[Clinical study of the bone conduction thresholds before and after tympanoplasty in chronic suppurative otitis media].

Department of Otolaryngology, the Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, 210008, China.
Lin chuang er bi yan hou ke za zhi = Journal of clinical otorhinolaryngology 02/2008; 22(1):25-7.
Source: PubMed


To study the relative factors of the changes of preoperative and postoperative bone conduction thresholds in chronic suppurative otitis media.
The preoperative and postoperative bone conduction thresholds were prospectively investigated in 45 patients with unilateral chronic suppurative otitis media after tympanoplasty. Preoperatively (within 3 days before operation), 10 dB or more depression of bone conduction threshold at least in consecutive 2 frequencies between 0.25 kHz and 8.00 kHz was considered to be significant. Similarly in the postoperative period (3 months after operation), 10 dB or more improvement or impairment of bone conduction threshold at least in consecutive 2 frequencies between 0.25 kHz and 8.00 kHz was regarded as significant.
Thirty-five of 45 cases (77.8%) were found to have depressed bone conduction threshold before operation, 6 of 35 cases (17.1%) had improved bone conduction thresholds and 5 of 45 cases (11.1%) had depressed bone conduction thresholds after tympanoplasty.
In cases with chronic suppurative otitis media, successful results could be achieved after tympanoplasty disregarding air conduction threshold, the air-bone gap and deteriorated bone conduction threshold. Impairment of bone conduction thresholds could be induced by chronic suppurative otitis media itself and could also be induced by touching the ossicle chain crudely and by the noise of drilling during the operation.

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    ABSTRACT: The use of a silicone tube and a microphone enables peroperative noise recordings in cadavers and should be safe to apply in vivo. Our preliminary data indicate that noise levels during inner ear surgery reach levels that can cause noise-induced hearing loss. Our method is easily performed and enables future uncomplicated and safe noise recordings and we suggest future application in vivo to expand knowledge regarding peroperative noise levels. To evaluate the safety and utility of a silicone tube connected to a microphone probe in noise recordings during middle ear surgery and to achieve preliminary results regarding drill-related noise levels. Peroperative noise recordings were obtained during mastoidectomy and at the round window during cochleostomy in a cadaver model by means of a silicone tube connected to a microphone and a Matlab(®) computer program. Our method enabled recordings of radiated noise levels close to the drill ranging from 84 to 125 dB SPL during drilling in cortical bone and from 85 to 117 dB during drilling in the mastoid cavity. During cochleostomy noise levels ranged from 114 to 128 dB SPL when recordings were made close to the round window. Maximal noise levels were underestimated due to microphone overload above 80 Pa.
    No preview · Article · May 2010 · Acta oto-laryngologica