Superparamagnetic Nanoparticle Delivery to the Cochlea Through Round Window by External Magnetic Field: Feasibility and Toxicity.

Introduction. The objective of this study was to evaluate the feasibility and toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) administered into the cochlea through the round window (RW) by an external magnetic field. Materials and Methods. In 5 Wistar rats, the left RW was punctured. SPIONs suspended in hyaluronic gel (5 mg/mL) were applied in the RW niche and covered by a muscle graft. The nanoparticles were mobilized using a rare earth magnet (0.54 T) held in 4 consecutive positions around the head. The right ear served as control. Hearing function was monitored by auditory brainstem responses (4-32 kHz tone bursts). Results. The auditory thresholds remained unchanged 1 month after the administration. The histological study of the cochleae showed that SPIONs were driven into the scala tympani in the basal turn, the second turn, and the apex. Conclusion. Superparamagnetic nanoparticles can be driven inside the cochlea toward the apex with a preserved hearing up to 1 month in rats.

Implantation of the Auditory Nerve via the Middle Ear Cavity in Rats with Partial Hearing Preservation.

The aim of this study was to evaluate the residual hearing function and cochlear morphology after auditory nerve implantation via middle ear spaces in rats. A titanium rod (1.5 mm long and 0.3 mm thick) coated with Parylene was inserted in the cochlear apex in the direction of the modiolus in 9 Wistar rats. Auditory brainstem-evoked responses to tone bursts at 2, 8, 12 and 32 kHz were recorded before surgery and on postoperative days 0, 2, 15 and 30. Eight cochleas were examined microscopically. The rod was inside the modiolus in 4, and partly or totally outside the modiolus in 4 animals. Residual hearing was present in all cases. The average threshold shift in cochleas with modiolar implant was 39 ± 11.2, 54 ± 9.7, 48 ± 20.3 and 43 ± 21.3 dB SPL on postoperative days 0, 2, 15 and 30, respectively. The transmodiolar approach allows a minimally invasive cochlear implantation and a partial hearing preservation.

Contralateral routing of signal hearing aid versus transcutaneous bone conduction in single-sided deafness.

The aim of this study was to compare a contralateral routing of signal (CROS) hearing aid to a transcutaneous bone-anchored device in the same conditions. This prospective crossover study included 18 adult patients with a single-sided deafness (SSD). After a trial period of 60 days with CROS and 7 days with a transcutaneous bone-anchored device (Alpha 1®, Sophono, Boulder, Colo., USA) on a headband, 13 (72%) patients opted for Alpha 1, 2 patients for CROS, and 3 rejected both rehabilitation methods. Clinical tolerance, satisfaction, hearing performances (pure-tone audiometry, speech test in quiet and in noise, stereo audiometry, sound localization, and Hearing in Noise Test), and quality of life (Glasgow Benefit Inventory, Abbreviated Profile of Hearing Aid Benefit and Glasgow Hearing Aid Benefit questionnaires) were measured at 3 and 12 months after the implantation. Both devices improved equally the hearing in noise and the quality of life. Transcutaneous devices represent an effective option in SSD.

Effect of Sound Coding Strategies on Music Perception with a Cochlear Implant.

The goal of this study was to evaluate the music perception of cochlear implantees with two different sound processing strategies. Methods: Twenty-one patients with unilateral or bilateral cochlear implants (Oticon Medical®) were included. A music trial evaluated emotions (sad versus happy based on tempo and/or minor versus major modes) with three tests of increasing difficulty. This was followed by a test evaluating the perception of musical dissonances (marked out of 10). A novel sound processing strategy reducing spectral distortions (CrystalisXDP, Oticon Medical) was compared to the standard strategy (main peak interleaved sampling). Each strategy was used one week before the music trial. Results: Total music score was higher with CrystalisXDP than with the standard strategy. Nine patients (21%) categorized music above the random level (>5) on test 3 only based on mode with either of the strategies. In this group, CrystalisXDP improved the performances. For dissonance detection, 17 patients (40%) scored above random level with either of the strategies. In this group, CrystalisXDP did not improve the performances. Conclusions: CrystalisXDP, which enhances spectral cues, seemed to improve the categorization of happy versus sad music. Spectral cues could participate in musical emotions in cochlear implantees and improve the quality of musical perception.