Implantable and Semi-Implantable Hearing Aids: A Review of History, Indications, and Surgery

Abstract

Introduction The complaints associated with the use of conventional amplifying hearing aids prompted research at several centers worldwide that ultimately led to the development of implantable devices for aural rehabilitation. Objectives To review the history, indications, and surgical aspects of the implantable middle ear hearing devices. Data Synthesis Implantable hearing aids, such as the Vibrant Soundbridge system (Med-El Corporation, Innsbruck, Austria), the Maxum system (Ototronix LLC, Houston, Texas, United States), the fourth-generation of Carina prosthesis (Otologics LLC, Boulder, Colorado, United States), and the Esteem device (Envoy Medical Corporation - Minnesota, United States), have their own peculiarities on candidacy and surgical procedure. Conclusion Implantable hearing aids, which are currently in the early stages of development, will unquestionably be the major drivers of advancement in otologic practice in the 21st century, improving the quality of life of an increasingly aged population, which will consequently require increased levels of hearing support.

A technical review and evaluation of implantable sensors for hearing devices

“…3 ) to be coupled to the incus or the stapes. Detailed technical characteristics of the device have not been described in the literature, but some reviews [ 25 , 26 ] state that Carina has two ECMs, one of them oriented to the outside to capture external sounds, and the other to the inside to capture body signals, allowing body noises to be then canceled out by the DSP. This configuration has also been mentioned in some patents [ 59 , 60 ].…”

“…The most relevant problems related to Carina ’s subcutaneous microphone (A3) are: perception of body noise [ 48 ], skin infections and partial extrusion of the device [ 25 ]. Furthermore, feedback influenced Carina ’s functional gain, limiting its bandwidth to 4 kHz, affecting therefore the selection criteria [ 26 ]. It should be noted, however, that these problems could not be attributed only to the sensor used in Carina , since the actuator and DSP also modify the device’s performance.…”

“…The performance of most of the implantable sensors has been analyzed by means of different techniques, including lumped parameter models [ 23 ], finite element (FE) models [ 19 ], or experimentally through tests with prototypes in laboratory set-ups [ 24 ] or directly in animal or human temporal bones (TBs) [ 16 , 20 ]. Nevertheless, for the sensor designs that can be found in TIHAs currently commercialized ( Carina and Esteem ) technical information is quite scarce, and the literature related to these commercial devices [ 25 , 26 ] have focused mainly on patient satisfaction and clinical evaluation. Although a recent review on implantable sensors for hearing devices has been presented [ 27 ], a thorough technical comparison between different approaches is still inexistent; i.e.…”

Active Middle Ear Vibrant Soundbridge Sound Implant

“…Indeed, two manufacturers have now designed completely implantable middle ear devices. In addition, depending on the MEI, if there is no device in the ear canal, there is no insertion loss with a net boost in high-frequency sound transmission ( 2 ).…”

“…There are several theoretical reasons why direct drive MEI hearing devices might indeed produce better sound quality than conventional acoustic hearing aids. The theoretical issues which might impact qualitative judgments include increased high frequency gain (more high frequency energy can be delivered via the Vibrant Soundbridge than would typically be anticipated using traditional hearing aid technology), improved signal coupling (bypassing the tympanic membrane, yielding a potentially more efficient high frequency sound transfer system, reduction in acoustic feedback because the signal is not acoustically delivered into the external auditory canal, less acoustic feedback is likely), no insertion loss, no occlusion effect, and reduced distortion from external auditory canal resonances because the external auditory canal is not occluded while using direct drive MEI systems ( 2 ).…”