Hearing influence of the posterior ear canal wall, in the conductive hearing loss after tympanomastoidectomy

Abstract

Introduction: Cholesteatomas treatment is surgical and the goals are complete re- section of it, to prevent complications and recurrences. The gold standard operative technique is canal wall down tympanomastoidectomy (CWDT), which reduces the recurrence rate lower than 2%. Studies on human temporal bones have defined that CWDT causes a decrease of 1 to 5 dB at frequencies below 1000 Hz and 0 to 10 dB between 1000 and 3000 Hz. Aim: To determine how many decibels the hearing is improved by reconstituting the posterior wall of the ear canal (EC) in patients after CWDT. Material and method: Experimental study. In patients after CWDT, the posterior wall of EC was reconstructed temporarily. Audiometry was performed before and after the procedure. Results: 23 patients were enrolled (25 ears evaluated). Average age 48.8 years (ran- ge 18 to 72 years). In 96% of the ears there was a difference after the procedure with a hearing improvement of 4.2 ± 2.8dB. In frequencies below 1000 Hz, hearing impro- vement was 6.0 dB (p<0.001), between 1000-3000 Hz, the improvement was 2.6 dB (p<0.001) and >3000 Hz there was no difference. When considering the airway-con- duction pure tone average (PTA), the difference was a 4.6 dB improvement (p<0.001). Conclusions: Our study shows that there is a hearing improvement in the vast ma- jority of ears that were evaluated by reconstituting the posterior wall of the EC, reaching a gain of 6 dB at frequencies <1000 Hz and 2,6 dB at mid frequencies. Considering the airway PTA, the improvement is 4.6 dB in the presence of posterior canal wall.