Primary stapedotomy: Influence of prosthesis diameter on hearing outcome

To evaluate the success rate of primary stapedotomy and to investigate the influence of prosthesis diameter on hearing outcome.

Retrospective medical chart review of 125 cases who underwent primary small fenestra stapedotomy, from January 2001 to December 2018. The study population was divided in two groups based on Teflon prosthesis diameter - .6mm (60%, N=75) and .4mm (40%, N=50). Pre- and postoperative (≥12 months) air-conduction (AC), bone conduction (BC) and air-bone gap (ABG) thresholds were compared.

Postoperative ABG≤10dB and ≤20dB was achieved by 65.7% and 90% of the patients. A functional hearing (PTA-AC≤30dB) was achieved by 59.2% of patients. Sensorineural hearing loss (SNHL, worsening in BC-PTA>10dB) was identified in 7.2% of patients. Comparison of the .6mm- and .4mm-groups, revealed no differences regarding improvements in AC-PTA (22.4 vs. 20.7dB, p=.56), BC-PTA (3.4 vs. 2.3dB, p=.54) and ABG-PTA (19.1 vs. 18.4dB, p=.77). Hearing outcome evaluation identified similar postoperative success rate (.6mm, 79.7% vs. .4mm, 62%, p=.336) and comparable functional hearing (.6mm, 64% vs. .4mm, 52%; p=.197). The incidence of postoperative SNHL was similar between the two pistons (.6m, 5.3% vs. .4mm, 10%, p=.481).

Primary small fenestra stapedotomy is an effective and safe procedure. A postoperative ABG within 10dB was achieved in 67.2% of patients and there was a reduced incidence of sensorineural hearing loss. Hearing outcome was not influenced by diameter of the selected prosthesis. Postoperative bone conduction hearing thresholds did not differ between the groups, which revealed no significant inner ear trauma caused by the larger piston. Although we did not find evidence to suggest one piston over the other, our results showed a trend toward better results with the larger prosthesis.