Boyce AM, et al. - This trial encompassed the characterization of audiologic and otologic manifestations in subjects with fibrous dysplasia (FD) and McCune-Albright syndrome (MAS). The purpose was to determine the potential mechanisms of hearing loss. It was reported that hearing loss in craniofacial FD was common and mild to moderate in maximum patients. This was known to arise from FD crowding of the ossicular chain and elongation of the internal auditory canal (IAC). On the other hand, external auditory canal (EAC) stenosis and otic capsule invasion were revealed to be less common causes. Those with craniofacial FD were recommended to undergo otolaryngologic analysis and monitoring, including assessment, which would aid in detecting those with high-risk features.

Methods

• As a part of this research, subjects with craniofacial FD seen at a clinical research center underwent clinical, biochemical, computed tomographic, audiologic, and otolaryngologic analyses.
• The main outcome measure included the scrutiny of clinical and radiologic features associated with hearing loss and otologic disease.
• Conductive hearing loss was presumed to be related to narrowing of the external auditory canal (EAC), FD involving the epitympanum, and FD crowding the ossicular chain.
• It was hypothesized that sensorineural hearing loss was linked with FD affecting the internal auditory canal (IAC) and otic capsule.

Results

• Among the 130 study candidates with craniofacial FD who were examined, 116 (89.2%) reported FD that involved the temporal bone (median age, 19.6 years; range, 4.6-80.3 years; 64 female [55.2%]), whereas 14 (10.8%) had craniofacial FD that did not involve the temporal bone.
• Among the 183 ears with temporal bone FD, hearing loss was identified in 41 ears (22.4%) and was conductive in 27 (65.9%), sensorineural in 12 (29.3%), and mixed in 2 (4.9%).
• Maximum patients were presented with hearing loss which was mild and nonprogressive.
• In contrast, EACs were narrower in ears with FD (mean difference [MD], 0.33 mm; 95% CI, 0.11-0.55 mm).
• This data correlated with conductive hearing loss in only 4 enrollees.
• A link was determined between fibrous dysplasia crowding of the ossicles with conductive hearing loss (odds ratio [OR], 5.0; 95% CI, 2.1-11.6).
• The IAC length did not vary between ears with and without FD (MD, -0.37; 95% CI, -0.95 to 0.211).
• Nevertheless, elongated canals were found in ears with sensorineural hearing loss (MD, -1.33; 95% CI, -2.60 to -0.07).
• The involvement of otic capsule was observed in only 4 participants, 2 of whom had sensorineural hearing loss.
• The correlation between both MAS-associated growth hormone excess (OR, 3.1; 95% CI, 1.3-7.5) and neonatal hypercortisolism (OR, 11; 95% CI, 2.5-55) with an increased risk of hearing loss was unveiled in this research.