Otosclerosis: The University of Minnesota Temporal Bone Collection

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A study of 1452 human temporal bones revealed a previously unpublished material of 144 bones with otosclerosis.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.

Lack of association between SNP rs3914132 of the RELN gene and otosclerosis in India

“…This may be due to the small sample size included in the study or due to differences in race and incidence of otosclerosis. However, histological studies do not confirm the gender ratio difference (Altmann et al, 1967;Hueb et al, 1991). The mean age of onset of hearing loss was found to be 34 years, but a mean of 41 years was reported in a South African population (Tshifularo and Joseph, 2008).…”

“…Histological otosclerosis is present in 2.5 to 12% of the Caucasian population without clinical manifestation and can be diagnosed by CT scanning or sectioning of temporal bone at autopsy (Declau et al, 2007). Epidemiological studies have shown the prevalence of histological otosclerosis in Asians and blacks is 5 and 1%, respectively (Guild, 1944;Hueb et al, 1991). Bone remodeling in both clinical and histological otosclerosis is caused by the same or different causes that have yet to be discovered.…”

Bone Conduction Improvement After Surgery for Conductive Hearing Loss

“…Chronic otitis media can definitely cause labyrinthitis and can cause sensorineural hearing loss but it does not explain the reason behind the depressed bone conduction in so many patients without any symptoms of inner ear involvement. Similarly cochlear otosclerosis may be a definite entity but the belief that it can cause pure sensorineural hearing loss have been strongly criticized by histopathological examination of temporal bones [13,14]. Audiometric studies by Glorig et al [15] concluded that otosclerosis does not increase the sensorineural hearing loss above that to be expected in the general population.…”

Correlation between the Size, CT Density of Otosclerotic Foci, and Audiological Tests in Cases of Otosclerosis

“…The disease may also manifest as cochlear otosclerosis by developing as sensorineural hearing loss alone [2] . Otosclerosis is a bilateral disease in approximately 80% of cases [3] .…”