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  • Updated 10.21.2020
  • Released 09.13.2000
  • Expires For CME 10.21.2023

Otic capsule dysplasia

Introduction

Overview

The author explains the clinical presentation, pathophysiology, diagnostic workup, and management of otic capsule dysplasias. A number of deformities of the osseus labyrinth have been described, including the large vestibular aqueduct syndrome described by Valvassori and Clemis in 1978. Cases of large vestibular aqueduct may have congenital hearing loss and commonly have fluctuating but progressive sensorineural hearing loss in the first, second, or third decade of life, often with abrupt worsening of hearing loss associated with minor head trauma or exercise. Some patients may be at increased risk of meningitis because of CSF perilymph fistulas.

Key points

• Otic capsule dysplasias are bilateral in two thirds of cases and unilateral in one third, but even the radiologically normal ear in unilateral cases often has significant hearing loss.

• Hearing loss in otic capsule dysplasia is generally of a sensorineural type, but one third of affected ears also have significant conductive hearing loss (greater than 20 dB) as a result of middle ear problems such as fixation or atresia of components of the ossicular chain, serous otitis media, chronic otitis media, and oval window perilymphatic fistula.

• Some have used the term “Mondini dysplasia” for all forms of otic capsule dysplasia, whereas others reserve this term for the deformity originally described by Mondini in 1791, ie, congenital deafness with an enlarged vestibular and a cochlea shortened from 2.75 to 1.5 turns and lacking a complete interscalar septum.

• Cases of large vestibular aqueduct may have congenital hearing loss and commonly have fluctuating but progressive sensorineural hearing loss in the first, second, or third decade of life, often with abrupt worsening of hearing loss associated with minor head trauma or exercise.

• Some patients may be at increased risk of meningitis because of CSF perilymph fistulas.

Historical note and terminology

In 1791 Carlo Mondini described a case of congenital deafness wherein the vestibule was enlarged, and the cochlea was shortened from 2.75 to 1.5 turns and lacked a complete interscalar septum (43; 97; 50; 114; 07). Subsequently, a number of deformities of the osseus labyrinth have been described, including the large vestibular aqueduct syndrome described by Valvassori and Clemis in 1978. Some have used the term “Mondini dysplasia” for all forms of otic capsule dysplasia, whereas others reserve this term for the deformity originally described by Mondini (99). This chapter adopts the latter approach. Prior to the development of polytomographic x-ray studies in the 1950s, diagnosis of inner ear malformations was possible only on postmortem examination.

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