Anatomical study of the human middle ear for the design of implantable hearing aids

OBJECTIVE: To generate anatomical data on the human middle ear and adjacent structures to serve as a base for the development and optimization of new implantable hearing aid transducers. Implantable middle ear hearing aid transducers, i.e. the equivalent to the loudspeaker in conventional hearing aids, should ideally fit into the majority of adult middle ears and should utilize the limited space optimally to achieve sufficiently high maximal output levels. For several designs, more anatomical data are needed. METHODS: Twenty temporal bones of 10 formalin-fixed adult human heads were scanned by a computed tomography system (CT) using a slide thickness of 0.63 mm. Twelve landmarks were defined and 24 different distances were calculated for each temporal bone. RESULTS: A statistical description of 24 distances in the adult human middle ear which may limit or influence the design of middle ear transducers is presented. Significant inter-individual differences but no significant differences for gender, side, age or degree of pneumatization of the mastoid were found. Distances, which were not analyzed for the first time in this study, were found to be in good agreement with the results of earlier studies. CONCLUSION: A data set describing the adult human middle ear anatomy quantitatively from the point of view of designers of new implantable hearing aid transducers has been generated. In principle, the method employed in this study using standard CT scans could also be used preoperatively to rule out exclusion criteria.

Echinococcosis presenting as an otogenic brain abscess: an unusual lesion of the middle ear cleft and temporal lobe

This paper presents a case of a 28-year-old male with a seizure episode and a 4-year history of intermittent tinnitus on the left ear. On computed tomography and magnetic resonance imaging, a density with rim enhancement was found at the temporal lobe, associated with mastoid tegmen destruction and middle ear mass, indicating cholesteatoma with complicating brain abscess. Evacuation of the brain abscess was performed with a combined otolaryngologic and neurosurgical procedures (canal wall-down mastoidectomy and temporal craniotomy). The pathology turned out to be infestation with Echinococcus granulosus.

Cholesteatoma surgery in children: long-term results of the inside-out technique

OBJECTIVE To present the anatomical and functional results of the inside-out technique applied in pediatric cholestetaoma surgery and to evaluate functionality with good hearing results against radicality with lower recurrence rate. METHODS Retrospective analysis and evaluation of the postoperative outcome in a consecutive series of 126 children or 130 ears operated between 1992 and 2008. With the inside-out technique, cholesteatoma is eradicated from the epitympanum toward the mastoid and, as a single stage procedure, functional reconstruction of the middle ear is achieved by tympanoossiculoplasty. RESULTS In 89.2% of all cases, the ear was dry postoperatively. 80.9% of the ears reached a postoperative air-bone gap of 30 dB or less and the median air conduction hearing threshold was 29 dB; in 60.9% of all cases, hearing was postoperatively improved. The recurrence rate was 16.2% in a mean postoperative follow-up 8.5 years. Altogether, 48 ears (36.9%) underwent revision surgery. The complication rate was 3.1% and involved only minor complications. CONCLUSION The inside-out technique allows a safe removal of cholesteatoma from the epitympanum toward the mastoid with a single-stage reconstruction of the ossicular chain. For this reason we support our individual approach, which allows creation of the smallest possible cavity for the size of the cholesteatoma. Our results confirm that the inside-out technique is effective in the treatment of pediatric cholesteatoma.

Comparison of co-located independent ground-based middle atmospheric wind and temperature measurements with numerical weather prediction models

High-resolution, ground-based and independent observations including co-located wind radiometer, lidar stations, and infrasound instruments are used to evaluate the accuracy of general circulation models and data-constrained assimilation systems in the middle atmosphere at northern hemisphere midlatitudes. Systematic comparisons between observations, the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analyses including the recent Integrated Forecast System cycles 38r1 and 38r2, the NASA’s Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalyses, and the free-running climate Max Planck Institute–Earth System Model–Low Resolution (MPI-ESM-LR) are carried out in both temporal and spectral dom ains. We find that ECMWF and MERRA are broadly consistent with lidar and wind radiometer measurements up to ~40 km. For both temperature and horizontal wind components, deviations increase with altitude as the assimilated observations become sparser. Between 40 and 60 km altitude, the standard deviation of the mean difference exceeds 5 K for the temperature and 20 m/s for the zonal wind. The largest deviations are observed in winter when the variability from large-scale planetary waves dominates. Between lidar data and MPI-ESM-LR, there is an overall agreement in spectral amplitude down to 15–20 days. At shorter time scales, the variability is lacking in the model by ~10 dB. Infrasound observations indicate a general good agreement with ECWMF wind and temperature products. As such, this study demonstrates the potential of the infrastructure of the Atmospheric Dynamics Research Infrastructure in Europe project that integrates various measurements and provides a quantitative understanding of stratosphere-troposphere dynamical coupling for numerical weather prediction applications.