The doctors here in Sweden haven't done this operation on someone younger than 6 years and a friend of mine's daughter who is almost 4 years old needs this surgery pretty badly.
I know a child who lives in the Netherlands who has had this operation. She had an operation in her lower back. But I think that she was 9years or so. I really don't know if there is someone younger who has had this operation. This girl has had her operation in Utrecht at the Wilhelmina Kinderziekenhuis by Dr Hanlo, but unfortunatly this neurosurgeon has died recently. Maybe you can try Dr. Han, he is also a neurosurgeon at the Wilhelmina Kinderziekenhuis and he has done Bastiaans surgery.
Good luck for your friends daughter!
Moeder van Femke en Bastiaan (AP)