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U N I T 7
Kidney and Urinary Tract Function
Treatment
The goals of treatment for neurogenic bladder disorders
focus on preventing bladder overdistention, urinary tract
infections, and potentially life-threatening kidney dam-
age. The methods used in treatment are individualized
based on the type of neurologic lesion that is involved;
information obtained through the health history, includ-
ing fluid intake; report or observation of voiding pat-
terns; presence of other health problems; urodynamic
studies when indicated; and the ability of the person to
participate in the treatment. Treatment methods include
catheterization, bladder training, pharmacologic manip-
ulation of bladder function, and surgery.
Catheterization involves the insertion of a small-
diameter latex or silicone tube into the bladder through
the urethra. The catheter may be inserted on a one-
time basis to relieve temporary bladder distention, left
indwelling (i.e., retention catheter), or inserted intermit-
tently. The methods used for bladder retraining depend
on the type of lesion causing the disorder. Methods used
to supplement bladder retraining include monitoring
fluid intake to control urine volume and osmolality and
prevent urinary tract infections, developing scheduled
times for urination, and using body positions that facili-
tate micturition.
Pharmacologic manipulation includes the use of
drugs to alter the contractile properties of the bladder,
decrease the outflow resistance of the internal sphinc-
ter, and relax the external sphincter. Antimuscarinic
drugs decrease detrusor muscle tone and increase blad-
der capacity in persons with spastic bladder dysfunc-
tion.
7
Cholinergic drugs that stimulate parasympathetic
receptors provide increased bladder tone and may prove
helpful in the symptomatic treatment of milder forms
of flaccid neurogenic bladder. Muscle relaxants may
be used to decrease the tone of the external sphincter.
Intravesical injection of medications such as capsaicin
and resiniferatoxin, which are specific C-fiber afferent
neurotoxins, may be used to decrease bladder hyperac-
tivity. Botulinum toxin type A injections may be used to
produce paralysis of the striated muscles of the external
sphincter in persons with neurogenic overactive bladder.
The effects of the injection last about 6 months, after
which the injection must be repeated.
12
Among the surgical procedures used in the man-
agement of neurogenic bladder are sphincterectomy,
reconstruction of the sphincter, and resection of the
sacral reflex nerves that cause detrusor overactivity or
the pudendal nerve that controls the external sphinc-
ter.
12
Extensive research is being conducted on meth-
ods of restoring voluntary control of the storage and
evacuation functions of the bladder through the use of
implanted electrodes.
Urinary Incontinence
Urinary incontinence represents the involuntary loss
or leakage of urine. It can occur without the person’s
knowledge; at other times, the person may be aware of
the condition but be unable to prevent it. A number of
conditions can lead to incontinence, which is a common
problem, particularly in older adults.
8,16–19
Types and Causes of Incontinence
Urinary incontinence is commonly divided into three
main types: stress incontinence, urge incontinence, and
mixed incontinence, which is a combination of stress
incontinence and urge incontinence. Other types of
incontinence include overflow incontinence, which is a
term used to describe leakage of urine associated with
urinary retention, and nocturnal enuresis, which is the
involuntary loss of urine during sleep. Post-micturition
dribble and continuous urinary leakage are other forms
of incontinence.
17-20
Stress Incontinence.
Stress incontinence represents
the involuntary loss of urine that occurs when, in the
absence of detrusor muscle action, the intravesical
pressure exceeds the maximum urethral closure pres-
sure.
21–24
Among the proposed causes of stress inconti-
nence are changes in the anatomic relationship between
the bladder and the urethra, so that increases in intra-
abdominal pressure are unevenly distributed to the
urethra.
8,19
Stress incontinence, which is a common problem in
women of all ages, occurs as the result of weakness or
disruption of pelvic floor muscles leading to poor sup-
port of the vesicourethral sphincters. Except during the
act of micturition, intraurethral pressure is normally
greater than intravesical pressure. The pressure dif-
ference between the urethra and bladder is known as
the
urethral closure pressure
. If intra-abdominal pres-
sure increases as it does during actions such as cough-
ing, laughing, or sneezing, and if this pressure is not
equally transmitted to the urethra, then incontinence
occurs. Diminution of muscle tone associated with nor-
mal aging, childbirth, or surgical procedures can cause
weakness of the pelvic floor muscles and decrease the
urethral closure pressure, resulting in stress inconti-
nence by changing the relationship between the bladder
base and the posterior urethral junction.
Another cause of stress incontinence is intrinsic
urethral deficiency, which may result from congenital
sphincter weakness, as occurs with meningomyelocele.
It also may be acquired as a result of trauma, irradia-
tion, or sacral cord lesions. Stress incontinence in men
may result from trauma or surgery to the bladder outlet,
as occurs with prostatectomy.
19,24
Neurologic dysfunc-
tion, as occurs with impaired sympathetic innervation
of the bladder neck, impaired pelvic nerve innervation
to the intrinsic sphincter, or impaired pudendal nerve
innervation to the external sphincter, may also be a con-
tributing factor.
Urge Incontinence.
Urge incontinence is the involun-
tary loss of urine associated with a strong desire to void
(urgency).
8,19
It is often associated with overactive blad-
der, which the International Continence Society defines
as “urinary urgency, usually accompanied by frequency
and nocturia, with or without urinary incontinence, in
