I'll try and answer the questions for you Rhayden.
The dye they inject is to see if there are any leaks or breaks or blockages in veins and arteries.
They can watch it as it moves around the body and pinpoint blockages or breakages.
Put simply, sclerosis is scar tissue, multiple sclerosis is when the covering of the spinal cord nerves is damaged and scar tissue forms, leaving scar and patches of plaque interrupting the electrical impulses. I can't simplify it any more than that.
So imagine say power conduit, you break the protective covering, patch it up, and it doesn't work as well, if at all. It's like that.
The symptoms of MS are varied and unpredictable
MS can damage the central nervous system in many different locations, which means no two people will share the same symptoms. Some of the more common symptoms include:
Blurred or double vision
Numbness or pins and needles
Weakness in the arms or legs
Loss of balance
Tendency to drag one foot
Loss of coordination
Extreme fatigue
Continence problems
Hand tremors
Loss of mobility
Problems with or changes in memory functioning
Speech difficulties and slurring.
So similar symptoms to a stroke, except in a stroke it comes from the brain itself.