Association of Hearing Loss and Otologic Outcomes With Fibrous Dysplasia

Abstract

Importance: Fibrous dysplasia (FD) and McCune-Albright syndrome (MAS) are rare bone and endocrine disorders in which expansile fibro-osseous lesions result in deformity, pain, and functional impairment. The effect of FD on hearing and otologic function has not been established.

Objectives: To characterize audiologic and otologic manifestations in a large cohort of individuals with FD/MAS and to investigate potential mechanisms of hearing loss.

Design, setting, and participants: In this natural history study, individuals with craniofacial FD seen at a clinical research center underwent clinical, biochemical, computed tomographic, audiologic, and otolaryngologic evaluations.

Main outcomes and measures: Clinical and radiologic features associated with hearing loss and otologic disease were evaluated. Conductive hearing loss was hypothesized to be associated with narrowing of the external auditory canal (EAC), FD involving the epitympanum, and FD crowding the ossicular chain. Sensorineural hearing loss was hypothesized to be associated with FD affecting the internal auditory canal (IAC) and otic capsule.

Results: Of the 130 study participants with craniofacial FD who were evaluated, 116 (89.2%) had 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. Of 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%). Hearing loss was mild and nonprogressive in most participants. Whereas EACs were narrower in ears with FD (mean difference [MD], 0.33 mm; 95% CI, 0.11-0.55 mm), this finding was associated with conductive hearing loss in only 4 participants. Fibrous dysplasia crowding of the ossicles was associated with conductive hearing loss (odds ratio [OR], 5.0; 95% CI, 2.1-11.6). The IAC length was not different between ears with and without FD (MD, -0.37; 95% CI, -0.95 to 0.211); however, canals were elongated in ears with sensorineural hearing loss (MD, -1.33; 95% CI, -2.60 to -0.07). Otic capsule involvement was noted in only 4 participants, 2 of whom had sensorineural hearing loss. 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) were associated with an increased risk of hearing loss .

Conclusions and relevance: Hearing loss in craniofacial FD is common and mild to moderate in most individuals. It typically arises from FD crowding of the ossicular chain and elongation of the IAC, whereas EAC stenosis and otic capsule invasion are less common causes. Individuals with craniofacial FD should undergo otolaryngologic evaluation and monitoring, including assessment to identify those with high-risk features.

Figure 1.. Bony External Auditory Canal Axial Diameter as Measured by Computed Tomography in Normal Ears and Those Affected by Temporal Bone Fibrous Dysplasia (FD)

Horizontal line in box indicates median; box, interquartile range; and whiskers, range.

Figure 2.. External Auditory Canal (EAC) and Canal Cholesteatoma in Ears With Fibrous Dysplasia (FD)

Figure 3.. Axial Computed Tomography of the Epitympanum

A, White arrowhead indicates normal epitympanum. B, Black arrowhead indicates fibrous dysplasia (FD) involvement surrounding the epitympanum. C, Yellow arrowhead indicates an epitympanum that is involved with FD and is crowding the ossicular chain.

Figure 4.. Axial Computed Tomography of the Internal Auditory Canal (IAC)

Axial computed tomographs show the technique for measuring IAC width. A, Normal left IAC is shown in a participant with normal hearing. B, Elongated and distorted IAC in a participant with temporal fibrous dysplasia (FD) and sensorineural hearing loss.