Kimmarie ~
I'm sorry to learn of your friend's horrific complications following AN surgery. This is not normal. Unfortunately, these kinds of complications can occur as a result of numerous factors, including the surgeon's skill (or lack thereof) and other factors that simply cannot be foreseen. Obviously, no one, especially your friend's doctors, want this to happen.
We're not doctors and cannot offer a cogent explanation for these issues your friend is suffering with. You should attempt to secure an explanation from her doctors but as a non-family member, that could be problematic if they don't chose to give you an explanation. Still, it's worth trying. AN surgery is very challenging for the doctors and sometimes unforeseen problems arise during the operation that can put the patient in a medical crisis. It's rare, but not unknown. I suspect your friend is suffering from hydrocephalus and once that is controlled she may well improve.
She'll be in many thoughts and prayers, I can assure you. Please try to keep us updated. Thanks.
Jim