Chapter Outline
Introduction and Definitions
Bladder compliance describes the relationship between changes in bladder volume and changes in detrusor pressure. Compliance is calculated as the change in volume (Δ V ) divided by the change in detrusor pressure (Δ P det ) and is expressed mathematically as C (mL/cm H 2 O) = Δ V (mL)/Δ P det (cm H 2 O) ( ).
Compliance is a measure of the bladder viscoelastic properties, allowing storage of large volumes of urine with minimal changes in intravesical pressure. Decreased compliance is defined as <20 mL/cm H 2 O, measured from the onset of urodynamic bladder filling to maximum cystometric capacity or immediately before the onset of a detrusor contraction that results in significant leakage ( Fig. 37.1 ) ( ).
Poor compliance can result from changes in the viscoelastic properties of the bladder, changes in detrusor muscle tone, or a combination of the two. Clinically, poor compliance is most commonly seen in neurologic conditions (e.g., spinal cord injury, myelodysplasia, Shy-Drager syndrome, cauda equina syndrome, multiple sclerosis) but can also be from surgical denervation (e.g., radial hysterectomy, abdominoperienal resection), inflammation or infection (e.g., radiation, tuberculosis, interstitial cystitis), and chronic bladder outlet obstruction.
In a landmark article by , myelodysplactic children with detrusor leak point pressures >40 cm H 2 O invariably developed upper tract disease ( ). In a later study by McGuire involving another group of myelodysplactic children, all of the children with upper tract changes also had very poor bladder compliance ( ).Therefore, sustained detrusor pressures of >40 cm H 2 O during storage, regardless of the bladder volume, can lead to upper tract damage and require careful follow-up to protect renal function.
First-line management of compliance abnormalities involves reducing sustained detrusor pressures to below 40 cm H 2 O by using anticholinergic medications and manual bladder drainage if necessary. If patients fail medical therapy, more invasive options are implemented. This chapter will focus on the indications, surgical techniques, clinical results, and complications of sacral neuromodulation, botulinum toxin, and augmentation cystoplasty (AC) for the treatment of bladder compliance abnormalities.
Patient Evaluation
The evaluation should include salient features of the history and physical examination, including ambulatory status and manual dexterity. In addition to a bladder diary, patients are asked to respond to two self-administered questionnaires, urogenital distress inventory-short form (UDI-6) and the incontinence impact questionnaire-short form (IIQ-7), such that subjective improvement or progression with treatment can be monitored routinely.
A careful history and physical examination will reveal the nature (acute versus chronic) and possible cause (neurogenic, anatomic, postsurgical, functional, inflammatory, and/or idiopathic) of the lower urinary tract dysfunction (see Box 37.1 ). A postvoid residual (PVR) and urinalysis should be obtained. If the patient has >3 to 5 RBCS/HPF on microscopic urinalysis, upper tract imaging and cystoscopy are mandated. According to the 2012 American Urological Association (AUA) Guidelines for asymptomatic microscopic hematuria, urine cytology should only be obtained in patients with persistent microscopic hematuria, irritative voiding symptoms, or risk factors for carcinoma in situ (e.g., tobacco use, chemical exposures) ( ).
| History |
| Sequential progression of urinary symptoms |
| Neurologic symptoms (vision, gait, coordination, parasthesia, etc.) |
| Sensation of pelvic pressure or heaviness |
| Bowel habits/constipation |
| Sexual history |
| Prior urologic disease |
| Urogenital trauma |
| Diabetes |
| Thyroid disease |
| Herpes simplex virus infection |
| Back pain or disk disease |
| Pelvic, anorectal, or spinal surgery |
| Previous therapies including medications |
| Physical examination |
| Ambulatory status |
| Manual dexterity |
| Back: skin or spinal cord anomalies |
| Abdomen: scars, mass, tenderness |
| Pelvis and vagina: pelvic organ prolapse, enlarged uterus, pelvic or vaginal mass |
| Urethra: mass, tenderness |
| Anus and rectum |
| Neurologic examination |
| Urinalysis |
| Postvoid residual volume (bladder scan or catheter) |
Further assessment of bladder function with urodynamic studies, including cystometrogram, pressure-flow studies, and electromyography (EMG), are performed on a selected basis. EMG is strongly recommended in suspected cases of neurogenic bladder dysfunction, detrusor-sphincter dyssynergia, or Fowler’s syndrome. It is important to remember that the characteristics of neurogenic bladder, as seen in patients with multiple sclerosis and spinal cord injury, can change with time and disease progression. Therefore, reevaluation with urodynamic testing and assessment of the upper urinary tracts may be needed when symptoms change despite active medical intervention.
Cystourethroscopy may yield information helpful in making a diagnosis. Anatomic lesions such as urethral stricture, bladder neck fibrosis, trabeculation, and bladder lesions are found in some women with bladder outlet obstruction. Upper urinary tract imaging should be performed in any patient with compliance changes on urodynamics (e.g., sustained detrusor pressures of ≥40 cm H 2 O) or a history of compliance changes, in patients with neurologic disease, or if indicated by history or physical examination.
Surgical Treatments
Augmentation Cystoplasty
Before the introduction of sacral nerve stimulation in the late 1990s, the mainstay of surgery for impaired bladder compliance was AC. Bladder augmentation was first introduced in 1899 by Mikulicz as a means of increasing urinary storage, preserving renal function, and providing continence ( ). It was not until the 1950s that the technique was popularized, and not until the 1980s, with the introduction of clean intermittent catheterization, that the procedure was widely accepted ( ).
Indications
AC is indicated in patients with poorly compliant bladders who have or are at risk for upper tract deterioration, and have neurogenic and idiopathic detrusor overactivity, and who have either failed medical management or are not appropriate candidates for less invasive therapies like neuromodulation and onabotulinum toxin. AC requires that patients have adequate dexterity or a caregiver that can perform intermittent self-catheterization (ISC). If the patient or caregiver is unable to perform ISC then a continent catheterizable channel should be performed at the time of AC.
AC is contraindicated in patients with bowel disease (e.g., inflammatory bowel disease, congenital bowel anomalies, short gut syndrome) and bladder malignancies and in patients who are unable (e.g., impaired cognition or manual dexterity) or unwilling to perform intermittent catheterization ( ). Even if patients are able to void spontaneously after AC, ISC still may be necessary to remove sediment and mucus. In patients who cannot void spontaneously, ISC must be performed regularly to preserve renal function and prevent potentially life-threatening complications associated with spontaneous bladder perforations.
Surgical Technique
Augmentation is most commonly performed using various gastrointestinal segments, but can also be performed using ureter (ureterocystoplasty) or autoaugmentation. Ileal and colonic are the most commonly performed forms of augmentation, although stomach, ileum, or jejunum may be used. The choice of gastrointestinal segment is very important as it carries with it unique metabolic considerations that need to be considered preoperatively and managed postoperatively.
Given that ileocystoplasty is the most commonly performed form of AC, this is the procedure that will be discussed in detail. Patients should be admitted 1 to 2 days prior to surgery for an antibiotic, as well as mechanical bowel preparation. According to the AUA Best Practice Policy Statement on Urologic Surgery Antimicrobial Prophylaxis updated in 2012 and 2014, <24 h of antibiotics, either a second- or third-generation cephalosporin or, if allergic, an aminoglycoside plus metronidazole or clindamycin, should be administered ( ).
Open ileocystoplasty is typically performed through a midline open abdominal incision. The bladder is bivalved from the dome to 3 cm above the ureteral orifices, using a transverse incision. A 25 to 30 cm piece of ileum, 15 cm from the ileocecal valve, is harvested. It is important to determine if the ileal segment has adequate mesentery to allow it to reach the native bladder without tension. Either a hand-sewn or a stapled enteroplasty is performed. The ileal segment is then detubularized by opening it on its antimesenteric border. The ileum is folded into a U-shape and the adjacent borders are anastomosed using running absorbable sutures to create the posterior and anterior walls. The posterior aspect of the ileum is then anastomosed to the native bladder in a two-layer fashion with absorbable suture. A suprapubic tube is placed in the native bladder. The anterior wall of the ileum is sutured to the bladder in a similar fashion as the posterior closure. A drain is placed in the pelvis.
Laparoscopic and robotic-assisted ileocystoplasty can be performed in a similar fashion using pure laparoscopy or in combination with extracorporeal bowel work. Several small case series have shown that the procedure is feasible and safe, with similar short-term outcomes, including improvements in maximum cystometric capacity and decreases in maximum detrusor pressure ( ).
Results
Overall continence rates vary from 78% to 100%. Additional interventions including clean intermittent catheterization, anticholinergic medications, bladder neck closure, and artificial urinary sphincter may be needed to achieve dryness.
In several large series, patients who underwent either concomitant or subsequent artificial urinary sphincter had higher continence rates (85%-90%) than patients who underwent AC alone (78%) ( ).
Studies by and showed persistent improvement in urodynamic parameters at long-term follow-up, including significant increases in maximum cystometric capacity (mean increases of 400 mL) and mean decrease in maximal detrusor pressure from 53 to 14 cm H 2 O.
Complications
Early complications of AC, ranging from 0% to 5%, include wound infection, small bowel obstruction, and bleeding requiring reoperation ( ). Long-term complications are more common, ranging from 10% to 40%, and include metabolic disturbances, deterioration in renal function, mucus accumulation leading to stone formation, bacteriuria, diarrhea, B12 vitamin deficiency, progressive loss of compliance, spontaneous perforation, carcinoma, and persistent incontinence ( ).
Each bowel segment confers a different type of potential metabolic complication. Patients undergoing ileocystoplasty should be monitored for hyperchloremic acidosis, resulting from the reabsorption of ammonia and ammonium chloride and secretion of bicarbonate by the bowel. Renal deterioration can occur and occurs more commonly in patients with creatinine clearance 15 mL/min ( ). Resection of the terminal ileum can lead to vitamin B12 deficiency, causing pernicious anemia and diarrhea.
Exposure of bowel segments to urine has been shown to induce changes in the intestinal epithelium that are associated with four potential long-term complications: (1) increased mucus production, resulting in stone formation; (2) loss of intestinal compliance from fibrosis of enteric submucosa; (3) increased risk of spontaneous perforation; and (4) the development of malignancies. Although the risk of neoplasm is uncertain, most malignancies occurred at the enterourothelial junctions, and intermittent endoscopic surveillance of augmented bladders is typically recommended 5 to 10 years after augmentation ( ).
Several more recent series have found no increase in cancer rates in patients with AC. performed a prospective analysis of 92 consecutive patients who underwent routine cystoscopy 10 years after AC. The median follow-up was 10 to 33 years. No cancers were identified either with surveillance on cystoscopy or on routine biopsies. compared a series of 153 patients with ileal/colonic cystoplasty and age-matched controls with neurogenic bladder performing ISC and found no difference in the incidence of bladder cancer in patients with AC (7 patients (4.6%)) versus controls (4 patients (2.6%)).
Sacral Neuromodulation
Since the late 1990s, there has been an evolution in the understanding and management of the impaired bladder compliance. Until InterStim ® (Metronic Inc., Minneapolis, MN) was approved by the U.S. Food and Drug Administration (FDA) in 1997, AC was the mainstay of therapy for the treatment of impaired bladder compliance.
Neuromodulation is an innovative treatment for lower urinary tract symptoms and dysfunctions secondary to neuromuscular etiologies. Currently, InterStim ® is the only implantable device currently approved for sacral neuromodulation therapy to treat refractory urgency/frequency syndrome, urge incontinence, nonobstructive urinary retention, and (as of April 2012) fecal incontinence.
Sacral neuromodulation involves the stimulation of the pelvic plexus and pudendal nerves that innervate the bladder, pelvic floor muscles, and rectum. Several theories about the mechanism of action have been proposed but it remains largely uncertain. Electrical stimulation may modulate reflex pathways involved in both the storage and emptying phases of the micturition cycle, as reviewed by .
Indications
Sacral neuromodulation is frequently attempted in patients who have failed traditional conservative measures such as bladder retraining, pelvic floor biofeedback, and medications, before more invasive surgical procedures such as enterocystoplasty or urinary diversion.
There are few data on defined preclinical factors or urodynamic predictors of which patients will benefit from sacral neuromodulation. In a small prospective study of 55 patients with both idiopathic and neurogenic refractory urinary urge incontinence who underwent stage II InterStim after a successful stage I test stimulation, individuals older than 55, those with three or more chronic conditions (e.g., arthritis, hypertension, diabetes, or depression), or those with a neurologic condition had a lower cure rate ( ). In two smaller studies, neurogenic patients with Parkinson disease, progressive neurologic diseases, and retention secondary to detrusor hypocontractility had lower success rates ( ).
Surgical Technique
The procedure is performed in one of two ways—a two-stage procedure versus percutaneous nerve evaluation (PNE), followed by a combined stage I and II procedure. Stage I is a clinical trial of a permanent tined lead for external stimulation, and stage II is implantation of a subcutaneous implantable pulse generator (IPG). Each stage can be done using monitored anesthesia supplemented with local anesthesia.
PNE is performed by placing bilateral percutaneous leads in the S3 foramen (with or without fluoroscopic guidance) using local injectable anesthesia. The leads are then connected to an external pulse generator and worn by the patient for several days. Although PNE can be done in the office, it has a lower success rate and therefore a lower implantation rate, which may be attributed to improper lead placement and migration. In a study by , 88% of patients with refractory urge incontinence who underwent stage I, versus 46% who underwent PNE, went on to stage II ( p = 0.02). In another study of 92 patients with refractory overactive bladder (OAB), 46% of the patients screened with PNE, versus 69% of patients who had a stage I, met the criteria for stage II. Of the 41 patients in whom PNE failed, 44% had successful stage I using tined lead and went on to stage II ( ). Therefore both studies suggest higher false-negative results in patients undergoing PNE than those having stage I.
After lead placement, changes in lower urinary tract symptoms and PVR volumes are recorded in a detailed bladder diary. If improvement is minimal or absent, placement of stage I (in patients who had PNE), revision, or bilateral percutaneous lead placement may be attempted. If patients report a greater than 50% improvement in symptoms, a permanent IPG is implanted. The length of the trial with the external pulse generator may vary slightly from patient to patient, for indications, and by surgeon preference. In our experience, in patients with urgency/frequency syndrome and urge incontinence, a 2-week trial is adequate. For urinary retention, a longer trial of 3 to 4 weeks may be necessary before obtaining a desired clinical response.
Stage I
Before 2002, lead placement required a more time-consuming surgical dissection of the layers above the sacral foramina and had unreliable lead fixation with anchors. Changes to the lead have made implantation of the lead easier and less prone to migration. were the first to present their experience using the tined lead neuroelectrode, which we continue to use today.
Patients are asked to shower with chlorhexidine gluconate on the day of surgery. Preoperative intravenous antibiotics are given before each stage of the procedure and aseptic techniques of foreign body implants are implemented. The patient is placed in the prone position on a fluoroscopic table. Chest rolls and pillows can be used for position. The buttocks are taped, allowing visualization of the anus. The anus and tape are prepped in standard sterile fashion and covered with a separate clear plastic drape. The patient’s feet should be bare and the sterile drape folded back to expose the feet.
After the patient receives sedation and the local anesthesia, the S3 foramina are identified. The location of the S3 foramina is approximated by measuring 9 cm cephalad to the drop-off of the sacrum, and 1 to 2 cm lateral to the midline on either side. Alternatively, the site may also be localized by palpating the cephalad portions of the sciatic notches bilaterally and drawing a connecting line that intersects the midline of the sacrum; one fingerbreadth on either side of the midline of the sacrum at this intersection defines the location of the S3 foramina ( Fig. 37.2 ). The foramen needle is then inserted into the S3 foramen, ideally at a 45° angle. The pelvic plexus and pudendal nerve run alongside the pelvis and therefore the needle should be placed just inside the foramen. The position of the needle is confirmed using fluoroscopy ( Fig. 37.3 ). The nerve is test-stimulated for the appropriate motor responses, which are dorsiflexion of the great toe and bellows contraction of the perineal area, which represents contraction of the levator muscles (bellows reflex) ( Box 37.2 ). The foramen needle stylet is removed and replaced with the introducer sheath. The distal aspect of the lead consists of four electrodes numbered 0 through 3. The lead is placed into the introducer sheath as directed to expose the electrodes. Usually, electrodes are positioned such that electrodes 2 and 3 straddle the ventral surface of the sacrum, as shown in Figure 37.3 . Test stimulation is repeated on each electrode and the responses are observed. An S3 response should be noted on at least two of the electrodes. Once satisfied with the position, the sheath is removed, releasing the tines that anchor the lead. A sensory response with sensation of stimulation in the perineum is not needed to confirm proper placement if the correct S3 motor response is observed. However, when a motor response is absent, raising the consciousness level of the patient during the procedure and detecting the correct sensory response confirms proper localization; a clinical response thus may still be obtained during the screening trial period despite the absence of the motor response.
