Minoo Lenarz

Publications

• The influence of the coupling of actuation drivers of implantable hearing systems on the mechanics of the middle ear.

  M Stieve, M Winter, Rd Battmer, M Lenarz, Th Lenarz

  Cochlear implants international. 05/2009;

  We used multifrequency tympanometry to provide middle ear mechanics after implantation of different implantable hearing aids. A total of 34 patients were included in the investigation; 19 of them were fitted with the Otologics system and 15 with the MED-EL Vibrant Soundbridge system. With the Otolog... [more] We used multifrequency tympanometry to provide middle ear mechanics after implantation of different implantable hearing aids. A total of 34 patients were included in the investigation; 19 of them were fitted with the Otologics system and 15 with the MED-EL Vibrant Soundbridge system. With the Otologics recipients, measurements were made preoperatively and both two months and at least 12 months postoperatively. Measurements involving the MED-EL patients were taken at least 12 months postoperatively. For all measurements, the non-implanted contralateral side was used as a control. Preoperatively, the resonance frequency of the Otologics patients was 904.3 +/- 218.2 Hz for the implanted side and 907.1 +/- 161.8 Hz for the non-implanted side. Postoperatively, a significant increase (p < 0.01) compared with the preoperative value and the control side was observed after two months: 1111.3 +/- 234.7 Hz, as opposed to 823.8 +/- 274.5 Hz on the contralateral side. After 12 months, the resonance point was restored to approximately the preoperatively measured values: 975 +/- 55.3 Hz (implanted side) and 901.3 +/- 207.1 (control side). The resonance frequency in the Symphonix patients, as measured after at least 12 months (on average, 35 months), was 1006.3 +/- 269.5 Hz on the non-implanted side and 900.1 +/- 249.3 Hz on the implanted side. It is apparent that the resonance frequency on the implanted side was higher than on the control side, although the difference was not significant (p = 0.496). Monitoring following the implantation of active hearing systems is therefore recommended in order that conclusions can be drawn regarding the adequacy of the coupling of the actuation driver to the ossicular chain. Copyright (c) 2008 John Wiley & Sons, Ltd.
• 0.30

  Impact points

  [Image-guided minimal-invasive cochlear implantation--experiments on cadavers]

  O Majdani, S H Bartling, M Leinung, T Stöver, M Lenarz, C Dullin, Th Lenarz

  Laryngo- rhino- otologie. 02/2008; 87(1):18-22.

  BACKGROUND: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the ... [more] BACKGROUND: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation. METHODS: A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 microm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy. RESULTS: Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75 min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2 mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen--this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously. CONCLUSIONS: This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools).