Neurogenic bowel dysfunction

Neurogenic bowel dysfunction (NBD) is the inability to control defecation due to a deterioration of or injury to the nervous system, resulting in faecal incontinence or constipation. It is common in people with spinal cord injury (SCI), multiple sclerosis (MS) or spina bifida.

The gastrointestinal tract has a complex control that relies on coordinated interaction between muscular contractions and neuronal impulses. Faecal incontinence or constipation occurs when there is a problem with the normal bowel functioning; this could be for a variety of reasons. The normal defecation pathway involves contractions of the colon in order to help mix the contents, absorb water and propel the contents along the intestine. This results in the faeces moving from the colon to the rectum. The presence of stool in the rectum causes a reflexive relaxation of the internal anal sphincter, so the contents of the rectum can move in to the anal canal. This causes the conscious feeling of the need to defecate. At a suitable time our brain can send signals causing the external anal sphincter and puborectalis muscles to relax as these are under voluntary control and this allows defecation to take place.

Spinal cord injury and other neurological problems mostly affect the lower GI tract leading to symptoms of incontinence or constipation. However, the upper GI tract may also be affected and patients with neurogenic bowel often present with multiple symptoms. Research shows there is a high prevalence of upper abdominal complaints, for example a study showed that approximately 22% of SCI patients reported feeling bloated and about 31% of SCI patients’ experienced abdominal distension.