MyD patient s or controls. The density of neurons in the ARC in MyD patients with hypov entilation was significantly lower than in MyD patients without hypoventila tion and control groups A and B. There was no significant difference in the neuronal density of the ARC between MyD patients without hypoventilation a nd control groups A and B. These data suggest that the neuronal loss of the ARC is associated with the presence of hypoventilation in MyD.