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Biomedical subjects

K Kiyomizu

Publications and source records attributed to K Kiyomizu.

6 recordsLinked to original sources
PubMed1999

[Clinical experiences and postoperative results with partially implantable middle ear implant].

A partially implantable middle ear implant using an ossicular vibrator of a piezoelectric ceramic bimorph has recently been developed in Japan as a new rehabilitative method for hearing. Four patients at the Miyazaki Medical College Hospital were implanted with this device between September 1994 and October 1996. Implantation of the internal component was performed under local anesthesia after confirmation of sufficient sensitivity to the ossicular vibrator in an intraoperative vibratory hearing test. All patients regained socially useful hearing with the middle ear implant without any foreign body reactions or recurrence of otitis media. None of the cases showed any elevations of bone conduction thresholds 2 to 4 years postoperatively. Natural and clear sounds without interference noise and howling due to acoustic feedback were highly satisfactory in all patients. However, the first case, who had an implant in an ear following cholesteatoma surgery using the intact canal wall technique, experienced about a 10dB deterioration of the average hearing level with the implant 2 years after implantation. Gradual deterioration appeared to be caused by the retracted tympanic membrane interfering with the mobility of the ossicular vibrator. The following three cases were implanted in ears previously operated on by radical mastoidectomy, showing stable or improving hearing results with the implant. Closure of the external canal skin at the cartilaginous portion at the time of implantation seemed appropriate to maintain a sufficient middle ear space for the ossicular vibrator to work properly. Our case study confirms that the partially implantable middle ear implant is a safe and useful tool for patients with mixed deafness which cannot be satisfactorily rehabilitated by tympanoplasty and/or a conventional hearing aid.

Deafness↗
PubMed1998

Cochlear implantation in a patient with profound hearing loss with the A1555G mitochondrial mutation.

OBJECTIVE: This study aimed to describe the performance of a cochlear implant in a patient with profound hearing loss with the A1555G mitochondrial mutation. SETTING: The study was conducted at two university hospitals. PATIENT: A 50-year-old Japanese man in whom bilateral profound hearing loss developed after administration of streptomycin at the age of 23 participated. The pedigree of the family showed exclusively maternal transmission of hearing impairment. INTERVENTION: Genetic study and auditory rehabilitation with a cochlear implant were performed. RESULTS: The A1555G point mutation was identified from the patient's mitochondrial DNA. Since activation of the implant, the patient has been using it successfully with a monosyllable recognition score of 78% using Japanese word lists for speech audiometry. CONCLUSIONS: The current case indicated that cochlear implantation may be a valuable choice of therapy for the patient with profound hearing loss with the A1555G mutation. The excellent auditory performance with a cochlear implant suggests that hearing loss associated with this mutation is primarily caused by insult to the cochlear tissue containing rich mitochondria (i.e., hair cells or stria vascularis or both), not to the cochlear nerve and its central connections.

Antibiotics, Antitubercular↗
PubMed1997

[High-resolution CT of otosclerosis].

High-resolution CT (HRCT) scans of thirty-two patients (60 ears) with the clinical diagnosis of fenestral otosclerosis were evaluated retrospectively. HRCT was performed with 1-mm-thick targeted sections and 1-mm (36 ears) or 0.5-mm (10 ears) intervals in the semiaxial projection. Seven patients (14 ears) underwent helical scanning with a 1-mm slice thickness and 1-mm/sec table speed. Forty-five ears (75%) were found to have one or more otospongiotic or otosclerotic foci on HRCT. In most instances (30 ears), the otospongiotic foci were found in the region of the fissula ante fenestram. No significant correlations between CT findings and air conduction threshold were observed. We found a significant relationship between lesions of the labrinthine capsule and sensorineural hearing loss. We conclude that HRCT is a valuable modality for diagnosing otosclerosis, especially when otospongiotic focus is detected.

Adolescent↗
PubMedDate not supplied

Different clinical characteristics of aminoglycoside-induced profound deafness with and without the 1555 A-->G mitochondrial mutation.

Recent genetic studies have shown that hereditary susceptibility to aminoglycoside antibiotics is caused by the 1555 A-->G mitochondrial mutation. We found the 1555 mutation in 4 out of 68 postlingual deaf patients who were candidates for cochlear implantation. All 4 patients developed bilateral profound hearing loss following administration of aminoglycosides. The pedigree of the family shows exclusively maternal transmission of hearing impairment in each case. On comparison with neuro-otological findings from aminoglycoside-induced deaf patients without the 1555 mutation, four distinct characteristics were noted: (1) a progressive nature of hearing loss; (2) better residual pure-tone thresholds; (3) lower thresholds for electrical promontory stimulation, and (4) well-preserved vestibular function. Although other factors such as differing dosages and/or administration routes may also be involved, profound hearing loss associated with the 1555 mutation may be due to a different pathogenic mechanism, i.e., strial dysfunction rather than a direct insult to the hair cells.

Aged↗