Introduction
Botulinum toxins (BoNTs) are licensed for the treatment of a number of conditions characterized by striated muscle spasticity. However, in recent years, their unlicensed use in the treatment of lower urinary tract conditions has been described (Smith et al., 2004). Chief amongst these are conditions characterized by detrusor overactivity. Treatment of vulvodynia and chronic pelvic pain, benign prostate hyperplasia, and detrusor sphincter dyssynergia are other emerging indications with promising positive results.
Overactive bladder
The International Continence Society (ICS) report of 2002 defined the overactive bladder syndrome as urgency, with or without urge incontinence, usually with frequency and nocturia, in the absence of local pathological or hormonal factors (Abrams et al.,2002). The prevalence in Europe and USA was estimated to be 3% among men 40–44 years of age, 9% among women 40–44 years of age, 42% among men 75 years of age or older, and 31% among women 75 years of age or older (Tubaro, 2004). The symptoms of overactive bladder have many potential causes and contributing factors. Urination involves the higher cortex of the brain, the pons, the spinal cord, the peripheral autonomic, somatic, and sensory afferent innervation of the lower urinary tract, and the anatomical components of the lower urinary tract itself. Disorders of any of these structures may contribute to the symptoms of overactive bladder (Figure 18.1).
A variety of efferent and afferent neural pathways, reflexes, and central and peripheral neurotransmitters are involved in urine storage and bladder emptying.