What are “spastic” and “flaccid” bowel?

Authors: SCIRE Community Team | Reviewer: Bonnie Nybo | Published: 20 March 2018 | Updated: 23 October 2024

Spastic bowel can lead to constipation because of tightened sphincter muscles.³

Spastic bowel (also called reflex bowel or upper motor neuron bowel) usually occurs when the spinal cord is injured at T12 and above. With spastic bowel, the bowel’s natural reflexes are retained, but they no longer receive control from the brain. This causes increased muscle tension in the walls of the intestines, tightening of the anal sphincter muscles, and uncontrolled reflex emptying when something is present in the rectum.

Spastic bowel is typically experienced as constipation and an inability to pass a stool (stool retention). People with spastic bowel are usually able to empty the bowel by activating the bowel reflexes. This is usually done every other day through techniques like digital stimulation or the use of suppositories.

Flaccid bowel leads to a loss of muscle tension, and incontinence can be experienced.⁴

Flaccid bowel (also called non-reflex bowel or lower motor neuron bowel) usually occurs when the spinal cord is injured below T12. Flaccid bowel involves a loss of control from the brain and a loss of bowel reflex activity. This leads to a loss of muscle tension in the walls of the intestines and the anal sphincter muscles, which causes the bowel muscles to be floppy and loose.

Flaccid bowel is typically experienced as involuntary leaking of stool (incontinence) and constipation. With flaccid bowel, the stool usually needs to be removed by manual evacuation (also called disimpaction) once or twice per day to empty the bowel.