宽频带白噪声适度暴露对小鼠听力损害的实验研究

目的通过100dB SPL宽频带白噪声对成年C57小鼠进行单次2小时的暴露,观察该种噪声对小鼠听功能损害的特点。方法选取5⁶周龄ABR听阈正常的C57小鼠(每组5-7只),随机分为5个实验组分别为:噪声暴露后即刻(P0)、1天(P1)、3天(P3)、7天(P7)、14天(P14)。实验组小鼠于100dB SPL宽频带白噪声环境下暴露2h,本实验采用噪声暴露前的小鼠作为对照组。每只实验小鼠分别于噪声暴露前及暴露后各时间点进行ABR阈值检测以评估听力受损情况,实验采用统计噪声暴露前、后各时间点小鼠ABR差值(阈移)的方法分析实验结果。结果噪声暴露后即刻,小鼠各频率的ABR阈移均为最大值(P<0.01):Click(11.92±7.51dB)、4kHz(11.92±5.60dB)、8kHz(12.31±5.99dB)、16kHz(21.54±8.75dB)、32kHz(20.00±8.90dB),且在各个频率的阈移中,以16kHz及32kHz处的高频听力损失最严重,明显高于Click、4kHz及8kHz处的阈移(P<0.05)。脱离噪声环境24小时后各频率的ABR阈移开始下降,2周以后,小鼠各频率ABR阈值均完全恢复至暴露前水平(P>0.05):Click(1.11±6.01dB)、4kHz(1.11±3.33dB)、8kHz(1.11±4.17dB)、16kHz(1.67±4.33)、32kHz(2.78±4.41)。结论 100dB SPL宽频带白噪声单次有限暴露可以造成小鼠出现一定程度的听力损害。在频率分布上,高频区域的听力损害更为明显。同时,本研究表明,这种噪声下小鼠听力损害可以表现自我主动恢复的特征。     

补肾活血通窍中药复方对庆大霉素耳中毒小鼠耳蜗NT-3表达的影响

目的观察补肾活血通窍中药复方对庆大霉素（gentamicin,GM）耳中毒小鼠听性脑干反应（ABR）反应阈及耳蜗神经营养因子-3（neurotrophic factor3,NT-3）表达的影响。方法健康昆明小鼠40只,随机分为5组,每组8只（16耳）。空白对照组正常喂养,GM＋中药组（补肾活血通窍中药复方分为高、中、低三个浓度组）及GM4-生理盐水组每天腹腔注射GM100mg／kg,连续15天,腹腔注射GM第一天起GM＋中药各组分别灌服高、中、低浓度中药复方汤剂,GM＋生理盐水组灌服等量生理盐水,连续20天,灌胃结束后测试ABR反应阈,采用蛋白免疫印迹（Western Blot）方法检测各组耳蜗组织中NT-3的表达。结果与空白对照组比较,GM＋生理盐水组及GM＋低浓度中药组ABR波Ⅲ反应阈显著升高（P〈0．01）,耳蜗NT-3蛋白含量下降（P〈0．01）;GM＋高、中浓度中药组ABR波Ⅲ反应阈升高,耳蜗NT-3蛋白含量下降,但差异均无统计学意义（P〉0．05）。结论高、中浓度补肾活血通窍中药复方可显著减轻GM所致的小鼠耳蜗NT-3含量降低和ABR反应阈升高的程度（P〈0．01）,从而有效减轻GM对小鼠的耳毒性。     

二甲基亚砜对在体耳蜗毛细胞的毒性作用

目的研究二甲基亚砜(DMSO)对在体耳蜗毛细胞的毒性作用。方法取清洁级健康、ABR阈值正常SD大鼠32只,雌雄不限,体重100-120g。随机分成4组,人工外淋巴液对照组(即0%组)8只;0.1%DMSO溶液组8只;1%DMSO溶液组8只;5%DMSO溶液组8只。所有动物均取右耳作为实验耳。通过耳蜗鼓阶打孔显微注射向每个实验耳注入不同浓度DMSO溶液4ul。术前1天和术后7天分别进行ABR(click和toneburst)检测。激光共聚焦显微镜观察DMSO溶液导入7天后的毛细胞变化。结果人工外淋巴液对照组click、4kHz、8kHz、16kHz处阈移平均值均<5dBSPL,仅于32kHz处有约13dBSPL的阈移,形态方面未见明显损伤;0.1%浓度组在click、4kHz、8kHz处阈移平均值均<5dBSPL,而32kHz处阈移约25dBSPL,与人工外淋巴液对照组比较提示有统计学意义,激光共聚焦显微镜观察底回时偶见少数内毛细胞胀大;1%浓度即可引起OHC大量丢失,造成相应纤毛表皮板缺如,且以底回最重,各频率ABR阈移均>15dBSPL,32kHz处阈移>30dBSPL;当浓度增加到5%时,不仅损伤耳蜗底回的外毛细胞,也导致内毛细胞的丢失,所造成的听力损失在32kHz处较1%组严重。结论 DMSO对毛细胞的损伤存在剂量依赖性,损伤程度自耳蜗底回向顶回逐渐减轻。     

0～6岁听力损失儿童短纯音诱发的听性脑干反应研究

目的比较听力损失儿童短纯音听性脑干反应（auditory brainstem response，ABR）反应阈与40Hz听觉事件相关电位（auditory event-related potentials，AERP）及短声ABR反应阈的相关性，评价短纯音ABR在儿童听力评估中的应用。方法应用SmartEP听觉诱发电位仪在0～6岁听力损失儿童中记录短声、短纯音ABR及40 Hz AERP的反应阈，共43例85耳（男／女=27／16）。结果0．5、1、2kHz短纯音ABR反应阈与40 Hz AERP反应阈的线性相关系数分别为0．84、0．80、0．80，反应闯之差分别为3．6±12．2、5．9±14．8、1．7±13.7dB。0．5、1、2、4kHz短纯音ABR反应阈与短声ABR反应阈的线性相关系数分别为0．81、0．89、0．94、0．91，反应阈之差分别为6．6±13．4、0．2±10．7、1．5±8．1、4．2±10．2dB。2kHz、4kHz短纯音反应阈的平均值与短声ABR反应阈的线性相关系数为0．93，反应阈之差为2．8±8．3dB。结论短纯音ABR的反应阈可作为一种儿童听力评估的方法。     

同步多频听觉稳态诱发反应与听性脑干诱发电位相关性研究

目的探讨同步多频听觉稳态诱发反应(auditory steady-state responses to multiple simultaneous stimuli,MSS-ASSR)与听性脑干诱发电位(auditory brainstem response audiometry,ABR)的关系。方法受试者为不同程度听力损失的儿童70名(140耳),年龄范围为3月龄～6岁。测试状态为水合氯醛镇静睡眠。仪器采用美国INTELLEGENT HEARING的诱发电位仪,MSS-ASSR及ABR测试的软件分别为SMART ASSR和SMART EP,刺激声信号的载波频率为0．5kHz、1kHz、2kHz及4kHz。左耳上述各个载波频率的调制频率分别为77Hz、85Hz、93Hz、101Hz,右耳为79Hz、87Hz、95Hz、103Hz。测试时,双耳八个调幅调制声信号经ER-3A标准插入式耳机同时给出。ABR的刺激声为短声,极性为交替波,刺激速率为19．3次／分,耳机也是ER-3A插入式耳机。受试儿先进行ABR测试、然后进行MSS-ASSR的测试,分别以降10升5法得出二者的反应阈。将MSS-ASSR 0．5kHz、1kHz、2kHz和4kHz的反应阈与ABR反应阈比较,以SPSS 10．0软件进行相关性分析。结果除去58耳ABR无反应外,剩余82耳ABR反应阈与MSS-ASSR 0．5kHz、1kHz、2kHz、4kHz的反应阈相关性具有显著性意义(P=0．000)。Pearson相关系数分别为0．757,0．854,0．906,0．912。结论MSS-ASSR作为儿童听力定量诊断的客观方法有很大的临床应用价值。     

正常青年人短纯音ABR和ASSR的相关性研究

目的比较正常青年人短纯音听性脑干反应（auditory brainstem response，ABR）和听性稳态反应（auditory steady-state response，ASSR）反应阈的差异及相关性。方法对10名（20耳）听力正常青年人进行短纯音ABR和ASSR反应阈测试，分别记录0．5．1、2和4 kHz的反应阈，比较这两种不同测试方法所得反应阈的特点及相关性。结果短纯音ABR和ASSR反应阈无显著性差异（P〉O．05），两者在0．5、1、2和4 kHz处的相关系数分别为0．49、0．52．0．64和0．76。结论正常青年人短纯音ABR反应阈和ASSR反应阈存在一定的相关性，高频处的相关性较低频好。     

不同放射剂量及时间对Balb/c小鼠畸变产物耳声发射和听性脑干反应的影响

目的　探讨不同剂量放射线照射及时间对小鼠畸变产物耳声发射（distortion product otoacoustic emission,DPOAE）、听性脑干反应（auditory brainstem response,ABR）的影响。方法 选取70只健康的Balb/c小鼠随机分成4组,对照组和3个实验组,实验组分别给予一次性8、12、16 Gy放射线剂量的照射,每个实验组随机分成2个小组,分别在照射后第3、7天对小鼠行DPOAE及ABR检测。结果　实验组小鼠分别接受8、12、16 Gy照射剂量后第3天DPOAE幅值与对照组比较无明显改变（P >0.05）;照射后第7天不同照射剂量组小鼠8、10、12 kHz的DPOAE幅值均较正常对照组小鼠显著降低（P <0.05）;正常对照组与各照射组小鼠的DPOAE幅值随着剂量的增加依次逐渐降低,在8、10、12 kHz有统计学意义（P <0.05）,在4、6 kHz无统计学意义（P >0.05）。分别给予小鼠8、12、16 Gy放射剂量后行ABR检测发现照射后第3天反应阈出现短暂的提高,照射后第7天反应阈恢复正常,呈波动性改变,照射第3天反应阈的改变与对照组比较有统计学意义;I、II潜伏期在照射后第3天较正常对照组时间显著延长（P <0.05）,在照射后第7天潜伏期恢复正常,与对照组比较没有明显改变（P >0.05）。 结论　放射线一次性照射后第7天可导致小鼠高频听功能出现损伤,但是耳蜗以上的听觉神经通路可能是短暂的可逆性功能障碍。     

68例感音神经性耳聋患者ASSR测试听阈与ABR测试V波反应阈的相关性研究

目的旨在探讨ASSR与ABR在诊断感音神经性耳聋中的相关性。方法68例临床诊断为感音神经性耳聋患者分别行0．5kHz，1kHz，2kHz，4kHzASSR测试及ABR测试，进行不同耳别、不同测试频率ASSR阈值与不同耳别ABRV波反应阈之间的相关分析。结果除了0．5kHz ASSR阈值与ABRV波反应阈的相关系数低而无显著意义外，1kHz，2kHz，4kHz ASSR阈值均与ABRV波反应阈有极显著性相关（P〈0．01），且随着测试频率的递增两者的相关系数随之增加，尤其是4kHz ASSR与ABRV波相关系数达到0．95以上（P〈0．01）。结论ASSR诊断感音神经性耳聋是可靠客观的，具有频率特性，可弥补ABR测试在诊断耳聋疾病中的频率局限性。     

小鼠内耳圆窗基因导入的实验研究

目的研究携带增强型绿色荧光蛋白（enhanced green fluorescent protein,EGFP）腺病毒（Ad-EG-FP）经由小鼠耳后圆窗径路导入内耳的可行性,分析EGFP在耳蜗内的表达特点。方法 19只健康的8～9周龄C57BL/6J雄性小鼠随机分为三组：Ad-EGFP组7只,人工外淋巴液组6只,两组通过耳后切口圆窗径路注射,分别导入Ad-EGFP和人工外淋巴液;空白对照组6只,未予处理。各组均于术前3日和术后7日行听性脑干反应（ABR）检查;术后7日取出耳蜗于荧光显微镜下观察EGFP在内耳的分布并行免疫组化观察EGFP在基底膜的表达。结果 3组动物术前ABR反应阈差异无统计学意义（P〉0.05）,术后7日,Ad-EGFP组ABR反应阈为62.86&#177;9.94dBSPL,人工外淋巴液组ABR反应阈为60.83&#177;9.70dBSPL,均较术前（37.86&#177;8.59和34.16&#177;8.04dBSPL）及空白对照组（40.83&#177;8.61dBSPL）高（P值均〈0.05）;空白对照组实验前后ABR反应阈无变化,Ad-EGFP组与人工外淋巴液组术后7天ABR反应阈差异无统计学意义（P值均〈0.05）。Ad-EGFP组Ad-EGFP导入后在基底膜上可见EGFP呈广泛表达,人工外淋巴液组和空白对照组基底膜未见荧光表达。结论外源性基因可经内耳圆窗导入并在耳蜗基底膜上广泛表达。     

短纯音诱发的听性脑干反应测试中声诱发短潜伏期负反应研究

目的 总结在有听力损失儿童中行短纯音诱发的听性脑干反应(tbABR)测试时记录到的声诱发短潜伏期负反应(acoustically short latency negative response,ASNR)的特点.方法 在有听力损失的0～6岁儿童中应用SmartEP听觉诱发电位仪记录短声和短纯音ABR的反应阈,在记录到ASNR的受试者中分析其反应阈和潜伏期.结果 在所有80受试耳中共7耳(8.75%)在cABR测试中引出ASNR,40耳(50%)在tbABR测试中引出ASNR,其中1 kHz引出率最高(37耳,46.25%),2 kHz次之(25耳,31.25%).引出ASNR者ABR波V反应阈最低65 dB nHL,ASNR反应阈最低80 dB nHL.0.5、1、2和4 kHz短纯音诱发的ASNR潜伏期分别为6～8、5～7、3～5、3～4 ms.随刺激强度的增加,其潜伏期缩短.结论 有听力损失的儿童tbABR测试中可以记录到AS-NR,但不影响以波V反应阈评估听力.     

Vestibular and cochlear ototoxicity of topical antiseptics assessed by evoked potentials

OBJECTIVES/HYPOTHESIS: To evaluate and compare the effect of chlorhexidine gluconate, povidoneiodine, and alcohol-three antiseptics used before ear surgery-on the function of the vestibular and cochlear parts of the sand rat's inner ear. The assessment of damage is based on the recording of vestibular evoked potentials (VsEPs) and auditory brainstem response (ABR). STUDY DESIGN: Prospective controlled animal study. METHODS: Fat sand rats were randomly assigned to five different groups, each receiving topical application of a different agent: saline (control), gentamicin (ototoxic control), chlorhexidine, povidone-iodine, and alcohol. Right-side total labyrinthectomy was performed, and a polyethylene tube was inserted into the left (contralateral) middle ear. After baseline recordings were taken of VsEPs and ABR, each animal received five consecutive daily applications of the specific agent into the left middle ear. Three days after the fifth application, evoked potential recordings (VsEPs and ABRs) were repeated and compared with baseline measurements. RESULTS: Administration of saline affected neither VsEPs nor ABR. In contrast, as expected, neither of these responses could be recorded after gentamicin application. After application of chlorhexidine all waves disappeared in all sand rats. Alcohol caused the waves to disappear in some of the animals only. Povidone-iodine did not affect VsEP recordings and had only a small effect on ABR. CONCLUSIONS: Chlorhexidine and alcohol had a clear toxic effect on the vestibular and cochlear function of the inner ear of the sand rat, whereas povidone-iodine did not. Thus, taking into consideration that this is an animal study, it appears that povidone-iodine might be preferable to the other agents tested in disinfecting ears with a perforated tympanic membrane.     

Effect of topically applied povidone-iodine on transient evoked otoacoustic emissions in guinea pigs

The possible cochlear toxicity of topically applied povidone-iodine solution was investigated in guinea pigs by measuring transiently evoked otoacoustic emissions (TEOAEs). Seven adult pigmented guinea pigs (14 ears) with a normal acoustic pinna reflex were used. After the baseline TEOAE measurements, 0.1 mL of povidone-iodine solution was applied transtympanically into the middle ear in the study group. Saline solution and gentamicin were used as negative and positive control, respectively. TEOAE measurements were repeated on the 10th day, and four weeks after the first application. Tympanometric measurements were also carried out for both ears of all animals at the end of the study. Responses in all ears, which had povidone-iodine applied to them, disappeared in a way similar to those recorded in gentamicin-treated ears. Tympanometric measurements at the end of the study showed 'type A' tympanograms in all ears of all animals. The present study showed that povidone-iodine could have a cochleotoxic effect in guinea pigs. A study in humans with TEOAE before and after middle-ear surgery, where povidone-iodine can reach into the middle-ear cavity, may be useful for evaluating this result for clinical practice.     

Auditory nerve and brainstem-evoked responses before and after middle ear corrective surgery

Auditory brainstem response (ABR) recordings were made in two groups of middle ear pathology--middle ear effusion and otospongiosis before and after rehabilitation surgery. The ability of ABR recordings to quantify the hearing improvement (threshold and latency) after insertion of ventilating tubes and after stapedioplasty is demonstrated.     

Predictors for postoperative otorrhea following tympanostomy tube insertion.

This controlled prospective study was designed to identify predictors for postoperative otorrhea among 157 children with chronic otitis media with effusion undergoing myringotomy and tympanostomy tube placement (intubation). Ear canal disinfection with 70% alcohol or povidone-iodine did not significantly alter ear canal or middle ear effusion bacteriology, or the frequency of otorrhea during the first 7 days after surgery. However, the risk of otorrhea on the second postoperative day was significantly increased by the presence of a bacterial pathogen in the ear canal (relative risk, 2.4), or in the middle ear effusion (relative risk, 1.9), and the presence of inflamed middle ear mucosa at surgery (relative risk, 1.7) after controlling for age, preoperative antibiotics, and postoperative ototopical cortisporin treatment. The use of systemic antimicrobial treatment in children with inflamed middle ear mucosa at surgery or whose ear canal or middle ear effusion cultures are positive for bacterial pathogens might reduce the incidence of post-operative otorrhea in children undergoing intubation for chronic otitis media with effusion.     

腭裂修复术对中耳影响的初步探讨

目的　探讨腭裂修复术与中耳功能改善的关系。方法　对 35例 (70耳 )腭裂患者分别于术前、术后 1周进行ABR听阈测试 ;对能配合的 2 3例 (4 6耳 )腭裂患者分别于术前、术后 1周及术后 3月进行纯音听阈测试及鼓室导抗测试。结果　经统计学配对t检验和x2 检验 ,腭裂术前、术后ABR听阈及纯音听阈无显著差异 (P >0 .0 5 ) ;鼓室导抗图术前与术后 1周有非常显著差异 (P <0 .0 1)、术前与术后 3月无显著性差异 (P >0 .0 5 )。结论　腭裂修复术对中耳功能的影响需要一定的时间 ,因此 ,术后应长期追踪随访 ,及时发现并治疗中耳疾患 ,提高听力 ,改善语言功能     

Effect of middle ear fluid on sound transmission and auditory brainstem response in guinea pigs

Combined measurements of middle ear transfer function and auditory brainstem response (ABR) in live guinea pigs with middle ear effusion (MEE) are reported in this paper. The MEE model was created by injecting saline into the middle ear cavity. Vibrations of the tympanic membrane (TM), the tip of the incus, and the round window membrane (RWM) were measured with a laser vibrometer at frequencies of 0.2-40?kHz when the middle ear fluid increased from 0 to 0.2?ml (i.e., full fill of the cavity). The click and pure tone ABRs were recorded as the middle ear fluid increased. Fluid introduction reduced mobility of the TM, incus and RWM mainly at high frequencies (f?>?1?kHz). The magnitude of this reduction was related to the volume of fluid. The displacement transmission ratio of the TM to incus varied with frequency and fluid level. The volume displacement ratio of the oval window to round window was approximately 1.0 over most frequencies. Elevation of ABR thresholds and prolongation of ABR latencies were observed as fluid level increased. Reduction of TM displacement correlated well with elevation of ABR threshold at 0.5-8?kHz. Alterations in the ratio of ossicular displacements before and after fluid induction are consistent with fluid-induced changes in complex ossicular motions.     

A Model of Spontaneous Chronic Otitis Media with Effusion in Mice with ENU Induced Mutations

Background Chronic otitis media (COM) is a significant clinical problem. Understanding the mechanisms of COM is critical for its control and treatment. However, little is known of the processes leading to COM as a result of lack of animal models of N-ethyl-N-nitrosourea (ENU) induced mutations in otitis media with effusion (OME). Methods Otoscopy and auditory brain response(ABR) evaluation were carried out under sedation in Nmf391 nmf/nmf mice of 2, 4, 6 and 8 months of age. The mice were killed for study of middle and inner ear pathology. Results Tympanic membrane visualization and ABR thresholds in 1- to 8-month-old Nmf391 nmf/nmf mice showed spontaneous OME and inner ear diseases in approximately 100% of the animals.The significant elevation of ABR thresholds suggested a sensorineural component in hearing loss in addition to the conductive loss. Middle and inner ear histology showed various degrees of outer hair cells loss and middle ear inflammation in all the mice, but no inflammation cells in the inner ear. The ABR threshold at 32 kHz was significantly elevated. Conclusions This study shows histopathologic changes in the Nmf391 nmf/nmf mouse model of COM with effusion that have not been reported in human COM. This ENU induced mutation model of COM will be valuable for the characterization of middle ear inflammation and inner ear disease processes that are induced by middle ear infections. We propose that COM with effusion in this ENU induced mutation model is the cause of the cochlea hair cells damage.     

Cochlear ototoxicity of chlorhexidine gluconate in cats

Summary Chlorhexidine gluconate is a derivative of chlorhexidine and is a popular desinfectant with a strong bactericidal action that is widely used for preoperative sterilization in ear surgery. The purpose of this investigation is to ascertain the potential ototoxity of this agent. After topically applying chlorhexidine gluconate solutions to the middle ear cavities of 12 cats, we observed the excised cochleas using both scanning and transmission electron microscope studies. Either 0.05% or 2% chlorhexidine gluconate solutions were infused into the right ear of the test animal through one of two tubes chronically installed in the tympanic bullae. The left ears were utilized as controls and were infused with sterilized physiological saline. The solutions were administered once every other day for three separate infusions. Nine animals were decapitated 7 days after the third application, while the other three animals were sacrificed at 4 weeks. In the 2% chlorhexidine group, we found that hair cells in the organ of Corti had degenerated and had lost their hair bundles over a wide range. This pathology was more marked in the lower cochlear turns. In the animals sacrificed at 4 weeks, the injuries present seemed to have progressed. Even at a clinical concentration of 0.05%, chlorhexidine caused intracellular degeneration but with little surface damage. Our findings would suggest a cause of hearing loss when chlorhexidine is used clinically in the ear.     

The round window as access route for agents injurious to the inner ear

The ototoxicity of 50% propylene glycol, 70% isopropyl alcohol, 2% acetic acid, Otic Domeboro solution (Miles Pharmaceuticals, West Haven, CT), 1% Gentian violet (Purepac Pharmaceutical, Elizabeth, NJ), Vosol Otic solution (Wallace Laboratories, Cranbury, NJ), Genoptic Ophthalmic solution (Allergan Pharmaceuticals, Irvine, CA), Cortisporin Otic suspension (Burroughs Wellcome, Greenville, NC), Coly-Mycin S Otic (Parke-Davis, Rochester, MI), and Pyocidin Otic (Berlex Laboratories, Cedar Knolls, NJ) was studied in rats according to their effect on the latencies of the second peak of the auditory brainstem responses (ABR) at different sound pressure levels. The substances were instilled into the round window (RW) niches of rats, and the ABR to 1-kHz and 6-kHz tonebursts were obtained, 30 minutes, two hours, and 1 week after exposure. For all substances except isopropyl alcohol and propylene glycol, which evidently quickly penetrated the RW, approximately two hours of exposure were required before inner ear function was affected. The ototoxic effect of the antibiotic drugs was to some degree reversed with time, whereas the recorded potentials for antiseptics such as 1% Gentian violet, 2% acetic acid, and Otic Domeboro indicate that they caused severe damage to inner ear function. Some increases in latencies were also noted after exposure to propylene glycol and isopropyl alcohol, except when the latter was quickly withdrawn from the RW niche.     

Antiadhesive effect of bioresorbable polylactide film in abraded middle ear mucosa

Background and objectivePolylactide film (PLF) is used to prevent postoperative peridural adhesion in spinal surgery. Up until now, the antiadhesive effect of bioresorbable PLF in ear middle surgery has not been reported. The purpose of this study is to evaluate the antiadhesive effect of PLF in guinea pigs serving as a model for middle ear mucosal trauma.Materials and methodsThe animals were divided into two groups: the PLF group and the silastic sheeting group. There were seven guinea pigs (fourteen ears) in both groups. Under aseptic conditions, the middle ear mucosa was abraded using a pick inserted transbullaly. A PLF or silicone sheet was then placed into the guinea pigs’ middle ear cavities. The auditory brainstem responses (ABRs) were assessed preoperatively and at three weeks postoperatively while the animals were under general anesthesia. A histopathological study was performed 3 weeks after the operation.ResultsThe difference between the ABR results before the operation and three weeks postoperatively were not statistically significant. The adhesion formation did not appeared in either group. Prominent fibrous capsule formation and inflammation were observed in the silastic sheeting group, but not in the PLF group. Mild fibrous thickening of regenerated mucosa was observed in the PLF group.ConclusionFrom our results, bioresorbable PLF is nonototoxic and biocompatible with the guinea pig's middle ear cavity by short-term evaluation. Further long-term evaluation study is necessary before clinical application.