Neurogenic Bladder

In the normal urinary tract system the bladder serves to store and eventually expel urine using a complex and exquisitely orchestrated process. The coordination of urination is regulated by both the central nervous system (brain and spinal cord) and the peripheral nervous system. The term neurogenic bladder applies to a urinary tract system that malfunctions because of either internal or external neurologic damage.

The symptoms of a neurogenic bladder will depend upon the site of the neurologic insult. In other words, if the neurological system was damaged centrally the symptoms will be different than those of an individual who suffered a peripheral neurologic damage.

The brain is the center of control for the entire urinary tract system. Inside the frontal lobe is located a center that sends signals to the detrusor muscle or that muscle which controls the release of urine from the body. Certain types of diseases in the brain, including stroke, cancer and even dementia, can result in the loss of voluntary control because of the damage to the neurological system in the brain. The signal that originates in the brain must pass through the brain stem and the spinal cord before reaching the bladder.

The brain stem is located at the base of the skull just north of the neck. Inside the brain stem is a very specialized area that is the major relay center between the brain and the bladder, called the pons. This area of the brain is responsible for the coordination of activities so that the bladder and surrounding musculature work in synergy.

When we consciously feel the need to urinate, sensations are transmitted to the pons from the cerebral cortex. This process is also affected by emotions which may be why some people can experience urinary incontinence when they are excited or very scared. This area of the brain also requires complete development before a child can be sufficiently toilet trained.

The spinal cord begins at the base of the brain stem and continues down the spinal column to the lumbosacral area. In a normal adult the spinal cord is approximately 14 inches long and has many nerve branches which sprout off leading to different parts of the body. This is the communication pathway between the brainstem and the muscles. In the case of the bladder these nerve endings exit at the end of the spinal cord, called the sacral cord. In the normal cyclical pattern of bladder filling and emptying the spinal cord is an important means of communication between the bladder and the brainstem.

If the sacral cord is injured, potentially from a tumor, injury or herniated disc, the bladder may not function at all. These individuals will develop retention. In other words they will not be able to release urine and the bladder can fill to the point that it ruptures.

The peripheral nerves are the final piece of the neurological puzzle in bladder control. They form an intricate network, originating from the main trunk of the spinal cord and branching out to cover the entire area. These nerves convert the stimulation from the environment to electrical signals so the brain can interpret them.

Under normal circumstances the sympathetic and parasympathetic nervous systems are the final system in this complex orchestration of events.

During the course of a single day a normal person will go to the bathroom between 4 and 8 times in a 24 hour period of time. The bladder is responsible for filling with urine and holding it for a period of time before the muscle is stretched to a specific capacity and then it signals to the brain that it is ready to empty.

As the bladder fills, pressure in the two sphincters and urethra keep the individual continent. During the emptying phase the bladder may empty involuntarily or voluntarily. An involuntary reflex happens in an infant when the capacity stretches the wall and signals the sacral cord.

Although bladder function is automatic it is also completely controlled by the brain. The final decision in a healthy adult of when and where to void is a controlled activity.

When a problem is present in the neurological system the entire system is affected. Any part can be affected which will result in a dysfunctional condition that will exhibit symptoms ranging from retention, incontinence or an overactive bladder. Specific injuries that will impact this system include brain lesions which can destroy the control center and cause a complete loss of control. Spinal cord lesions or injuries will result in a spastic, overactive bladder that empties too quickly and too frequently. In some instances both the bladder and external sphincter become spastic at the same time which negatively impacts the ability of the system to work in synergy.

A sacral cord injury can prevent the bladder from emptying completely and the individual may not have sensation and so can\’t tell when the bladder is full. In some cases teenagers will suddenly develop an abnormal pattern of urination. In these cases they will be evaluated for tethered cord syndrome. This is a neurological condition in which the sacral cord is stuck near the sacrum and cannot stretch as the child grows.

Individuals who suffer from diabetes and AIDS can also experience peripheral neuropathy that results in the inability to void. The disease destroys the nerves that lead to the bladder. Individuals who have diabetes may lose the sensation of the bladder filling and will have difficulty urinating.

Individuals who suffer from neurogenic bladder require adequate diagnosis and treatment protocols in order to decrease their risk of developing urinary tract infections related to an adequate emptying of the bladder. With consistent medical assistance and careful planning most people are able to achieve functioning that allows them to be fully functional in social situations.

RESOURCES

US National Library of Medicine: Neurogenic Bladder

MedlinePlus: Neurogenic Bladder

Cleveland Clinic: Neurogenic Bladder

Johns Hopkins Health Library: Neurogenic Bladder

Wexner Medical Center: Neurogenic Bladder