OBJECTIVES:: The objectives of this study were to evaluate the effect of reimplanting a cochlear implant electrode in animal normal-hearing cochlea to propose measures that may prevent cochlear injury and, given its close phylogenetic proximity to humans, to evaluate the macaque as a model for electroacoustic stimulation. DESIGN:: Simultaneous, bilateral surgical procedures in a group of 5 normal-hearing specimens (Macaca fascicularis) took place in a total of 10 ears. Periodic bilateral auditory testing (distortion product otoacoustic emissions and auditory brainstem evoked responses [ABR]) took place during a 6-month follow-up period. Subsequently, unilateral explantation and reimplantation was performed. Auditory follow-up continued up to 12 months, after which animals were sacrificed and both temporal bones extracted for histological analysis. RESULTS:: Implantation and reimplantation surgeries were performed without complications in 9 of 10 cases. Full insertion depth was achieved at reimplantation in four of five ears. Auditory evaluation: Statistically significant differences between implanted and reimplanted were observed for the frequencies 2000 and 11,000 Hz, the remaining frequencies showed no differences for distortion product otoacoustic emission. Before the procedure, average thresholds with click-stimuli ABR of the five animals were 40 dB SPL (implanted group) and 40 dB SPL (reimplanted group). One week after first implantation, average thresholds were 55 dB SPL and 60 dB, respectively. After 12 months of follow-up, the average thresholds were 72.5 dB SPL (implanted group) and 65 dB SPL (reimplanted group). Hearing loss appeared during the first weeks after the first implantation and no deterioration was observed thereafter. Differences for ABR under click stimulus were not significant between the two ear groups. Similar results were observed with tone-burst ABR. A 15 dB shift was observed for the implanted group preoperatively versus 1-week post surgery and an additional 17.5 dB shift was seen after 12-month follow-up. For the reimplanted group, a 20 dB shift was observed within the first week post reimplantation surgery and an additional 5 dB after 6 months follow-up. Statistical analysis revealed significant differences between the implanted and reimplanted ear groups for frequencies 4000 Hz (p = 0.034), 12000 Hz (p = 0.031), and 16,000 Hz (p = 0.031). The histological analysis revealed that the electrode insertion was minimally traumatic for the cochlea, mainly indicating rupture of the basilar membrane in the transition area between the basal turn and the first cochlear turn only in Mf1 left ear. CONCLUSIONS:: With application of minimally traumatic surgical techniques, it is possible to maintain high rates of hearing preservation after implantation and even after reimplantation. Partial impairment of auditory thresholds may occur during the first weeks after surgery, which remains stable. Considering the tonotopic distribution of the cochlea, we found a correlation between the histological lesions sites and the auditory findings, suggesting that a rupture of the basilar membrane may impact hearing levels. The macaque was observed to be a functionally and anatomically an excellent animal model for cochlear implantation

CONCLUSION: The effect of visual condition is more intense in the first trial response in normal subjects and patients and in last trial response only in patients. The first trial effect is more evident in compensated patients in the eyes open condition with any type of perturbation, and in non-compensated patients with the angular displacements in either visual condition. OBJECTIVE: The study of body reaction to FTR can help to understand the complex mechanisms involved in the postural response and to develop new therapies to improve stability and prevent falls in unilateral vestibular deficit (UVD). This work describes the adaptation effect and the visual influence on the postural response to repetitive balance perturbation stimulus in normal subjects, compensated, and uncompensated UVD patients. METHODS: The magnitude of displacement has been measured when the support surface is linearly or angularly displaced. The differences between results in the first and late trial, and the differences between the eyes open and eyes closed situation have been compared. RESULTS: Compensated patients recover the adaptation ability to unexpected changes on the support surface through visual preference mechanism. Not compensated patients present hypermetric postural response with greater instability in the eyes open and eyes closed situations.

OBJECTIVE: To describe the surgical technique under local or general anesthesia of 5 cases that have undergone this procedure and the audiologic results obtained with this new device. PATIENTS: Four patients with mixed hearing loss and 1 patient with single-sided deafness. INTERVENTION: Therapeutic. MAIN OUTCOME MEASURES: The surgery was planned beforehand with a 3D reconstruction of a CT scan. The procedure was documented and timed in every case. Air and bone conductive pure tone audiometry and disyllabic words discrimination were tested after and before the procedure. Results were statistically analyzed. RESULTS: All patients tolerated well the procedure. Four patients were intervened under local anesthesia and 1 under general anesthesia because of an associated procedure. All patients showed statistically significant difference between the presurgery and postsurgery audiologic tests. CONCLUSION: Implantation of the Bonebridge with local or general anesthesia is a safe and feasible procedure, with audiometric results that can come close with the ones provided by BAHD users.

Hypothesis: Evaluate, based on morphologic and histologic parameters, the atraumaticity of 2 electrode arrays implanted in 10 human temporal bones. Background: Atraumatic surgery and electrode arrays are current topics in otologic surgery. The preservation of cochlear anatomy and its functions is a priority and morphologic evaluation of the surgical trauma is essential to continue improving in this field. Methods: Ten preserved human temporal bones (TB) without anatomic alterations were used in this study. They were divided into 2 groups of 5, and atraumatic surgery was performed to insert HiFocus 1J (group A) and HiFocus Helix (group B) electrode arrays. Anatomic comparisons were performed using computed tomography and histologic analysis. Results: Group A: the mean length for the cochlear longitudinal axis was 10.30 mm, and the cochlear transversal axis was 7.2 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 19.2 mm and 325.5°, respectively. Lateral location of the electrode array was achieved in all specimens. No significant correlation was observed between these dimensions and depth of insertion. Group B: the mean length for the cochlear longitudinal axis was 9.52 mm, and cochlear transversal axis was 6.38 mm. Scala tympani insertion was achieved in 4/5 TB studied, with a mean depth and angle of insertion of 17.5 mm and 352°, respectively. Modiolar location of the electrode array was achieved in all specimens. A positive correlation was established between the linear and angular insertion depths (p = 0.044). Conclusion: In summary, it is safe to state that neither electrode array shows significant insertion trauma.

Objective: Quantify the improvement and impact of the active middle ear implants (AMEIs) on a moderate-to-severe mixed hearing loss population. Study Design: Retrospective study on the indications and results obtained by individuals implanted with the AMEI. SettingS: Tertiary referral center. Patients: Thirteen adult patients with moderate-to-severe hearing loss were evaluated. Air and bone conductive pure tone audiometry and disyllabic word discrimination was performed before and after surgery. The follow-up period was from 5 to 64 months. INTERVENTION: Surgical implantation of the AMEI. MAIN OUTCOME MEASUREMENT: Auditory performance analyzed using pure tone and speech audiometry with AMEI off and on. Results: The average auditory gain in the frequency range 0.5 of 6 kHz was 44.07 dB. The average AC audiometric performance after activating the device is significantly better than the preoperative BC performance in 10 of 13 patients, with an average gain of 11.3 dB. Speech audiometry performance using disyllabic words showed a significant improvement. The detection threshold reduced significantly, from 65 to 24 dB (p = 0.012) with the AMEI. The speech recognition score at 65 dB SPL also showed a significant improvement from 28% to 90% post surgery (p = 0.004). The maximum speech recognition score also improved post surgery, from 56% to 93% with the AMEI (p = 0.023). Conclusion: The AMEI is considered an appropriate device to be used by patients with BC losses up to 70 dB, provided that hearing levels are present in all frequencies between 0.5 and 4 KHz, and the speech recognition percentage is above 60% in the ear chosen for implantation.