Hi...u mentioned a few symptoms, gait, slurred speech, does she have others? It is possible to have herniated cerebral tonsils and and it is an issue with the cerebellum part of the brain.....
Do have ur friend get copies of her MRI and the report and get another Dr to view it for her to get a few more details as to what may be going on.
I pray u find answers, and u r a good friend to help and advocate this way for ur friend : )
Cerebellum is not a disease, it is a part of the brain.