Neurogenic Bladder

The normal function of the bladder is to store and empty urine in a coordinated, controlled fashion. This coordinated activity is regulated by a complex interaction of the central and peripheral nervous systems. But what happens when the bladder malfunctions? This can be due to anatomic or neurologic anomalies from congenital defects, diseases or injuries. The information below will help define characteristics of a normal and abnormal bladder along with proper evaluation and management.

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What happens under normal conditions?

The urinary bladder is a spherical organ with unique properties that enable it to store and empty urine. The bladder is composed of two functional layers an inner urothelial lining and an outer smooth muscle layer. In addition to the bladder, the bladder neck is a funnel-like outlet of the bladder which leads to the urethra. It is also known as the internal sphincter. The urethra a tube-like structure which serves as a channel to carry urine from the bladder to the external surface, and the external urethral sphincters composed of striated muscles (group of muscles which surround the urinary passage distal to the bladder neck) complete the lower urinary tract.

The muscles and nerves of the urinary system must function in a coordinated fashion with the bladder in order to perform its two major functions of storage and elimination of urine. Nerves carry messages from the bladder to the brain and then from the brain to the muscles of the bladder telling them to tighten or release, allowing the bladder to empty during urination.

There are two main components to a normal micturition cycle of the bladder: storing and emptying. The bladder will initially fill (store urine) under a low pressure (high compliance). This requires both relaxation of the detrusor muscle along with its elastic properties of the bladder wall to enable the bladder to expand under low pressure. At the same time the striated sphincter is required to be contracted to maintain an elevated outlet resistance preventing urinary leakage. In order for the bladder to empty, the sphincter relaxes followed by a bladder contraction. Any abnormality in either component of the micturition cycle leads to bladder dysfunction.

What is neurogenic bladder?

Neurogenic bladder is the loss of normal bladder function caused by damage to part of the nervous system. The damage can cause the bladder to be underactive, in which it is unable to contract and unable to empty completely, overactive, in which it contracts to frequently without being able to be inhibited or inability to coordinate bladder contractions with sphincter relaxation (Detrusor Sphincter Dysnergey or DSD).

What are some risk factors for neurogenic bladder?

Risk factors for neurogenic bladder include various birth defects, which adversely affect the spinal cord and function of the bladder, including spina bifida or sacral agenesis and other spinal cord abnormalities. Tumors within the spinal cord or pelvis may also disrupt normal nervous tissue function and place an individual at risk. Traumatic spinal cord injury is also a major risk factor for development of neurogenic bladder.

What are the symptoms of neurogenic bladder?

Inability to control urination, also known as urinary incontinence is associated with the neurogenic bladder. This may be caused by abnormalities in bladder capacity or malfunction of control mechanisms such as the bladder neck and/or external urethral sphincter muscle that are important for the bladder's storage function.

Symptoms including a dribbling urinary stream, straining during urination or inability to urinate may also be associated with neurogenic bladder. Urinary retention may result either from loss of bladder muscle contracting performance or loss of appropriate coordination between the bladder muscle and the external urethral sphincter muscle. In addition, symptoms of repeated UTIs or new findings of hydronephrosis (dilation of the kidneys) can be initial symptoms of a neurogenic bladder.

Increased bladder pressures from neurogenic bladders can be caused by the inability of the bladder muscle to relax properly and expand to store urine. This can be caused from the inability to coordinate relaxation of urethral sphincter with contraction (DSD) or from inability to relax urethral sphincter. Patients with increased bladder pressures are at an increased risk for UTIs and pyelonephritis along with kidney damage and even failure secondary to long standing high pressures.

Stones may also form in the urinary tract of individuals with a neurogenic bladder caused by the stoppage of urine flow and/or infection.

Abnormal backup of urine from the bladder to the kidney(s), also known as vesicoureteral reflux (VUR), may develop as a means of releasing high pressure within the bladder. A UTI is of particular concern as VUR may place the patient at significant risk for a severe kidney infection by transporting infected bladder urine directly to the kidney(s).

How is neurogenic bladder diagnosed?

When neurogenic bladder is suspected, both the nervous system (including the brain) and the bladder itself are tested. In addition to complete medical history and physical examination, diagnostic procedures may include:

Bladder function tests including Urodynamic evaluations, which has two components CMG (Cystometrogram) which measures bladder function, capacity, compliance and voiding and storage pressures. Along with EMG (Electromypography) which measures which help measure urethral sphincter tone and bladder coordination.

Radiologic imaging of the of the spine and brain including x-ray and MRI can be used

Imaging tests of the bladder and kidneys are performed

How is neurogenic bladder treated?

The main goal of Urologic management is to prevent damage to the upper tracts (kidneys). The secondary goal is minimize any social disabilities.

Medication for treatment of overactive bladder may improve or relieve irritating symptoms and/or incontinence. Other medications may improve bladder control by increasing outlet resistance at the bladder neck.

In 1981 Dr. McGuire observed that upper tract deterioration occurred when the detrusor leak point pressure exceeded 40cm/H20 measured by Urodynamics. Detrusor sphincter dysnergy (DSD) has also been found to be a significant risk factor for upper tract deterioration. Denervation of the external sphincter can lead to a fixed open sphincter resulting in bladder outlet obstruction. Both DSD and bladder outlet obstruction leads to bladder hypertrophy and loss of bladder compliance and decrease in capacity leading to elevated bladder pressures.

Clean intermittent catheterization (CIC) was developed by Dr. Jack Lapides in the early 1970s as a means of emptying the bladder in the case of a bladder muscle that is unable to contract or in patients with loss of appropriate coordination between the bladder muscle and the external urethral sphincter muscle (DSD). The same medications used to treat bladder overactivity (anticholinergic medications) are used to help improve bladder storage pressures.

There have been numerous studies demonstrating that aggressive early management with patients with neurogenic bladders at high risk (patients with DSD or elevated bladder pressures) with CIC and anticholinergic medications have lead to decrease upper tract deterioration (kidney damage and failure) along with decreased need for future bladder augmentation surgery.

Surgical cutting or dilation of the external urethral sphincter with the use of an endoscope passed through the urethra and can eliminate the need for CIC in order to empty the bladder but at the expense of total urinary incontinence and frequently is only temporary.

At times, however, damage to bladder anatomy and function is so severe that capacity needs to be improved with bladder augmentation (increasing bladder size with various tissues), vesicoureteral reflux needs to be corrected and/or an alternate tube (catheterizable channel) for emptying the bladder may need to be surgically constructed for patients that are unable to catheterize through their urethras.

What can be expected after treatment for neurogenic bladder?

A person can expect extensive follow-up evaluation of bladder and kidney function. This may involve repeated X-rays, ultrasound, blood tests and bladder function tests.

Although some characteristics of the neurogenic bladder may improve or resolve, most issues typically require constant attention and reevaluation.

Proactive management of patients with a neurogenic bladder may decrease the risk of damage to the bladder and kidney(s) and, therefore, potentially limit the need for future intervention. This has been shown in management of neurogenic bladder patients with spina bifida.

Frequently asked questions:

What is the likelihood that my child with spina bifida will develop neurogenic bladder?

The risk of neurogenic bladder is significant in this population and, therefore, careful and frequent evaluation of bladder function is recommended. >What are expected limitations for a patient with neurogenic bladder?

Limits are typically a function of the cause of neurogenic bladder (such as spinal cord injury, for example), rather than the neurogenic bladder itself. With proactive management and close medical follow-up, patients with neurogenic bladders can expect to be both socially continent of urine along with preservation of renal function.

Can the effects of a neurogenic bladder be prevented?

Some effects of neurogenic bladder are preventable with aggressive management with medication and at times appropriate surgical reconstruction.

Reviewed February, 2010

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Glossary Terms

anatomy:
	The physical structure of an internal structure of an organism or any of its parts.
bladder:
	The bladder is a thick muscular balloon-shaped pouch in which urine is stored before being discharged through the urethra.
bladder augmentation:
	Operation that uses a piece of the intestine (bowel) to enlarge the bladder.
bladder control:
	The ability to control the timing of urination. Also referred to as continence.
bladder neck:
	Area of thickened muscle fiber where the bladder joins the urethra. Acting on signals from the brain, bladder neck muscles can either tighten to hold urine in the bladder or relax to allow urine out and into the urethra. These muscles also tighten during ejaculation to prevent backflow of semen into the bladder.
catheter:
	A thin tube that is inserted through the urethra into the bladder to allow urine to drain or for performance of a procedure or test, such as insertion of a substance during a bladder X-ray.
catheterization:
	Insertion of a narrow tube through the urethra or through the front of the abdominal wall into the bladder to allow urine drainage.
CIC:
	Also known as clean intermittent catheterization. Periodic insertion of a clean catheter into the urethra after washing your hands to drain the urine from the bladder.
continence:
	The ability to control the timing of urination or a bowel movement.
contract:
	To shrink or become smaller.
dysuria:
	Painful or difficult urination, most frequently caused by infection or inflammation but it can also be caused by certain drugs.
EEG:
	Also known as electroencephalogram. A procedure that records the brain's continuous electrical activity by means of electrodes attached to the scalp.
electroencephalogram:
	Also known as EEG. A procedure that records the brain's continuous electrical activity by means of electrodes attached to the scalp.
endoscope:
	A lighted medical instrument consisting of a long tube inserted into the body, usually through a small incision. It is used for diagnostic examination and surgical procedures.
external urethral sphincter muscle:
	Muscle surrounding the external opening of the urethra, the tube that carries urine outside the body from the bladder.
incontinence:
	Loss of bladder or bowel control; the accidental loss of urine or feces.
infection:
	A condition resulting from the presence of bacteria or other microorganisms.
intermittent catheterization:
	Periodic insertion of a narrow tube through the urethra or through the front of the abdominal wall into the bladder to allow urine drainage.
ions:
	Electrically charged atoms.
kidney:
	One of two bean-shaped organs that filter wastes from the blood and discharge these waste products in urine. The kidneys are located on either side at the level of the 12th ribs toward the back. The kidneys send urine to the bladder through tubes called ureters.
kidney infection:
	Also called pyelonephritis. Urinary tract infection involving the kidney. Typical symptoms include abdominal or back pain, fever, malaise and nausea or vomiting.
nephritis:
	Inflammation of the kidneys.
neurogenic bladder:
	Also called neuropathic bladder. Loss of bladder control caused by damage to the nerves controlling the bladder.
overactive bladder:
	A condition in which the patient experiences two or all three of the following conditions: urinary urgency, urge incontinence or urinary frequency--defined for this condition as urination more than seven times a day or more than twice at night.
paralytic agent:
	Drug used to temporarily paralyze an individual.
pelvis:
	The bowl-shaped bone that supports the spine and holds up the digestive, urinary, and reproductive organs. The legs connect to the body at the pelvis.
peripheral:
	Near the surface of an organ.
pyelonephritis:
	Also referred to as kidney infection usually caused by a germ that has traveled up through the urethra, bladder and ureters from outside the body. Typical symptoms include abdominal or back pain, fever, malaise and nausea or vomiting.
reflux:
	Backward flow of urine. Also referred to as vesicoureteral reflux (VUR). An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.
sphincter:
	A round muscle that opens and closes to let fluid or other matter pass into or out of an organ. Sphincter muscles keep the bladder closed until it is time to urinate.
sphincter muscle:
	Circular muscle that helps keep urine from leaking by closing tightly like a rubber band around the opening of the bladder.
spina bifida:
	A condition at birth in which part of the vertebral bodies (or back bones) fail to seal off completely and some part of the spinal cord protrudes through this opening. This condition is often associated with bladder and bowel control problems as well as lack of control of voluntary movement in the lower body.
stent:
	With regard to treating ureteral stones, a tube inserted through the urethra and bladder and into the ureter. Stents are used to aid treatment in various ways, such as preventing stone fragments from blocking the flow of urine.
tissue:
	Group of cells in an organism that are similar in form and function.
ultrasound:
	Also referred to as a sonogram. A technique that bounces painless sound waves off organs to create an image of their structure to detect abnormalities.
ureter:
	One of two tubes that carry urine from the kidneys to the bladder.
ureteral:
	Pertaining to the ureter. Also referred to as ureteric.
ureters:
	Tubes that carry urine from the kidneys to the bladder.
urethra:
	A tube that carries urine from the bladder to the outside of the body. In males, the urethra serves as the channel through which semen is ejaculated and it extends from the bladder to the tip of the penis. In females, the urethra is much shorter than in males.
urethral:
	Relating to the urethra, the tube tha carries urine from the bladder to outside the body.
urethral sphincter:
	Muscle fibers around the outside of the urethra that tighten to close off the flow of urine or relax to open the urethra to allow the passage of urine.
urinary frequency:
	Urination eight or more times a day.
urinary incontinence:
	Inability to control urination.
urinary tract:
	The system that takes wastes from the blood and carries them out of the body in the form of urine. Passageway from the kidneys to the ureters, bladder and urethra.
urinary tract infection:
	Also referred to as UTI. An illness caused by harmful bacteria, viruses or yeast growing in the urinary tract.
urinate:
	To release urine from the bladder to the outside. Also referred to as void.
urine:
	Liquid waste product filtered from the blood by the kidneys, stored in the bladder and expelled from the body through the urethra by the act of urinating (voiding). About 96 percent of which is water and the rest waste products.
UTI:
	Also referred to as urinary tract infection. An illness caused by harmful bacteria growing in the urinary tract.
vas:
	Also referred to as vas deferens. The cordlike structure that carries sperm from the testicle to the urethra.
vesicoureteral reflux:
	Also referred to as VUR. An abnormal condition in which urine backs up from the bladder into the ureters and occasionally into the kidneys, raising the risk of infection.

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