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Otosclerosis: the University of Minnesota temporal bone collection
M M Hueb1, M V Goycoolea, M M Paparella
1Department of Otolaryngology, University of Minnesota, Edina.
Abstract:
A study of 1452 human temporal bones revealed a previously unpublished material of 144 bones with otosclerosis. After exclusion of infants and individuals of races other than white, the incidence of otosclerosis was 12.75%. Of the bones with otosclerosis, 56.1% belonged to men and 43.9% to women. The incidence of clinical and histologic otosclerosis was practically the same for men (44.7% to 55.3%) as for women (47% to 53%). However, the incidence of bilateral otosclerosis was higher in women (88.9%) than in men (65.2%). Bilateral otosclerosis was present in 75.6%, whereas it was unilateral in 24.4%. Sixty-six (66) ears (45.8%) had clinical otosclerosis, whereas 78 (54.2%) had histologic otosclerosis--frequently unifocal lesions. The most common site was anterior to the oval window (117 ears, 81.25%), followed by round window niche (52 ears, 36.11%), apical and medial cochlear wall (31 ears, 21.52%), and anterior wall of the internal auditory canal (27 ears, 18.75%). The activity of lesions was directly related to their size. Smaller lesions were predominantly inactive, whereas medium and larger lesions were predominantly active. There was a positive correlation when the size of the lesions, activity, and degree of cochlear endosteal involvement were compared with bone conduction thresholds (37 cases). Correlations between size and activity, and between activity and associated sensorineural hearing loss did not necessarily follow the sequence of an initial active stage (spongiotic) to a final inactive one (sclerotic). Comparison of cases of otosclerosis with equivalent age groups of the normal population yielded worse bone conduction thresholds for the otosclerosis cases only in the age group 60 to 69 years and older. Comparison of average bone conduction thresholds between bones with one site of endosteal involvement (28.26 dB HL) revealed no significant differences. Bones with two or more sites of endosteal involvement had significant differences. Bones with two or more sites of endosteal involvement had significantly worse bone conduction thresholds (62 dB HL). The overall results are not suggestive of an association of sensorineural hearing loss with otosclerosis without stapedial fixation.
Insights
Otosclerosis affects 12.75% of white temporal bones, with higher bilateral incidence in women. Multiple lesion sites significantly worsen bone conduction thresholds, suggesting a link to hearing loss.
Area of Science:
- Otolaryngology
- Pathology
- Auditory Science
Background:
- Otosclerosis is a bone disease affecting the middle and inner ear.
- Previous studies have varied in reported incidence and risk factors.
Purpose of the Study:
- To determine the incidence and characteristics of otosclerosis in a large human temporal bone collection.
- To investigate the relationship between otosclerosis lesion characteristics and bone conduction thresholds.
Main Methods:
- A retrospective analysis of 1452 human temporal bones was conducted.
- Bones were analyzed for the presence, location, size, and activity of otosclerosis lesions.
- Bone conduction thresholds were compared between otosclerosis cases and controls, and correlated with lesion characteristics.
Main Results:
- Otosclerosis was identified in 12.75% of eligible white temporal bones.
- Bilateral otosclerosis was more common in women (88.9%) than men (65.2%).
- Lesion size and activity correlated with bone conduction thresholds, with multiple sites significantly worsening thresholds (62 dB HL).
Conclusions:
- Otosclerosis incidence is significant in the studied population, with distinct gender differences in bilaterality.
- The extent of endosteal involvement, particularly multiple sites, is a critical factor in the severity of hearing loss.
- Sensorineural hearing loss is not consistently associated with otosclerosis unless stapedial fixation is present.