Neurogenic bowel characteristics differ among spinal cord injured (SCI) individuals, and appear to depend primarily on the level and completeness of injury. It is thought that upper motor neuron lesions in the spinal cord above L1-2 results in a hyperreflexive bowel with increased colonic wall tone and loss of cortical control over the relaxation of the external anal sphincter (EAS). These changes result in chronic high sphincter tone and dyssynergic defecation. The main symptoms in these patients are constipation and fecal retention, or difficulty with evacuation (DWE). In many of these individuals, some nerve connections between the spinal cord and the colon may be preserved, and stool propulsion and reflex coordination may remain intact and under control of the central nervous system. Furthermore, individuals with spinal lesions above T7 experience loss of voluntary control over abdominal muscles and an inability to increase intra-abdominal pressure, which results in more DWE and constipation. Lower motor neuron (LMN) lesions in the spinal cord below L1-2 result in the interruption of the centrally mediated innervation to the bowel, which causes slowing of peristalsis, a flaccid EAS, and atonic levator ani muscles. This is also called an areflexic bowel. The main symptoms in these patients are constipation from slowed peristalsis and fecal incontinence (FI) from atonic EAS and levator ani muscles. While the symptoms of bowel dysfunction in persons with SCI are known, function and motility of the anal canal have not been documented in this population. Anorectal manometry can provide valuable information about sphincter strength, defecation dynamics and reflex mechanisms. New high-resolution anorectal manometric systems (Given Imaging, Duluth, GA), simultaneously captures pressure data from the rectum, IAS, EAS and atmosphere. High resolution manometry also allows for much clearer display of pressure events compared to line tracing series, and direction of contractions are much easier to discern. To date, anorectal high resolution topographical studies have not been conducted in a SCI population.

Modalities in which the patient can be trained to control the internal anal sphincter (IAS) and EAS are promising solutions to FI, and have been shown to be useful in able bodied (AB) populations. For example, anorectal biofeedback methods teach patients to recognize sensations of a distended rectum while also teaching abdominal or pelvic muscles to voluntarily contract for short periods of time in order to improve continence. Such biofeedback modalities have also been shown to decrease constipation in AB populations by teaching proper external sphincter relaxation and rectal muscle contraction. The concept of biofeedback is based on principles of operant conditioning, in which information concerning a normally subconscious physiological function in relayed to patients and that become actively engaged in learning to consciously control this function. During bowel (re)training programs, patients are provided with visual feedback on voluntary and reflex sphincter and rectal muscle contractions, so that they can learn to recognize diffuse sensations and gradually regain control.