Yasuhiro Minowa

Ototoxicity of the Anticancer Drug Cisplatin:An Experimental Study

Cisplatin was administered to guinea pigs. Hearing function was tested using ABR, and morphological studies were conducted by scanning and transmission electron microscopy. The following findings were made. (1) The susceptibility to cochlear damage by cisplatin was dose dependent. (2) At the same dose, damage was most severe in the lower turns, particularly in the second turn. This tallies with the high tone loss. (3) Mainly the outer hair cells are the site of the damage and the inner hair cells are rarely damaged. (4) The first row of the outer hair cells tend to be more severely damaged. (5) Variation of the stria vascularis was moderate compared with the damage to the organ of Corti. (6) A tendency of recovery was observed in ABR in some animals after they were given 2 mg/kg/day cisplatin intramuscularly consecutively for 8 days.

Evoked otoacoustic emissions from ears with idiopathic sudden deafness.

Evoked otoacoustic emissions (EOEs) were examined in ears with idiopathic sudden deafness (ISD) at an early stage after onset and were compared with those in ears with long-standing sensorineural hearing losses of unknown etiology (SHLUE). In ears with SHLUE, EOEs were not recordable from ears with a hearing loss exceeding 35 dB at minimum hearing level of 4 audiometric frequencies: 500, 1,000, 2,000 and 4,000 Hz (4 MHL). On the other hand, although 4 MHLs were greater than 35 dB in most of the ears, EOEs could be detected in about one-half of the ears with ISD, and, moreover, the majority of these EOE detectable ears showed a good hearing prognosis in spite of the degree of hearing loss. There was, however, no correlation between EOE threshold and degree of hearing recovery. From these results it seems that EOE testing might be clinically applicable for predicting whether or not hearing loss due to ISD can be recovered.

Enhancement of Ciliary Action by a β-Adrenergic Stimulant

It is known that β-adrenergic stimulants enhance mucociliary transport in the respiratory tract. The present study clearly indicated that such an enhancement resulted from not only the alteration in secretory function but also the direct stimulation of ciliated cells. However, the enhancement of ciliary beating depended on the morphological changes in ciliated cells. On the other hand, the effect of terbutaline aerosol, a β-adrenergic stimulant, on patients with chronic sinusitis was evaluated by paranasal sinus radiography. Consequently, marked improvements in shadows were achieved after 4 weeks in 40% of the cases examined.

Application of Loop Diuretics for Treatment of Sensorineural Hearing Impairment

In a series of animal experiments on guinea pigs and rats, conducted in an attempt to find a better solution for the treatment of sensorineural hearing impairment and tinnitus-known as diseases almost impossible to heal-it was revealed electrophysiologically, biochemically and electronmicroscopically that loop diuretics, referred to as ototoxic drugs, cause an increased amount of the therapeutic preparation to transfer to the inner ear fluid. It is concluded, on the basis of the encouraging results of these experiments, that combined medication with metabolic activator, steroid hormone and loop diuretics is significantly more effective in improving the symptoms of patients with inner ear deafness and tinnitus.

Alteration of striai capillary transport in kanamycin-treated guinea pigs

SummaryFerritin transport through the striai capillary during kanamycin intoxication was examined under a transmission electron microscope. Twelve guinea pigs were treated intramuscularly with kanamycin (400 mg/kg/day) for 2–3 weeks. When full hearing loss was recognized by estimating the Preyer reflex or auditory brain-stem response (ABR), ferritin was given intravenously and animals were sacrificed 1/3, 1, and 2 h later. At 1/3 h, ferritin was present diffusely not only in the endothelial cell but also in the basal lamina and within vesicles in the striai cell. Alternatively, it was discharged into the endolymphatic space. At 2 h, ferritin was seen on the luminal surface and in the cytoplasm of the endolymphatic cells of Reissners membrane. These results suggest that the basal lamina of the striai capillary was altered qualitatively by kanamycin administration.

Frequency Analysis of Evoked Otoacoustic Emissions

Evoked otoacoustic emissions (EOEs) were examined in 8 normal hearing ears without spontaneous otoacoustic emissions (SOEs), and the frequency of the first 10 ms after appearance of the EOE response wave was analyzed, dividing it into the first 5 ms half (First half A) and the last 5 ms half (Last half B). In the First half A, the peak frequency of the power spectrum tended to match the stimulus frequency, but in the Last half B, the peak frequency tended to be constant and moreover, it tended to match the frequency at which EOE can best be recorded. These findings suggest that each ear has its own characteristic EOE frequency.

Cartilage ossiculoplasty by lever method.

Conclusion. We invented a new ossicular chain reconstruction by lever methods (OCRLM) in tympanoplasty type III with the canal wall down technique and investigated the postoperative hearing results of the 24patients who had undergone this surgery. Postoperative air–bone gaps (ABGs) followed up for 2.1–3.2years gave satisfactory improvement audiometrically compared with former reports. Objective. To present newly devised methods applied from the viewpoint of mechanical dynamics for ossicular chain reconstruction in tympanoplasty. Materials and methods. A total of 24 cholesteatoma patients who underwent tympanoplasty with mastoidectomy using the canal wall down technique and ossicular chain reconstruction with OCRLM between May 2003 and April 2004 were investigated. The postoperative ABG of a four-frequency (0.5, 1, 2, and 4kHz) average of OCRLM followed up for 2years or more was assessed. Results. Patients who underwent OCRLM showed good postoperative hearing results. Average postoperative ABGs of less than 10, 15, 20, 25, and 30dB were 4.2, 37.5, 70.8, 91.6, and 100%, respectively. A gap of >30dB was absent and the mean postoperative ABG was 17.2dB. The OCRLM method was satisfactory to improve hearing and effectively reduce the ABG postoperatively over the period of observation.

A Comparative Study with Vestibular Tests of Patients with Ménière's Disease in Uppsala University and Osaka City University

1980年12月より1981年7月までのウプサラ大と1981年10月より1982年12月までの大阪市大の2施設のメニエール病患者47名と34名にっき, 神経耳科学的検査を, 同一方法を用いて行い, その結果を比較した.1) 性別, 年齢, 罹病期間, 検査時期については統計的有意差を認めなかった.2) 純音聴力検査では, 平均聴力損失, 聴力像共に有意差を認めなかった.3) 自発眼振, 頭位胆振の出現率に有意差を認めなかった.4) カロリック検査のCP, DP, OKNのDPの出現率に有意差を認めなかった.