Candidacy for the Bone-Anchored Hearing Aid

Abstract

The BAHA (bone-anchored hearing aid) is a bone conduction hearing aid with percutaneous transmission of sound vibrations to the skull. The device has been thoroughly evaluated by various implant groups. These studies showed that, in audiological terms, the BAHA is superior to conventional bone conduction devices. In comparison with air conduction devices, the results are ambiguous. However, a positive effect is found with respect to aural discharge. The most powerful BAHA can be applied to patients with a sensorineural hearing loss component of up to 60 dB HL. It was shown that bilateral BAHA application leads to binaural sound processing. Preliminary results on the application of the BAHA in patients with unilateral conductive hearing loss suggest that stereophonic hearing can be re-established. The application of the BAHA as a transcranial CROS (contralateral routing of signal) device in unilateral deafness minimizes head shadow effects.

Results and complications of the Baha system (bone-anchored hearing aid)

“…Numerous studies performed on a large number of patients have demonstrated that the Baha system oVers far better results than conventional bone-conduction hearing aids in both adults and children, with substantial improvement in both tonal and speech audiometry [3,[23][24][25]. This is easy enough to explain if we consider that direct (percutaneous) conduction is more eVective than transcutaneous conduction, which, as we know, attenuates the signal by 10-15 dB [26].…”

“…This makes it possible to use the Baha ampliWer at lower levels, with a lower rate of distortion compared to traditional bone-conduction transducers [27]. Furthermore, compared to them the Baha system yields better results in language comprehension tests, which can be attributed to the better performance achieved in the highfrequency range, which is widely known to be fundamental for good speech discrimination [25]. It is also important to consider that the application of a conventional bone-conduction hearing aid often leads to local problems such as irritated skin and itching in the retromastoid area, due to the pressure of the transducer on the skin [3].…”

“…From a strictly audiological standpoint, the comparison between the performance of the Baha system and that of conventional air-conduction hearing aids is not as clear-cut: among patients who went from one type of ampliWcation to the other, some prefer the performance of the boneanchored system while others favour the conventional system [25]. According to Mylanus [4], the patients' variable preference is closely tied to the extent of the air-bone gap.…”

Surgical Outcome of Bone Anchored Hearing Aid (Baha) Implant Surgery: A 10 Years Experience

“…It can be used effectively by pediatric and adult patients who are not suitable surgical candidates for canalplasty. Baha implant has to be surgically implanted to obtain skin penetrating coupling [2,3]. The indications for Baha implant are classified as otological or audiological.…”

Transcranial Attenuation in Patients with Single-Sided Deafness

“…Additionally, the role of TA in the selection of transcutaneous devices is warranted. Transcutaneous implants are subject to attenuation of sound due to less effective transmission of the signal compared to direct bone conduction [Hakansson et al, 1984;Snik et al, 2004]. Attenuation for transcutaneous stimulation varies considerably, and threshold shift for transcutaneous versus percutaneous stimulation can vary by almost 20 dB [Mylanus, 1994].…”