Bone conduction changes following successful tympanoplasty type I

The effects of tympanic membrane perforation on bone conduction hearing level

OBJECTIVE

To assess the effects of pure tympanic membrane perforation on bone conduction hearing level.

PATIENTS AND METHODS

Fifty-six ears of 52 consecutive patients with dry perforated tympanic membrane, and without any middle and/or inner ear pathology were involved in this retrospective study. Of these 52 patients 23 (44.2%) were male and 29 (55.8%) were female. Mean age and age range were 32.01±12.73 and 10-49 years, respectively. Bone conduction thresholds before and after the paper patch manipulation were recorded at the same day. Two measurements were compared to find out the effect of perforated tympanic membrane on the bone conduction hearing level.

RESULTS

There were statistically significant differences between pre and post-paper patch values of bone conduction thresholds at 0.5, 1, 2 and 4kHz frequencies (P=0.001, 0.001, 0.001 and 0.01, respectively).

CONCLUSIONS

Pure tympanic membrane perforation increases bone conduction thresholds. The exact mechanism that deteriorates the bone conduction hearing level in patients with pure dry perforated tympanic membrane needs further studies.

Evaluation of improvement of hearing in type I tympanoplasty & its influencing factors

study included 40 patients treated for CSOM with central perforation. Only type I tympanoplasty was done in 30 patients with dry central perforation and simple mastoidectomy with type I tympanoplasty was performed in 10 patients with moist or discharging perforation. Type I tympanoplasty utilizing an underlay technique with TFG shows high probability of success (85%). Presence of bilateral perforations lowers the success rate (66.66%). Status of non-operated ear is a significant factor for success rate. An overall hearing gain of about 10db was achieved. Poor pre-operative hearing status of elderly adversely influences post-operative improvement of hearing. Typel tympanoplasty with simple mastoidectomy results excellent surgical success rate (100%) but gives less improvement of hearing (closure of A-B gap= 3.3db). In type I tympanoplasty alone surgical success rate drops to 80-75% but is offers more improvement of hearing (closure of A-B gap = 6.708 db).

Extended high-frequency audiometry in traumatic tympanic membrane perforations

Air- and bone-conduction audiometry in the frequency ranges 0.125-18 kHz and 0.25-16 kHz respectively were performed in 38 patients with unilateral traumatic tympanic membrane perforation. Sensorineural threshold elevation was found in 16 ears. In nine of these this was permanent and in four restricted to the frequency range > 8 kHz. Both sensorineural threshold elevation and tinnitus (n = 16) diminished with time. A temporary, mean 5 dB, bone-conduction threshold elevation > or = 8 kHz was seen in 26 ears before spontaneous tympanic membrane closure. Closure resulted in a 7-20 dB improvement of air-conduction thresholds in the 0.125-18 kHz range, somewhat less in the upper than in the lower frequencies. A 3 dB mean final conductive hearing loss > 8 kHz was found in these 26 ears approximately 5 months after injury, probably due to scars in the pars tensa at the site of the former perforations. Thirty-seven of 38 perforations had healed at final follow-up examination.