Objective To determine the effects of combined administration of furosemide and kanamycin on inner ear structures and the auditory nerve in rats. Methods The rats in the treatment group received intravenous injections of combined furosemide and kanamycin sulfate, and the rats in the normal control group received no treatment. The auditory brainstem response (ABR) test was carried out 7 days after drug administration to determine the effects of drug administration on hearing. Cochlear slice and cochlear wholcmount were prepared after 7 days of drug treatment. Results After 7 days of drug administration, ABR thresholds were significantly higher in the treatment group than in the control group and neurofilaments were significantly reduced, although the number of spiral ganglia showed no decrease and there were no signs of supporting cell injury. Conclusions Combined administration of furosemide and kanamyein sulfate has an apparent synergistic ototoxic effect. Although spiral ganglion damage may not be apparent within a short time period of drug administration, damage to auditory nerve fibers is obvious.
Objects To investigate the extent of hearing loss in an elderly sample population to estimate hearing disorders among the age-equivalent population in China and to study primary clinical characteristics of presbycusis. Methods Clinical data from 110 hearing loss patients of both senium and pre-senium ages (95 males and 15 females, mean age = 74.4±12.1 years) were reviewed. Patients aged from 50 to 59 years were accepted as the pre-seni- um control group (n=15). The 95 senium patients (〉 60 years of age) were divided into 4 groups according to age: 60+ group(60 to 69 years, n=25), 70+ group (70 to79 years, n=26), 80+ group (80 to 89 years, n=32) and 90+ group (90 years or older, n=12). Pure tone audiometry thresholds were measured in all 110 patients. Hearing loss severity of each tested ear was rated according to the Goodman classification criteria. Besides, audiometric configuration was examined in each ear. Results Audiometric testing showed normal hearing in 65 ears (29.5%), slight to moderately severe hearing loss in 131 ears (59.5%), and severe and profound loss in 24 ears (11%). Air-bone gaps were found in 12 ears (5.45%) indicating conductive hearing loss. Except the 12 ears with conductive hearing loss, audiograms showed gradually sloping loss in 99 ears (45%), sharply sloping loss in 34 ears (15.45%), fiat loss in 45 ears (20.45%), notch pattern loss in 5 ears(2.27%), trough and rising pattern loss in 2 ears(0.91%), total deafness in 2 ears (0.91%), and normal hearing in 21 ears(9.55%). On average, hearing thresholds increased at a rate of approximately 10 dB per 10 year for subjects aged 60 and older. Conclusions Hearing thresholds tend to be stable in presbycusis patients aged from 50 to 70 years, increase significantly between 70 and 80 years of age, and reach another stable stage at high levels after 80 years of age, especially in high frequencies. Hearing loss in middle frequencies accounts for most of recession in
JI Fei LEI Lei ZHAO Su-ping LIU Ke-fang ZHOU Qi-you YANG Shi-ming
Hair cells in the mammalian inner ear are very fragile and are often injured as a result of acoustic trauma or exposure to ototoxic drugs (cisplatin, aminoglycosides, etc) [1]. In amphibians and birds, spontaneous
SHU Wei-ningZHAO Li-dongZHANG Xiao-bingYANG Shi-ming
Objective Using optical imaging in brainstem slices, we studied evoked responses in the mouse cochlear (CN) and vestibular (VN) nuclei. Methods The use of optical imaging allowed us to visualize the spatiotemporal patterns of excitatory propagation in the CN and VN. Optical recordings can differentiate excitatory propagation in the ventral CN(VCN) from that in the dorsal CN(DCN). Furthermore, we assessed the relative distribution of NMDA and non-NMDA receptors in these regions using the glutamate antagonists APV (NMDA receptor antagonist) and CNQX (non-NMDA receptor antagonist) in mouse brainstem slices during postnatal days 1 to 3. Results The average sensitivity to APV was 99.1% in the VCN, 76.0% in the DCN and 64.9% in the VN. The average sensitivity to CNQX was 0.9% in the VCN, 24.0% in the DCN and 35.1% in the VN. These results indicate that the effect of APV dominated in the VCN, while both APV and CNQX were effective antagonists in the DCN and VN. In the VN, the distribution of APV-and CNQX-sensitive cells was almost completely uniform. However, in the DCN the distribution of APV-and CNQX-sensitive cells was highly complex. The area that was more sensitive to CNQX was located in the superficial layer of the DCN while the area with a higher sensitivity to APV was located progressively in the deep layer. Conclusion This optical recording data suggests that there is a differential distribution of NMDA and non-NMDA receptor mediated neurotransmission in the VCN, DCN and VN.
Doi TadashiKaneko ToshihikoMatsumoto AyumiAsako MikiyaYamashita Toshio
Objective To report experiences with use of otoendoscopy in cerebellopontine angle(CPA) surgeries.Methods Twenty five cases of CPA surgeries performed between November 2002 and December 2008 in which microscope enabled otoendoscopy was used were reviewed.The 25 cases included 19 cases of acoustic neuroma,3 cases of CPA facial nerve tumors,1 case of trigeminal neurinoma,a case of glossopharyngeal neuralgia and 1 case of hemifacial spasm.Endoscopy was used in all cases together with monitoring of brainstem auditory responses and facial electromyography.Postoperative hearing and facial nerve function were evaluated and compared to pre-operative levels.Results Endoscopy provided improved visualization of local anatomy,revealed hidden lesions and reduced unnecessary anatomical distortions.Total resection was achieved in 18 of the 19 acoustic neuroma cases,Facial nerve anatomical integrity was preserved in all 19 cases.One week postoperative House-Brackmann grading was I in 3 cases,Ⅱ in 10 cases and Ⅲ in 6 cases.Facial nerve function continued to improve in some cases at 3 months.Total tumor resection was achieved in all 3 patients with facial neurinoma.The facial nerve was sacrificed in 2 of the 3 cases with primary faciohypoglossal nerve anastomosis.Facial nerve function was Grade Ⅱ and Grade III one year after surgery,respectively.In the case with anatomically preserved facial nerve,postoperative facial nerve function was initially Grade Ⅲ and improved to Ⅱ at 3 months.The tumor was completely resected in the trigeminal neurinoma patient with a Grade Ⅲ postoperative facial nerve function which improved Grade II three months later.Seventeen of the 19 patients with acoustic neuroma retained hearing postoperatively,of these 12 maintained preoperative levels of hearing.Preoperative hearing capacity was preserved in 2 of the 3 patients with facial nerve tumors,but lost in patients with other tumor types.Glossopharyngeal neurotomy(n=1) and microvascular decompression(n=1) resulted in satisfactory symptom relie
YANG Shi-ming,YU Li-Mei,ZOU Yi-hui,YU Li-Ming,JI Fei,YANG Wei-yan,HAN Dong-yi Dept.Otolaryngology Head and Neck Surgery,Institute of Otolaryngology,Chinese PLA General Hospital,Beijing 100853
目的研究腺病毒携带Math1-EGFP基因经完整圆窗膜途径及鼓阶打孔途径导入耳蜗后对听功能和转导效率的影响,为内耳基因治疗提供实验基础和理论依据。方法健康成年白色红目豚鼠40只,雌雄不限,体重250~300g。随机分成四组,完整圆窗膜组12只,鼓阶打孔组12只,各组分别设对照8只。实验组(24只)导入重组腺病毒携带的Math1基因及增强型绿色荧光蛋白基因(enhanced green fluorescent protein,EGFP),对照组(16只)导入人工外淋巴液,所有动物均以左耳作为导入耳。术前及术后分别行听性脑干反应(ABR)检查。分别于术后5天、14天取双侧耳蜗标本做基底膜铺片观察基因表达情况。结果完整圆窗膜组导入耳ABR阈值,术后5天各频率与术前比较无显著性差异(P>0.05);鼓阶打孔组导入耳ABR阈值,术后5天在2kHz、4kHz与术前比较无差异(P>0.05),8kHz较术前增高(P<0.05),16kHz、20kHz较术前明显增高(P<0.01),术后14天在16kHz、20kHz较术后5天时明显好转(P<0.01),但较术前仍有增高(P<0.05)。转导成功率鼓阶打孔组为91.6%,优于完整圆窗膜组的50%。两种转导途径对目的基因在耳蜗内的表达部位和表达时间没有显著影响。结论完整圆窗膜途径及鼓阶打孔途径在转导成功率及听功能保护方面各有优劣。完整圆窗膜途径因其对耳蜗的损伤极小,在临床应用方面具有更好的发展前景。