<prompt> Schwartz operation is done in -CSOMSerous otitis mediaOtosclerosisAcute mastoiditis  <response>: Indications of simple cortical mastoidectomy Schwartz operationAcute coalescent mastoiditis.Incompletely resolved acute otitis media with reservoir sign.Masked mastoiditis.As a initial step to perform:Endolymphatic sac surgeryDecompression of facial nerveTranslabyrinthine or retrolabyrinthine procedures for acoustic neuroma. 