122 CHAPTER 4 Incontinence
Overactive bladder: conventional treatment
Definition
Overactive bladder (OAB) is a symptom syndrome that includes urgency, with or without urge incontinence, frequency, and nocturia. The symptoms are usually caused by bladder (detrusor) overactivity, but can be due to other forms of voiding dysfunction. Roughly 17% of the population >40 years old in Europe has symptoms of OAB.1
Conventional treatment
Conservative
Patient management involves a multidisciplinary team approach (urologists, gynecologists, continence nurse specialists, physiotherapists, and community-based health care workers). Treat underlying causes (urethral obstruction, bladder stones, spinal disease, tumor).
TURP for bladder outlet obstruction due to BPH can provide symptomatic relief in >66% of men. Treatment of the SUI component includes pelvic floor exercises, biofeedback, and high-frequency electrical stimulation (which strengthens the pelvic floor and sphincter by increasing tone through sacral neural feedback systems).
Behavioral modification
This involves modifying fluid intake, avoiding stimulants (caffeine, alcohol), and bladder training for urgency (delay micturition for increasing periods of time by inhibiting the desire to void).
Medication
Most patients will benefit from medication.
•Anticholinergic drugs act to inhibit bladder contractions and increase capacity (oxybutynin, tolterodine, trospium chloride, solifenacin, darifenicin, fesoteridine). Oxybutynin also exerts a direct muscle effect and can be administered directly into the bladder (intravesically) in patients performing intermittent catheterization (5 mg in 30 mL normal saline q8h after emptying the bladder).
•Contraindications include closed angle glaucoma.
•Side effects are dry mouth, constipation, and blurred vision.
•Tricyclic antidepressants (imipramine) exert a direct relaxant effect on bladder muscle as well as produce sympathomimetic and central effects.
•Desmopressin (DDAVP) is a synthetic vasopressin analog that acts as an antidiuretic. It is used intranasally to alleviate nocturia in adults. Oral DDAVP is effective for nocturnal polyuria.
•Baclofen is a GABA receptor agonist, used orally or via intrathecal pump in patients with bladder dysfunction and limb spasticity.
1 Milsom I, Abrams P, Cardozo L, et al. (2001). How widespread are the symptoms of an overactive bladder and how are they managed? A population-based prevalence study. Br J Urol Int 87(9):760–766.
This page intentionally left blank
124 CHAPTER 4 Incontinence
Overactive bladder: options for failed conventional therapy
Neuromodulation (see also p. 528)
This involves electrical stimulation of the bladder’s nerve supply to suppress reflexes responsible for involuntary bladder muscle (detrusor) contraction.
The Interstim device stimulates the S3 afferent nerve, which then inhibits detrusor activity at the level of the sacral spinal cord. An initial percutaneous nerve evaluation is performed, followed by surgical implantation of permanent electrode leads into the S3 foramen, with a pulse generator that is programmed externally.
Surgery
The aim is to increase functional bladder capacity, decrease maximal detrusor pressure, and protect the upper urinary tract (also see p. 512).
Augmentation enterocystoplasty (“clamshell” ileocystoplasty)
This procedure is the gold-standard method of providing a high-volume low-pressure storage system for the pathological bladder. It relieves intractable frequency, urge, and UUI in 90% of patients.
The bladder dome is bivalved and a U-shaped detubularized segment of ileum is patched into the defect, creating a larger bladder volume that can store urine at lower pressures.
Many patients will void spontaneously but most will need to perform intermittent catheterization periodically to empty completely.
Conduit diversion
This is a noncontinent urinary outlet in which the ureters are anastomosed to a short ileal segment, which is brought out cutaneously as a stoma in the right lower quadrant.
Ileocystoplasty: acts like an ileal conduit attached to the bladder, performed in conjunction with bladder neck closure to provide conduit drainage without the need for ureteral reconstruction.
Auto-augmentation (detrusor myectomy)
Detrusor muscle is excised from the dome of the bladder, leaving the underlying bladder endothelium intact. A large epithelial bulge is created which augments bladder capacity.
Intravesical pharmacotherapy
Botulinum toxin A (BTX-A) injection therapy acts by inhibiting calciummediated release of ACh at the neuromuscular junction, reducing muscle contractility. It is used predominantly for neuropathic bladder dysfunction, but increasingly is being used for failed medical therapy of the OAB in non-neuropaths. It is injected directly into detrusor muscle under cystoscopic guidance (flexible cystoscopy or rigid under regional or general anesthetic) at 20–30 random sites, excluding the trigone (dose dependent on supplier’s recommended dose schedule).
OAB: OPTIONS FOR FAILED CONVENTIONAL THERAPY 125
Repeat treatments are required (6–12 months between injections), and ISC may be needed to empty residuals (5% of non-neuropaths).
Mild flu-like reactions lasting a week or so can occur. Generalized weakness, swallowing or breathing difficulty are rarely reported. Allergic reactions are uncommon.