# The Role of Powered Surgical Instruments in Ear Surgery: An Acoustical Blessing or a Curse? [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (S.K.) [PERSON]  
1 Department of Otolaryngology, Head and Neck Surgery, Yamagata University Faculty of Medicine; Yamagata 990-9585, Japan; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (T.F. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (K.F. ); melindahull@nifty. The majority of current ear surgery procedures can be broken down into two broad approaches: conventional microscopic ear surgery (MES) and the more recently developed transcanal endoscopic ear surgery (TEES). While powered surgical instruments are a standard part of MES, such instruments are only used in a subset of TEES procedures referred to as powered TEES. As was noted above, TEES has not totally eliminated the need for a mastoidectomy, because some surgeons are more comfortable with MES, and some procedures are not indicated for TEES, such as the mastoid air cells, inner ear, and skull base that are beyond its reach. This paper presents an overview on types and causes of hearing loss in the context of ear surgery; a brief history of surgical instruments used to access the internal anatomy of the ear focusing on the powered surgical instruments, specifically electric drills and ultrasonic devices; an overview of the two main surgical procedures of MES and TEES used in ear surgery to access the internal anatomy of the ear; and a review of the literature on the potential for hearing loss caused by noise and vibrations produced by powered surgical instruments used in MES and TEES procedures  
hearing loss, while vibrations, or more precisely, skull vibrations, have garnered much less attention until recently and deserve further study and consideration. Such hearing loss is measured based on the degree to which the hearing threshold sensitivity has risen and is classified as either a permanent threshold shift or a temporary threshold shift [2]. Most sensorineural hearing loss caused by powered surgical instruments fortunately falls into the temporary threshold shift category. Separate from these two types of hearing loss caused by powered surgical instruments is the physical contact of an instrument with the ossicular chain. Such drill-to-bone contact results in vibrations which are transmitted via the ossicular chain to the cochlea. The subsequent damage to the cochlea generally results in permanent hearing loss.