Depending on the level of spinal cord injury (SCI), patients experience a change in bowel motility and anal sphincter control.  Injury above the conus medullaris (upper motor neuron) results in hyperreflexic bowel and a tight anal sphincter, which causes constipation and fecal retention.  Stool evacuation is induced by reflex activity in the rectum.  Injury at the conus medullaris and cauda equina (lower motor neuron) results in areflexic bowel and loss of peristaltic control, resulting in prolonged stool transit particularly in the rectosigmoid region.  Furthermore, loss of control over the external anal sphincter can result in fecal incontinence. Completeness of the injury also impacts bowel function.  Patients with incomplete SCI may retain sensation of rectal fullness and the ability to evacuate bowels.²

A congenital malformation that results from failed closure of the neural tube during embryonic development of the spinal cord.  Individuals with spina bifida (SB) often have a neurological deficit below the level of the lesion, usually at the conus medullaris or cauda equina. This results in areflexic bowel and prolonged stool transit in the rectosigmoid region.  Anal resting and squeeze pressures are reduced and sensitive, causing fecal incontinence.^4,5