Which Preparation of Botulinum Toxin A Should Be Used, Where Should It Be Injected, and How Should Its Efficacy Be Assessed?

Managing urinary incontinence: what works?

Urinary incontinence is a common condition, which, although not life-threatening, impairs the health-related quality of life of affected individuals. All women complaining of incontinence require a basic assessment and those with complex or refractory symptoms may benefit from urodynamic studies. Initial treatment includes lifestyle advice, behavioral modifications, bladder retraining and pelvic floor muscle training. For those women with persistent stress urinary incontinence following conservative therapy, surgical management might be considered. The development of the minimally invasive, retropubic, synthetic, mid-urethral sling procedures has revolutionized stress incontinence surgery and reduced the popularity of 'traditional' procedures, such as colposuspension and autologous fascial sling. In an attempt to reduce further the morbidity, transobturator and single-incision slings have been introduced. While antimuscarinic agents are the mainstay of the current medical management of urgency urinary incontinence, a recently developed selective β3-adrenergic receptor agonist (mirabegron) offers an alternative pharmacological option. Modalities such as intravesical botulinum toxin and neuromodulation (peripheral or sacral) are available to women with refractory urgency incontinence. Finally, when all other options have been explored and proven unsuccessful, inappropriate or not feasible, reconstructive surgery or catheter insertion might be considered as a last resort. The aim of this paper is to review conservative, medical and surgical management for urinary incontinence by using the best available evidence in the literature.

OnabotulinumtoxinA for the treatment of overactive bladder

OnabotulinumtoxinA injection is a safe and effective treatment for adults with refractory overactive bladder. There is sufficient level 1 evidence to support offering onabotulinumtoxinA injections as a second-line treatment to patients who have failed behavioral therapy and oral medications such as antimuscarinics and β3 agonists. An intradetrusor injection of 100 U of onabotulinumtoxinA is likely the optimal dose to balance risks and benefits, and this is the dose approved by the US Food and Drug Administration. Improvement in urgency urinary incontinence episodes, as well as symptom scores and quality of life, were seen in around 60%-65% of patients, and were significantly improved compared with those on placebo. Most studies have reported a duration of symptom relief ranging from 6 to 12 months, with repeat injections being safe and efficacious. Overall, the risk of urinary retention was around 6% across the study populations.

Emerging treatments for overactive bladder: clinical potential of botulinum toxins

Overactive bladder (OAB) is a symptom syndrome including urgency, frequency, and nocturia - with or without incontinence. It is a common manifestation of detrusor overactivity (DO). DO is a urodynamic observation of spontaneous or provoked contractions of the detrusor muscle is seen during the filling phase of the micturition cycle. OAB is, therefore, both a motor and sensory disorder. Botulinum toxin is a purified form of the neurotoxin from Clostridium botulinum and has been used in medicine for many years. Over the last 10 years, it has been used for the treatment of DO and OAB when standard treatments, such as bladder training and oral anticholinergic medication, have failed to provide symptom relief. Botulinum toxin acts by irreversibly preventing neurotransmitter release from the neurons in the motor end plate and also at sensory synapses, although the clinical effect is not permanent due to the growth of new connections within treated tissues. It is known that botulinum toxin modulates vanillioid, purinergic, capsaicin, and muscarinic receptor expression within the lamina propria, returning them to levels seen in normal bladders. Clinically, the effect of botulinum toxin on symptoms of OAB and DO is profound, with large effects upon the symptom of urgency, and also large effects on frequency, nocturia, leakage episodes, and continence rates. These effects have been seen consistently within eight randomized trials and numerous case series. Botulinum toxin appears safe, with the only common side effect being that of voiding difficulty, occurring in up to 10% of treated patients. Dosing regimens are variable, depending on which preparation is used, but it is clear that dose recommendations have fallen over the last 5 years. There is limited evidence about the efficacy of repeat treatments. Botulinum toxin is an effective and safe second-line treatment for patients with OAB and DO.

The management of overactive bladder refractory to medical therapy

Overactive bladder (OAB) is a clinical syndrome describing the symptom complex of urgency, with or without urgency incontinence and is usually associated with frequency and nocturia. Whilst many women may be initially managed using a clinical diagnosis alone a number will fail primary therapy and will require further investigation. Those women with refractory symptoms following initial conservative and medical therapy may benefit from alternative treatment modalities including intravesical Botulinum toxin, neuromodulation or reconstructive surgery. This review, the second of two covering the treatment of intractable OAB symptoms in women, will focus on management following the failure of medical therapy. It will principally focus on the role of Botulinum toxin, neuromodulation and reconstructive surgery.