I have heard that physical therapy can do more harm than good if you have Chiari I malformation. My neurosurgeon recommended the same after I had 8 VP shunt surgeries. I declined and found a neurosurgeon at Emory Hospital in Atlanta, GA that felt I needed the Chiari Decompression surgery immediately. I had the surgery and it has relieved most of my lingering Chiari symptons. However, neither of my neurolgist in Augusta, GA or Atlanta, Ga have agreed that physical therapy could make it worse. But it makes sense to me since you brain is pushing through the base of your skull, any type of exercises and/or movement could make it worse prior to having the Chiari Decompression.