X-linked deafness/incomplete partition type 3: Radiological evaluation of temporal bone and intracranial findings.

Purpose: X-linked deafness (XLD) is a rare disease, characterized by typical cochlear incomplete partition type 3 anomaly (IP-III). Accompanying hypothalamic anomalies were also recently described. The purpose of this study was to document the temporal bone and intracranial imaging findings in a series of patients with XLD with a review of the literature, to better understand this anomaly.

Methods: The CT and MRI studied of 13 XLD patients were retrospectively evaluated. All structures of the otic capsule (OC) were subjectively and retrospectively assessed. The OC thickness and the size of the cochlea were measured and compared to the age-matched control group. Intracranial structures were also evaluated with specific attention to the hypothalamic region.

Results: All cases had bilateral IP-III anomaly, bulbous internal auditory canals (IACs), absent bony modiolus with preserved interscalar septa, intact cochleovestibular, and facial nerves. OC thickness was decreased in all cases compared to the control group (p<0.001). In XLD patients, the cochlea had decreased transverse dimension and increased height compared to the control group (p< 0.001). Five patients (38.4%) had bilateral cystic structures adjacent to the vestibule and/or semicircular canals (SCCs). Hypothalamus was thickened or had a lobular appearance in all cases (subtle in one). Additionally, hamartoma-like appearance of the hypothalamus was present in half.

Conclusion: XLD is a rare inner ear anomaly that is frequently associated with hypothalamic malformations. The OC thickness of IP-III patients appears to be decreased with accompanying decreased transverse dimension of the cochlea which could have implications in electrode selection during cochlear implantation. Cystic /diverticular lesions surrounding the vestibule and semicircular canals are also frequently seen but a rarely reported finding.