Bladder Function After a Spinal Cord Injury
After a spinal cord injury, the bladder will no longer work as it did before the injury. If the injury is above the T12 level, the bladder may empty by "reflex." Any injury in this area may be able to have a "reflex" bladder. For a reflex to occur, the bladder message needs to travel within the cord at any level but does not need to travel up to the brain. When the bladder empties by reflex, it is called a "Reflex Bladder."
Reflex Bladder: Process of Urination
The bladder fills with urine and stretches.
The stretching bladder pushes out onto nearby nerves.
The nerves send signals to the spinal cord.
The message loops around in the cord (below the injury) and sets off the reflex.
The message goes back down the cord to the bladder.
The bladder contracts, the sphincter muscles open and the urine is let out. It may let the urine out at an inconvenient time because the brain it not involved to determine the "right time" to urinate. Therefore, the person could have bladder accidents at inappropriate times.
If the spinal cord injury is below the T12 level, the bladder will probably not be able to empty by a reflex. Because the spinal cord ends at about L2, the signals of a full bladder have no place to travel. Since the injury is below the level of the cord, the signals cannot ever reach the cord to stimulate the reflex to occur. When the bladder is not able to empty by a reflex, it is called an "areflexic Bladder."
Areflexic Bladder: Process of Urination
The bladder fills with urine and stretches. The stretching bladder pushes out onto nearby nerves.
The nerves send signals to the spinal cord but they are not able to reach the cord. The signals are there but have no place to travel.
Because the cord never received the signals, the bladder does not get a message to contract. The sphincters stay closed.
The urine does not empty by reflex, nor does the brain instruct the bladder to empty at all since the signals are not able to reach the cord or the brain. The bladder becomes very full. When it becomes "too full," the urine will eventually leak out from the bladder, resulting in bladder accidents.
In addition to the problems associated with nerve pathways up and down the cord, there are other problems that often affect bladder size, pressures and bladder muscle function. All of these affect the ability of the bladder to hold/store urine as well as properly release the urine. For example, some bladders may have a very tight sphincter muscle that makes it difficult to allow urine to pass. The bladder may empty incompletely, thus leaving residual urine in the bladder. The residual urine stays inside the bladder too long and is prone to causing urinary tract infections.
Changes in bladder function after spinal cord injury require new ways of emptying the bladder. Bladder programs may vary from person to person depending on his/her particular needs. Some people may use intermittent catheterizations and/or wear a condom catheter. Others may require an indwelling catheter, suprapubic catheter or other types of surgical intervention. The lessons in this course will review common types of bladder emptying as well as bladder problems associated with spinal cord injury.