Study of the improvement in bone conduction threshold after stapedectomy

INTRODUCTION AND OBJECTIVES

Bone conduction threshold depression is not always a result of inner ear and cochlear nerve pathology. In fact, middle ear pathologies may be responsible for such threshold depression, as occurs in otosclerosis. The aims of this study were to evaluate the improvement of bone conduction threshold in patients with otosclerosis that underwent stapedectomy and to study the postoperative audiological results.

MATERIAL AND METHODS

This was a retrospective study on 95 patients (116 ears) diagnosed with otosclerosis having conductive or mixed hearing loss that received surgery (stapedectomy and complete removal of the footplate) consecutively. Audiometry was performed on all patients pre- and postoperatively (one month and one year after surgery). Bone and air conduction thresholds were measured at 4 frequencies (500, 1000, 2000 and 4000Hz).

RESULTS

The air-bone gap was closed, with a residual air-bone gap below 10dB in 92.2% of the patients and below 5dB in 79.3% of the cases. The air conduction threshold improved an average of 25dB. The patients that had an affected bone conduction threshold preoperatively improved bone conduction postoperatively at the frequencies of 1000 and 2000Hz (6 and 12dB, respectively). Consequently, the Carhart notch disappeared on the audiogram. These results were maintained at one year of follow up.

CONCLUSIONS

We found a significant improvement in the bone conduction threshold at the frequencies of 1000 and 2000Hz and a disappearance of the Carhart notch in the audiogram after stapedectomy and total footplate removal in patients diagnosed with otosclerosis having mixed hearing loss.

Hearing screening using auditory steady state responses obtained by simultaneous air- and bone-conduction stimuli

INTRODUCTION AND OBJECTIVES

Minimising false positives rates is an important goal of universal newborn hearing screening programmes. An adequate way for reaching that goal could be differentiating between transient conductive hearing losses (false positives) and permanent sensorineural hearing impairments (true positives) by means of a methodology that studies electrophysiological responses obtained using both air- and bone-conduction stimuli. Our objective was to evaluate the efficiency of an automated hearing screening test based on auditory steady state responses obtained using simultaneous air- and bone-conduction stimuli.

METHODS

A sample of 80 high risk babies lees than 2 months of born were screened using the automatic screening test. A confirmatory clinical and electrophysiological evaluation was used as the gold standard.

RESULTS

The estimated diagnostic efficiency of this screening test was equivalent (100% sensitivity and 97.7% specificity) to the efficiency reported for otoacoustic emissions and automated auditory brainstem responses. The introduction of bone conduction in the screening reduced the false positive rate from 13.3% to 2.2%. The test duration was 5.3 (± 1.9)min. In 34% of babies only one repetition of the test was needed to raising the result.

CONCLUSIONS

The screening test performed quite well in this initial clinical trial, differentiating transient conductive hearing losses from permanent neurosensory impairments and improving the diagnostic efficiency of auditory steady state responses.