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The Baha® Attract system can provide effective and stable hearing amplification for patients with microtia. Concurrent surgeries of auricle reconstruction and Baha® Attract implantation do not result in more soft tissue complications. The number of adverse events increased with the duration of implantation, even one year postoperatively. Benign skin evolutions, including skin thinning and erythema at the implant side, are commonly seen in Baha® Attract users. Implants are not necessarily removed when skin necrosis occurs in Baha® Attract users.

Purposes: To evaluate the instant auditory benefit of an adhesive bone conduction hearing aid (ADHEAR) on children with bilateral congenital microtia, especially the sound localization ability under unilateral and bilateral fitting. Methods: Twelve patients with bilateral congenital microtia aged from 6 to 17 were included in this study. Pure tone threshold under sound field, speech recognition threshold in quiet and sound localization abilities were tested and compared before and after wearing the device. The pure tone threshold test was additionally repeated for two different wearing method – adhesive or fixed with softband; the sound localization test was repeated for both unilateral and bilateral fitting. Correlation analysis was then conducted to find the influencing factors of sound localization improvement. Results: Significant auditory improvement were found: the average pure tone threshold (PTA) reduced by 24.8 (adhesive) and 27.3 dB HL (softband), with no significant difference between the two wearing methods. The speech recognition threshold also improved by 29.0 dB. As for sound localization abilities, no significant improvement was found under unilateral fitting; but half (6 of 12) of the patients were notably benefited from bilateral fitting. The improvement was found to be strong correlated with the patients’ unaided sound localization ability – those with poorer localization abilities tends to benefit more. Moreover, it was found that the sound localization improvement was also negatively related with the malformation degrees of the patients’ head. Summary: ADHEAR affords significant auditory benefits for children with bilateral congenital microtia, in terms of sound and speech perception. The sound localization abilities could be partly improved instantly by bilateral fitting, and the improvement is related with factors such as adaption and skull malformations.

Objective To investigate the effects of long-term moderate noise on hearing functions, MOCR, and MEMR. Methods Mice were exposed to the moderate noise (11.2 – 22.4 kHz, 80 dB SPL, 6 h/day, 4 weeks). Subsequently, the hearing functions, including threshold and input-output roles of ABR (auditory brainstem response) and cubic (2f1–f2) DPOAEs (distortion product otoacoustic emissions) were evaluated. Also, MEMR and MOCR were assessed shortly after or at four weeks following the termination of exposure to the noise. Results The mice's acoustic suppression reflex was strengthened, hearing functions and MEMR were unaffected four weeks after the moderate noise. For primary tones of 16, 20 and 24 kHz, the strengths of contralateral and ipsilateral suppression in the noise group were about double those recorded in the control group. In order to further determine whether the functional changes of the afferent or efferent nerves increased the strengths of acoustic suppression, the mouse's left ear was inserted the earplug, and then exposed the moderate noise for four weeks. The strengths of contralateral suppression at 16, 20 and 24 kHz were increased for the noise + earplug than for the control group and were indistinguishable between the noise + earplug and the noise group. While no significant changes were found in the strengths of ipsilateral suppression at all frequencies for the noise + earplug group compared with the control group. Under ketamine/xylazine anesthesia, the broadband suppressor noise did not stimulate the MEMR by 20 min post-induction at all frequencies in three groups. Conclusion Our data demonstrated that the long-term moderate noise-exposure strengthened mice's MOCR by changing its afferent nerves, and unaffected cochlear hair cells and type I spiral ganglion neurons.

Introduction: Studies have shown that higher response levels can be obtained when the bone conduction stimulation position is closer to the cochlea. However, the morphological characteristics of round window niche and posterior tympanum in congenital aural atresia (CAA) and stenosis (CAS) patients were different from the normal. These affected the position of the cochlea at the cranial base. It was still unknown whether the distances from the cranium of CAA and CAS patients to the cochlea were the same as those of normal patients or not. Objective: To measure distances from various points on the lateral surface of the cranium to the cochlea and the cranium thickness on these points among a CAA group, CAS group and normal control group, which may provide valuable information for the better position of bone conduction stimulation. Methods: CT images of CAA, CAS patients and these patients’ healthy sides were analyzed. Firstly, the Frankfurt horizontal plane (Pfrkt) was established. Secondly, a model of part of the cranium was three-dimensionally reconstructed. Then, the Pfrkt plane was rotated down 20, 30 and 40° according to the superior margin of the external auditory canal. At every angle, points 25, 30, 35 and 40 mm away from the superior margin of the external auditory canal were marked out on the surface of the model and recorded as P20A, P30A, P40A, P20B, etc. The spatial distances between the cranium and ipsilateral cochlea were defined as lengths of points on the surface of the model to the cochlea apex (CA), cochlear base (CB) and modiolus midpoint (MM), respectively, recorded as P20A/CA, P20A/CB, P20A/MM, P30A/CA, etc. Results and Conclusions: In all groups, the length of P20D/CA was the shortest compared to P30D/CA and P40D/CA (p < 0.05). The P20A/CB and P20A/MM were also the shortest (p < 0.05). When the Pfrkt plane was rotated down 30 and 40°, the results were the same as at 20° (p < 0.05). However, P20D, P30D and P40D were almost on the mastoid air cells. We suggest that the bone conduction stimulation position is placed closer to the ear, while avoiding the mastoid air cells in the CAA and CAS patients.

Background As an alternative pathway to air conduction, bone conduction is a multipathway process that transmits sound energy to the inner ear through the skull in general. Based on this mechanism, bone conduction devices (BCDs) have been used widely in the rehabilitation of hearing loss. Although great efforts have been devoted to improving BCDs, drawbacks still exist in most categories of BCDs due to the complicated process of bone conduction. We hypothesized that if a bone conduction transducer was placed on the cochlea to stimulate it directly, the attenuation would be minimized, and the frequency dependency would be different from that of the vibratory response induced by traditional BCDs. This study aimed to explore the feasibility of direct promontory stimulation and to investigate its frequency-response characteristics. Methods Measurements were conducted in twelve cat ears. To stimulate the promontory directly, the floating mass transducer (FMT) of the Vibrant Soundbridge© (VSB) implant was glued to the promontory coupled with an oval window (OW) coupler. Auditory brainstem response (ABR) and laser Doppler vibrometry (LDV) measurements were used to evaluate the auditory response induced by the FMT. In both measurements, the FMT was driven by direct voltage stimuli. Results ABR waves could be induced under direct promontory stimulation by the FMT. In the frequency range of 1–12 kHz, the variation in the voltage threshold level were limited to 16 dB SPL with a maximum of 0.2 V at 1 kHz and a minimum of 0.04 V at 10 kHz. In the LDV measurements and the relative motion of the round window membrane (RWM) and the promontory were used to evaluate the cochlear response. The LDV results indicated a weak frequency dependency from 1 to 12 kHz. Conclusion Different from traditional stimulation via transcranial bone conduction, direct promontory stimulation is a new method in which a small bone conduction transducer stimulates the cochlear shell directly. The current experimental data demonstrate that it is feasible to generate sensations through bone conduction by stimulating the cochlea directly. Furthermore, the cochlear response induced by this type of stimulus in cats was weakly frequency dependent at frequencies ranging from 1 to 12 kHz. This study may provide a basis for the design of new transducers that can perform well over a wide range of frequencies.

To investigate whether differences existing in the distance between facial nerve (FN) and round window niche opening among congenital aural atresia (CAA), congenital aural stenosis (CAS) and a normal control group and to assess its effect on the round window implantation of vibrant soundbridge, CT images of 10 normal subjects (20 ears), 27 CAS patients (30 ears) and 25 CAA patients (30 ears) were analyzed. The distances from the central point of round window niche opening to the terminal point of the horizontal segment, the salient point of pyramidal segment, the beginning point of the vertical segment, and the vertical segment of the facial nerve (abbreviate as OA, OB, OC, OE, respectively) were calculated based on three-dimensional reconstruction using mimics software. The results suggested that the pyramidal segment of the FN was positioned more closely to round window niche opening in patients with both CAA and CAS groups than that in control group, whereas there was no significant difference between CAA and CAS group (P < 0.05). The vertical portion of the FN was positioned more closely to round window niche opening in the CAA group than those in both the CAS and control groups with statistical significance (P < 0.05). Furthermore, the vertical portion of the FN was positioned more closely to round window niche opening in the CAS group than that in control group (P < 0.05). In conclusion, the dislocation between facial nerve and round window niche in patients with congenital auditory canal malformations could have significant effects on the round window implantation of vibrant soundbridge. Moreover, three-dimensional measurements and assessments before surgery might be helpful for a safer surgical approach and implantation of vibrant soundbridge.

To better understand the relationship between the sound conduction system's structure and function, the authors developed a virtual platform that integrates 3D reconstruction and finite element modeling of the peripheral auditory organ to simulate biomechanical behavior of the middle and inner ear.

Objectives To assess the functional performance of the Bonebridge (BB, MED-EL), a newly-designed transcutaneous bone conduction implant that allows the skin to remain intact and to compare it with the current clinical model of choice, a percutaneous bone conduction implant (BAHA BP100, Cochlear Bone Anchored Solutions AG). Materials and methods The devices were compared using two methods: (1) Measurements of cochlear promontory acceleration in five cadaver heads: Accelerations of the cochlear promontories on both ipsilateral and contralateral sides were measured using a Laser Doppler system, with free-field sound stimuli of 90 dB SPL in the frequency range of 0.3–10 kHz (2) Measurements of pure-tone sound field thresholds in 5 normally hearing human adult subjects under a condition of simulated hearing loss. For the latter measurements, the devices were applied to the head using a Softband, and measurements were performed in the frequency range of 0.25–8 kHz. Within investigation comparisons (i.e., in cadavers or listeners) and a cross-comparison analysis of the cadaver and human results were done. Results Results from the cadaver heads showed that the cochlear promontory acceleration with the BB was higher within 10 dB on the ipsilateral side and lower within 5 dB on the contralateral side than the acceleration with the BAHA, in the frequency range of 0.7–10 kHz. The transcranial attenuation of the acceleration for the BB was greater than for the BAHA within 20 dB. For the sound-field threshold assessments with human subjects, the BB and BAHA showed similar threshold improvements of more than 10 dB HL for the ipsilateral side. For the contralateral side, the threshold improvement with the BB was less than with the BAHA, indicating better separation between ipsilateral and contralateral sides. Conclusions Preclinical results imply that the BB has functional performance similar to the BAHA and could be beneficial to patients suffering with conductive and mixed hearing losses as well as for those with unilateral impairment. Based on these preliminary results, a carefully designed clinical trial with conservative inclusion criteria can be recommended. This article is part of a Special Issue entitled “MEMRO 2012” .