Previous reviews have noted that patients with spinal cord injury are at increased risk for renal failure, kidney and bladder stones, bladder tumors, urinary tract infections, and vesicoureteral reflux (VUR). In addition, problems such as urinary incontinence and impotence after spinal cord injury also have a significant negative impact on the quality of life of patients. Therefore, the main therapeutic goals in this patient population are to prevent the degeneration of upper urinary tract function, to reduce the risk of urinary tract infections and to improve the patient’s quality of life.
Because of the complexity and diversity of these patients’ conditions, a thorough and complete assessment of the urinary system at the beginning of the injury and regular follow-up thereafter is essential. To systematically review the diagnosis and treatment options for neurogenic bladder, Goldmark et al. from the University of Southern California reviewed previous literature and wrote an article published in the October 2014 online issue of Curr Urol Rep.
I. Pathophysiology
In order to better understand the pathophysiological mechanisms of spinal cord injury involving the urethra, the normal voiding process must first be understood. The loops required for the normal voiding process are neural loops established from the brain and spinal cord to the smooth muscle of the bladder and urethra, and the facilitation and inhibition of voiding are controlled by the voiding centers located in the sacral medulla (S2-S4), the pontine voiding center (PM), and the cerebral cortex. Signals from the cerebral cortex control the spontaneous voiding process through the PMC.
The acute phase of spinal cord injury is known as the spinal shock phase. During this period, urodynamic testing and surgical interventions are not performed. This phase typically lasts 6 to 12 weeks. During the spinal shock phase, the patient typically presents with urinary retention, at which point a clean catheterization technique (CIC) or indwelling catheter may be used to cope. Clinical manifestations that terminate during the spinal shock phase include the presence of voluntary voiding/incontinence and lower extremity spasticity.
II. Classification of voiding disorders
The plane of injury usually predicts the clinical symptoms and urodynamic profile of the patient. Urodynamic evaluation can help determine the patient’s initial bladder emptying disorder as well as clarify whether the patient is at risk for upper urinary tract dysfunction.
1. Supratentorial lesions
Neuropathy over the PMC usually affects voiding function. The main finding of urodynamic examination is in overactivity of the detrusor muscle without a synergistic disorder of the urinary sphincter. Under normal conditions, the sphincter remains relaxed during light contractions of the bladder, when the sensory function of the bladder is normal.
2. Suprasacral lesions
In patients with spinal cord injury, the urodynamic findings are usually overactivity of the detrusor (DO) as well as detrusor external sphincter synergy disorder (DESD), which is a failure to intermittently relax or completely relax during bladder contraction and emptying. These patients usually overcome the forces generated by the contraction of the external sphincter by increasing the pressure of emptying within the bladder, which usually leads to hydronephrosis and upper urinary tract dysfunction.
3. Sacral lesions
Spinal cord injuries at the sacral level are usually hypercompliant incompetent bladder. At this level, the external sphincter is able to maintain function, which may cause overfilling of the bladder. If the lesion is distal to the sacral medulla, bladder compliance may be lost. Since patients with sacral injuries have normal hand function, they can perform self-intermittent catheterization well and can remain non-incontinent due to intact sphincter function.
III. Upper urinary tract injury
Prompt assessment of function in patients with spinal cord injury after the spinal shock period is essential. In a recent study, investigators found that in their cohort of spinal cord injury patients followed, the causes of death were ranked as follows: urologic disease and suicide, ischemic heart disease, neoplasm, sepsis, pneumonia, and influenza.
In 1981, McGuire and colleagues published a landmark article in which they followed patients with spinal cord dysplasia for 7 years and demonstrated an association between increased forceps pressure and upper urinary tract injury.
The risk of VUR was 68% and the risk of ureteral dilatation was 81% if the forceps pressure exceeded 40 cmH2O. There is a relationship between intravesical pressure and outlet pressure, such that increased forceps pressure leads to decreased bladder compliance and outlet obstruction, and from this result we understand that in patients with neurogenic bladder, a forceps pressure above 40 cmH2O may cause upper urinary tract injury.
IV. Initial urologic evaluation
According to the guidelines of the Spinal Cord Medical Consortium, patients with spinal cord injury require an annual assessment of the urinary tract. However, in clinical practice, there is no consensus on the tests to be performed and their frequency.
Assessment of upper urinary tract function (e.g., renal scan and blood creatinine) and anatomic assessment (e.g., ultrasound or CT) are important. Evaluation of the lower urinary tract includes urodynamic assessment of bladder function, cystography screening for the presence of reflux, and cystoscopy to assess for anatomic abnormalities.
There are no studies that have explored the optimal frequency of screening. At Goldmark et al, the initial evaluation of patients with spinal cord injury included urodynamic testing, abdominal plain films, and renal/bladder ultrasound.
After the patient has undergone urodynamic testing, the physician develops a treatment plan based on the patient’s plane of injury as well as the patient’s own preferences and clinical presentation.
V. Bladder emptying
In patients with spinal cord injury, a complete evaluation includes a careful history, with the tests described above, which helps the clinician determine which aspect of the patient’s dysfunction is present, whether it is a storage or voiding disorder, or both. Regular bladder emptying plays an important role in protecting the upper urinary tract and preventing urinary tract infections.
Depending on the level of impairment, the patient may not be able to empty the bladder on his or her own and intermittent catheterization (either done by the patient or by a caregiver) may be required. Patients with incomplete impairment who have urinary incontinence may benefit from behavioral therapy.
VI. Clean intermittent catheterization
Since its introduction in 1972, clean intermittent catheterization has been the treatment of choice for patients with partial or complete urinary retention, and the CIC guidelines have made it the gold standard technique for emptying the bladder, especially if the patient is willing to undergo intermittent catheterization or if the caregiver can help. However, patients with abnormal urinary anatomy, abnormal conduction pathways, or poor cognitive function are not candidates for intermittent catheterization.
In patients who are unable to empty their bladders voluntarily, timed catheterization is also a normal way of emptying the bladder. The purpose of intermittent catheterization is to facilitate the storage and emptying of urine. If bladder volume is normal and bladder pressure is low, then patients with NGB can apply CIC alone; however, in most cases, CIC must be combined with medication or surgical treatment in order to achieve the goal.
CIC will be described in detail in the second half of this article. To prevent bladder overstretch, catheterization should be performed every 4-6 hours because the normal bladder volume is less than 500 cc. If the bladder volume is consistently higher than 500 cc, the patient will need to adjust fluid intake or catheterization frequency.
Although urinary tract infections are the most common complication of CIC, their overall incidence is still low. The rate of bacteriuria per catheterization is 1-3%, and the number of bacteriuria occurrences is approximately 1-4 times in 100 days of CIC. The need for antibiotics for these patients is still controversial, and there are more opposing views.
VII. Suprapubic catheterization
Compared to CIC, indwelling catheterization significantly increases the risk of renal failure, bladder and kidney stones, urethral fistulas, strictures, urethral erosions and bladder tumors. Unfortunately, not all patients are candidates for CIC, and women with upper spinal cord injuries face a number of barriers to effective CIC, such as poor hand function, inability to transfer catheterization on their own, and lack of caregiver assistance. Some patients have to be indwelling catheterized to prevent possible abnormal neurological reflexes during catheterization.
The advantages of suprapubic catheterization (SPT) over indwelling catheterization are as follows: it avoids damage to the urethra, eliminates the need to pass a catheter, and avoids the presence of a catheter in the vulva in patients with sexual needs.
In patients with quadriplegia, suprapubic catheters are preferable to clean intermittent catheterization. Possible reasons include patient dependence on caregivers, spasticity, and persistent urinary incontinence (already on maximum dose anticholinergic therapy).
The incidence of epididymitis is higher in patients with indwelling catheters compared to patients with SPT, as is the incidence of periurethral abscesses, medically induced hypospadias and urinary fistulas. In addition, some women with long-term indwelling catheters have an increased risk of developing urethral erosion, which can lead to urethral dilatation and uncontrollable urinary incontinence. From our experience, the best treatment is bladder neck closure combined with SPT rather than extensive reconstruction to shunt the urine.
VIII. Timed voiding
Timed voiding involves instituting urination and going to the toilet, but this is highly dependent on the function of the bladder and the patient’s work schedule. In general, timed voiding is more appropriate in patients with complete spinal cord injury and can be used to prevent acute episodes of urinary incontinence, or “urge” incontinence.
Incontinence can be avoided by preventing overfilling of the bladder and urgency. A “voiding diary” is an essential part of determining the best course of action. However, timed voiding can only be effective in patients who have some degree of partial bladder control.
In a study by Ersoz et al, they applied continuous filling cystometry to 72 patients with traumatic spinal cord injury to examine bladder filling sensation. In all patients with incomplete spinal cord injury, bladder filling sensation was present to some degree. This study points to the feasibility of sensory-dependent bladder emptying techniques in patients with spinal cord injury.
IX. Drug therapy
X. Surgical treatment
If multiple conservative treatments have been tried but have not worked, or if it appears that increased pressure in the lower urinary tract will affect the function of the upper urinary tract in the long run, surgical treatment needs to be attempted at this time.
1. External sphincterotomy
The first application of external urethral sphincterotomy was made by Ross et al. They aimed to preserve the function of the upper urinary tract by reducing the voiding pressure. Indications for surgery include DSD, UTI, upper urethral dilatation, abnormal autonomic reflexes, or failure of CIC treatment. Sphincterotomy is a single incision of the mucosal and muscular layers in a 12-point direction (from the proximal end of the seminiferous tuberosity to the proximal end of the urethral bulb).
At one time, urethral stenting and sphincterotomy were considered to be similarly effective, but due to the high complication rate of urethral stenting and the high incidence of re-intervention, urethral stenting is no longer recommended.
After sphincterotomy, a decrease in PVR and forceps pressure can be observed. However, if the patient is unable to maintain adequate forceps pressure, he or she will not respond well to sphincterotomy, leading to an increase in PVR and the need for a change in bladder management protocol.
The reoperation rate for sphincterotomy is high, approximately 15% to 40%. An external device for urine collection needs to be prepared after the sphincterotomy.
2. Enlarged cystoplasty
Invasive treatment may be required when the combination of CIC and the anticholinergic BoNT-A fails to improve bladder volume and to maintain lower bladder pressure during urinary storage. In patients with refractory NDO, refractory urinary incontinence and upper urinary tract dysfunction due to increased bladder pressure, bladder enlargement kyphoplasty is an important surgical intervention.
This treatment option is well defined, with high patient satisfaction with the treatment, and can help control voiding as well as protect the upper urinary tract in 80-95% of patients. The most common long-term complications include bladder stones and UTI, and there is also a risk of metabolic abnormalities, especially hyperchloremic acidosis, developing.
3. Surgical treatment of urinary incontinence by diversion of urine flow
In bladder tumors invading the muscularis, ileal substitution of the bladder is the standard urinary diversion option, which is also used in patients with neurogenic bladder (combined with or without cystectomy) to provide a continuous voiding experience without foreign body sensation. This treatment option may be considered in patients with tetraplegia or in patients with recurrent episodes of indwelling urinary catheterization UTI.
A postoperative assessment of patients’ quality of life found a high level of satisfaction with the procedure, and no patient regretted the choice of surgical treatment. Complications of the diversion procedure included pyelonephritis, bowel obstruction, urethral stricture, urinary leakage, abscesses, and anastomotic and tubular strictures, and the number of complications increased with the duration of follow-up.
Ileal controlled output tract cystostomy requires anastomosis of the ileum and bladder with the ultimate goal of draining urine at a lower pressure. The advantages over ileal substitution cystostomy are the avoidance of stricture of the anastomosis and the preservation of the original anti-reflux mechanism. This procedure is particularly indicated in patients with small bladders and overactive patients.
XI. Treatment to enhance urinary drainage
In patients with spinal cord injury, treatment of patients with stress urinary incontinence is a challenge. In women, fascial suspension can be performed, but treatment of male patients with SUI and voiding outlet weakness is more difficult. One thing to keep in mind when following these patients is to ensure a low-pressure environment, as there may be a risk of upper urinary tract injury in high-pressure situations.
In male patients, sexual pubic prostate suspension at the distal urethra to the prostate is an option with a success rate of 83%, but requires an abdominal incision. Bladder neck closure is considered a treatment of last resort and is used only in patients with irreparable urethral damage secondary to long-term indwelling catheterization or pressure sores causing urethral perineal damage.
XII. Risk of bladder tumor development associated with neurogenic bladder
Patients with neurogenic bladder have a significantly higher risk of developing bladder tumors compared with the general population. In the group of patients aged 50-60 years diagnosed with neurogenic bladder, the incidence of bladder tumors ranged from 0.27% to 10%. In these patients, chronic inflammation and irritation, UTIs, stones, and long-term indwelling catheters all played a significant role in the increased risk of bladder tumor development.
Of those patients diagnosed with tumors, 50% were squamous cell carcinomas. Cystoscopy and urine cytology are not very effective in patients with spinal cord injury and in patients with prolonged indwelling catheterization.
XIII. Monitoring
There is no uniformity of opinion on how to target the urinary system for monitoring in patients with spinal cord injury with neurogenic bladder. In the institution where Goldmark et al. work, follow-up consists of annual questioning to collect a history, physical examination, and to perform BUN/Cr, KUB, and RUS tests.
Patients are recommended to have a UDS every 5 to 10 years or scheduled when a UDS is clinically indicated. Urinalysis screening and urine culture are not routine tests. Given the cost-effectiveness and sensitivity of nerve bladder ultrasonography in detecting hydronephrosis (compared to IVP and VCUG), it has become the recommended surveillance method for many clinical providers.
The sensitivity of KUB in detecting urinary tract stones is 14% to 54%. Experts recommend that it is not suitable as a screening tool for urinary tract stones. In patients with spinal cord injury, it is not possible to determine the optimal frequency of performing UDS. Some investigators perform screening annually or biennially, while others determine whether to schedule screening based on the presence of symptoms in patients.
The authors concluded that there are no studies evaluating the different effects of regular screening for UDS versus screening at enrollment. Regardless of the choice of follow-up, it is important to recognize the characteristics of neurogenic bladder. Judgment based on clinical symptoms alone may not identify treatment failure.
XIV Conclusion
Treatment of neurogenic bladder is extremely complex and requires maintaining a balance between preservation of renal function and optimization of quality of life. Ultrasonography and urodynamics of the renal bladder are required in all patients. Patients should be followed up frequently to determine the presence of urinary stones, urinary tract infections, malignant changes and the tendency of upper urinary tract degeneration. Annual patient history, physical examination and renal bladder ultrasound are needed to maintain long-term stability of renal function in patients with spinal cord injury.