What could cause numbness in thumb?

hi I had carpal tunnel surgery on my left hand August 20, 2012. They were also suppose to remove what they thought was a ganglion cyst on the palm side of my wrist. It was causing pain and was also a large lump on wrist. It truly looked like a ganglion cyst. During surgery they found out it was a vericose vein wrapped around and artery in my wrist that was causing the swelling and lump. They then closed it up and said they could not repair it because of how it was wrapped around the artery. I now have numbness in my thumb and below on the pad of my thumb. Is this normal? Can I put ice on the where the incision is to get rid of the numbness?