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Overactive Bladder (cont.)

Overactive Bladder Causes

The urinary bladder is comprised of nerves, muscles, and connective tissue. The most important muscle in the bladder is the detrusor muscle. In normal circumstances, when the bladder fills with urine, it can stretch to hold the urine. When the volume in the bladder reaches close to 300 cc, the stretch in the wall of the bladder can trigger a nerve response to initiate urination (micturition). This reaction results in loosening of the sphincter in the neck of the bladder (connecting the bladder to the urethra) and contraction of the detrusor muscle so that urination can ensue. This response can be overridden voluntarily by an individual to prevent urination if it is not the right time or place.

Overactive bladder can result from dysfunction of the nerves or muscles in the bladder, most commonly the dysfunction of the detrusor muscle. In OAB, the detrusor can contract inappropriately regardless of how much urine is stored in the bladder, hence the term detrusor overactivity.

Common conditions such as urinary tract infection, kidney and bladder stones, or bladder tumors can all cause overactivity of the detrusor muscle, resulting in overactive bladder.

Some nervous system conditions can increase the susceptibility to develop overactive bladder. These conditions include diabetic neuropathy, stroke, multiple sclerosis, spinal cord injury, dementia, and Parkinson's disease.

Sometimes no identifiable cause for overactive bladder can be found. This is termed idiopathic overactive bladder.

Medically Reviewed by a Doctor on 12/17/2015

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