Multiple sclerosis develops when nerve cells in the brain and spinal cord lose the insulating mylien sheaths that surround them.This can happen anywhere in the CNS and is random.
Symptoms are Muscle weakness, loss of sensory input from the skin and other areas, poor vision and mental problems due to the loss of the protective mylien the neurons stop conducting the impulses and hence there is a loss of functions controlled by the areas of the CNS concerned.
Hope this helps! :)
