Mondini-like malformation mimicking otosclerosis and superior semicircular canal dehiscence

Abstract

In 2003, it was reported that superior semicircular canal dehiscence can mimic otosclerosis because of low-frequency bone conduction hearing gain and dissipation of air-conducted acoustic energy through the dehiscence. We report the case of a 17-year-old girl with left-sided combined hearing loss thought to be due to otosclerosis. Bone conduction thresholds were -10 dB at 250 and 500 Hz and she had a 40 dB air-bone gap at 250 Hz. When a tuning fork was placed at her ankle she heard it in her left ear. Acoustic reflexes and vestibular evoked myogenic potentials could be elicited bilaterally. Imaging of the temporal bones showed no otosclerosis, superior semicircular canal dehiscence or large vestibular aqueduct, but a left-sided, Mondini-like dysplasia of the cochlea with a modiolar deficiency could be seen. Mondini-like cochlear dysplasia should be added to the causes of inner-ear conductive hearing loss.

Cochlear-Internal Canal and Cochlear-Facial Dehiscence: A Novel Entity

“…However, symptoms and the disease persisted despite medical and intratympanic treatments. As in other reported cases of otic capsule dehiscence, VEMPs were preserved [7] . Although VEMPs are highly sensitive and specific for SSCD [10] , the negative finding in this scenario may be attributed to the small size of the dehiscence [2] .…”

“…An otic capsule dehiscence opens up a third window into the inner ear, and clinical findings such as a low-frequency bone conduction hearing loss, dizziness, vertigo, or Tullio phenomenon have been reported [2,7] . When presuming an otic capsule dehiscence, it is important to consider other conditions that might resemble or mimic a third window syndrome, as is the case of vestibular aqueduct enlargement or perilymphatic fistula.…”

Cochlear‐facial dehiscence—A newly described entity

“…For example, cochlear‐carotid dehiscence has been described, with manifestations ranging from pulsatile tinnitus and hearing loss to pressure‐induced vertigo . Similarly, two instances of bony dehiscence between the internal auditory canal and cochlea have been reported . Here we describe two cases of cochlear‐facial dehiscence (CFD), which we believe to be the first in the English literature.…”

“…). These include four reports of carotid artery–cochlear dehiscence and two reports of internal auditory canal and cochlea dehiscence . However, none of these cases was associated with a dehiscence between the facial nerve and the cochlea.…”

Superior Canal Dehiscence Syndrome: Lessons from the First 20 Years

“…Aside from dehiscence of the superior semicircular canal, several other sources of labyrinthine dehiscence can lead to symptoms similar to those in SCDS, including that of the posterior semicircular canal (52, 53), lateral semicircular canal (17, 54), vestibular aqueduct (55), facial nerve (56), internal auditory canal (57), and the carotid canal (58, 59). Merchant and Rosowski synthesized many of these reports and broadly proposed that any dehiscence of the inner ear can lead to an inner ear conductive hearing loss from a third mobile window (60).…”