MS and Bladder Dysfunction: Why doesn’t my bladder work?
Claire Yang, MD
Multiple sclerosis can affect any bodily function, including bladder
function. If you are healthy, you don’t think about bladder control, or going
to the bathroom: you just do it, and don’t give it a second thought.
However, if you have a neurological disease such as MS, bladder function
and control can become a much more prominent factor in your life.
MS causes nerve demyelination, whereby the “insulation” on the
nerves deteriorates. With the loss of insulation, the messages traveling
through the nerves gets lost, or “short-circuited”. Because bladder function
is highly dependent on nerve function, the nerve damage as a result of MS
commonly results in bladder problems.
How does MS affect bladder function? First, it is important to
understand what the bladder is doing in the healthy state. Kidneys filter
waste products from the blood, and makes urine, which drains to the
bladder. The bladder stores urine until it is time to empty. As the bladder
fills with urine, messages go to the brain, telling the brain that the bladder is
filling up. The brain sends messages back down to the bladder, telling the
bladder NOT to squeeze unless it is full, and only when it is socially
appropriate to urinate. (This is what we learn when we are toilet trained as
When the bladder is full, the brain is receiving messages of fullness,
and that is what prompts us to go to the bathroom. When the bathroom
door is closed, and everything is as it should be, the brain then removes its
message to NOT squeeze. The bladder then begins to squeeze, and the
muscles (sphincters) that typically hold the urine in the bladder relax,
allowing urine to pass out unimpeded. The bladder squeezes long enough,
and forcefully enough, to empty in one sustained contraction. When the
bladder is empty, the sphincter muscles close, the bladder relaxes, and the
cycle starts again.
In MS, one or more of four possible things happen that can result in
a) The bladder’s message to the brain gets lost, so that the
brain does not know how full the bladder is. If the brain
never gets the message that the bladder is full, the brain
cannot tell the bladder to empty. This can result in
incomplete bladder emptying, with overly large volumes of
urine being carried in the bladder.
b) The brain’s message to the bladder gets lost. The message
NOT to squeeze is short circuited, and then the bladder
becomes like a baby’s bladder: it squeezes before it is full,
and before it is socially appropriate to do so. As a result, the
patient feels that she has to go to the bathroom frequently,
and experiences urinary urgency. These sensations are a
result of having the bladder start to contract before the
patient is ready to urinate. The urgency often results in urine
leakage, as a result of not getting to the bathroom in time.
c) The bladder may not squeeze long enough and forcibly
enough to empty, leaving behind large volumes of urine in
the bladder. The bladder is not being efficient, resulting in
urinary frequency, since the bladder is reaching capacity in
shorter periods of time (because it is never empty).
d) The sphincter muscles are not coordinated with bladder
contraction. This results in a sensation to urinate, but no
urine comes out of the bladder. Or, the person may be
urinating, and suddenly the urine stream will cut off, and
perhaps will restart a few seconds later. This situation also
results in incomplete bladder emptying.
Depending on your symptoms and situation, there are different behavioral
modifications, medications, and perhaps catheterization techniques that
you can try to minimize the likelihood of bladder infections and other
problems, as well as minimize the inconvenience of bladder dysfunction.
No one medication or treatment is universally applicable to all MS patients.