Dulra I had to have one, as I had to have surgery on a broken wrist. They tried to do a nerve block and it didn't work.
It also meant that when i had an Elcs (it was my 3rd baby) the epidural didn't last. After dd2 was delivered, I could feel everything that was happening, and ended up with a general to finish off ( I was being sterilisied at the same time).