Radiologically Assessed Stapes Footplate Thickness and Audiologic Outcomes in Patients with Otosclerosis

Introduction: Otosclerosis is a known cause of particularly conductive hearing loss of a variable extent. Radiological examination reveals footplate thickening in addition to heterogeneously distributed hypodense foci. The objective of this study was to investigate the correlation between a thickened stapes footplate and its association with perioperative audiometric findings and postoperative complications.

This was a retrospective data analysis conducted at a single tertiary referral center on 63 surgically confirmed otosclerotic ears from 56 patients. Stapes footplate thickness was measured in the stapes axial plane of a preoperative computed tomography scan. Measured stapes footplate thickness was assessed regarding its relationship between pre- and postoperative audiometric data and vestibulocochlear complications associated with stapedotomy.

Radiological assessment of stapes footplate thickness demonstrated considerable variation between otosclerotic ears, with a mean value of 0.85 mm (range 0.5-1.37 mm). No statistically significant correlation was identified between pre- and postoperative audiometric data for air-bone gap, air conduction, and bone conduction in the overall population or within subgroups. One case showed postoperative inner ear hearing loss (PTA-BC 26.3-37.5 dB HL), resulting in severe combined hearing loss, occurring 40 days after uneventful surgery (footplate thickness 0.79). Regardless of footplate thickness, no further cases of postoperative sensorineural hearing loss were reported. Postoperative vertigo was observed in 20 patients, none of whom showed pathological findings in clinical head impulse testing or exhibited spontaneous nystagmus, without association with footplate thickness (t(61) = 0.83, p = 0.41). Significant improvements regarding the air-bone gap (26.45 dB HL, SD 9.24 to 7.70 dB HL, SD 5.69, p < 0.0001), as well as air-conduction (48.65 dB HL, SD 14.24-26.29 dB HL, SD 10.24, p < 0.0001) and bone-conduction (22.20 dB HL, SD 9.20-18.13 dB HL, SD 10.11, p < 0.0001) pure-tone average thresholds, were observed from last pre- to last postoperative audiometric data after stapedotomy. Comparison of first to last postoperative audiometric data revealed significant improvement in air-bone gap (10,74 dB HL, SD 7.20-7.70 dB HL, SD 5.691, p = 0.0002), as well as air conduction (31.63 dB HL, SD 12.30-26.29 dB HL, SD 10.24, p < 0.0001) and bone conduction (20.08 dB HL, SD 10.26-18.13 dB HL, SD 20.11, p = 0.011), at a mean postoperative follow-up time of 12.6 months, SD 9 months (2.4-37.3 months).

Stapes footplate thickness in otosclerosis cases is not correlated with presurgical or postoperative hearing, nor with the incidence of postoperative complications. Stapedotomy can be performed safely regardless of the thickness of the stapes footplate.