CASE 12603 Published on 06.06.2015

Brothers with X-linked congenital hearing loss

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

McGarry P, Turner J.

Ulster Hospital,
Upper Newtonards Road,
Dundonald, N. Ireland, BT16 1RH.
Patient

255 years, male

Categories
Area of Interest Ear / Nose / Throat ; Imaging Technique MR, CT
Clinical History
We present the story of two brothers with hearing loss. Patient 1 was 2 years old at time of CT/MRI investigation. Patient 2 was 6 years old at time of CT/MRI investigation. Both patients had bilateral sensorineural hearing loss.
Imaging Findings
Both cases display similar imaging characteristics. Common imaging findings to both cases include: bulbous internal auditory canal (IAC) bilaterally; bilateral hypoplasia of the basal turn of the cochlea which cannot be separated from the IAC; absence of the bony modiolus bilaterally.
Patient 1 has unique abnormalities of the prominent vestibular aqueduct and abnormality of the vestibule bilaterally.
Given the clinical history and imaging findings, the diagnosis of x-linked congenital hearing loss was made for both patients.
Discussion
X-linked congenital hearing loss or x-linked congenital mixed deafness is a rare but well recognised congenital anomaly [1].

The condition is caused by hypoplasia or absence of the bony modiolus and basal turn of the cochlea, with lack of separation from the lateral aspect of the internal auditory canal. This results in an abnormal fistulous connection between the cerebrospinal fluid in the internal auditory canal and the presence of perilymphatic fluid in the scala vestibuli of the cochlea. As a result, there is increased pressure inside the cochlea and also at the oval window at the stapes insertion, resulting in mixed or sensorineural hearing loss [2].

Imaging findings include bulbous dilatation of the IAC, absence or severe hypoplasia of the bony modiolus and absence or hypoplasia of the basal turn of the cochlea. Other reported findings include possible widening of the labyrinthine segment of the facial nerve canal and widening of the vestibular aqueduct [3, 4]. Fixation of the stapes footplate is also present, which is not overtly apparent on imaging [2]. As previously discussed, both our cases display the primary listed features, with patient 1 also showing prominence of the vestibular aqueducts bilaterally.

The entity was first described in 1968 in two half-brothers [2] and in our case we provide an example of the condition within two full brothers. Now the imaging findings are considered so typical that the diagnosis can be made in the absence of a family history, however, the positive findings should still prompt the radiologist and clinician to review the family history in order to avoid complications in the possible treatment of relatives [1]. Indeed that is what prompted imaging in patient 2.

The main differential diagnoses to be considered for this condition would include otosclerosis or other congenital abnormalities of the inner ear. The radiologist needs to be aware of this condition and how its recognition alters treatment and precludes stapedectomy. If stapedectomy is attempted in these patients as a method of treating their conductive hearing loss, then this can result in profuse leakage of CSF from the oval window (“stapes gusher”) which can lead to worsening deafness [1]. Imaging is also an important part of the workup for cochlear implantation as the majority of cases with this condition would be unsuitable for this intervention [3].
Differential Diagnosis List
X-linked congenital deafness
Otosclerosis
Other developmental anomalies of the inner ear
Final Diagnosis
X-linked congenital deafness
Case information
URL: https://eurorad.org/case/12603
DOI: 10.1594/EURORAD/CASE.12603
ISSN: 1563-4086