Studies of the reflex activity of the external sphincter ani in spinal man

Abstract

Electromyographic studies on the reflex activity of the external anal sphincter were carried out in 42 patients with lesions of the spinal cord. All cases, with the exception of one (tabes dorsalis), were complete lesions at various levels of the cord. The external anal sphincter was found to show continuous tonic contraction at rest which depends on the integrity of the sacral segments and their peripheral outflow. Factors eliciting reflex excitation and inhibition resulting in increased contraction or relaxation of the tone of the external anal sphincter are described in detail. In particular the effects of increased intra-abdominal pressure, skin stimulation and distension of the anal canal and rectum are reported. The reflex mechanism of defaecation is discussed in the light of the management of bowel function in paraplegia. © 1964, International Spinal Cord Society. All rights reserved.