Neurogenic Bowel and Bladder
The terms neurogenic bowel or neurogenic bladder refer to dysfunction in the respective organs following central or peripheral nervous system injuries. The clinical manifestation of both is largely related to the location of the lesion and the motor neurons involved.
Box 1 | Pathophysiology of Neurogenic Bowel and Bladder
The function of the bowel is regulated by the autonomic nervous system by both the parasympathetic (S2-S4, increases peristalsis, or contraction of smooth muscles of the intestines to propel contents through the digestive tract) and the sympathetic nervous system (T5-L2, decreases peristalsis). Normal bowel functioning involves a sequence of actions beginning with involuntary activities:
- Advancing of stool through the colon to the rectum
- Rectal distension that results in internal anal sphincter (IAS) relaxation
- An urge to defecate then begins
- And a holding reflex is initiated with the external anal sphincter (EAS) and other muscles
Two voluntary actions follow:
- Relaxing the EAS
- Muscle contraction expelling the stool.
Depending on the level of the SCI/SCD, a person may have different impairments in bowel function. For complete spinal cord injuries, lesions involving the upper motor neuron (i.e. those originating in the cerebral cortex) generally result in what is known as reflexive bowel – a condition associated with increased muscle tone in the EAS and puborectalis muscles, as well as a “spastic colon” with increased contractility and tone. Where lower motor neurons (bring nerve impulses from upper motor neurons out to the muscles) are affected, complete SCI/SCD patients will have an areflexive bowel. This results in a flaccid and denervated EAS muscle, decreased muscle tone and the retention of the so-called rectal-anal inhibitory reflex. For those with incomplete lesions, the neurological manifestations in bowel functioning are not so clear and there can be significant variation from patient to patient. Bowel dysfunction can lead to incontinence, constipation, obstipation or diarrhea. Other complications include ulcers, esophageal reflux, hemorrhoids, anal fissures, nausea, delayed or unplanned defecation, appetite loss and autonomic dysreflexia, a condition known as that result in high blood pressure and headaches.
The function of the bladder is regulated by the interaction between the peripheral parasympathetic, sympathetic and somatic innervations of the lower urinary tract.The parasympathetic supply originates primarily from the sacral spinal cord (S2-S4), and the sympathetic innervation starts from T11-L2. Normally, urine passss from the bladder through the urethra, which controls urination through two sphincters – an external sphincter that can be controlled voluntarily and another that is internal and involuntary. When the bladder is full, signals are sent from the “micturition center” through the pelvic nerve to the spinal cord. Following these signals, the process of urination begins with the relaxation of both sphincters. Importantly, the voluntary, external sphincter allows a person to determine when urination occurs.
Symptoms of neurogenic bladder depend upon the location of the lesion. For incomplete lesions, functioning will vary greatly between patients. Sacral lesions often result in an acontractile bladder (or detruser areflexia) and, in combination with an intact sphincter, can result in bladder overdistension. Lesions above the sacral spinal cord cause detruser hyperreflexia resulting in a reflexive bladder and a loss of the bladder-voiding reflex. In general, immediately following an injury during the “spinal shock” phase, 2-12 weeks of areflexia and “transient urinary retention” is common. While specific timeframes vary, a patient will develop a “more consistent pattern of voiding with attendant dysfunction”. Complications associated with bladder function beyond incontinence include autonomic dysreflexia, urinary tract infections, renal stones, hydronephrosis and renal failure.
Clinical interventions for neurogenic bladder and bowel
Bladder management issues are an immediate and ongoing part of the clinical picture for patients with SCI/SCD. It is nearly universal that an indwelling catheter will be utilized initially. This facilitates the determination of appropriate hydration and renal function in an unstable patient. The questions remain about when to discontinue this method of urinary management and begin alternative measures and which measures should be taken.
Horton et al. (2003)4
Treatment for neurogenic bladder aims to normalize bladder functions, prevent secondary conditions and achieve and maintain continence. For areflexia, catheterization or implantations of artificial sphincters (to prevent incontinence with flaccid bladder necks) or bladder pulse generators (to promote urination) can help minimize effects. Drugs may also be used in addition to “charting” that map out timing, fluid intake and output volumes. For hyperreflexia, in men, urinary condoms or intermittent catheterization are often used to empty the bladder. In women, intermittent catheterization must be utilized. Other less common interventions for bladder management include bladder augmentation, artificial stents and sphincterotomies.
Bowel dysfunction, both reflexive and areflexive, require careful management to maintain continence, and at the same time, avoid obstipation. Therefore for each condition, charting the regularity of bowel evacuations is important. Manual evacuation and colonic massages may be necessary for areflexive bowel.To treat constipation associated with reflexive bowel, manual evacuation, enemas, rectal stimulation, anal stretching and suppositories may be necessary. In both cases, pro-kinetic medication can help. Rarely, a colostomy may be necessary. Additionally, there are a number of other factors that can affect bowel dysfunction including diet, the intake of cigarettes and coffee, the side effects of drugs, mobility, pain, spasticity and co-traumas.56
Consequences of neurogenic bladder and bowel
The treatment and management of bladder and bowel dysfunction may impact numerous social aspects that can negatively affect quality of life.7 Interventions for both problems may require the use of medical devices, be uncomfortable, time-consuming and learning self-care activities such as self-catheterization and digital evacuation of the bowel can be initially unpleasant. For SCI/SCD patients, there is the added complication of mobility impairments that impact the ability to perform toileting independently, and also require wheelchair accessible toilets in the public area. Resulting fears of being in public spaces where toilets may not be readily available can lead to social isolation.
For neurogenic bladder, the following behaviours in relation to the consequences on the individual and the societal level have been described in one study:7
- Restricting the intake of fluids which may cause dehydration, constipation or other health problems
- Reducing physical activity
- Mapping of toilet locations in public areas
- Reduced social interaction
In cases of neurogenic bowel, specific bowel management, dietary restrictions and limitations to outdoor mobility are often necessitated.68These behaviours help to mitigate or compensate for symptoms; but they can also negatively impact a person’s quality of life, and in some cases health.7 Furthermore, they may also reinforce feelings of dependency, be stigmatizing and additionally imply a lack of self-control9 or inability to care for oneself. Hence, both social and medical consequences need to be addressed in SCI/SCD patients with bladder and bowel dysfunctions. From a rehabilitative perspective, the overarching goal is to understand the factors affecting a patient’s bowel and bladder management and improve his or her quality of life by achieving regular, controlled bowel movements and urinary continence, and also minimize or eliminate associated social impairments and prevent infections or other secondary conditions.
This case study aims to illustrate the challenges in managing neurological bladder and bowel, patients and providers have to deal with. It will highlight the importance of appropriate, patient-focused management within the rehabilitation process.