Temporal bone and intracranial abnormalities in syndromic causes of hearing loss: an updated guide

Abstract

To describe in detail the temporal bone and brain findings in both common and rare syndromic causes of hearing loss, with the purpose of broadening among radiologists and enhance the current understanding of distinct imaging features in paediatric patients with syndromic hearing loss. Methods: A detailed search of electronic databases has been conducted, including PubMed, Ovid Medline, Scopus, Cochrane Library, Google Scholar, National Institute for Health and Care Excellence (NICE), Embase, and PsycINFO. Results: Syndromic causes of hearing loss are characterised by different and sometimes specific abnormalities in the temporal bone. Conclusion: A complete knowledge of the image findings in the temporal bones, brain, skull and other body regions is critical for the optimal assessment and management of these patients. 2.1. Inner ear The inner ear development starts late in the 3rd week of gestation, with the formation of the otic placode (an ectodermal thickening on both sides of the developing head).The otic placode later invaginates to form otic pits which then fuse to form the otic vesicle. By day 26, the ventral region of otic vesicle differentiates into the saccule, the lower pole of which gives rise to the cochlear duct, which will form 2.5 turns by the 8th week. During the 7th week, cochlear duct epithelial cells differentiate to form the Organ of Corti. The mesenchyme surrounding the cochlear

The link between inner ear malformations and the rest of the body: what we know so far about genetic, imaging and histology

“…Among different types of Waardenburg, SOX10 mutation is characterized by almost pathognomonic combination of inner ear malformations as described above, Kallmann syndrome and Hirschsprung disease ( Fig. 1d) [2].…”

“…1b) [15]. Waardenburg syndrome is considered a neurocristopathy and variable non-inner ear features may include white matter signal abnormalities, Hirschsprung intestinal aganglionosis, white forelock, depigmentation of skin patches, intensely blue eyes or iris heterochromia and dystopia canthorum, agenesis or hypoplasia of the olfactory bulbs and nerves, isolated cerebellar dysplasia and parotid and lacrimal gland absence or hypoplasia [2]. Among different types of Waardenburg, SOX10 mutation is characterized by almost pathognomonic combination of inner ear malformations as described above, Kallmann syndrome and Hirschsprung disease ( Fig.…”

“…Down syndrome (trisomy 21) patients have measurable hypoplasia of the cochlea, cochlear nerve canal stenosis and of the small bony island of the semicircular canals associated with characteristic facial abnormalities [2].…”

“…The basal turn is normal and there is variable absence of the upper portion of the interscalar septum in the lateral aspect of the cochlea, in association with enlarged vestibular aqueduct (VA) and dilated vestibule (so-called Mondini triad). Mondini triad is the radiological hallmark of SLC26A mutations (Pendred syndrome); the associated non-labyrinthine finding in the Pendred syndrome is thyroid goitre secondary to iodine organification defect [2]. Dilated vestibular aqueducts may also be seen in isolation with KCNJ10 and FOXI1 mutations [17].…”

“…Hereditary hearing loss (HL) encompasses approximately 50% of congenital SNHL cases and syndromic associations have been described with additional abnormalities involving other organ systems [2]. These syndromes may have genetic and/or environmental causes, posing interesting questions on the developmental and genetic links between the ear and the rest of the body [3].…”