As a RN and a migraine sufferer I can tell you not to panic yet. You may just be at the start of your journey. Mine has been going on for seven years and to date has not really been treated with meds but I am not the norm and still believe in the medical establishment. Some of the main points that I have learn in my long journey is that not all migraines (if that is what she has) are all vascular only in cause so propranalol which is a low blood pressure med may not be the cure. Many are more like seizures or hyperactivity goining on in the brain and this is causing the nerve endings to flare in pain and that is why antiseizure meds work well to control the headaches. Some patients need a combination of both. Maintaining good communication with you doctor and be realistic to the fact that it may take long time and a lot of experiementing with several drugs to find the right combination for her. The great thing is that once the combination is found, her life will go on as before. There also has been great advancements in the area of abortive meds the stop the headache as it is coming on if the preventives are working. These new drugs are not narcotics so she can function normally. This is another important discussion to have with her doctor. I hope that the information that I have provided was helpfull and if you have any more questions, please don't hesitate to ask. I feel that I have been given this condition for a reason and if I can help even one person not have to go through what I have I will have been worth it.
As far as I know scar tissue doesn't change. They are probable looking more for changes due to the headaches then at the actual scar tissue. If there is any changes in the scan while she continues to have the headaches, then they know that it is not just migraines but possibly something else and they need to expore other options and treatments. I too had follow up MRI's to rule out MS. MS will show up as changes where migraines wont. Don't fear though, my friend who has MS had spots on her first MRI as well so I didn't fret it when they told me they wanted me to repeat mine due to me fainting and having eye issues that they found could go either way. My first and since MRI's have all been clean. You will find doctors are overly cautious and thats better then them missing something big right? I am sure that since they didn't see anything on this one she just has migraines and the next one will come out just the same. If you have any other questions just let me know and I will be glad to help in any way I can.