What is neurogenic bowel dysfunction?

Neurogenic bowel dysfunction is when the bowel fails to function properly due to disruption or damage to the nervous system, such as from a spinal cord injury, brain injury, or neurological condition (e.g. Parkinson’s disease). Constipation and faecal incontinence tend to be the main symptoms.  Severe neurogenic bowel dysfunction can occur in 24-71% of people after a spinal cord injury, depending on the level and completeness of the injury. Most of the research and protocols for neurogenic bowel management have been developed for individuals with spinal cord injuries, so this article will limit its focus to that population. However, with individual assessment, the key principles can also be applied to other neurological conditions as well.

What is ‘normal’ bowel function?

As infants, we were all incontinent—our bladders and bowels emptied automatically through a simple reflex arc. When the body sensed the need to pass stool, a signal travelled via nerves in the sacral region to the spinal cord at the T12/L1 (Thoracic level 12/Lumbar 1) level, triggering a reflex to empty the bowel. Through potty training, we learned to interpret these signals and gained the ability to consciously control and override them. Being continent of faeces depends on our ability to accurately distinguish between gas, liquid, and solid stool in the rectum and our ability to respond appropriately.  For example, we need to be able to assess whether we can pass gas and then delay a bowel movement until later (by moving stool back into the sigmoid colon) or whether we need to rush to the toilet, due to having diarrhoea.

Neurogenic bowel dysfunction can present in 2 different ways (1, 2, 3, 4)

Voluntary control of bowel movements is often impaired or lost following a spinal cord injury.  Whether the injury is above or below the T12/L1 thoracic vertebrae will determine how bowel function is affected. The completeness of the spinal cord injury must also be considered, as it determines whether rectal sensations are present or not.

• Injuries ABOVE T12/L1 usually present with an upper motor neuron (reflex) bowel – this is when the reflex arc is still intact (similar to early infancy). This means the bowel is able respond to stimulation such as digital stimulation, suppositories and stimulant laxatives. These clients have increased tone in the walls of the colon and anus, causing the anal sphincter to remain tight which promotes stool retention (and constipation).  These clients need a bowel regime because passing stool cannot be initiated by voluntary relaxation of the external anal sphincter.

• Injuries BELOW L1 usually present as a lower motor neuron (flaccid) bowel – this occurs when the nerves that would normally trigger the reflex arc are damaged or non-functional. As a result, the colon has reduced tone and is less responsive to stimulation. The external anal sphincter also becomes lax or flaccid. Because the reflex for defecation is absent or severely impaired, manual evacuation or enemas are often required. Individuals with this type of injury frequently experience constipation (due to slow colonic transit), as well as faecal incontinence (because of the weakened anal sphincter). A structured bowel management program is essential to address these challenges.

Managing neurogenic bowel – what are we aiming for? (1, 2, 3, 4)

When managing neurogenic bowel dysfunction, the aim is to have a proactive bowel regime in place that:

• occurs at regular, predictable and socially acceptable times,
• takes less than 60 minutes to complete,
• results in minimal to no constipation, no impaction and in those with a spinal cord injury above T6, no autonomic dysreflexia (AD) either,
• results in no incontinence (also called accidents), or loss of quality of life due to concerns around bowel accidents.

For injuries above T12/L1 with an upper motor neuron (reflex) bowel – the goal is for stools to be Bristol Stool Type 4 and for bowels to open in a routine of either every day or every other day.

For injuries below L1 presenting as a lower motor neuron (flaccid) bowel – the goal is for stools to be Bristol Stool Type 3 (to reduce faecal incontinence and make manual evacuation easier).  These clients may need to engage in their bowel regime 1-2 times daily.

In both cases, the goal is to achieve the above stool consistency by adjusting food and fluid intake.  If this cannot be achieved through diet alone (due to lack of mobility and/or multiple medications), laxatives and/or fibre supplements should be considered (see below for examples). Start with a non-stimulant laxative (e.g. Macrogol) to achieve the desired stool consistency. If necessary, follow with scheduled doses of oral stimulant laxatives (e.g. Senna) to prepare the bowel for timed care.

Case managers can assess a client’s bowel management regime using The Neurogenic Bowel Dysfunction Score.  If clients are not achieving the targets above, then their bowel regime should be reviewed by a specialist bowel nurse or spinal consultant.

Example of a conservative bowel routine

• Start with an oral stimulant laxative (e.g. Senna) 8 – 12 hours before bowel care (if needed).
• Stimulate the gastrocolic reflex by eating and drinking 20-30 minutes before the start of bowel care. This reflex causes the colon to contract in response to the stomach being stretched.
• Complete a Digital Rectal Examination (i.e. ‘Digital Check’) to assess for stool in the rectum.
• Insert rectal stimulant (i.e. suppository or micro enema) and allow time for it to stimulate a response – REFLEX INJURIES ONLY.
• Complete abdominal massage by following the direction of the colon.
• Use Digital Rectal Stimulation with a single finger against the rectal wall for approximately 20-60 seconds. Repeat until the response tires or stool is evacuated – REFLEX INJURIES ONLY.
• Perform Digital Removal of Faeces (i.e. ‘Manual Evacuation’) if stool remains in the rectum after stimulation. If assistance is required, this procedure can be carried out on a height-adjustable bed.
• Do a single digital check to ensure the rectum is empty after approximately 5 minutes and repeat digital stimulation and/or digital removal if stool is still present.
• Record the outcome on the bowel chart (i.e. Bristol Stool Type 1-7 and amount).
• Record any unplanned results (i.e. ‘accidents’) which occur outside of scheduled bowel care.

Transanal irrigation may be considered if the above is not achieving adequate results despite all efforts.

Colostomy formation may also be considered if an acceptable routine cannot be established. 

What about diet, lifestyle factors and medication?

Dietitians can review a client’s food and fluid intake to assess their impact on bowel function (and abdominal pain), and dial them up or down as needed to manipulate stool consistency.  Consideration will need to be made to any pre-injury diet or bowel-related issues, such as irritable bowel syndrome and/or food intolerances.  People often respond differently to the factors below, so advice will need to be personalised as appropriate. Dietitians can also liaise with the GP regarding medications and/or laxatives which may be affecting the client’s gut (positively or negatively).

Here are the top 10 diet and lifestyle tips for neurogenic bowel dysfunction:

1. Fibre

Fibre adds bulk to the stool and can influence how quickly food moves through the gut.  If clients are eating a lot of sandwiches, takeaway and ready meals, they are not usually eating enough fibre.  The exact amount of fibre needed for someone with neurogenic bowel dysfunction is not yet known and is likely to be highly individual.  However, targets are generally set for 15-25 grams of fibre per day.1, 3.  This is less fibre than what is recommended for the general population.  This is because too much fibre in a very slow-moving gut (or fibre combined with not enough fluid), can be counterproductive and make the constipation worse.  Also, some types of fibre can “ferment” in the large intestine and can cause excess gas, bloating and abdominal pain in susceptible individuals.  These clients should be referred to a dietitian for specialist assessment and advice.

2. Fluid

Fluid must be combined with fibre to add bulk to the stool.  Too much fibre, without enough fluid to soften it, can result in faecal impaction.  Ensure clients are drinking enough fluid (e.g. a minimum of 1.5 litres per day).  Many clients are advised to drink much more than this, depending on their bladder management regime.

3. Fat

Fat affects people in different ways. For some, a high-fat diet can slow stomach emptying and slow the speed at which food travels through the gut (making constipation worse). 3  In other people, it speeds up gut emptying and can result in loose stools.

4. Meal frequency

After a major trauma, many clients need to reduce their calorie intake in order to manage their weight.  Some clients choose to eat only 1-2 times daily in order to achieve this.  Only eating 1-2 times daily will reduce the gastrocolonic reflex, which acts to push food and stool through the digestive tract.  This can make constipation worse.  These clients often find it more difficult to get enough fibre as well (see above).

5. Caffeine

Caffeine can stimulate the bowel and move food more quickly through the digestive tract. 3  This can be helpful for people with constipation, but problematic if someone has loose stools or incontinence.

6. Alcohol

Alcohol can stimulate the bowel and result in loose stools. 3

7. Prunes, figs, fruit juice

The natural sugar found in these foods can have a laxative effect and result in looser stools. 3 This can be helpful for people with constipation but, again, problematic if someone has loose stools.

8. Certain artificial sweeteners (e.g. any ending in -ol, such as sorbitol)

Sugar alcohol sweeteners can have a laxative effect and result in loose stools. 3

9. Medication

Several medications and prescribed supplements can increase the risk of constipation (e.g. opioids; anti-spasmodics; iron supplements; anti-cholinergics for bladder management).

Conversely, other medications can cause loose stools (e.g. antibiotics).

10. Laxatives

Different laxatives can help manage constipation in different ways:

• Bulking laxative/fibre supplement – e.g. Fybogel and Hyfiber
• Stool softener – e.g. docusate
• Osmotic laxative – e.g. Movicol/Macrogol, Cosmocol, Laxido, lactulose, magnesium citrate
• Stimulant laxative – e.g. senna, bisacodyl (tablets)
• Prokinetic agent – e.g. prucalopride
• Rectal stimulant (e.g. suppository or enema) – eg. glycerin suppositories, bisacodyl suppositories, lecicarbon E, or enemas (e.g. microenemas, docusate enemas, sodium citrate or Micralax).

It can take 10–14 days to see results from changes to diet, lifestyle, or medication. The key is to be patient, stay consistent, and avoid making too many changes at once!

To refer a client for a comprehensive dietetic assessment, please contact Specialist Nutrition Rehab at 0121 384 7087 or info@specialistnutritionrehab.co.uk.

A huge thank you to Jane Stanbridge, Neurogenic Specialist Nurse from JPEL training, for helping us with this article.  To refer a client to her for a nursing bowel and bladder assessment, contact Jane at 07740411215/01908 262 142 or hello@jpeltraining.co.uk.

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