Does stapedotomy improve high frequency conductive hearing?

Frequency-Specific Audit of Audiological Outcomes Following Stapedotomy for Otosclerosis

Stapedotomy is an effective surgical intervention used for the treatment of conductive hearing loss associated with otosclerosis. The present study aims to quantitatively evaluate the hearing outcomes following primary stapedotomy performed in patients with otosclerosis. It also aims to investigate frequency-specific hearing results of stapedotomy in these patients. This retrospective study enrolled 49 patients with clinical otosclerosis, who underwent primary stapedotomy at a tertiary-care hospital, between January 2014 and December 2019. Pure-tone audiometry (PTA) was performed pre and post-operatively (> 1 year after surgery). Post-operative air conduction (AC) and bone conduction (BC) thresholds were recorded. The primary outcome measure was post-operative air-bone gap (ABG). Low frequency (LF) ABG was calculated as the mean ABG of thresholds at 0.5 and 1 kHz. High frequency (HF) ABG was calculated as the mean ABG of thresholds recorded at 2 and 4 kHz. In all the study patients, the mean post-operative AC and the mean postoperative BC thresholds, showed significant improvement across the tested frequencies of 0.5, 1, 2 and 4 kHz (P < 0.05). The mean post-operative ABG closure was superior at HF, as compared to that at LF (9.54 ± 6.30 dB vs. 12.0 ± 6.63 dB, P = 0.014). A successful surgical outcome (post-operative ABG closure to ≤ 10 dB) was achieved in 61.22% of the study patients. Further, a greater number of patients (71.45%) recorded successful surgical outcome at HF, when compared with those at LF (46.95%, P < 0.05). Favourable hearing outcomes of this study underscore the effectiveness of primary stapedotomy in the treatment of patients with clinical otosclerosis. Better postoperative ABG closure to ≤ 10 dB was recorded at higher frequencies. Further studies assessing post-stapedotomy hearing results at HF are warranted for ensuring better hearing outcomes in the HF range as well.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-04126-0.

Methods for the calibration of bone conduction transducers at frequencies from 5 to 20 kHz

Techniques for standardizing the output of bone conduction transducers over the 5-20 kHz range are presented. The techniques include definitions of the standard artificial mastoid (AM) impedance and force sensitivity in that high-frequency range using an impedance head coupled to a vibration source. The AM impedance is shown to vary with the contact area of the vibration source. The AM force sensitivity does not vary with the contact area but does exhibit sharp frequency dependences over the 14-20 kHz range. The sharp frequency dependence complicates the use of the AM force sensor as a stand-alone calibration device at these high frequencies. An alternative calibration scheme that uses an accelerometer interposed between the vibrator and the AM impedance is described. Comparisons of the two schemes demonstrate that the accelerometer method produces more consistent results. Comparisons of the force and acceleration output of one bone conduction vibrator at high frequencies suggest those outputs depend on the driven load. The loads used in the two calibration schemes are compared to what is known of the impedance of the skin-covered head.