The word sclerosis comes from a Latinized version of the Greek word for scar. Simply put, Multiple Sclerosis means Many Scars (scars are also called plaques or lesions). Someone with MS has scarring in their brain, spinal cord or both. Here is a simple explanation of the scarring process.
The position of the scars relates to the symptoms the person with MS has. For example, if someone has scarring on their frontal lobe they may have problems with speech and concentration.
The majority of my scars are in my cervical spine (neck) whose job is to send messages for mobility, hence affectively being a spinal cord injury resulting in paraplegia. I have a scattering on either side of the top of my brain which corresponds to the hands and touch making it challenging to type and write, hold scissors, a knife and fork, hairbrush etc.; some on my optic nerve which affects my vision in terms of color, (I see dark blue/grey/black as the same); and a few other sprinkled here and there.
I was thinking about scarring when I created this collage.
Here is a photo of an MRIs showing what MS scars look like in the brain of someone newly diagnosed. The white spots are MS scars.
A final note: Something really cool that has been found during postmortems is that sometimes people have a brain full of scars when they die yet never knew or felt any affect from them!