My two year old son had a simple mastoidectomy in december of 2003. At that time the procedure took four hours and his dura was thinning. He has recurrent low grade fever off and on and has been on antibiotics 75% of the time since this infection. He also has asthma and a chronic cough which is supressed with xopenex and pulmicort. He many allergies as well. He had a recent ct scan which showed residual fluid in the mastoid air cells with some chronic erosion of bony septa. Is this normal considering he had a mastoidectomy in december?