Masakazu Suzuki

Further Clinical Experiences with Middle-Ear Implantable Hearing Aids: Indications and Sound Quality Evaluation

Since 1983, when the 5-year project on the middle-ear implantable hearing aids (MEI) was completed, we have been concentrating our studies on the clinical application of the partially implantable MEI (PMEI). The study was on the indication of implantation, improvement of the implantation operation, follow-up of the implanted patients, minor modification of the MEI, preparation of necessary surgical tools, and so on. Clinical study was also necessary for our team to finally confirm the clinical usefulness of this device. The present report is focussed mostly on the problem of indication for the application of PMEI.

Portions of Tone Pips Contributing to Frequency-Selective Auditory Brain Stem Responses

The portions of tone pips that are effective in increasing the amplitudes of auditory brain stem responses were studied using 6 cats. The responses evoked by pips with identical slopes but different rise times were compared to one another. The results indicated that the effective portion of the tone pips extended more than 4 ms from onset at 500 and 1 000 Hz, and more than 2 ms at 2 000 Hz. Each cycle within these ranges contributed to the increase in response amplitude. These results support the contention that the frequency selectivity of the brain stem response elicited by tone pips is sufficient for objective audiometry.

Long Term Follow-Up of Secretory Otitis Media in Children: The Effects of Adenotonsillectomy with Insertion of a Ventilation Tube

The long term effects of adenotonsillectomy and ventilation tube were studied in 78 children with serous otitis media. Duration of postoperative follow-up range from 2 to 8 years, with an average of 4.5 years. Repeated preoperative and postoperative pure tone audiometry as well as otoscopic examinations under a microscope were undertaken routinely for the assessment of the progress or improvement of the disorder. Three months after the operation, an average improvement of the hearing thresholds was 16.3 dB. However, it was 20.3 dB in the final examination. Under the otoscopic examinations, 35% of the ears were noted to have various kinds of pathological changes. Tympanic atelectasis of Grade I and II (Sadé) was noted in 17% of all the ears. Retraction pocket of the pars flaccida was found in 2%, permanent perforation in 4% and cholesteatoma in 2% of these ears.