Bilateral Dehiscence of the Bony Cochlear Basal Turn

Cochlear‐facial dehiscence—A newly described entity

“…The notch at 2 kHz in the left ear was present in both air‐ and bone‐conducted thresholds. Similar air conduction notches were also noted in audiograms presented in other case reports describing cochlear dehiscences . We hypothesize that the focal hearing loss is related to the decreased efficiency in sound conduction within the cochlea due to the dissipation of energy through the mobile third window, corresponding to the frequency of the cochlear turn adjacent to the labyrinthine segment of the facial nerve.…”

“…Our workup included an audiogram and CT imaging, followed by VEMP testing once the dehiscences were seen. Close inspection of the CT scan revealed the cochlear-facial dehiscences, but in retrospect the 3 Kim and Wilson, 4 Neyt et al, 5 Lund and Palacios 6 ). (B) Cochlear-internal auditory canal dehiscence (Karlberg et al, 7 audiograms also provided subtle clues.…”

Contemporary Neuroradiographic Assessment of the Cochleo-Carotid Partition

“…CT scanning of the temporal bones showed unilateral dehiscence of the bony partition between the cochlear basal turn and the petrous carotid artery and contralateral thinning of this bony partition (CCP = 0.2 mm). The authors proposed that the similarity in audiometric findings in this patient, and that reported on by Modugno et al [9], may be attributable to pressure changes transmitted from the carotid to the cochlea, triggered by excitement, exercise, or atmospheric pressure change, resulting in hair cell stimulation. The mid-frequency SNHL would correspond to damage to the mid-portion of the cochlear basal turn.…”

Carotid-cochlear dehiscence: a dangerous mimicker of inner ear pathologies

“…Only six cases of CCD have been reported in literature, making characterisation of the affected patient population difficult 2–76.…”

“…SNHL and air-bone gap in the 500–2000 Hz range were reported on audiometric assessment. Only one prior study used vestibular evoked myogenic potential (VEMP) and reported bilateral lowering of detection thresholds in a patient with bilateral dehiscence 2. VEMP was not performed for the patient presented in this study.…”