Fully implantable hearing aids in patients with congenital auricular atresia

Patients with congenital auricular atresia suffer from a conductive hearing loss (HL) with an air-bone gap of 50 to 60 dB. Conventional bone conducting or bone anchored hearing aids are treatment options with several disadvantages and a biophysical limitation of almost no sound attenuation in the skull bone. Surgical construction of the sound conducting apparatus has been performed by others and modified by us into a three-step procedure with in vivo prefabrication of the external ear canal and the tympanic membrane. Although the results improved after inauguration of our modifications, there still remains an air-bone gap that makes air conducting hearing aids necessary in many patients. Implantable hearing aids have been developed for patients with perceptional HL and normal middle ear function but not for patients with middle ear disease or malformation.

Our objectives were to improve the hearing results of auricular atresia.

Prospective.

The surgical instruments, the transducer, and the operative technique of the only fully implantable hearing aid (Otologics Fully Implantable Middle Ear Transducer) clinically available were modified. They were implanted in five patients with congenital auricular atresia and their audiologic outcome evaluated.

After activation and fitting of the devices, patients experienced an improvement of sound-field thresholds up to 50 dB HL. The mean functional gain in a three frequency pure-tone average was approximately 35 dB HL.

This technique appears to provide a completely new dimension for the audiologic rehabilitation of patients with severe malformation of the middle ear.