VP shunt and cranioplasty?

Hi everyone,
On Oct 8th we entered the world of AVM's when my then 21 yr old son had a severe brain hemorrhage caused by a left temporal lobe AVM grade 4.5 deep in the brain. They did a decompression craniectomy to save his life, 2 angiograms and he spent 3 weeks in the hospital and a week in rehab. We are still waiting for gamma knife surgery. He has been recovering remarkably well at home. He has right side hemianopsia, and aphasia and alexia. The aphasia and alexia are doing well.
In February we went to have his cranioplasty done, got all the way into surgery, sedated, when the surgeon decided "He wasn't ready". Needless to say my son was less than pleased. At that time they said he didn't have hydrocephalus, and to wait. And so we did. Fast forward to this last week when he had a CT. Now they are saying that he DOES have hydrocephalus and that he they want to do a VP shunt and the cranioplasty at the same time. He definitely has swelling-- he doesn't have the usual "cave in" of the skull that we were expecting. Has anyone else had the VP shunt done during the cranioplasty? What should I expect? Ever the worried mom!
Thanks!