The person ultimately may be unable to urinate because urine flow is blocked or because the muscles of the bladder wall can no longer contract. In children, blockage of the lower urinary tract may be caused by narrowing of the end of the urethra or of the bladder neck. Even constipation can cause overflow incontinence because when stool fills the rectum, pressure can be put on the bladder neck and urethra. A number of drugs that affect the brain or spinal cord or that interfere with nerve transmission, such as anticholinergic drugs and narcotics, may impair the bladder's ability to contract, resulting in a distended bladder and overflow incontinence. A neurogenic bladder can result from many causes, including injury to the spinal cord and nerve damage from multiple sclerosis, diabetes, injury, alcoholism, or drug toxicity.
Total incontinence is the condition in which urine constantly drips from the urethra, day and night.
It occurs when the urinary sphincter doesn't close adequately. Some children have this type of incontinence because of a birth defect in which the urethra didn't close off as a tube. In women with total incontinence, the cause is usually an injury to the bladder neck and urethra during childbirth. In men, the most common cause is an injury to the bladder neck and urethra resulting from surgery, particularly removal of the prostate because of cancer. Psychogenic incontinence is incontinence resulting from emotional rather than physical causes.