| ICD-10 | N32.8 |
|---|---|
| ICD-9 | 596.51 |
Overactive bladder (OAB) is a urological condition defined by a set of symptoms: urgency, with or without urge incontinence, usually with frequency and nocturia. Frequency is usually defined as urinating more than 8 times a day. The International Continence Society is responsible for this definition. There exists, however, some controversy over the use of this term because these symptoms taken in isolation may overlap with those of other bladder conditions, including interstitial cystitis, or rarely even bladder tumours.
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The etiology of OAB is unclear, and indeed there may be multiple possible causes. It is often associated with overactivity of the Detrusor urinae muscle, a pattern of bladder muscle contraction observed during urodynamics. Treatments for OAB are usually synonymous with treatments for detrusor overactivity. OAB is distinct from stress urinary incontinence, but when they occur together, the condition is usually known as mixed incontinence.
Earlier reports estimated that about one in six adults in the United States and Europe had OAB.[1][2] The prevalence of OAB increases with age,[1][2] thus it is expected that OAB will become more common in the future as the average age of people living in the developed world is increasing. However, a recent Finnish population-based survey[3] suggested that the prevalence had been largely overestimated due to methodological shortcomings regarding age distribution and low participation (in earlier reports). It is suspected, then, that OAB affects approximately half the number of individuals as earlier reported.[3]
In 2008 researchers found that simulating the condition in rats caused overactivation of their locus coeruleus, and it is thought this could cause anxiety and disrupted sleep in humans.[4]
Treatment for OAB includes lifestyle modification (fluid restriction, avoidance of caffeine), bladder retraining, antimuscarinic drugs (e.g. darifenacin, hyoscyamine, oxybutynin, tolterodine, solifenacin, trospium), and various devices (Urgent PC Neuromodulation System, InterStim). Botulinum toxin A (Botox) is approved by the FDA in adults with neurological conditions, including multiple sclerosis and spinal cord injury. [5] Botulinum Toxin A injections into the bladder wall can suppress involuntary bladder contractions by blocking nerve signals and may be effective for up to 9 months. [6] The antimuscarinic fesoterodine was recommended for approval by the European Medicines Agency in February 2007. A surgical intervention involves the enlargement of the bladder using bowel tissues, although generally used as a last resort. This procedure can greatly enlarge urine volume in the bladder.