2007 ICD-9-CM Procedure 20.22 Incision of petrous pyramid air cells 20.22 is a specific code that can be used to specify a procedure 20.22 contains 10 index entries View the full Volume 3 20.* hierarchy Index entries containing 20.22: Almoor operation (extrapetrosal drainage) 20.22 Eagleton operation (extrapetrosal drainage) 20.22 Exploration -- see also Incision petrous pyramid air cells 20.22 Frenckner operation (intrapetrosal drainage) 20.22 Incision (and drainage) petrous pyramid (air cells) (apex) (mastoid) 20.22 Operation Almoor (extrapetrosal drainage) 20.22 Eagleton (extrapetrosal drainage) 20.22 Frenckner (intrapetrosal drainage) 20.22 Ramadier (intrapetrosal drainage) 20.22 Ramadier operation (intrapetrosal drainage) 20.22