How Digestion Occurs, the Effects of Paralysis and Immobility

Posted by Nurse Linda in Daily Dose on August 08, 2022 # Health

Healthy gut stock photo from iStockPhoto by piotr_malczykBowel function is taken for granted until it does not work well. There can be many issues in the bowel but first, let’s look at how the bowel functions. The bowel is constantly working in the body. It does work faster in the daytime and tends to slow at night, but it never stops. It is processing food for the consumption of nutrients in the body for use.

The first smell of food can trigger the bowel to speed up as the body will recognize food is coming. Even seeing food can be appealing. Digestion begins when food is taken into the mouth. Chewing mixed with saliva begins the digestion process. Food is swallowed and travels through the esophagus to the stomach, where stomach acids break down the food further. Food will stay in the stomach for about 20 minutes or longer, depending on the consistency and amount, to allow stomach acids to work.

From the stomach, food enters the small intestine as chyme (a thick gooey substance of broken-down food), where nutrients and some water are withdrawn in microscopic amounts to enter the body. The small intestine is very long, so much of the work of digestion happens here. The chyme then moves to the large intestine, where much more of the fluid is removed. The removal of fluid allows the chyme to be formed into the stool to remove leftover waste from the body.

The bowel is a one-way organ keeping the digestive flow from the mouth to the rectum. There are sphincters throughout the digestive tract to help prevent backflow. If these sphincters fail or pressure becomes too great in the digestive system, backflow can occur, causing heartburn, nausea, and vomiting.

The digestive system consists of many branches of nerves exiting from the brain through to the end of the spinal cord. For instance, chewing is controlled by the trigeminal and mandibular nerves. The vagus nerve controls the esophagus, stomach, pancreas, and intestines with branch exit points at multiple locations in the spinal cord. Other nerves that exit the spinal cord at L1, L2, and L3 control the removal of stool from the body. Therefore, any interruption in the brain, spinal cord, or peripheral nerves that affect digestion can affect the digestion process, including removing waste from the body.

Paralysis affects the nerves of the body. Neurogenic bowel is diagnosed when nerves of the bowel and rectum are affected by neurological injury from trauma or disease. Neurogenic bowel occurs when there is a miscommunication of the nerves to and from the brain and the bowel. It occurs as a result of injury to the nervous system, in particular paralysis. Causes of neurogenic bowel can be from spinal cord injury from trauma or disease, or brain injury affecting the motor nerves including stroke or trauma, and diabetes mellitus, as well as other diseases. Direct injury to nerves in the pelvis from childbirth or trauma such as falls can also lead to neurogenic bowel. The neurogenic bowel requires its own treatment. Because most individuals have never heard of neurogenic bowel prior to neurological injury, it is a new concept to think about.

With paralysis or partial paralysis, the digestive system can slow down. You may not be able to chew your food or swallow as well or as easily. Stomach emptying can be delayed as well as movement through the small and large intestines (peristalsis). This leads to not feeling hungry as well as a full gut that is slowly processing chyme. Coordination of the sphincters to control the expulsion of stool from the body may be affected as well as the ability to push stool out of the body.

Immobility can affect digestive function in a variety of ways. Most often, gastric reflux (heartburn, burping) and constipation occur. The movement of chyme and stool relies on the functioning of the colon through peristalsis and muscle movement in the abdomen. When one or both of these activities is decreased or absent, the movement of waste slows further.

Many individuals confuse the issues of a neurogenic bowel diagnosis with other digestive processes. Constipation happens when the movement of chyme and especially stool through the bowel slows, allowing more and more time for water to be withdrawn from chyme or stool. As a result, the waste product becomes extremely dry and more difficult to pass along in the bowel. It is harder for the bowel to move dry stool than moist stool. Constipation can be an issue for anyone, including those with neurogenic bowel, although many individuals with neurogenic bowel do not have constipation. These two issues, neurogenic bowel and constipation, are separate issues that require separate treatments. Treatment for constipation will not cure neurogenic bowel.

Diarrhea occurs when stool is too watery. It can be a one-time issue or multiple occurrences in a short amount of time. Typically, it develops from a virus or contaminated food; however, it does occur in those with neurogenic bowel. In addition, it can develop from the overuse of oral bowel evacuation products and enemas. For this reason, these treatments are not recommended for individuals with neurogenic bowel. Diarrhea can even be produced as a bodily response to anxiety.

Neurogenic bowel can lead to the inability to pass stool from the body, leakage, or bowel accidents. You may experience indigestion and stomach aches. Developing an appetite can be a challenge from neurogenic bowel as well as the immobility that results from paralysis.

There are three types of neurogenic bowel, reflex, flaccid and mixed, each with its own treatment for control and containment. Stool must be removed from the body, or it builds up in the bowel leading to issues not only of constipation but impaction (hard stool immobilized in the bowel), fissures in the bowel, diverticulitis, pain, episodes of autonomic dysreflexia, among others. Not having stool controlled and contained can lead to social isolation and embarrassment.

Reflex neurogenic bowel occurs in individuals with injury to the nerves in the upper spine. This may occur in the brain for those with brain injury or stroke. Typically, it is seen in injury in the cervical (neck) area and thoracic (rib) sections of the spine. In this type of neurogenic bowel, the rectal sphincters cannot be relaxed to let stool pass. The sphincters remain closed. The internal sphincter typically relaxes as stool presses against it. The external sphincter relaxes or tightens under your control unless neurogenic bowel is present. You may spontaneously release some or all the stool in your bowel or none of it. Unexpected bowel movements occur with partial emptying, not full expulsion. Bowel accidents can occur unless you plan for complete elimination with a bowel program. A build-up of stool occurs in the rectum and bowel if the stool is not removed.

Flaccid neurogenic bowel occurs in individuals who have lower-level injuries in the lumbar or sacral regions of the spinal cord. In this case, stool collects in the rectum but will not be contained there. There is no resistance of the rectal sphincter to hold the stool until an appropriate time for expulsion. In this case, manual removal of stool before there is time for uncontrolled expulsion is performed.

In rare cases, there is a mixed type of neurogenic bowel. A reflex neurogenic bowel happens when it is mixed with some effects of a flaccid neurogenic bowel. This can be due to complications of injury in the brain, a double spinal cord injury with one area of injury in the upper spinal cord and a second area injury in the lower spinal cord, or a combination of brain injury in a specific part of the brain and a spinal cord injury. Treatment in this situation is devised specifically for the individual's particular needs. Different aspects of the reflexic and flaccid neurogenic bowel programs are combined for the best outcome.

As the month progresses, a further discussion of bowel program tips and techniques will be discussed. Achieving manual bowel control and containment is possible in a reasonable amount of time. For some, regulating the bowel is challenging, but success is within reach. Nurse Linda

Pediatric consideration:

Infants use diapers until the time that their nervous system develops to be able to control bowel movements through toileting. Because this method of containment is so socially acceptable, it is often accepted for babies with neurogenic bowel. However, emptying is not accomplished. Stool is often left in the bowel, overstretching the colon, and leading to constipation and impaction. Even in infants with neurogenic bowel, a bowel program is imperative. The neurogenic bowel program is designed to meet the infant’s specific needs required for lifelong health.

As children grow, especially with peers, diaper-wearing can become a point of social ostracism. Bowel accidents are disastrous at any age but particularly horrific in the pre-teen and teen years. Treatment for neurogenic bowel is necessary. A successful bowel program can eliminate this issue.

As a child develops, they can learn to provide their own bowel program. It is up to the parent to make this process normal for them because it is their normal. Children need to develop independence in self-care. Children can learn to perform their own bowel program or, if hand function or understanding is challenged, to be able to direct their bowel program. Nurse Linda

Linda Schultz is a leader, teacher, and provider of rehabilitation nursing for over 30 years. In fact, Nurse Linda worked closely with Christopher Reeve on his recovery and has been advocating for the Reeve Foundation ever since.

In our community, Nurse Linda is a blogger where she focuses on contributing functional advice, providing the "how-to" on integrating various healthcare improvements into daily life, and answering your specific questions. Read her blogs here.

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The National Paralysis Resource Center website is supported by the Administration for Community Living (ACL), U.S. Department of Health and Human Services (HHS) as part of a financial assistance award totaling $8,700,000 with 100 percent funding by ACL/HHS. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by ACL/HHS, or the U.S. Government.