Since 1997 when the term Overactive Bladder Syndrome (OAB) was initially introduced to the urological community, it has figured among the most studied and propagated voiding dysfunctions in the literature.
Of relatively homogeneous prevalence, it is estimated that around 16% of the world population complains the syndrome. The possibility of establishing the diagnosis based only on clinical data allowed greater access to treatment of patients with urinary urgency, increasing number of day and night voiding, with or without urinary incontinence. As a consequence, physical and behavioral therapy became part of Urological routine. A large number of anticholinergics, more and more selective for M3 predominant receptors in the bladder, have being included in the therapeutic list of OAB. Recently, a new class of medication, the Beta-3 agonists, had it effectiveness demonstrated in controlling OAB symptoms. However, the dropout rate to this conservative treatment is high, either by a lack of patient adherence to physical therapy measures, either by unsatisfactory objective results and common adverse events associated with oral medications intake.
Parallel to the better understanding of the pathophysiology of the OAB symptoms the intravesical injection of botulinum toxin conquered space as an option for cases refractory to the above mentioned conservative measures. Since the publication of the first results of bladder administration of botulinum toxin in patients with neurogenic detrusor overactivity over four hundred studies have been published. Recently, a presentation at the 2015 AUA Annual Meeting reported four years follow-up of patients undergoing repeated injections of botulinum toxin with a mean interval of nine months and maintenance of good clinical outcome; half of patients with full urinary continence.1
The positive outcomes with neurogenic disorders have been replicated in idiopathic overactive bladder patients. A systematic review and meta-analysis about the use of botulinum toxin in idiopathic OAB included 12 randomized trials, with over 1,000 treated patients. Significant improvement was observed in urinary frequency, urinary incontinence and gain in the quality of life. In contrast, large residual volumes and the increased incidence of urinary tract infections remain barriers to be overcome.2 New methods of detrusor botulinum toxin administration, as its instillation using lipid soluble molecules and via electromotive envision a lower risk of these adverse effects. Even though, a multicenter study (USA, Canada, UK, Germany and Belgium) also with long-term results (3.5 years) focused in efficacy and safety of OAB treatment with onabotulinuntoxin 100 U revealed that discontinuation due adverse events was as low as 5.3% following conventional detrusor injections. The reinjection interval was longer than six months for two thirds of patients.3
Pharmacoeconomic studies conducted in several countries compared botulinum toxin intravesical injections to sacral neuromodulation for OAB refractory cases. Uneven results from different economic realities and differences in public health policy haven´t allowed definitive conclusions yet. In turn, surgical procedures, and their usual prolonged hospitalization, with significant morbidity have become an increasingly distant treatment option for overactive bladder and neurogenic detrusor overactivity.
References:
1. Rovner E, Kohan A, Chatier-Kastler E, Jünemann K, Del Popolo G, Herschorn S et al. Long-term Efficacy and Safety of OnabotulinumtoxinA in Patients With Neurogenic Detrusor Overactivity: Analysis Among Patients Who Completed 4 Years of Treatment . J Urol. 2015; 193 (4 Suppl): e35.
2. Cui Y, Wang L, Liu L, Zeng F, Niu J, Qi L, Chen H. Botulinum toxin-A injections for idiopathic overactive bladder: a systematic review and meta-analysis. Urol Int. 2013;91(4):429-38.
3. Radomski S, De Ridder D, Sussman D, Sand P, Sievert K, Chapple C et al. Long-term onabotulinumtoxinA treatment in patients with over- active bladder provides durable improvements in urinary symptoms and quality of life: Final results of a 3.5 year study. Can Urol Assoc J. 2015 May-Jun; 9(5-6 Suppl 2): S17-18.
Written by:
JC Truzzi
Federal University of Sao Paulo Rua Doutor Diogo de Faria 775 conj 84 Vila Clementino - Sao Paulo / SP - Brazil.
Abstract: Overactive bladder syndrome, detrusor overactivity and the botulinum toxin