**6. Conclusions**

*Advances in Rehabilitation of Hearing Loss*

case of more advanced forms of SNHL.

to provide an efficient auditory amplification and in highly selected cases. More specifically, with a vibratory, direct stimulation of the anatomical structures located close to the cochlea, such as the stapes, footplate, or round window membrane, the

The activity of the Implanting Centre at Sapienza University has been displayed by the application of several types of bone conductive implants and AMEI, these latter as semi- and fully implantable devices. Among them, the Esteem® AMEI was specifically considered attractive for the invisibility as well as for the absence of an implanted microphone. This premise has allowed us to collect the largest European experience since 2007, with several subjects that have reached today a long-term use of the device so as to allow us to draw some interesting remarks that are worth being

First to mention is the typology of mechanical stimulation that is obtained via a piezoelectric modality. The bellow of both transducers is in fact made of several layers of crystals that are able to deliver energy when displaced, and to be displaced when reached by energy. Furthermore, this type of modality can be considered optimal for high-frequency stimulation with limited energy consumption. This latter factor explains why for the Esteem® there is no need to recharge the battery that, however, needs to be replaced after a certain time of use (around 5 years on average in our overall experience). In this regard, it has been noticed that the battery was more likely to be extinguished faster in case of a continuous (24/24, 7/7) use and in

The surgical procedure is somewhat demanding even for experienced otosurgeons who must undergo laboratory training before starting with clinical application. The complexity of the procedure is mostly related to a few, important steps that require the use of different types of cement, as well as to specific dexterity in working in very narrow spaces opened during the procedure, like for example when cementing the driver together with the precoated stapes head through the posterior tympanotomy. This is explaining why the surgical procedure can take long time especially with the first cases. In this regard, it is noteworthy to stress the importance of a bioengineer present in the operating theater, carrying out objective measurements by LDV during and at the end of surgery, thus offering confident and supporting data to the surgeon for a beneficial final functional outcome. As far as cement is concerned, two different types were used: a bio glass cement in small amounts for stapes pre-coating, incus neo-joint and stapes/driver fusion, and when larger amounts of cement were needed, as for stabilization of the transducers body

within the mastoidectomy cavity, a hydroxyapatite compound was used.

normality in all cases within the first month after onset.

"transition" to cochlear implantation.

Apart from the inescapable complications related to the laser resection of part of the incus long process and to the ablation of the chorda tympani nerve, no other intraoperative complications were recorded in our series. However, in less than 10% of the subjects, delayed, transient facial nerve palsy developed, with return to

The auditory outcome has been shown to be positive in over 80% of the subjects,

although with variable degrees of improvement. In very few cases, it has been necessary to perform a revision surgery for debridement of newly formed fibrous tissue in the middle ear that was impeding the normal motility of the transducers. Another interesting finding relates to the observation of a striking decrease of the auditory threshold (as bone conduction) observed over time especially in those individuals who presented an advanced SNHL, being severe-to-profound, while not affecting the contralateral, non-implanted ear, so as to rule out to be dependent upon the causative factor. This new functional situation was in some cases still managed by setting the Esteem SP accordingly, while in a few subjects required the

delivered energy is much lower than that required for a cHA.

shared with the interested professionals (audiologists, otologists, etc.).

**98**

The fully implantable Esteem® active middle ear device has shown to provide a beneficial hearing gain in the majority of the implanted subjects. Our experience has shown that this may be achieved with very low morbidity as verified by the low incidence of complications. Other than for moderate-to-severe SNHL, the Esteem® may be indicated also for worse hearing threshold for which it can still provide a beneficial auditory and quality of life outcome. Despite its active mechanical role for eliciting cochlear stimulation, in certain candidates, it has been shown a progressive deterioration of the bone conduction threshold so as to limit the use of the implant and rather suggest cochlear implantation.

## **Acknowledgements**

The authors wish to express their gratitude to Dr Kelly Brooks who helped with intra-operative measurements and patients' audiological fitting.

### **Conflict of interest**

No conflict of interest to declare.
