Urinary urgency is the sensation that postponing urination is impossible. The brain works with your bladder to control urination. When the bladder becomes full, it sends impulses to the brain and you feel the need to go to the bathroom. Then, when you are ready to go, the brain signals back to the bladder and its muscles to contract and allow urine to exit the body. When urinary urgency takes place, the signals that coordinate urination are disrupted and you experience this uncontrollable urge to go.
Incontinence is the loss of urinary control.
When the spinal nerves coordinate urination, the bladder pushes out the urine, while sphincter muscles, which close or open to release urine, relax to let the urine pass out of the body. Muscles that line the bottom of your pelvis also help keep the urethra closed and the bladder in its proper place. Sometimes MS will disrupt the nerve signals sent to the bladder, sphincter, and pelvic muscles, allowing urine to be lost involuntarily. Nocturia , sometimes called nocturnal enuresis, is the involuntary loss of urine during sleep. There are a number of causes for this type of incontinence, but persons with MS may experience nocturia due to the interruption of brain impulses that travel up and down the spine to coordinate urination.