[Clinical analysis of cochlear implants related inflammatory reaction].

OBJECTIVE: This article discusses the clinical features and treatment methods of the inflammatory reaction associated with cochlear implants, and analyzes the possible pathogenesis and related factors. METHOD: We retrospectively analyzed postoperative inflammation cases from February 2002 to October 2013 among 825 cochlear implantation patients. Their symptoms, signs and treatment processes and outcomes were described and summarized. RESULT: Incidence of implants related inflammatory reaction was 1.58%. The onset time ranged from 2 months to 11 years post-operatively. There were 6 cases of implants related non-infectious inflammation, with an incidence of 0.73% (6 of 825). Post auricular swelling and subcutaneous non-infectious discharge were found in all these 6 cases. Pressure dressing with bandage and steroid, antihistamine medications was effective. There were 7 cases of post auricular infection, with an incidence of 0.85%, resulted from flap trauma or acute otitis media. Antibiotics and drainage was used for them to treat the infection, and rotation scalp flaps were used to cover the exposed device. Five of these cases were cured but cochlear implants had to be removed out in the other 2 cases of staphylococcus aureus infection. CONCLUSION: Cochlear implantation surgery is safe and effective for profound deafness. However, the implants-related non-infectious and infectious inflammatory reaction impacts the effect of cochlear implants, even lead to removal of the implants.

[The impact of malleus processing in ossicular chain reconstruction on the therapeutic effect in patients with tympanosclerosis].

OBJECTIVE: To investigate the effect of different malleus treatments on the postoperative efficacy in the tympanosclerosis patients receiving ossicular chain reconstruction. METHOD: Fifty-nine patients (62 ears) with tympanosclerosis were treated by ossicular chain reconstruction. All the patients were divided into three groups, including malleus removal group (A, 24 ears), retaining only the malleus handle group (B, 18 ears) and the intact malleus group (C, 20 ears). All the patients were followed up 3 months pre-operation, 3 months and 1 year post-operation by audiometric measurement (the average hearing threshold at 0.5, 1.0, 2.0 kHz HI). Tympanic membrane was examined by ear endoscope. RESULT: The pre-operation mean air bone gap (ABG) in these groups were 40.07 +/- 77.56 dB, 37.31 +/- 76.45 dB, and 36.75 +/- 76.72 dB, among which the difference had no statistical significance (P > 0.05). At 3 months after operation, the ABG in all cases was improved at 0.5, 1 and 2 kHz. The difference of ABG improvement among these three groups had no statistical significance (P > 0.05). One year after surgery, the ABG of the three groups were decreased by 17.92 +/- 9.28 dB, 16.76 +/- 5.19 dB and 10.58 +/- 7.38 dB respectively. The hearing improvement in group C is less than the other two groups (P = 0.03, P = 0.016). The difference of hearing improvement between group A and group B had no statistical significance(P > 0.05). Group A and group B each have one case of tympanic membrane perforation and artificial ossicle falling off. CONCLUSION: The operating processes of malleus in ossicular chain reconstruction of patients with tympanosclerosis were introduced. In terms of short-term efficacy, the three groups showed no significant difference. However, the long-term efficacy of the patients in the group A and group B were better compared with the group C.

[Normal anatomy of aditus of antrum and antrum on high-resolution CT and three-dimensional reconstruction].

OBJECTIVE: To study the normal anatomy of aditus of antrum and antrum on the high-resolution CT (HRCT) and the three-dimensional reconstruction, testing the normal range. And comparison was carried out according to the age, sex and side. METHOD: Ninety cases were randomly selected without ear lesions. Scanning were taken in sagittal, transverse and coronal planes on HRCT respectively. The structure of aditus and antrum was displayed by three-dimensional reconstruction. The left-right distances and up-down distances, antero-posterior distances were measured and analyzed. RESULT: The image of antrum varied with age, while aditus remained constant on the HRCT and the three-dimensional reconstruction. The average of left-right distance of aditus was (5.19 +/- 1.39) mm, and the average of up-down distance of aditus was (5.74 +/- 1.16) mm. The average of left-right distance of antrum was (8.27 +/- 1.41) mm (<6 years old) and (5.41 +/- 1.32) mm (> or = 6 years old). The average of up-down distance of antrum was (11.78 +/- 1.65) mm (<6 years old) and (9.91 +/- 2.04) mm (> or = 6 years old). The average of antero-posterior distance of antrum was (12.25 +/- 1.23) mm (<6 years old) and (10.05 +/- 1.69) mm (> or = 6 years old). No statistically significant differences were seen in left-right distance of aditus by age, sex and side (P > 0.05). Significant differences in up-down distance of aditus was found between male and female, and the distance in male was greater than that in female (P < 0.05). Statistically significant differences were seen in left-right distance and up-down distance, antero-posterior distance of antrum by age (P < 0.05), but no statistically significant differences by sex or side (P > 0.05). CONCLUSION: Imaging of aditus ad antrum is relatively constant in the normal persons, while the aditus is more diverse. Significant gender differences were seen in up-down distance. There were significant differences in left-right distance, up-down distance, and antero-posterior distance of aditus among all age groups.

[Applied anatomy of facial recess and posterior tympanum related to cochlear implantation].

OBJECTIVE: To investigate the related parameters of temporal bone structure in the surgery of cochlear implantation through facial recess approach so as to offer a theoretical reference for the avoidance of facial nerve injury and the accurate localization. METHOD: In a surgical simulation experiment, twenty human temporal bones were studied. The correlation parameters were measured under surgical microscope. RESULT: Distance between suprameatal spine and short process of incus was (12.44 +/- 0.51) mm. Width from crotch of chorda tympani nerve to stylomastoid foramen was (2.67 +/- 0.51) mm. Distance between short process of incus and crotch of chorda tympani nerve was (15.22 +/- 0.83) mm. The location of maximal width of the facial recess into short process of incus, crotch of chorda tympani nerve were (6.28 +/- 0.41) mm, (9.81 +/- 0.71) mm, respectively. The maximal width of the facial recess was (2.73 +/- 0.20) mm. The value at level of stapes and round window were (2.48 +/- 0.20 mm) and (2.24 +/- 0.18) mm, respectively. Distance between pyramidalis eminence and anterior round window was (2.22 +/- 0.21) mm. Width from stapes to underneath round window was (2.16 +/- 0.14) mm. CONCLUSION: These parameters provide a reference value to determine the position of cochlear inserting the electrode array into the scale tympani and opening facial recess firstly to avoid potential damage to facial nerve in surgery.

[Applied anatomy of scala tympani inlet related to cochlear implantation].

OBJECTIVE: To investigate the related parameters of the temporal bone structure for determining the position of implanting electrode into the scala tympani in cochlear implantation surgery through the facial recess and epitympanum approach. METHODS: In a surgical simulation experiment, 20 human temporal bones were studied and measured to determine the related parameters of the temporal bone structure. RESULTS: The distance 5.91∓0.29 mm between the short process of the incus and the round window niche, 2.11∓0.18 mm between the stapes and the round window niche, 6.70∓0.19 mm between the facial nerve in the perpendicular paragraph and the round window niche, 2.22∓0.21 mm from the pyramidal eminence to the round window, and 2.16∓0.14 mm between the stapes and the round window. The minimal distance between the implanting electrode and the vestibular window was 2.12∓0.19 mm. The distance between the cochleariform process and the round window niche was 3.79∓0.17 mm. The position of the cochlear electrode array insertion into the second cochlear turn was 2.25∓0.13 mm under the stapes. The location of the cochlear electrode array insertion into the second cochlear turn was 2.28∓0.20 mm inferior to the pyramidal eminence. CONCLUSION: These parameters provide a reference value to determine the different positions of cochlear electrode array insertion into the scale tympani in different patients.

[Cochlear implantation and rehabilitation in prelingually deafened adolescents and young adults].

OBJECTIVE: To investigate the outcomes of prelingually deafened adolescents and young adults receiving cochlear implantation (CI). METHODS: Thirty-three patients with prelingual deafness aged 7-33 years at the time of CI were followed up for 4 years. The Speech Discrimination Score (SDS) was tested using disyllabic words and short sentences with close-set and open-set, respectively. RESULTS: After appropriate mapping, sound field audiometry with warble tone showed that the warble tone threshold average (WTA) of the patients reached 25-41 dBHL, with a mean threshold of 28.62∓2.37 dBHL. At 1 year after the operation, the mean value of SDS was 70.03% in close-set word list with lip-reading and 61.18% without lip-reading, and was improved to 82.12% and 72.67% at 4 years, respectively. In open-set word list, the mean value of SDS was 77.94% with lip-reading and 67.85% without lip-reading. The safety and the benefits-cost evaluation of CI for prelingually deafened school age children and adolescents had been recognized by 90.9% of the families involved. CONCLUSION: These patients can obtain appropriate speech discrimination scores with improved quality of life after CI.

[The expressions of alpha-enolase in the nasopharyngeal cancer tissue].

OBJECTIVE: To study the meaning of expressions of ENO1 in the nasopharyngeal cancer tissue. METHOD: By using SP immunohistochemical methods. RESULT: The positive expressions for ENO1 were 60.0% in the nasopharyngeal cancer tissues,significantly higher than that (27.5%, 11/40) of in inflammatory nasopharyngeal mucosa (P<0.05). The positive expression rate of ENO1 protein in stage T1 + T2 + T3 was higher than that of in patients with T4 (chi2 = 11.424, P<0.05). But there was no significant relationship between expression of ENO1 and lymph node metastasis and postradiotherapy distant metastasis (P>0.05). CONCLUSION: The results show that ENO1 over expression may play a important role in cell proliferation and canceration of nasopharyngeal cancer.

[Study of three-dimensional speech chart by time-frequency analysis in Chinese Mandarin Monosyllabic word phonemes].

OBJECTIVE: To investigate the physical characteristic of Chinese Mandarin Monosyllabic word phonemes by the time-frequency analysis. METHODS: Manufactured and study the three-dimensional speech chart which was on the basic of information of the time-frequency analysis in 40 monosyllabic words with the SigmaPlot 9.0 and Matlab 7.0 software. RESULTS: The mean value of basic frequency in 40 monosyllabic words was between 220 to 320 Hz area, and the mean value of four groups has significant difference by t-test. It is indicated by time-frequency analysis that the characteristics vary according to the tone of monosyllabic words. With the change of time, the various frequencies and its intensity of tone first remain basically unchanged, the curve is horizontal type; the different frequencies of tone second gradually tend to high-frequency direction, the graph is upward-type, additionally, the intensity of some tone drops little; the divers frequencies of tone third firstly deflect to low-frequency areas, then increasingly deviate to high-frequency direction of bias after maintaining a period of time, the figure is v-type, intensity changes are concave-shaped; The various frequencies of tone fourth deviate from high-frequency to low-frequency areas, and its intensity drops sharply, the graph is decreased type. CONCLUSION: Through time-frequency analysis and three-dimensional speech chart observation, we consider that the physical characteristic of Chinese Mandarin Monosyllabic word phonemes mainly reflects the frequencies and intensity change with time.

[Therapeutic effect of ossicular reconstruction with bioceramic or porous macromolecular polyethylene partial ossicular replacement prosthesis in patients with tympanosclerosis].

OBJECTIVE: To evaluate the effect of ossicular reconstruction with partial ossicular replacement prosthesis (PORP) in patients with tympanosclerosis. METHODS: The data of 31 cases of tympanosclerosis treated between 1992 and 2009 were reviewed. Of the 31 patients, 17 (17 ears) underwent ossicular reconstruction with porous macromolecular polyethylene PORP, and 14 (14 ears) with bioceramic PORP. All the patients were followed up for 3-24 months. RESULTS: Significant improvement was found in postoperative speech frequency (500, 1000, 2000 Hz) pure tone average (PTA) and air-bone gap (ABG) (P < 0.05) after the treatments without statistically significant differences between the two groups (P > 0.05). CONCLUSION: Porous macromolecular polyethylene and bioceramic are valuable ossicular prosthesis for tympanosclerosis.

[Cochlear implantation in patients with Waardenburg syndrome type II].

OBJECTIVE: To describe the multi-channel cochlear implantation in patients with Waardenburg syndrome including surgeries, pre and postoperative hearing assessments as well as outcomes of speech recognition. METHOD: Multi-channel cochlear implantation surgeries have been performed in 12 cases with Waardenburg syndrome type II in our department from 2000 to 2008. All the patients received multi-channel cochlear implantation through transmastoid facial recess approach. The postoperative outcomes of 12 cases were compared with 12 cases with no inner ear malformation as a control group. RESULT: The electrodes were totally inserted into the cochlear successfully, there was no facial paralysis and cerebrospinal fluid leakage occurred after operation. The hearing threshold in this series were similar to that of the normal cochlear implantation. After more than half a year of speech rehabilitation, the abilities of speech discrimination and spoken language of all the patients were improved compared with that of preoperation. CONCLUSION: Multi-channel cochlear implantation could be performed in the cases with Waardenburg syndrome, preoperative hearing and images assessments should be done.

[Tumor-targeted human telomerase reverse transcriptase promoter/tk gene therapy against human nasopharyngeal carcinoma cells in vitro].

OBJECTIVE: To investigate the targeted killing effect of human telomerase reverse transcriptase promoter (hTERTp)/tk gene on human nasopharyngeal carcinoma (NPC) cells. METHODS: The recombinant plasmid hTERTp/tk/pGL3 was transfected into human NPC HNE1 cells and the expressions of TK and telomerase were investigated. The targeted killing effect induced by hTERTp/tk on HNE1 cells was assessed using RT-PCR and MTT assay. RESULTS: TK gene expression was detected in HNE1 cells transfected by hTERTp/tk/pGL3, and the cells showed reduced telomerase and hTERT expression as compared with the control cells. hTERTp/tk/pGL3 resulted in target killing of HNE1 cells but not of the normal control cells. The tumor cell-killing effect of hTERTp/tk/pGL3 was slightly milder than that of the positive control CMV/tk/pGL3 that produced nonselective cell killing. CONCLUSION: hTERTp/tk, a tumor-specific expression system, allows targeted tumor cell killing and reduces the activity of telomerase in NPC cells in vitro.

[Clinical analysis of 118 patients with tympanosclerosis].

OBJECTIVE: To study the incidence of tympanosclerosis (TS) and the major risk factors of hearing loss. METHODS: A total of 118 TS patients (137 ears) were compared with 265 patients with chronic otitis media (COM) (311 ears) for gender, age and course of disease. The disease regions and hearing loss of the TS patients were analyzed. RESULTS: TS showed higher prevalence in women of older ages. Sclerosis was seen most frequently in the tympanic membrane, followed by the malleus, incus, incudomalleolar joint, other regions, ariticulus incudostapedius and stapes. The patients with sclerosis or deterioration in the ossicular chain had worse hearing loss than the other patients. Carhart notch occurred in 45 ears (32.85%), an incidence similar to that of inverted "V"-shaped curve of air-conduction audiometry near 2 kHz (47 ears, 34.31%). The factors contributing to the hearing loss, listed in the order of their importance, included pathologies in the incus, malleus, incudomalleolar joint, ariticulus incudostapedius, stapes, other regions, tympanic membrane, and gender. CONCLUSIONS: Female patients may had increased risk of TS. The presence of Carhart notch and inverted "V"-shaped curve in air-conduction audiograph may indicate myringosclerosis or ossicular chain sclerosis. Abnormal ossicular chain is the leading factor contributing to hearing loss.

[Experience of 76 cases of large vestibular aqueduct syndrome, clinical diagnosis and treatment].

OBJECTIVE: To explore the disease incidence, clinical symptoms, prevention and treatment measures of the large vestibular aqueduct syndrome (LVAS). METHOD: Retrospective analyse the medical history, hearing, vestibular function examination and treatment of 76 LVAS patients who were diagnosed in our department of Otolaryngology from 2002 to 2008. RESULT: Most patients (93.4%) showed sensorineural hearing loss. Part of patients (61.8%) showed air-bone conduction gap in low frequency. The hearing loss of 43 ears is > 40-60 dB HL, > 60 -80 dB HL 47 ears, > 80 dB HL 62 ears. Decline curve is the characteristic of the Audiogram. The decline in high-frequency 112 ears, flat curve in 29 ears, island hearing in 11 ears. Forty-six patients were conducted the vestibular function examination, which showed low vestibular function. Tympanogram showed that 141 ears are type A, 11 ears are type C. High-resolution CT scan revealed that vestibular aqueduct minimum diameter is 2.2 mm and the largest is 6.2 mm, with a wide opening and deep narrower, and showed the "triangle" or "flared". Forty-two cases of this group were simple dilatation of the vestibular aqueduct, and no large vestibular semicircular canal malformation or cochlear malformation. There was no intellectual and other development disorders. In accordance with the degree of hearing loss, 20 cases of patients restored hearing after drug treatment. Eleven were cases fit a suitable hearing aid and carried out the language rehabilitation training. Forty-five very severe patients were implanted the cochlear and mapping one month later. CONCLUSION: Fluctuative and progressive hearing loss is the main clinical symptoms of large vestibular aqueduct syndrome. The patients should be examined by high resolution CT scan of the temporal bone. There is no precise and effective treatment for the disease. It is very important for the deaf children who have residual hearing to fit hearing aids and carry out the language rehabilitation training as soon as possible. As for the patients who suffer from hearing loss severely and the hearing aid cannot achieve effective compensation, the cochlear implant should be considered.

[Cochlear implant in patients with congenital malformation of the inner ear].

OBJECTIVE: To summarize the clinical experience with multi-channel cochlear implantation in patients with inner ear malformations and evaluate and the outcomes of speech rehabilitation. METHODS: A retrospective study was conducted in 295 patients receiving cochlear implantation from 1998 to 2007, including 25 patients with large vestibular aqueduct syndrome (LVAS), 9 with Modini malformation, and 5 with common cavity deformity. All the patients received the Nucleus24 cochlear implants. In LVAS cases, 4 had Nucleus 24R (ST) implants, 8 had Contuor implants, 10 had Contuor Advance, and the remaining cases used Nucleus24(M) straight-electrode implants. RESULTS: Severe gusher appeared in 3 cases of LVAS, and perilymph fluctuation were seen in other 15 cases. Four patients with Mondini malformation and 2 with common cavity malformation also experienced severe gusher, but the electrodes were inserted smoothly in all the patients without postoperative facial paralysis or cerebrospinal fluid leakage. The hearing threshold in these patients was similar to that in patients with normal cochlear structure. After speech rehabilitation for over 6 months, the abilities of speech discrimination and spoken language improved in all the cases in comparison with the preoperative lingual functions. CONCLUSION: Multi-channel cochlear implantation can be performed in patients with inner ear malformation, but should not be attempted in patients with poor cochlear and cochlear nerve development. A comprehensive pre-operative radiographic and audiological evaluation is essential.

[Cochlear implantation in patients with large vestibular aqueduct syndrome].

OBJECTIVE: To evaluate the hearing and speech recognition in patients with large vestibular aqueduct syndrome undergoing multi-channel cochlear implantation. METHODS: From 2005 to 2008, multi-channel cochlear implantation surgeries were performed in 22 patients with large vestibular aqueduct syndrome. All the patients received multi-channel cochlear implantation through transmastoid facial recess approach. The postoperative outcomes of the patients were compared with those of 22 patients with non-malformed cochlear. RESULTS: Severe gusher occurred in 3 cases during the implantation, and perilymph fluctuation was found in another 15 cases, with a rate of anomalies of 81.8%. All the electrodes were totally inserted into the cochlear, and no facial paralysis or cerebrospinal fluid leakage occurred after the operation. The hearing threshold in these patients was similar to that in patients with normal cochlear receiving the implantation. After speech rehabilitation for over 6 months, all the patients showed improved hearing and verbal ability. CONCLUSION: Multi-channel cochlear implantation can be performed in patients with large vestibular aqueduct syndrome, but preoperative hearing assessment and radiographic examinations should be performed.

[Effect of surgical reconstruction of congenital aural atresia via the mastoid antrum approach: analysis of 48 cases].

OBJECTIVE: To assess the effect of surgical reconstruction of congenital aural atresia via the mastoid antrum approach and investigate method for preventing postoperative atresia of the reconstructed aural canal. METHODS: From 2000 to 2008, aural canal reconstruction and tympanoplasty was performed via the mastoid antrum approach. In 48 patients with congenital aural atresia (54 ears, including 45 ears of type II, 9 ears of type III). All the patients were followed-up for 18 months to assess the therapeutic effect. RESULTS: The mastoid antrum was located uneventfully for all the 54 ears, all showing ossicular chain anomalies involving most frequently the malleus and the incus followed by the upper structures of the stapes. Facial nerve abnormalities were seen in 23 ears (42.6%). Hearing improvement to over 20 dB was achieved in 45 ears (83.3%) and to over 25 dB in 25 ears (46.2%) one year later. CONCLUSION: The mastoid antrum approach for surgical reconstruction of congenital aural atresia is safe and reliable. Maintenance of the width of the aural canal and prevention of lateral healing of the transplanted tympanic membrane are crucial in the treatment of congenital aural atresia.

[Long-term results of endolymphatic sac decompression and endolymphatic-mastoid shunting for Meniere's disease].

OBJECTIVE: To investigate the efficacy of endolymphatic sac surgery for Meniere's disease, and compare the effects of endolymphatic sac decompression with endolymphatic-mastoid shunting. METHOD: Twelve patients(13 ears) undergoing endolymphatic-mastoid shunting and eleven patients (11 ears) undergoing endolymphatic sac decompression were retrospectively compared for hearing results and vertigo controlled rates. All of them have been followed up for more than two years after surgery. RESULT: According to Chinese Meniere's disease diagnosis and curative effect standard evaluation criteria published in 2006, for vertigo symptom of endolymphatic mastoid shunting group, 9 cases (69.2%) achieved grade A(completely controlled), 4 cases (30.8%) achieved grade B (fundamentally controlled). There were 8 cases (72.7%) with grade A, 2 cases (18.2%) with grade B and one case (9%) with grade C among 11 patients who received endolymphatic sac decompression. There was not statistically significant differences in postoperative speech pure tone average and vertigo controlled rate between the two groups. CONCLUSION: Endolymphatic sac decompression and endolymphatic-mastoid shunting are effective management with less complication for intractable Meniere's disease. Particularly, the vertigo symptoms were controlled significantly. Patients with Meniere's disease in advanced clinical stages may also be relieved.

Electrically evoked auditory nerve responses in the cochlea with normal outer hair cells.

As hybrid cochlear implant devices are increasingly used for restoring hearing in patients with residual hearing it is important to understand electrically evoked responses in cochleae having functional hair cells. To test the hypothesis that extracochlear electrical stimulation (EES) from sinusoidal current can provoke an auditory nerve response with normal frequency selectivity, the EES-evoked compound action potential (ECAP) was investigated in this study. Brief sinusoidal electrical currents, delivered via a round window electrode, were used to evoke ECAP. The ECAP waveform was observed to be the same as the acoustically evoked CAP (ACAP), except for a shorter latency. The input/output and intensity/latency functions of ACAPs and ECAPs were also similar. The maximum acoustic masking for both ACAP and ECAP occurred near probe frequencies. Since the masked tuning curve of a CAP reflects the frequency selectivity of neural excitation, these data demonstrate a highly specific activation of the auditory nerve, which would result in high degree of frequency selectivity. This frequency selectivity likely results from the cochlear traveling wave caused by electrically stimulated outer hair cells.

[Therapeutic effects of small fenestra stapedotomy with semiconductor diode laser: a comparison with microdrill].

OBJECTIVE: To compare the effects of small fenestra stapedotomy with semiconductor diode laser and microdrill in patients with otosclerosis. METHODS: Twenty-six patients (29 ears) undergoing stapedotomy with semiconductor diode laser and 19 patients (21 ears) with microdrill were compared for the hearing results and complication rates. RESULTS: No statistically significant differences were found in postoperative speech frequency and high frequency pure tone average in closing the air-bone gap between the two groups. The ears treated by stapedotomy with semiconductor diode laser showed significantly better preoperative minus the postoperative air-bone gap and milder dizziness. CONCLUSION: In spite of the good hearing outcomes in both groups, small fenestra stapedotomy with semiconductor diodelaser can achieve better results and reduce the incidence of complications.

[Therapeutic effect of insulin-like growth factor-1 injection into the inner ears through scala tympani fenestration on gentamicin-induced hearing loss in guinea pigs].

OBJECTIVE: To study the therapeutic effect of insulin-like growth factor-1 (IGF-1) injection into the inner ears through a scala tympani fenestration on sensorineural deafness in a guinea pig model of gentamicin-induced hearing loss. METHODS: Twenty guinea pigs with gentamicin-induced hearing loss were randomized equally into IGF-1 group and control group. In both groups, scala tympani fenestration was performed for injection of IGF-1 (10 microl) or artificial perilymphatic fluid (10 microl). Auditory brainstem responses (ABR) test was performed before and 7 and 14 days after surgery, respectively, and the cochlea was removed by decollation of 3 guinea pigs from each group after ABR test for observing the changes in the hair cells using scanning electron microscope. RESULTS: Significant reduction in the ABR response threshold (RT) occurred in IGF-1 group 7 and 14 days after the surgery, and on day 14, ABR RT showed significant difference between IGF-1 group and the control group. Scanning electron microscopy revealed severer damages of the hair cells in the control group, and in the IGF-1 group, finger-like microvilli was detected on the surface of the damaged hair cells. CONCLUSION: IGF-1 injection in the inner ear through the scala tympani fenestration may ameliorate the damages of the auditory function and relieve sustained toxicity of gentamicin in guinea pigs possibly by protection and partial repair of the damaged cochlea hair cells as well as protection of the afferent nerves.