Inner ear anomaly

Abstract

The accurate diagnosis of inner ear anomalies on CT and/or MRI is of importance for understanding the pathogenesis of hearing impairment as well as balance disorders. Furthermore, it is possible to comprehend the molecular pathophysiology in some inner ear anomaly disorders in which a causative gene has been detected. Enlargement of the vestibular aqueduct (EVA) is the most common malformation of the inner ear. EVA can be observed in various disorders, including DFNB 4/Pendred syndrome caused by SLC 26 A 4 mutations, branchio-oto-renal/branchio-oto (BOR/BO) syndrome caused by mutations in EYA 1, SIX 1 or SIX 5, and distal renal tubular acidosis caused by mutations in ATP 6 V 1 B 1 or ATP 6 V 0 A 4. SLC 26 A 4 mutations can be responsible for EVA as well as incomplete partition type II and dilated vestibule. Characteristic phenotypes of EVA include fluctuating hearing loss and repetitive vertigo. However, such symptoms are not necessarily recognized in patients with the BOR/BO syndrome. The CHARGE syndrome is a disorder characterized by coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia and ear anomalies. Aplasia and hypoplasia of the semicircular canals are the most prevalent anomalies in the CHARGE syndrome. Other disorders associated with inner ear anomalies, including DFNX 2 and the Usher syndrome, are mentioned in the review article.