Clogged mastoid from radiation

Has anyone out there had to have their mastoid drained months after completing neck radiation? My ear has been clogged since 4 weeks into my radiation treatment. I have already had a tube inserted into my eardrum for drainage, but it has not taken care of the problem. I am now scheduled to have my mastoid drained in two weeks. If anyone can tell me about their experience with this it would be greatly appreciated.