Genetics of Inner Ear Malformations: A Review

Inner ear malformations are present in 20% of patients with sensorineural hearing loss. Although the first descriptions date to the 18th century, in recent years the knowledge about these conditions has experienced terrific improvement. Currently, most of these conditions have a rehabilitative option. Much less is known about the etiology of these anomalies. In particular, the evolution of genetics has provided new data about the possible relationship between inner ear malformations and genetic anomalies. In addition, in syndromic condition, the well-known presence of sensorineural hearing loss can now be attributed to the presence of an inner ear anomaly. In some cases, the presence of these abnormalities should be considered as a characteristic feature of the syndrome. The present paper aims to summarize the available knowledge about the possible relationships between inner ear malformations and genetic mutations.

A Case of Perilymphatic Fistula with Inner Ear Anomaly Diagnosed Preoperatively by the Cochlin-Tomoprotein Detection Test

We present a case of perilymphatic fistula (PLF) with inner ear anomalies having sudden, progressive sensorineural hearing loss and describe the fistula repair surgeries. We focus on the diagnosis methods of PLF and clinical course of PLF with inner ear anomaly. The cochlin-tomoprotein (CTP) detection test is very useful for the surgeons to encourage the earlier operation to sudden hearing loss cases. It is also helpful to define the diagnosis of PLF after operation. We could not get the good result as to hearing from the fistula repair surgery mainly because surgery was held 1 month after the onset. The results of the case, as well as recommendations of other reports, suggest that patients with sudden sensorineural hearing loss and PLF may need repair surgery within at most 2 weeks from the onset. We describe how to diagnose PLF more accurately using CTP detection combined with intraoperative findings.

Complete Labyrinthine Aplasia: A Unique Sign for Targeted Genetic Testing in Hearing Loss

Complete labyrinthine aplasia (CLA) is a rare inner ear anomaly. The only identified genetic cause of CLA with severe sensorineural hearing loss is labyrinthine aplasia, microtia, and microdontia (LAMM) syndrome. Here we report a child who presented with syndromic hearing loss and was diagnosed with LAMM syndrome. Genetic evaluation provided the family with confirmation of the diagnosis, provision of the prognosis, genetic counselling, and prenatal diagnosis. This report highlighted that CLA should be recognized as a unique sign to diagnose LAMM syndrome, to analyze FGF3 gene mutation, and also demonstrated the utility of genetic testing in patients with suspected LAMM syndrome to provide exact diagnosis and further management.