Function of the anal sphincters in spinal man

Area of Science:

• Neuroscience
• Physiology
• Urology

Background:

• Spinal cord injury (SCI) can significantly impact autonomic functions, including bowel control.
• Anal sphincter function is crucial for fecal continence and is regulated by complex neural pathways.

Purpose of the Study:

• To investigate the impact of traumatic transverse spinal cord lesions on anal sphincter function.
• To compare the rectoanal inhibitory reflex and striated sphincter electromyography in patients with SCI and healthy controls.

Main Methods:

• Continuous recording of anal pressure and electromyography (EMG) of striated sphincter muscles.
• Gradual rectal distension using an air-filled balloon in eight SCI patients and eight healthy controls.

Main Results:

• Patients with SCI demonstrated a greater tendency for cessation of striated muscle electrical activity during rectal distension.
• A less pronounced rectoanal inhibitory reflex was observed in SCI patients compared to controls.
• The smooth internal sphincter's function remained independent of cerebral influence in both groups.

Conclusions:

• Rectal distension in healthy individuals involves stimulation from both cerebral and spinal cord centers.
• SCI disrupts the coordinated neural control of the anal sphincters, affecting reflex responses.
• The smooth internal sphincter's autonomic regulation appears preserved despite transverse spinal cord lesions.