CT findings of the temporal bone in CHARGE syndrome: aspects of importance in cochlear implant surgery

Abstract

To provide an overview of anomalies of the temporal bone in CHARGE syndrome relevant to cochlear implantation (CI), anatomical structures of the temporal bone and the respective genotypes were analysed. In this retrospective study, 42 CTs of the temporal bone of 42 patients with CHARGE syndrome were reviewed in consensus by two head-and-neck radiologists and two otological surgeons. Anatomical structures of the temporal bone were evaluated and correlated with genetic data. Abnormalities that might affect CI surgery were seen, such as a vascular structure, a petrosquamosal sinus (13 %), an underdeveloped mastoid (8 %) and an aberrant course of the facial nerve crossing the round window (9 %) and/or the promontory (18 %). The appearance of the inner ear varied widely: in 77 % of patients all semicircular canals were absent and the cochlea varied from normal to hypoplastic. A stenotic cochlear aperture was observed in 37 %. The middle ear was often affected with a stenotic round (14 %) or oval window (71 %). More anomalies were observed in patients with truncating mutations than with non-truncating mutations. Temporal bone findings in CHARGE syndrome vary widely. Vascular variants, aberrant route of the facial nerve, an underdeveloped mastoid, aplasia of the semicircular canals, and stenotic round window may complicate cochlear implantation.

Otopathology in CHARGE syndrome

“…In the literature, the radiographic findings of otologic abnormalities in CHARGE syndrome underscore this wide range of cochlear and vestibular abnormalities. In a recent series of 42 patients with CHARGE syndrome, CT scans revealed abnormalities of the cochlea, semicircular canals, middle ear, and internal auditory canal . Common findings included underdeveloped or absent semicircular canals (77%), hypoplastic cochleas (38%), stenotic cochlear apertures (37%), and abnormal course of the facial nerves (19%).…”

“…Ear abnormalities are present in over 90% of patients and range from auricular malformations to ossicular dysplasia to inner ear anomalies, including dysplasia of the cochlea or semicircular canals. Over 80% of CHARGE patients have hearing loss as a result . Herein, we present the clinical case, radiologic findings, autopsy, and temporal bone pathology in an infant with CHARGE syndrome and bilateral cochleovestibular hypoplasia.…”

The Forgotten Second Window: A Pictorial Review of Round Window Pathologies

“…Round window absence is a rare abnormality that may be seen in conjunction with various syndromes, including incomplete partition anomalies, mandibulofacial dysostosis, and Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and deafness (CHARGE) syndrome, in addition to cases of aural atresia (Fig 3). [9][10][11] In very rare cases, it may also occur without an associated syndrome (Fig 4). 12,13 Some authors have posited that such nonsyndromic cases may represent an inherited autosomal dominant genetic disorder with variable penetrance.…”

Guidelines in CHARGE syndrome and the missing link: Cranial imaging

“…Middle ear pathology, such as dysplastic ossicles or an absent/stenotic oval or round window, is seen on mastoid CT in over 70% of patients (Vesseur, Verbist, et al, 2016b). In some of these children a bone‐anchored hearing aid (BAHA, sometimes known as BCD—bone conductive device) may be a good hearing solution.…”

“…One lesser‐known feature, however, is the otosclerosis‐like fusion of the stapes footplate to the cochlear oval window as described by Ogier et al (2014) in Looper mice. A recent study of CT images of the os petrosum of individuals with CHARGE syndrome showed that, in addition to the (known) abnormalities of the oval window, the stapes was dysplastic or not identifiable in half of the ears with a stenotic oval window (Vesseur, Verbist, et al, 2016b). …”