Questions about people with MS and bowel problems

​Here is My Question:
I am working through these thoughts and would appreciate any expert opinion/explanation that might be shared. The questions is based on the premise that 80% of people with MS experience some form of bladder/bowel dysfunction. Thanks for any insight you can share.

As 80% of people with MS have these Bowel and Bladder issues it would be expected that the same effected area could be identified on a MRI scan on whatever machine is used and for all the 80% of people scanned.

Do 80% of MSer’s have lesions on the spine at the same position? Does any research identify the reason why an attack on that nerve in the spine for 80% of people with MS, occurs? 

If the bladder and bowel are controlled in the frontal lobe of the brain, it appears unlikely that MSer’s would have lesion activity in that particular location. I believe lesions are generally not found in the lower section of the thoracic and lumbar spine where you would expect activity would affect bowel and bladder function.

The spinal cord at C3, C4, C5 has 31 pairs of nerves. What are the chances that lesions in 80% of people with MS affects the bowel and bladder function?

What is the commonality among people with MS that causes so many to have this problem?


​Answer:
​These are excellent questions on bladder control and relatively easy to answer.

It helps to understand that the control of urine and fecal storage and elimination (i.e. bladder and bowel control) is an essential function involving large areas of the central and peripheral nervous system stretching from the most anterior part of your frontal lobes to the very end of your spinal cord and the plexus of nerves that supply the organs of elimination. This provides a very large territory for any potential neurological disease to cause problems with elimination. This is one of the reasons why almost any multifocal neurological disease can, and often dose, cause problems with elimination control at some point in the illness. This is particular true of diseases like MS that create demyelination and axon loss in white matter tracts involved in the control of bladder function. In fact there is a fairly good correlation between involvement of the spinal cord or brainstem pathologically by MS and symptoms of bladder dysfunction;  both occurring, as you mentioned, in about 80 % of patients.

However, many of the neural pathways that control urination are in regions of the brainstem and spinal cord that are difficult to see on standard imaging techniques; this is due to the location of these pathways in or near the gray matter of the cord or cerebral aqueduct and fourth ventricle of the brainstem or the lower parts of the spinal cord, all areas more difficult to image on MRI. We also know that very small lesions, below the resolution of imaging, can create bladder symptoms because some of the important pathways are small and condensed. Lastly is far more common for bladder problems to occur with bilateral involvement of the spinal cord or brainstem but this bilateral involvement does not need to occur at the same level or location.

There is no single or common location for lesions to cause bladder symptoms and the urination symptoms created are the same (usually urinary urgency and hesitancy with variable amount of incontinence) regardless of the location of lesion anywhere between the brainstem and the sacral spinal cord.

I hope this helps.

Revere (Rip) Kinkel MD
Director of the Multiple Sclerosis Program
Clinical Neurosciences Director
Professor of Clinical Neurosciences
University of California San Diego