Optical measurements of eardrum vibrations and sound propagation in the ear canal for the fitting of active middle ear implants.

BACKGROUND: Middle ear implants (MEI) are for the medical rehabilitation of the hearing function in case of sound conduction hearing losses as well as cochlear hearing losses and their combinations. OBJECTIVES: An objective tool to reach the best fitting of the external worn sound processors is essential for patients who do not want or cannot participate in the fitting process. METHODS: In addition to Laser-Doppler-Vibrometry (LDV) measurement, the sound pressure was measured distant to the eardrum to attain additional information for comparison. Three groups of patients with different middle ear characteristics were examined. RESULTS: Because of the large spreading of measuring results even within a patient group with similar eardrum and middle ear conditions it is difficult to develop characteristic diagrams which represent the mean values of eardrum displacements with different sound processor adjustments being the base for normative data courses. CONCLUSIONS AND SIGNIFICANCE: The LDV measurements can be used as a tool for fitting sound processors by finding individual maximum eardrum velocities in the frequency range 125 Hz to 8 kHz. In comparison to acoustical measurements the optical measurements have advantages concerning lower variations of measurement values, higher spectral resolution, and robustness against disturbing acoustic noise, especially at low frequencies.

A Transcutaneous Active Middle Ear Implant (AMEI) in Children and Adolescents: Long-term, Multicenter Results.

OBJECTIVE: Evaluation of the long-term safety and performance of an active middle ear implant (AMEI) in the treatment of hearing loss in children and adolescents with a primary focus on improvement in speech discrimination. STUDY DESIGN: Prospective, multicentric, single-subject repeated-measures design in which each subject serves as his or her own control. SUBJECTS: Thirty-one pediatric subjects aged 5 to 17 years. INTERVENTION: Implantation of an active middle ear implant. METHODS: Improvement in word recognition scores, speech reception thresholds (SRT) in quiet and noise, in addition to air conduction, bone conduction, and sound field thresholds were evaluated in two age groups. RESULTS: Residual hearing did not change over time and speech intelligibility significantly improved and remained stable after 36 months. Children aged 5 to 9 improved in WRS from 21.92 to 95.38% and in SRT in quiet and in noise respectively from 62.45 dB SPL (sound pressure level) and +1.14 dB SNR to 42.07 dB SPL and -4.45 dB SNR. Adolescents aged 10 to 17 improved in WRS from 12.78 to 84.71% and in SRT in quiet and in noise respectively from 63.96 dB SPL and +3.32 dB SNR to 35.31 dB SPL and -4.55 dB SNR. CONCLUSIONS: The AMEI, under investigation, is a safe treatment for children and adolescents, and significantly improved audiological performance that remains stable on the long-term scale (up to 36 mo postimplantation). In general, all adult-related issues and questions regarding safety and performance can also be applied to the pediatric population, as no apparent specific issues developed.

The Vibrant Soundbridge in Children and Adolescents: Preliminary European Multicenter Results.

OBJECTIVE: Evaluation of safety and efficacy of the Vibrant Soundbridge in the treatment of hearing loss in children and adolescents with primary focus on improvement in speech discrimination. STUDY DESIGN: Prospective, single-subject repeated-measures design in which each subject serves as his/her own control. SETTING: Tertiary referral center. PATIENTS: Nineteen patients aged 5 to 17 years. INTERVENTION: Implantation of an active middle ear implant. MAIN OUTCOME MEASURE: Improvement in word recognition scores, speech reception thresholds, and signal-to-noise ratios (SNRs) were evaluated, in addition to air and bone conduction. Oldenburger Kids Satztest/Oldenburger Satztest sentences and Göttinger/Freiburger monosyllables at 65-dB hearing level were tested in two age groups. RESULTS: Significant speech discrimination improvement was seen in all patients after 6 months. In children 5 to 9 years old, mean monosyllable recognition improved from 28.9% (unaided) to 95.5% (Soundbridge-aided). Aided 50% sentence discrimination at 44.1 dB and SNR of -4.9 dB were measured. In patients 10 to 17 years old, mean word recognition improved from 18.5% to 89.0%, sentence reception threshold improved to 40.2 dB, and SNR to -3.6 dB. Comparison between age groups indicated a slight trend toward quicker adaptation by older subjects. However, after initial adjustment, a higher level of overall benefit was seen at 6 months in younger children. CONCLUSIONS: Currently, the only middle ear implant approved for pediatric patients, the Vibrant Soundbridge, provides an option in cases of congenital aural atresia or disease-induced defects, when surgical intervention and reconstruction is indicated. The 6-month results in this comparatively large study population validated conclusions found in previous trials.

Simulations and Measurements of Human Middle Ear Vibrations Using Multi-Body Systems and Laser-Doppler Vibrometry with the Floating Mass Transducer.

The transfer characteristic of the human middle ear with an applied middle ear implant (floating mass transducer) is examined computationally with a Multi-body System approach and compared with experimental results. For this purpose, the geometry of the middle ear was reconstructed from µ-computer tomography slice data and prepared for a Multi-body System simulation. The transfer function of the floating mass transducer, which is the ratio of the input voltage and the generated force, is derived based on a physical context. The numerical results obtained with the Multi-body System approach are compared with experimental results by Laser Doppler measurements of the stapes footplate velocities of five different specimens. Although slightly differing anatomical structures were used for the calculation and the measurement, a high correspondence with respect to the course of stapes footplate displacement along the frequency was found. Notably, a notch at frequencies just below 1 kHz occurred. Additionally, phase courses of stapes footplate displacements were determined computationally if possible and compared with experimental results. The examinations were undertaken to quantify stapes footplate displacements in the clinical practice of middle ear implants and, also, to develop fitting strategies on a physical basis for hearing impaired patients aided with middle ear implants.

Changes of oral trigeminal sensitivity in patients after middle ear surgery.

OBJECTIVES: The specific aim of this study was to re-investigate the effect of chorda tympani damage on both trigeminal sensitivity and taste ability. STUDY DESIGN: Prospective study. METHODS: Capsaicin-impregnated filter paper strips (5 concentrations, 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 seconds. Thresholds were estimated in two ways: 1) thresholds related to sensory perception and 2) intensity-related thresholds. The test was applied to 29 patients who underwent middle ear surgery (mean age, 49 yr; 16 females, 13 males). Results were compared with those of 63 healthy subjects (mean age, 40 yr; 36 females, 29 males). In addition to trigeminal thresholds, measures of gustatory function were also obtained using both the validated "taste strips" test kit and electrogustometry. RESULTS: For lateralized testing with capsaicin, significant differences were found between preoperative and postoperative thresholds and between the operated and nonoperated side, with thresholds being higher postoperatively on the operated side. The sensation-related thresholds from the operated tongue side exhibited a correlation with the corresponding postoperative electrogustometric thresholds. A higher degree of chorda manipulation was associated with higher postoperative capsaicin thresholds at the operated tongue side. CONCLUSION: Pain-related sensitivity of the tongue decreases after middle ear surgery, indicating that chorda tympani function also influences intraoral trigeminal sensitivity.