The Onuf's nucleus and the external anal sphincter muscles in amyotrophic lateral sclerosis and Shy-Drager syndrome

Abstract

The anterior sacral horns and external anal sphincter muscle were examined histologically with special reference to Onuf's nucleus in amyotrophic lateral sclerosis (ALS) and Shy-Drager syndrome. Onuf's nucleus and the external anal sphincter muscles were well preserved in ALS, but in Shy-Drager syndrome both structures showed marked degenerative changes. These findings suggest that Onuf's nucleus does not belong to the autonomic neurons, but to the motoneurons in anterior sacral horn, and it innervates the external sphincter muscles of the anus and urethra. © 1982 Springer-Verlag.