Classification of Neuropathic Bladder
The traditional classification was according to neurologic deficit. Thus, the terms motor, spastic, upper motor neuron, reflexic, and uninhibited were used to describe dysfunction found with injury above the spinal cord micturition center. The classification system recommended by the standardization committee for the International Continence Society includes description of bladder activity (normal, overactive, areflexic, impaired), bladder compliance (normal, decreased, increased), smooth sphincter activity (synergic, dyssynergic), striated sphincter activity (synergic, dyssynergic, fixed tone), and sensation (normal, absent, impaired) (Abrams et al, 2002).
Descriptions of neuromuscular dysfunction of the lower urinary tract should be individualized because no two neural injuries (no matter how similar) result in the same type of dysfunction.
Neuropathic Bladder Due to Lesions above the Sacral Micturition Center
Most lesions above the level of the cord where the micturition center is located will cause bladder overactivity. Sacral reflex arcs remain intact, but loss of inhibition from higher centers results in overactive bladder and sphincter behavior on the segmental level. The degree of spasticity varies between the bladder and sphincter, from lesion to lesion, and from patient to patient with similar lesions.
Common lesions found above the brain stem that affect voiding include dementia, vascular accidents, multiple sclerosis, tumors, and inflammatory disorders such as encephalitis or meningitis. These lesions can produce a wide range of functional changes, including precipitate urge, frequency, residual urine, retention of urine, recurrent urinary tract infections, and gross incontinence. Symptoms range from mild to disabling. Obviously, incontinence is especially troublesome. If the lesion is above the PMC, detrusor–striated sphincter dyssynergia usually does not occur. However, leakage may occur because the need to void cannot be felt or because the sphincter becomes more relaxed and can no longer inhibit spontaneous voiding. Lesions of the internal capsule include vascular accidents and Parkinson's disease. Both spastic and semiflaccid voiding disorders are found with these lesions.
Spinal cord injury can be the result of trauma, herniated intervertebral disk, vascular lesions, multiple sclerosis, tumor, syringomyelia, or myelitis, or it may be iatrogenic. Traumatic spinal cord lesions are of greatest clinical concern. Partial or complete injuries may cause equally severe genitourinary dysfunction. Sphincter spasticity and voiding dyssynergia can lead to detrusor hypertrophy, high voiding pressures, ureteral reflux, or ureteral obstruction. With time, renal function may be compromised. If infection is combined with back pressure on the kidney, loss of renal function can be particularly rapid.
Spinal cord injuries at the high thoracic (above T6) and cervical levels are often associated with (1) detrusor–sphincter (both smooth and striated) dyssynergia and (2) autonomic dysreflexia. Because the lesions occur above the sympathetic outflow from the cord, hypertensive blood pressure fluctuations, bradycardia, and sweating can be triggered by insertion of a catheter, mild overdistention of the bladder with filling, or dyssynergic voiding (see later). When a complete lesion is near the levels of sympathetic outflow, patient may develop bladder overactivity with no sensation, smooth sphincter synergy but striated sphincter dyssynergia.
In summary, the overactive neuropathic bladder is typified by (1) reduced capacity, (2) involuntary detrusor contractions, (3) high intravesical voiding pressures, (4) marked hypertrophy of the bladder wall, (5) spasticity of the pelvic-striated muscle, and (6) autonomic dysreflexia in cervical cord lesions.
Neuropathic Bladder Due to Lesions at or below the Sacral Micturition Center
Injury to the Detrusor Motor Nucleus
The most common cause of flaccid neuropathic bladder is injury to the spinal cord at the micturition center, S2–4. Other causes of anterior horn cell damage include infection due to poliovirus or herpes zoster and iatrogenic factors such as radiation or surgery. Herniated disks can injure the micturition center but more commonly affect the cauda equina or sacral nerve roots. Myelodysplasias could also be grouped here, but the mechanism is actually failure in the development or organization of the anterior horn cells. Lesions in this region of the cord are often incomplete, with the result commonly being a mixture of spastic behavior with weakened muscle contractility. Mild trabeculation of the bladder may occur. External sphincter and perineal muscle tone are diminished. Urinary incontinence usually does not occur in these cases because of the compensatory increase in bladder storage. The bladder pressure is low and little outlet resistance is needed to provide continence. Evacuation of the bladder may be accomplished by straining, but with variable success.
Injury to the Afferent Feedback Pathways
Flaccid neuropathic bladder also results from a variety of neuropathies, including diabetes mellitus, tabes dorsalis, pernicious anemia, and posterior spinal cord lesions. Here, the mechanism is not injury of the detrusor motor nucleus but a loss of sensory input to the detrusor nucleus or a change in motor behavior due to loss of neurotransmission in the dorsal horns of the cord. The end result is the same. Loss of perception of bladder filling permits overstretching of the detrusor. Atony of the detrusor results in weak, inefficient contractility. Capacity is increased and residual urine significant.
In summary, the flaccid neuropathic bladder is typified by (1) large capacity, (2) lack of voluntary detrusor contractions, (3) low intravesical pressure, (4) mild trabeculation (hypertrophy) of the bladder wall, and (5) decreased tone of the external sphincter.
Injury Causing Poor Detrusor Distensibility
Another cause of atonic neuropathic bladder is peripheral nerve injury. This category includes injury caused by radical surgical procedures such as low anterior resection of the colon or radical hysterectomy. Impaired innervation of detrusor and both the smooth and striated sphincters create outflow resistance and incomplete voiding. The end result is a bladder that stores poorly owing to failure to accommodate with filling.
Radiation therapy can result in denervation of the detrusor or sphincters. More commonly, it damages the detrusor, resulting in fibrosis and loss of distensibility. Other inflammatory causes of injury to the detrusor include chronic infection, interstitial cystitis, and carcinoma in situ. These lesions produce a fibrotic bladder wall with poor distensibility.
Selective Injury to the External Sphincter
Pelvic fracture often damages the nerves to the external sphincter. Selective denervation of the external sphincter muscle, with incontinence, can follow if the bladder neck is not sufficiently competent. Radical surgery in the perineum may affect sensory but not motor innervation of the external sphincter.
Spinal Shock and Recovery of Vesical Function after Spinal Cord Injury
Immediately following severe injury to the spinal cord or conus medullaris, regardless of level, there is a stage of flaccid paralysis, with numbness below the level of the injury. The smooth muscle of the detrusor and rectum is affected. The result is detrusor overfilling to the point of overflow incontinence and rectal impaction.
Spinal shock may last from a few weeks to 6 months (usually 2–3 months). Reflex response in striated muscle is usually present from the time of injury but is suppressed. With time, the reflex excitability of striated muscle progresses until a spastic state is achieved. Smooth muscle is much slower to develop this hyperreflexic activity. Therefore, urinary retention is the rule in the early months following injury.
Urodynamic studies are indicated periodically to monitor the progressive return of reflex behavior. In the early recovery stages, a few weak contractions of the bladder may be found. Later, in injuries above the micturition center, more significant reflex activity will be found. Low-pressure storage can be managed via intermittent catheterization. High-pressure storage should be addressed early to avoid problems with the upper urinary tract.
A seldom used but valuable test is instillation of ice water. A strong detrusor contraction in response to filling with cold saline (3.3°C [38°F]) is one of the first indications of return of detrusor reflex activity. This test is of value in differentiating upper from lower motor neuron lesions early in the recovery phase.
Activity of the bladder after the spinal shock phase depends on the site of injury and extent of the neural lesion. With upper motor neuron (suprasegmental) lesions, there is obvious evidence of spasticity toward the end of the spinal shock phase (eg, spontaneous spasms in the extremities, spontaneous leakage of urine or stool, and, possibly, the return of some sensation). A plan of management can be made at this time. A few patients will retain the ability to empty the bladder reflexively by using trigger techniques, that is, by tapping or scratching the skin above the pubis or external genitalia. More often, detrusor overactivity must be suppressed by anticholinergic medication to prevent incontinence. Evacuation of urine can then be accomplished by intermittent catheterization. Although incomplete lesions are more amenable to this approach than complete lesions, 70% of complete lesions ultimately can be managed using this program. Patients who cannot be managed in this way can be evaluated for sphincterotomy, dorsal rhizotomy, diversion, augmentation, or a bladder pacemaker procedure.
In cases of lower motor neuron lesions, it is difficult to distinguish spinal shock from the end result of the injury. Spontaneous detrusor activity cannot be elicited on urodynamic evaluation. If the bladder is allowed to fill, overflow incontinence will occur. Striated muscle reflexes will be suppressed or absent. The bladder may be partially emptied by the Credé maneuver (ie, by manually pushing on the abdomen above the pubic symphysis) or, preferably, by intermittent catheterization.
Diagnosis of Neurogenic Bladder
The diagnosis of a neuropathic bladder disorder depends on a complete history and physical (including neurologic) examination, as well as use of radiologic studies (voiding cystourethrography, excretory urography, computed tomography scanning, magnetic resonance imaging, when necessary); urologic studies (cystoscopy, ultrasound); urodynamic studies (cystometry, urethral pressure recordings, uroflowmetry); and neurologic studies (electromyography, evoked potentials). Patients should be reevaluated often as recovery progresses.
Neurogenic Overactive (Spastic, Hyperreflexic) Bladder
Overactive bladder results from extensive neural damage above sacral cord but below the PMC. The bladder functions on the level of spinal segmental reflexes, without efficient regulation from higher brain centers.
The severity of symptoms depends on the site and extent of the lesion as well as the length of time from injury. Symptoms include involuntary urination, which is often frequent, spontaneous, scant, and triggered by spasms in the lower extremities. A true sensation of fullness is lacking, although vague lower abdominal sensations due to stretch of the overlying peritoneum may be felt. The major nonurologic symptoms are those of spastic paralysis and objective sensory deficits.
A complete neurologic examination is most important. The sensory level of the injury needs to be established, followed by assessment of the anal, bulbocavernosus, knee, ankle, and toe reflexes. These reflexes vary in degree of hyperreflexia on a scale of 1–4. Levator muscle tone and anal tone should be gauged separately, also on a scale of 1–4. Bladder volumes in established lesions are usually <300 mL (not infrequently, <150 mL) and cannot be detected by abdominal percussion. Ultrasound is a useful and rapid means of determining bladder capacity. Voiding often can be triggered by stimulation of the skin of the abdomen, thigh, or genitalia, often with spasm of the lower extremities.
With high thoracic and cervical lesions, distention of the bladder (due to a plugged catheter or during cystometry or cystoscopy) can trigger a series of responses, including hypertension, bradycardia, headache, piloerection, and sweating (autonomic dysreflexia). Inserting a catheter and leaving the catheter on open drainage usually reverses the dysreflexia.
Virtually all patients experience one or more urinary tract infections during the recovery phase of spinal shock. This is due to the necessity of catheter drainage, either intermittent or continuous. Urinary stasis, prolonged immobilization, and urinary tract infections can predispose to stone formation. Renal function may be normal or impaired, depending on the efficacy of treatment and the absence of complications (hydronephrosis, pyelonephritis, urinary stones). Red blood cells (erythrocytes) in the urine may reflect a number of abnormalities. Uremia will result if complications are not addressed appropriately and the patient is not checked at regular intervals.
Periodic excretory urograms and retrograde cystograms are essential because complications are common. A trabeculated bladder of small capacity is typical of this type of neuropathic dysfunction. The bladder neck may be dilated. The kidneys may show evidence of pyelonephritic scarring, hydronephrosis, or stone disease. The ureters may be dilated from obstruction or reflux. A voiding film may detect a narrowed zone created by the spastic sphincter or identify a strictured segment of the urethra. Magnetic resonance imaging, especially the sagittal view, offers clear delineation of the bladder neck and posterior urethra if pathology if suspected.
Cystourethroscopy helps assess the integrity of the urethra and identify stricture sites. The bladder shows variable degrees of trabeculation, occasionally with diverticula. Bladder capacity, stones, competency of the ureteral orifices, changes secondary to chronic infection or indwelling catheters, and the integrity of the bladder neck and external urethral sphincter can be assessed. When indicated, ureteroscopy can also be used to inspect the ureter and the renal pelvis.
Combined recording of bladder and urethral sphincter activity during filling will reveal a low-volume bladder with spastic dyssynergy of the external sphincter (Figure 28–4). High voiding pressures in the bladder are common. Ureteral reflux or obstruction is more likely if voiding pressures exceed 40 cm of water. A high resting pressure is noted in the external sphincter on the urethral pressure profile, and labile spastic behavior is noted during filling and voiding. Various auras replace a true sense of bladder filling, for example, sweating, vague abdominal discomfort, and spasm of the lower extremities. Movement of a catheter in the urethra can trigger detrusor contraction and voiding.
Spinal cord injury at T12. Simultaneous recording of intravesical and urethral pressure with bladder filling. Note the rise in intravesical pressure associated with unstable activity of the external sphincter, as reflected on the urethral pressure tracing.
Spastic Neuromuscular Dysfunction
Incomplete lesions of the cerebral cortex, pyramidal tracts, or spinal cord may weaken, but not abolish, cerebral restraint. The patient may have frequency and nocturia or urinary incontinence due to precipitous urge or voiding. Common causes include brain tumors, Parkinson's disease, multiple sclerosis, dementias, cerebrovascular accidents, prolapsed disks, or partial spinal injury.
In many cases, the cause is unclear. The hyperreflexic behavior often seems to be associated with a peripheral abnormality (eg, prostatitis, benign prostatic hypertrophy, urethritis) or follows pelvic surgery (eg, anterior colporrhaphy, anteroposterior tumor resection). Symptoms are commonly associated with psychological factors.
Frequency, nocturia, and urgency are the principal symptoms. Hesitancy, intermittency, double voiding, and residual urine are also common. Incontinence may vary from pre- or postvoiding dribbling to complete voiding that the patient does not recognize or cannot inhibit once started.
The degree of voiding dysfunction does not parallel neurologic deficits. Slight physical disabilities can be associated with gross disturbances in bladder function, and the reverse is also true. However, it is always important to check lower extremity and perineal reflexes for evidence of hyperreflexia. Sensory or motor deficits may also be detected in the lumbar or sacral segments.
In the early stages, radiologically evident change is minimal or absent. Low bladder volume and mild trabeculation of the bladder are usually evident.
Cystoscopy and urethroscopy are generally unremarkable. Mild detrusor and sphincter irritability and diminished capacity may be demonstrated.
The behavior patterns of the sphincter and bladder are similar to those of the previous group but on a milder scale. Detrusor overactivity, evident urodynamically, may not be associated with the same symptom pattern on the clinical level. The patient occasionally perceives a sense of urgency and the need to void. However, these sensations may not be present, and the patient may complain of the occasional leakage as the main inconvenience. Morphologic changes in the bladder are slight, with changes in the upper urinary tract occurring rarely and late because of lower pressures in the bladder.
Neurogenic Areflexic (Flaccid, Atonic) Bladder
Direct injury to the peripheral innervation of the bladder or sacral cord segments S2–4 results in flaccid paralysis of the urinary bladder. Characteristically, the capacity is large, intravesical pressure low, and involuntary contractions absent. Because smooth muscle is intrinsically active, fine trabeculations in the bladder may be seen. Common causes of this type of bladder behavior are trauma, tumors, tabes dorsalis, and congenital anomalies (eg, spina bifida, meningomyelocele).
The patient experiences flaccid paralysis and loss of sensation affecting the muscles and dermatomes below the level of injury. The principal urinary symptom is retention with overflow incontinence. Male patients lose their erections. Surprisingly, despite weakness in the striated sphincter, neither bowel nor urinary incontinence is a major factor. Storage pressures within the bladder remain below the outlet resistance.
Neurologic changes are typically lower motor neuron. Extremity reflexes are hypoactive or absent. Sensation is diminished or absent. It is important to check sensation over the penis (S2) and perianal region (S2–3) for evidence of a mixed or partial injury. Anal tone (S2) should be compared with levator tone (S3–4), again for evidence of a mixed injury.
Similarly, sensation over the outside of the foot (S2), sole of the foot (S2–3), and large toe (S3) should be compared for evidence of mixed injury. Occasionally, extremity findings do not parallel those of the perineum, with the pattern being absent sensation and tone in the feet but partial tone or sensation in the perineum. This is especially true in patients who have spina bifida or meningomyelocele.
Repeated urinalysis at regular intervals is no less important in this group than in others. Infection with white blood cells (leukocytes) and bacteria may occur because of the need for bladder catheterization. Advanced renal change is unusual because bladder storage is under low pressure, but chronic renal failure secondary to pyelonephritis, hydronephrosis, or calculus formation is still possible.
A plain film of the abdomen may reveal fracture of the lumbar spine or extensive spina bifida. Calcific shadows compatible with urinary stone may be seen. Excretory urograms should be performed initially to check for calculus, hydronephrosis, pyelonephritic scarring, or ureteral obstruction secondary to an overdistended bladder. A cystogram may detect morphologic changes in the detrusor (it is usually large and smooth walled); vesicoureteral reflux may be present. Checks on the integrity of both the lower and upper urinary tracts can subsequently be made using ultrasound.
Cystoscopy and urethroscopy performed some months or weeks after the injury will confirm the laxity and areflexia of the sphincter and pelvic floor; the bladder neck is usually funneled and open and the bladder should be large and smooth walled. The integrity of the ureteral orifices should be normal. Fine trabeculation may be evident. Bladder stones and urethral stricture or obstruction may be seen in long-term cases.
The urethral pressure profile reflects low smooth and striated sphincter tone. Bladder filling pressures are low; detrusor contractions are weak or absent; voiding is accomplished by straining or by the Credé maneuver, if at all; and there is a large volume of residual urine. Awareness of filling is markedly diminished and usually results from stretch on the peritoneum or abdominal distention.
This test is classically performed by giving bethanechol chloride (Urecholine) 15 mg subcutaneously. A cystometrogram is performed after 20 minutes, and the results are compared with the findings obtained before the bethanechol was given. If the results are positive, a rise in filling pressure of more than 15 cm of water is noted, with a shift in the filling curve to the left. A finding of no change on filling reflects myogenic damage to the detrusor. The ice water test also checks for detrusor hypersensitivity.
Bethanechol does not facilitate a detrusor contraction; it can only increase tone in the detrusor wall, which in turn might trigger the voiding reflex. The test is not a check on the integrity of the voiding reflex but demonstrates denervation hypersensitivity in flaccid bladders and differentiates this condition from myogenic damage.
The test is not applicable in patients with reduced bladder capacity, decreased compliance (ie, sharp rise in detrusor-filling pressure), or forceful contractions of the detrusor.
Differential Diagnosis of Neurogenic Bladder
The diagnosis of neuropathic bladder is usually obvious from the history and physical examination. Neural impairment is evidenced by abnormal sacral reflex activity and decreased perineal sensation. Some disorders with which neuropathic bladder may be confused are cystitis, chronic urethritis, vesical irritation secondary to psychic disturbance, myogenic damage, interstitial cystitis, cystocele, and infravesical obstruction.
Inflammation of the bladder, both nonspecific and tuberculous, causes frequency of urination and urgency, even to the point of incontinence. Infections secondary to residual urine caused by neuropathic behavioral disturbance should be ruled out.
The urodynamics of the inflamed bladder are similar to those of the neurogenic overactive bladder. However, with inflammation, symptoms disappear after definitive antibiotic therapy, and the urodynamic behavior reverts to normal. If symptoms persist or infections return repeatedly, a neuropathic behavioral abnormality should be considered (eg, multiple sclerosis or even idiopathic detrusor–sphincter dyssynergia).
Symptoms of frequency, nocturia, and burning on urination may be due to chronic inflammation of the urethra not necessarily associated with infection. The urodynamics will show an irritable urethral sphincter zone with labile, spastic tendencies. The cause is unknown.
Vesical Irritation Secondary to Psychic Disturbance
Anxious, tense individuals or those with pathologic psychological fixation on the perineum may present a long history of periodic bouts of urinary frequency or perineal or pelvic pain. The clinical picture and urodynamic findings are similar to those described previously for chronic urethritis. Often, however, if the patient's anxieties can be allayed, the symptoms subside. The underlying problem is one of excessive pelvic muscle tension and inefficient sphincter behavior. Some of the symptoms may improve with manual therapy of pelvic floor myofascial trigger points (Weiss, 2001).
Interstitial cystitis is poorly understood chronic inflammation of the bladder (Hanno et al, 2011). The typical patient is a woman older than 40 years, with symptoms of frequency, nocturia, urgency, and suprapubic pain. The symptoms are brought on by bladder distention. Capacity is limited (often <100 mL in the most symptomatic and disabled patients). Urinalysis is normal, and there is no residual urine. Urodynamic studies show a hypertonic, poorly compliant bladder. Distention of the bladder with cystoscopy produces bleeding from petechial hemorrhages and fissuring in the mucosa. The condition represents an end-stage inflammatory process of unknown cause in the detrusor.
Relaxation of the pelvic floor following childbirth may cause some frequency, nocturia, and stress incontinence. Residual urine may be present and predispose to infection. Loss of urine occurs with lifting, standing, or coughing. Pelvic examination usually reveals relaxation of the anterior vaginal wall and descent of the urethra and bladder when the patient strains to void.
Bladder Outlet Obstruction
Urethral strictures, benign or malignant enlargement of the prostate gland, and congenital urethral valves all can produce significant obstruction of the urinary outlet. Hypertrophy (ie, trabeculation) of the detrusor develops, and residual urine can accumulate. Detrusor overactivity is often found at this stage and resembles that of the neurogenic overactive bladder.
If decompensation occurs, the vesical wall becomes attenuated and atonic, and capacity may be markedly increased. Overflow incontinence may develop. The behavior of the bladder is similar to that of the neurogenic areflexic bladder.
If the difficulty is nonneuropathic, the anal sphincter tone is normal and the bulbocavernosus reflex intact. Peripheral sensation, voluntary muscle contraction, and limb reflexes should also be normal. Cystoscopy and urethroscopy reveal the local lesion that causes obstruction. Once the obstruction is relieved, bladder function improves but may never return to normal.
Treatment of Neuropathic Bladder
The treatment of any form of neuropathic bladder is guided by the need to restore low-pressure activity to the bladder. In doing so, renal function is preserved, continence restored, and infection more readily controlled. Reflex evacuation may develop if detrusor integrity is protected and trigger techniques are practiced.
Following severe injury to the spinal cord, the bladder becomes atonic. During the spinal shock stage, some type of bladder drainage must be instituted immediately and maintained. Chronic overdistention can damage the detrusor smooth muscle and limit functional recovery of the bladder. Intermittent catheterization using strict aseptic technique has proved to be the best form of management. This avoids urinary tract infection as well as the complications of an indwelling catheter (eg, urethral stricture, abscess, erosions, stones).
If a Foley catheter becomes necessary, a few principles need to be followed. The catheter should not be larger than 16F and preferably should be made of silicon, and it should be taped to the abdomen. Taping the catheter to the leg puts unnecessary stress on the penoscrotal junction and bulbous urethra (ie, the curves in the urethra), and this can lead to stricture formation. The catheter should be changed with sterile procedure every 2–3 weeks.
Some urologists advocate the use of suprapubic cystostomy rather than a urethral catheter to avoid the risks associated with permanent indwelling catheters. Certainly, whenever catheter-related complications occur, the physician should not hesitate in resorting to cystostomy drainage.
Irrigation of the bladder with antibiotic solutions, use of systemic antibiotics, or covering the tip of the meatus with antibiotic creams does not significantly lower the long-term risk of bladder infection. However, keeping the meatus lubricated does help avoid meatal stricturing.
As peripheral reflex excitability gradually returns, urodynamic evaluation should be performed. A cystogram is needed to rule out reflux. The urodynamic study should be repeated every 3 months as long as spasticity is improving and then annually to check for complications of the upper urinary tract.
To control infection, a fluid intake of at least 2–3 L/day should be maintained (100–200 mL/h) if at all possible. This reduces stasis and decreases the concentration of calcium in the urine. Renal and ureteral drainage are enhanced by moving the patient frequently, with ambulation in a wheelchair as soon as possible, and even by raising the head of the bed. These measures improve ureteral transport of urine, reduce stasis, and lower the risk of infection.
Specific Types of Neuropathic Bladder
Once a neuropathic voiding disorder is established, regardless of cause, the following steps should be taken to attain optimum function.
Neurogenic Overactive Bladder
Patient with Reasonable Bladder Capacity
The goal is to rehabilitate the bladder to a functional state, that is, being able to go 2–3 hours between voiding and not be incontinent during this interval. Voiding is initiated using trigger techniques—tapping the abdomen suprapubically; tugging on the pubic hair; squeezing the penis; or scratching the skin of the lower abdomen, genitalia, or thighs. Patients can accomplish this on their own unless they are high quadriplegics with no upper limb function.
Some patients in this category can empty the bladder completely but are incontinent due to inconvenient triggering of the voiding reflex. They may be helped by low-dose anticholinergic medication or by neural stimulation (Gulur and Drake, 2010).
Patient with Markedly Diminished Functional Vesical Capacity
If the functional capacity of the bladder is <100 mL, involuntary voiding can occur as often as every 15 minutes. Satisfactory training of the bladder cannot be achieved, and alternative measures must be taken. Of course, one must first determine that reduced functional bladder capacity is not due to a large residual volume of urine. One of the following treatment regimens can then be administered.
A permanent indwelling catheter with or without anticholinergic medication.
A condom catheter and a leg bag in males if residual urine volumes are small and the patient does not have bladder pressures above 40 cm of water on urodynamic evaluation. If either of these parameters is found, the upper urinary tract is considered at risk from obstruction or reflux.
Performance of a sphincterotomy in males (Perkash, 2007). It is possible to turn the bladder into a urinary conduit by surgically eliminating all outlet resistance from the bladder. This option should be used only when other options have failed, as it is irreversible. Patients having this procedure usually have more serious sequelae of a highly spastic bladder (ie, upper urinary tract dilatation, recurrent urinary tract infections, or marked autonomic dysreflexia).
Conversion of the spastic bladder to a flaccid bladder through sacral rhizotomy. Complete surgical section or percutaneous heat fulguration of the S3 and S4 roots is necessary. Chemical rhizotomy is unreliable, as spasticity usually returns after 6–9 months. These procedures may cause loss of reflex erections, and the decision to perform them should be weighed accordingly. These procedures can relieve spasticity, lower intravesical pressures, increase bladder storage, and decrease the risk of damage to the upper urinary tract. The bladder would then be managed as a flaccid bladder (see later).
Neurostimulation of the sacral nerve roots to accomplish bladder evacuation (see the following section).
Urinary diversion for irreversible, progressive upper urinary tract deterioration. A variety of procedures are available, including the standard ileal conduit, cutaneous ureterostomies, transureteroureterostomy, or nonrefluxing urinary reservoir (eg, Mainz pouch, Koch pouch, or one of several other continent diversions designed to protect the upper urinary tract and kidneys).
In females with a spastic bladder, one does not have the option of performing a sphincterotomy. If pharmacologic methods are unsuccessful, surgical conversion to a flaccid, low-pressure system or a urinary diversion should be considered.
Muscarinic Receptor Antagonist
Because of the chronic nature of the neuropathic bladder, patients are not always willing to tolerate the side effects of muscarinic receptor antagonist. Several drugs in this category can be alternated to reduce the side effects of either drug. They may also be useful when given with skeletal muscle relaxants. Dosages must be individualized. Commonly used drugs and dosages are as follows: oxybutynin chloride (Ditropan) XL, 10 mg once daily, and tolterodine (Detrol) LA, 4 mg daily or other newer drugs (see Chapter 30). (Andersson, 2010; Andersson et al, 2010). These drugs may not be effective if incontinence is the result of uninhibited sphincter relaxation or compliance changes in the bladder wall.
Intravesical Instillation of Medications
Capsaicin and resiniferatoxin are specific C-fiber afferent neurotoxins. After spinal cord injury, C-fiber afferents proliferate in the bladder mucosa and are involved in detrusor hyperreflexia. In patients with NDO from spinal cord injury or multiple sclerosis, both capsaicin and resiniferatoxin showed better effect than placebo. However, the panel of the 4th International Consultation on Incontinence feels that they are of very limited clinical use in detrusor overactivity (Andersson et al, 2009). On the other hand, intravesical oxybutynin has been used successfully in neurogenic bladder (Lazarus, 2009).
Several studies have investigated injection of 100–300 units of botulinum-A toxin into 30–40 sites in the bladder in adults who have detrusor hyperreflexia (Alvares et al, 2010; Datta et al, 2010; Smaldone et al, 2010). Most published results conclude that intravesical injection of botulinum toxin resulted in improvement in medication refractory overactive bladder symptoms. However, the risk of increased postvoid residual and symptomatic urinary retention was significant. Several studies also showed the effect of repeated injection and its sustained effect (Png and Toh, 2010). The panel of the 4th International Consultation on Incontinence recommends its use in patients who are resistant to antimuscarinics (Andersson et al, 2009).
Neurostimulation (Bladder Pacemaker)
Neuroprosthetics are becoming an established alternative to managing selective neuropathic bladder disorders (Bosch and Groen, 1995; Burks et al, 2010). Patients are evaluated for a bladder pacemaker primarily by urodynamic monitoring of bladder and sphincter responses to trial stimulation of the various sacral nerve roots. Selective blocks are then prepared to the right and left pudendal nerves. If voiding is produced, patients are considered suitable for a neuroprosthesis. Other factors such as detrusor storage capability, sphincter competence, age, kidney function, and overall neurologic and psychological status are also taken into consideration.
Electrodes are implanted on the motor (ventral) nerve roots of those sacral nerves that will produce detrusor contraction on stimulation (always S3, occasionally S4). Steps are then taken to reduce sphincter hyperreflexia by selectively dividing the sensory (dorsal) component of these same sacral nerve roots and selective branches of the pudendal nerves. The electrodes are connected to a subcutaneous receiver that can be controlled from outside the body. Bladder or bowel evacuation or continence can then be controlled selectively by the external transmitter (Brindley, 1995; Tanagh et al, 1989).
The first two goals are to protect upper tract and restore continence. Both can be achieved by combining neurostimulation of the sphincter with selective sacral neurotomies that lead to increased bladder capacity and reduced bladder pressure. This approach preserves sphincter integrity and avoids the need for drugs. Other options include complete bladder denervation or bladder augmentation.
The third goal, restoration of controlled evacuation, eliminates the need for catheters and associated risk of infection. This is the most difficult goal to achieve, and patients need to be carefully evaluated for their suitability.
Neurogenic Areflexic Bladder
If the neurologic lesion completely destroys the micturition center, volitional voiding cannot be accomplished without manual suprapubic pressure, that is, the Credé maneuver. Bladder evacuation can be accomplished by straining, using the abdominal and diaphragmatic muscles to raise intra-abdominal pressures. Partial injuries to the lower spinal cord (T10–11) result in a spastic bladder and a weak or weakly spastic sphincter. Incontinence can then result from spontaneous detrusor contraction.
Bladder Training and Care
In partial lower motor neuron injury, voiding should be tried every 2 hours by the clock to avoid embarrassing leakage. This helps protect the bladder from overdistention due to a buildup of residual urine.
Any patient with adequate bladder capacity can benefit from regular intermittent catheter drainage every 3–6 hours (McGuire and Savastano, 1983). This technique eliminates residual urine, helps prevent infection, avoids incontinence, and protects against damage to the upper urinary tract. It simulates normal voiding and is easily learned and adapted by patients. It is an extremely satisfactory solution to the problems of the flaccid neuropathic bladder. A clean technique is used rather than the inconvenient, expensive, sterile technique. Urinary tract infections are infrequent, but if they occur, an antibiotic can be given. The method is contraindicated if ureteral reflux is present, unless the reflux is mild and the bladder emptied frequently.
Transurethral resection is indicated for hypertrophy of the bladder neck or an enlarged prostate, either of which may cause obstruction of the bladder outlet and retention of residual urine. It may also be performed in some male patients to weaken the outlet resistance of the bladder to permit voiding by the Credé maneuver or abdominal straining.
Complete urinary incontinence due to sphincter incompetence can be managed by implanting an artificial sphincter (Chung and Cartmill, 2010; Kastler et al, 2010). Bladder pressure should be low, however, for this to be successful. Bladder neck and posterior urethral reconstruction also may be considered as a way to increase outlet resistance (Churchill et al, 2010; Dave and Salle, 2008). Incontinence in this group of patients can be treated with drugs or neurostimulation if it results from mild bladder spasticity.
The stable derivatives of acetylcholine are at times of value in assisting the evacuation of the bladder. Although they do not initiate or effect bladder contraction, they do provide increased bladder tonus. They may be helpful in symptomatic treatment of the milder types of flaccid neuropathic bladder. Drugs may be tried empirically, but usefulness is best gauged during urodynamic evaluation. If filling pressure or resting tonus is increased after bethanechol chloride (Urecholine) is administered, evacuation of the bladder through trigger reflexes or straining should be more effective. The drug then should be clinically helpful.
Bethanechol chloride is the drug of choice. It is given orally, 25–50 mg every 6–8 hours. In special situations (eg, urodynamic study or immediately following operation), it may be given subcutaneously, 5–10 mg every 6–8 hours.
Neurogenic Bladder Associated with Spina Bifida
Spina bifida is incomplete formation of the neural arch at various levels of the spine. The defect is recognized at birth and closed immediately to prevent infection. The scarring that results can entrap and tether nerves in the cauda equina. With failure of the neural arch to close, there is failure of anterior horn cell development and organization. The end result is a mixed type of neuropathic defect. Roughly two-thirds of patients have a spastic bladder with weakness in the feet and toes. About one-third of patients have a flaccid bladder. Often, there is a greater degree of flaccidity in the pelvic floor than in the detrusor. The goals of therapy are to control incontinence and preserve renal function.
Clean intermittent catheterization is the best management. Parents can be taught to do this for the child, and eventually the child can take over this function. Frequency should be determined by the storage capacity of the bladder and the fluid intake, usually every 3–6 hours. An anticholinergic drug may be required to mediate bladder spasticity and improve storage function in order to control incontinence.
If there is occasional dribbling or some residual urine associated with lack of desire to void, the patient should try to void every 2 hours when awake. Manual suprapubic pressure enhances the efficiency of emptying. An external condom catheter or a small pad can be worn to protect against small-volume losses of urine.
If urinary incontinence is associated with residual urine or if ureteral reflux is found, the following steps should be taken:
- a. Hypotonic bladder—If reflux has been demonstrated, intermittent self-catheterization four to six times a day may protect the upper urinary tract from deterioration and the consequences of pyelonephritis. Ureteral reimplantation can be considered for bilateral reflux or a transureteroureterostomy for single-sided reflux if all other considerations are favorable. Intermittent catheterization should then be reinstituted.
- b. Hypertonic bladder—The problem with patients in this category is more serious because the bladder is spastic with reduced capacity and the sphincter is hypotonic. Virtually constant dribbling can result. The cystogram will reveal heavy trabeculation of the bladder, often with reflux and advanced hydroureteronephrosis. Anticholinergic medication should be given, and an indwelling catheter should be inserted for several months. Once upper urinary tract dilatation has been improved and the bladder has been restored to a more spheric shape, intermittent catheterization may be reinstituted. With time and care, many of these children develop a more balanced type of bladder behavior. Continence may be gained without compromising the upper urinary tract.
Most of these patients will not require urinary diversion if they are carefully followed up and if the parents actively participate in their care.
If the bladder is of the spastic type with diminished capacity, there are several surgical options short of actual urinary diversion. Sacral nerve block during urodynamic evaluation helps in determining whether sacral nerve root section would be beneficial. This helps in cases of spastic bladder but not in cases of poorly compliant, fibrotic bladder. Sectioning the S3 nerves reduces intravesical pressures, improves storage, and reduces the risk of reflux or obstruction of the ureters.
For patient with a mildly spastic bladder and reasonable storage capacity (>200 mL), urinary incontinence might be controlled via electrostimulation of the pelvic floor. Many of these patients have intact nerves to the sphincter. These can be stimulated to enhance sphincter tone and inhibit voiding. If the bladder has a limited capacity with poor compliance and poor contractility, augmentation cystoplasty (Duel et al, 1998) followed by intermittent self-catheterization is the treatment of choice.
If the refluxing patient has recurrent fever (equivalent to pyelonephritis) despite the presence of an indwelling catheter or if incontinence cannot be controlled because of poor detrusor compliance, urinary diversion must be considered. Nonrefluxing continent reservoirs offer the most favorable long-term outlook for preservation of the upper urinary tract.
In patient with hyperreflexic neurogenic bladder and detrusor external sphincter dyssynergia caused by complete suprasacral spinal cord injury, anastomosis between the L5 and S2/3 ventral roots, or between 11th and 12th intercostal nerves and the S2–S3 roots, has been carried out so that urination can be controlled by somatic afferent (Livshits et al, 2004; Xiao et al, 2003). Varying degree of success has been reported.
Control of Urinary Incontinence
Most men with spastic bladders rely on a condom catheter for protection against leakage and for practical urine collection. The only exception is patients who are predictably dry between catheterizations. The condom catheter attaches to the penis without pressure and has a conduit to a leg bag. The adhesives are nonirritating and long lasting. Problems involved in keeping these catheters in place are limited to noncircumcised patients and those with large suprapubic fat pads that shorten the length of the shaft of the penis. Circumcision or placement of a penile prosthesis will correct for these limitations.
Urethral compression by means of a Cunningham clamp is occasionally preferred by patients. This protects only against low-pressure leakage, however, and if it is applied too tightly, a urethral diverticulum may develop.
Other types of external collection devices are available (McGuire urinal, Texas catheter), but with advancements in adhesive glues for condom catheters and use of penile prostheses, the other methods are being used less frequently.
Extensive research continues to be conducted on methods of restoring voluntary control over the storage and evacuation functions of the bladder. Sacral and pudendal nerve anatomy has been determined so that surgical exposure of these nerves and their branches is possible. An electrode can be placed for selective stimulation of the bladder, levator, and urethral or anal sphincters (Schmidt, 1986; Tanagho et al, 1989; Thompson et al, 2010). A number of possibilities exist for neurostimulation or rhizotomy, but only a few are practical. Urodynamic evaluation of bladder function following a nerve block or during neurostimulation can help determine the therapeutic value of these treatments.
Single or multiple electrodes can be placed on selected nerves and coupled to a subcutaneous receiver (Brindley, 1995; Tanagho and Schmidt, 1988). The desired function (continence or evacuation) can be selected. Usually, one or the other is needed in any one patient. Much will change in this approach as technologic advances become adapted to the increased understanding of bladder physiology. Striking successes are also being seen with electroevacuation in highly selected patients.
Complications of Neurogenic Bladder
The principal complications of the neuropathic bladder are recurrent urinary tract infection, hydronephrosis secondary to ureteral reflux or obstruction, and stone formation (Pickelsimer et al, 2010). The primary factors contributing to these complications are the presence of residual urine, sustained high intravesical pressures, and immobilization, respectively.
Incontinence in neuropathic disorders may be passive, as in flaccid lesions when outlet resistance is compromised, or may be the result of uninhibited detrusor contractions, as in spastic lesions.
Infection is virtually inevitable with the neuropathic bladder state. During the stage of spinal shock that follows cord injury, the bladder must be emptied by catheterization. Sterile intermittent catheterization is recommended at this stage, but for practical purposes or for the sake of convenience, a Foley catheter is often left indwelling. Chronic catheter drainage guarantees infection regardless of any preventive measures taken.
The upper urinary tract is usually protected from infection by the integrity of the ureterovesical junction. If this becomes incompetent, infected urine will reflux up to the kidneys. Decompensation of the ureterovesical junction results from the high intravesical pressures generated by the spastic bladder. It is most important that these cases be treated aggressively with an intensive program of self-catheterization and anticholinergic medication. The Credé maneuver should not be used.
A number of infective complications can result from the presence of a chronically indwelling Foley catheter. These include cystitis and periurethritis resulting from mechanical irritation. A periurethral abscess may follow, with formation of a fistula via eventual rupture of the abscess through the perineal skin. Drainage may also take place through the urethra, with the end result being a urethral diverticulum. Infection may travel up into the prostatic ducts (prostatitis) or seminal vesicles (seminal vesiculitis) and along the vas into the epididymis (epididymitis).
Treatment of Pyelonephritis
Episodic renal infection should be treated aggressively with appropriate antibiotics to prevent renal loss. The source and cause of infection should be eliminated if possible.
Treatment of Epididymitis
This condition is a complication of either dyssynergic voiding or an indwelling catheter. Treatment consists of appropriate antibiotics, bed rest, and scrotal elevation. The indwelling catheter should be removed or replaced with a suprapubic catheter. Preferred long-term management is to place the patient on an intermittent self-catheterization program. Rarely, ligation of the vas is required.
Two mechanisms lead to back pressure on the kidney. Early, the effect of trigonal stretch secondary to residual urine and detrusor hypertonicity becomes compounded by evolving trigonal hypertrophy. The combination causes abnormal pull on the ureterovesical junction, with increased resistance to the passage of urine. A “functional” obstruction results, which leads to progressive ureteral dilatation and back pressure on the kidney. At this stage, this condition can be relieved by continuous catheter drainage or by combined intermittent catheter drainage and use of anticholinergics.
A delayed consequence of trigonal hypertrophy and detrusor spasticity is reflux due to decompensation of the ureterovesical junction. The causative factor appears to be a combination of high intravesical pressure and trabeculation of the bladder wall. The increased stiffness of the ureterovesical junction weakens its valve-like function, slowly eroding its ability to prevent reflux of urine during forceful bladder contractions.
When ureteral reflux is detected by cystography, previous methods of bladder care must be radically adjusted. An indwelling catheter may manage the problem temporarily. However, if the reflux persists after a reasonable period of drainage, antireflux surgery must be considered. In addition, measures to reduce high intravesical pressure are needed (bladder augmentation, sacral rhizotomy, transurethral resection of the bladder outlet, or sphincterotomy). Progressive hydronephrosis may require nephrostomy. Urinary diversion is a last resort, which should be avoidable if the patient is followed up regularly.
A number of factors contribute to stone formation in the bladder and kidneys. Bed rest and inactivity cause demineralization of the skeleton, mobilization of calcium, and subsequent hypercalciuria. Recumbency and inadequate fluid intake both contribute to urinary stasis, possibly with increased concentration of urinary calcium. Catheterization of the neurogenic bladder may introduce bacteria. Subsequent infection is usually due to a urea-splitting organism, which causes the urine to become alkaline, with reduced solubility of calcium and phosphate.
Because these stones are usually soft, they can be crushed and will wash out through a cystoscope sheath. Occasionally, they are large and need to be removed via a suprapubic cystotomy.
Virtually, all ureteral stones can now be removed by endoscopy via antegrade or retrograde retrieval methods or by extracorporeal shock wave lithotripsy (ESWL).
In a patient with neurogenic bladder, kidney stones generally are the result of infection; if the infection is untreated, the stones become the source of persistent renal infection and eventual renal loss. Most of the stones in the renal pelvis can be removed by either a percutaneous endoscopic procedure or ESWL. Occasionally, a large staghorn stone may require open surgery.
Secondary amyloidosis of the kidney is a common cause of death in patients with neuropathic bladder. It is a result of chronic debilitation in patients with difficult decubitus ulcers and poorly controlled infection. Fortunately, due to better medical care, this is an uncommon finding today.
Men who have had traumatic cord or cauda equina lesions experience varying degrees of sexual dysfunction. Those with upper motor lesions fare well, with the majority having reflexogenic erectile capability. Dangerous elevations in blood pressure can occur with erections in patients with high thoracic or cervical lesions. Problems of quality of erection or premature detumescence are found with all levels of injury. Patients with lower motor lesions are, as a rule, impotent, unless the lesion is incomplete. There is a high degree of variability in the sexual capabilities of patients with all levels of spinal injury. Fortunately, sexual function can be restored to most patients by oral phosphodiesterase type 5 inhibitors, transurethral medications, a vacuum erection device, intracavernous injection, or a penile prosthesis.
Often, patients with spinal injury lose the ability to ejaculate even with preservation of functional erections. This is a result of lost coordination between reflexes normally regulated through higher centers. Patients may have the capability to ejaculate after an erection, but they are either unable to trigger this sexual event or are unable to trigger it in proper sequence. Techniques using vibratory stimulation of the penis or transrectal electrical stimulation have been developed to accomplish semen collection in patients with “functional infertility.”
Autonomic dysreflexia is sympathetically mediated reflex behavior triggered by sacral afferent feedback to the spinal cord. The phenomenon is seen in patients with cord lesions above the sympathetic outflow from the cord (Weaver et al, 2006). As a rule, it occurs in rather spastic lesions above T1 but on occasion in lesions of mild spasticity or those as low as T5. Symptoms include dramatic elevations in systolic or diastolic blood pressure (or both), increased pulse pressure, sweating, bradycardia, headache, and piloerection. It can be triggered by pelvic autonomic afferent activity (overdistention of bowel or bladder, erection) or somatic afferent activity (ejaculation, spasm of lower extremities, insertion of a catheter, dilation of the external urethral sphincter). The headache can be severe and the hypertension can be life threatening. Treatment must be immediate. Immediate catheterization to empty the bladder usually brings about prompt lowering of blood pressure. Oral nifedipine (20 mg) has been shown to alleviate this syndrome when given 30 minutes before cystoscopy (Dykstra et al, 1987) or electroejaculation (Steinberger et al, 1990). The acute hemodynamic effect can be managed with a parenteral ganglionic blocking agent or alpha-adrenergic blockers. Transurethral sphincterotomy (Perkash, 2007) and peripheral rhizotomy have been used by some to prevent recurring autonomic dysreflexia.