The use of basic fibroblast growth factor to treat intractable Bell's palsy administered via transcanal endoscopic ear surgery.

PURPOSE: Facial nerve decompression surgery is an invasive procedure which has hitherto been the main option for patients with severe intractable Bell's palsy which is resistant to drug treatment. We have developed a new salvage treatment for such patients by using minimally invasive transcanal endoscopic ear surgery (TEES) to deliver the biological regenerative agent, basic fibroblast growth factor (bFGF), to the damaged facial nerve. MATERIALS AND METHODS: An endoscopic salvage treatment group was studied prospectively and was made up of severe intractable Bell's palsy patients who did not respond to high dose steroid treatment and had an ENoG value of 5 % or less. This surgery group was retrospectively compared to a similar control group who had received high dose steroid only. RESULTS: Complete recovery to House-Brackmann (HB) Grade I was achieved by 44.8 % of the endoscopic salvage treatment group which was significantly higher than the 21.2 % of the control group at one-year follow up. Patients with an ENoG value of 1 % to 5 % exhibited a significantly higher complete recovery rate of 71.4 % in the endoscopic salvage treatment group than the 28.6 % of the control group. In addition, no complications were observed including hearing loss. CONCLUSIONS: bFGF delivered via TEES shows considerable promise as a new salvage treatment of severe intractable Bell's palsy that is resistant to high dose steroid treatment without the risks presented by facial nerve decompression surgery.

The Feasibility and Treatment Results of Transcanal Endoscopic Myringoplasty.

OBJECTIVE: We reported on transcanal endoscopic myringoplasty in 25 cases preliminarily in 2014. Now our number of transcanal endoscopic myringoplasty reached to 209 ears and allowed us to adequately investigate the visibility, necessity of canalplasty, treatment results, and multivariate analysis. STUDY DESIGN: A prospective case series. SETTING: Tertiary referral center. PATIENTS: Transcanal endoscopic myringoplasty was performed on 209 ears in 201 patients between 2011 and 2019 and followed up over 1 year. METHODS: Preoperative endoscopic and microscopic views for the same patient were compared. We examined success rates at 1 year after surgery according to operation type, perforation size, operation side, gender, cause of perforation, and age, and also examined hearing results. Logistic regression analysis was performed to investigate the basic demographic and clinical characteristics of the patients associated with perforation closure. RESULTS: The anterior edge of the preoperative perforation was not visible under microscopy in 14.4% of patients. In contrast, endoscopic views revealed the entire tympanic membrane in one field. However, canalplasty was required in 2.4% of tympanic procedures due to difficulty of manipulation. The overall closure rate for perforations was 90.4%. Logistic regression analysis revealed that age > 11 was the only significant factor associated with perforation closure. The average reduction in air-bone gap was 12.1 dB. CONCLUSION: The endoscopic myringoplasty produced better visualization, the same or better closure rates, and the same or lower complication rates as compared with traditional microscopic techniques.

Daily short-term intratympanic dexamethasone treatment alone as an initial or salvage treatment for idiopathic sudden sensorineural hearing loss.

OBJECTIVE: Intratympanic (IT) steroid therapy has been proposed as an alternative treatment option for patients with idiopathic sudden sensorineural hearing loss (ISSNHL). However, the number and frequency of IT treatments and drug delivery methods remain to be determined. The purpose of this study was to evaluate the efficacy of daily short-term IT dexamethasone (DEX) treatment alone in ISSNHL patients using laser-assisted myringotomy (LAM) for the drug delivery route as an initial and/or salvage treatment. STUDY DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: Seventy-six ISSNHL patients receiving IT DEX. Patients with low-tone hearing loss, unilateral or bilateral fluctuating hearing loss or contralateral hearing loss were excluded. INTERVENTION: DEX (4 mg/ml) was injected through a perforation made by LAM. IT DEX administration was performed on 8 sequential days. MAIN OUTCOME MEASURES: Pre- and postprocedure hearing levels. The average hearing level was determined by 5 frequencies (250, 500, 1000, 2000 and 4000 Hz). RESULTS: Nineteen out of 76 patients fit the criteria for initial treatment in the study (group I), while 24 patients, who had failed systemic therapy, received salvage treatment (group S). The mean age of the patients in groups I and S was 56.2 years with a range from 31 to 73 years of age and 46.0 years with a range from 11 to 76 years of age, respectively. The mean number of days from onset of symptoms to IT therapy in groups I and S was 4.8 days with a range of 1-23 days and 15.3 days with a range of 6-28 days, respectively. In group I, 18 of the 19 patients (95%) showed improvement of more than 10 dB in the pure-tone audiogram, with a mean improvement of 40 dB. Twelve patients (63%) recovered completely and 16 patients (84%) demonstrated successful results with an improvement of more than 30 dB. In group S, 14 of the 24 patients (58%) showed improvement of more than 10 dB with a mean improvement of 16 dB. Two (8%) of the 7 patients (29%) with successful results recovered completely. CONCLUSIONS: Daily short-term IT DEX administration using LAM for ISSNHL patients without concurrent therapy showed a high response rate and high cure rate and proved to be an alternative therapeutic option to high-dose systemic steroids as a first- and/or second-line treatment.

Transcanal Endoscopic Ear Surgery for Congenital Middle Ear Anomalies.

OBJECTIVE: To demonstrate the efficacy of transcanal endoscopic ear surgery (TEES) for congenital middle ear anomalies. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Twenty-one patients ranging in age from 4 to 62 years old (median: 15 yr) who underwent TEES between 2011 and 2017 were compared with 19 patients ranging in age from 3 to 49 years old (median: 11 yr) who underwent microscopic ear surgery (MES) between 2000 and 2011. INTERVENTION: Ossiculoplasty or stapes surgeries were performed with TEES or MES. TEES was performed using a rigid endoscope with an outer diameter of 2.7-mm coupled with a full high-definition video system. MES was performed via a transcanal approach with a retroauricular incision. MAIN OUTCOME MEASURE: Middle ear anomaly classification, operating time, and hearing outcomes based on the American Academy of Otolaryngology and Head and Neck Surgery criteria were evaluated and compared between the TEES and MES groups. RESULTS: For Teunissen and Cremers class III anomalies, defined as ossicular chain malformations with a mobile stapes footplate, postoperative air-bone gap closure to 10 dB or less was achieved in 50% of the TEES group and 47% of the MES group. Postoperative air-bone gap closure to 20 dB or less was achieved in 86% of the TEES group and 100% of the MES group. No significant difference was found in the operating time between the two groups. All MES procedures required a retroauricular incision. CONCLUSION: Our results indicate that TEES has similar auditory outcomes compared with MES while avoiding a retroauricular incision.

Comparison of Postoperative Pain in Patients Following Transcanal Endoscopic Versus Microscopic Ear Surgery.

OBJECTIVE: To compare levels and causes of postoperative pain after cholesteatoma removal by transcanal endoscopic ear surgery (TEES) versus microscopic ear surgery (MES). STUDY DESIGN: Prospective case series. SETTING: Tertiary referral center. PATIENTS: One-hundred-and-sixty-one patients who had undergone middle ear surgery between February 2013 and April 2016. INTERVENTIONS: Comparison of postoperative pain between TEES and MES groups and among TEES and MES subgroups divided by range of bone removal. MAIN OUTCOME MEASURES: Two parameters were used to assess postoperative pain: a pain numeric rating scale (NRS) and number of times a non-steroidal anti-inflammatory drug (NSAID) was taken from postoperative days (PODs) 1 to 7. We also examined the primary factor behind postoperative pain looking at: 1) the surgical incision; 2) bone removal; and 3) number of involved middle ear regions. RESULTS: One-hundred-and-six patients underwent TEES and 55 underwent MES. The mean pain NRS for the 7-day postoperative period was significantly lower for the TEES group (1.1) than the MES group (2.8) (p < 0.001, Mann-Whitney U test). The number of times a NSAID was taken was lower for the TEES group (1.3 pills/wk) than the MES group (5.5 pills/wk) (p < 0.001, Mann-Whitney U test). The mean pain NRS of the TEES and MES subgroups also suggests that extent of bone removal or number of involved middle regions was less important in causing postoperative pain than presence or absence of the retroauricular incision. CONCLUSIONS: TEES is associated with lower postoperative pain and lower use of NSAIDs compared with MES patients.

Endoscopic transtympanic tympanoplasty in the treatment of conductive hearing loss: early results.

OBJECTIVE: We describe our initial experience with endoscopic transtympanic tympanoplasty and evaluate whether this approach is adequate and minimally invasive in the treatment of conductive hearing loss. STUDY DESIGN: Prospective trial. SETTING: University hospital. PATIENTS: Nine patients underwent endoscopic transtympanic tympanoplasty, with an average follow-up period of 17 months. Presurgical diagnosis was made by transtympanic endoscopy through a perforation made by OtoScan laser-assisted myringotomy in the outpatient clinic. METHODS: With clean endoscopic visualization, ossiculoplasty was performed by inserting a trimmed tragal cartilage through the myringotomy perforation made by laser-assisted myringotomy. Two types of ossiculoplasty were performed: columella reconstruction and interposition. The tympanic membrane was covered with a chitin membrane or sealed with a small piece of perichondrium from the tragal cartilage. MAIN OUTCOME MEASURES: Perioperative and postoperative complications and preoperative and postoperative hearing. RESULTS: Endoscopic transtympanic tympanoplasty with columella and endoscopic transtympanic tympanoplasty with interposition were performed in seven and two patients, respectively. Insertion of the cartilage was performed without conversion to a conventional otomicroscopic technique. The average hearing level before the operation was 59 dB. After the endoscopic transtympanic tympanoplasty, the average improved to the level of 27 dB, with an average air-bone gap of 11 dB. The myringotomy perforation was closed within 2 to 3 weeks. CONCLUSION: As opposed to conventional methods, this procedure does not require surgical exposure such as otosclerosis drilling and skin incision, and avoids the substantial risk of unnecessary injury to the chorda tympani. Endoscopic transtympanic tympanoplasty for a disrupted ossicular chain is an adequate and minimally invasive procedure and should prove to be a useful surgical procedure in future endoscopic tympanoplasty.

Comparison of intratympanic and intravenous dexamethasone treatment on sudden sensorineural hearing loss with diabetes.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of intratympanic administration of dexamethasone (IT-DEX) treatment on sudden sensorineural hearing loss (SSNHL) patients with diabetes by comparing the results with intravenous administration of dexamethasone (IV-DEX) treatment. STUDY DESIGN: Comparative study. SETTING: University hospital and affiliated hospital. PATIENTS: Ten sequential SSNHL patients with diabetes receiving IT-DEX and 21 sequential SSNHL patients with diabetes receiving IV-DEX. Patients with low tone hearing loss were excluded. INTERVENTION: In the IT-DEX group, two methods were applied to deliver DEX (4 mg/ml): injection through a perforation made by laser-assisted myringotomy or through a tympanostomy tube. IT-DEX administration was performed on 8 sequential days. In the IV-DEX group, DEX was administrated intravenously starting from an amount of 8 mg/d followed by taped doses for 10 days. MAIN OUTCOME MEASURES: Preprocedure and postprocedure hearing levels and complications. RESULTS: In the IT-DEX group, the average hearing level before the treatment was 79 dB. Overall, all 10 patients showed improvement of more than 10 dB in the pure-tone audiogram, with a mean improvement of 41 dB. Seven patients (70%) demonstrated successful results, and four recovered completely. In the IV-DEX group, 14 (67%) of the 21 patients showed improvement of more than 10 dB with a mean improvement of 25 dB. Thirteen patients (62%) demonstrated successful results. Free blood sugar during and after the IT-DEX treatment remained below the pretreatment levels, whereas four patients in the IV-DEX group demonstrated worsening of the hyperglycemia. CONCLUSION: IT-DEX treatment is at least as effective as IV-DEX treatment for SSNHL patients with diabetes.

Safety of heat generated by endoscope light sources in simulated transcanal endoscopic ear surgery.

OBJECTIVE: To determine whether heat generated by endoscope light sources during ear surgery is safe. METHODS: Transcanal endoscopic ear surgery (TEES) was simulated using 2.7-mm or 4-mm endoscopes coupled to xenon or LED light sources and a 3D model of human temporal bone. The endoscope tip was fixed at the center of tympanic annulus. Light sources were tested at clinical (30% for xenon and 40% for LED) and 100% settings. Temperatures were measured using thermocouples attached to the endoscope tip and three points within the middle ear cavity: promontory, horizontal portion of the facial nerve and lateral semicircular canal. RESULTS: Maximum temperatures measured within the middle ear cavity were below 31°C at clinical settings, while the temperatures rose to 44.1°C using a 4-mm endoscope with a xenon light source set at 100%. Temperatures measured at the tip were all safe at clinical settings, but rose dramatically to 110.1°C for the 4-mm endoscope with xenon at 100%. CONCLUSION: Endoscopes can be safely used within the middle ear at clinical settings. However, operators should not exceed clinical settings, particularly with 4-mm endoscopes with a xenon light source, to ensure temperatures generated within the middle ear cavity are safe.

Evaluation of attic retraction pockets by microendoscopy.

OBJECTIVE: Attic retraction pockets (RPs) are one of the important sequelae of otitis media with effusion and are classified on the basis of the findings of otoscopy or otomicroscopy. It is unclear when and how RPs turn into cholesteatomas. We compared the findings of RPs obtained with the use of a microendoscope with those from an otomicroscope to determine the extension of RPs. STUDY DESIGN: Comparative study. PATIENTS: Twenty-seven attic RPs (Tos type III or IV) and 10 precholesteatomas previously classified under an otomicroscope were reexamined. MAIN OUTCOME MEASURES: A high-resolution, fine, rigid microendoscope with an outer diameter of 1.0 mm was used to observe the extension of a retraction. In addition, to confirm the extent of the RP, computed tomography (CT) scans using water as the contrast media were performed in representative cases. RESULTS: Endoscopy with the microendoscope revealed that in 59%, the RP was deeper than indicated by the initial otomicroscopic estimation, suggesting that the extension of the RP was underestimated. The findings of water-enhanced CT scans were comparable with the endoscopic findings. The bottom was observable with the microendoscope and the otomicroscope in 20 (74%) and 11 (41%) of 27 RPs, respectively. Seven ears had a deeper RP, which extended beyond the incudomallear joint. Of the 10 precholesteatoma cases, in which the bottoms were not visible with an otomicroscope or conventional endoscopes, the microendoscope revealed the bottom in 5 (50%). CONCLUSION: On the basis of the observations of our study, we suggest that reexamination of cases of RP classified as Tos type III or IV, preferably with a microendoscope, if available, and assessment of the depth of the RP using water-enhanced CT, would be useful and that careful follow-up is necessary for deep RPs because of a potential risk of development into cholesteatoma.

Transcanal endoscopic ear surgery for pediatric population with a narrow external auditory canal.

OBJECTIVES: To retrospectively determine the size of the external auditory canal (EAC) in a pediatric population and to describe our experience with transcanal endoscopic ear surgery (TEES) in this pediatric population which had been successfully treated for middle ear disease using TEES. METHODS: We analyzed 31 patients ranging in age from 2 to 13 years old (median: 7.6 years) with middle ear disease who underwent TEES between November 2011 and August 2014. Sixteen of these patients had surgery for cholesteatomas; 11 for chronic otitis media; and 4 for malformation of the middle ear. A preoperative CT scan was performed to evaluate the middle ear disease. Transcanal endoscopic tympanoplasty was performed using a rigid endoscope with a 2.7mm outer diameter. Transcanal endoscopic atticoantrotomy was also performed, as necessary, on some patients to access pathologies in the antrum. The values of anterior-posterior diameters and superior-inferior diameters of the bony parts of EAC were measured retrospectively based on the preoperative CT scan data. RESULTS: TEES was successfully performed in all 31 pediatric patients without resorting to a retroauricular incision. Twenty-seven patients were evaluated for postoperative hearing levels which were found to fall within an acceptable range and for postoperative air-bone gap (ABG) by pure tone audiometry with a resulting mean of 8.6dB. The smallest anterior-posterior diameters of the external ear canal ranged from 3.2 to 7.1mm (5.0±1.0mm) and the smallest superior-inferior diameters ranged from 3.4 to 10.3mm (5.9±1.3mm). CONCLUSION: TEES can be used to safely and effectively treat middle ear disease even in the pediatric population in its narrow EAC.

The Efficacy of Color-Mapped Diffusion-Weighted Images Combined With CT in the Diagnosis and Treatment of Cholesteatoma Using Transcanal Endoscopic Ear Surgery.

OBJECTIVE: To assess the efficacy of a color-mapped diffusion-weighted image combined with a computed tomography scan (CMDWI-CT) in preoperatively evaluating the anatomical location of cholesteatomas and determining whether a patient is indicated for transcanal endoscopic ear surgery (TEES) to reduce intraoperative switching to microscopic ear surgery (MES). STUDY DESIGN: Prospective case study. SETTING: A single university hospital. PATIENTS: Fifty-five patients scheduled for middle ear cholesteatoma surgery. INTERVENTION: The CMDWI-CT is produced in a multistep process. A color-mapped fusion image (CMFI) is created by performing MR cisternography on a 1-mm thin-slice nonecho planar diffusion-weighted imaging (non-EPI DWI) and then by performing color mapping on the resulting image to enhance cholesteatoma visualization. False positives are reduced by taking a T1-weighted image (T1WI), whereas false negatives are further reduced by preoperative endoscopic examination. As cholesteatomas are difficult to locate on a CMFI in the temporal bone region, we stripped out the MR cisternography data from the CMFI and then fused the CMFI to the initial computer tomography (CT) scan to create a CMDWI-CT. This CMDWI-CT better clarifies the cholesteatoma position within temporal bone. MAIN OUTCOME MEASURE(S): CMDWI-CT preoperative findings were compared with intraoperative findings. The positive predictive value and negative predictive value were also evaluated depending on the cholesteatoma location. RESULTS: CMDWI-CT facilitated accurate detection of the cholesteatoma anatomical location in the temporal bone region which was reflected in positive predictive and negative predictive values of over 90% for all areas of the middle ear. CONCLUSION: CMDWI-CT is a reliable diagnostic modality for evaluating the anatomical location of cholesteatomas that seem as high-signal regions on a CMFI and for determining whether TEES is indicated for treatment in such patients.

The efficacy of color mapped fusion images in the diagnosis and treatment of cholesteatoma using transcanal endoscopic ear surgery.

OBJECTIVE: To assess the efficacy of color mapped fusion images (CMFIs) in preoperatively evaluating the anatomic location of cholesteatomas and determining whether a patient is indicated for transcanal endoscopic ear surgery. STUDY DESIGN: Prospective case study. SETTING: A single university hospital. PATIENTS: Ninety-two patients scheduled for middle ear cholesteatoma surgery. INTERVENTION: Imaging analysis was first performed using echo planar diffusion-weighted imaging (EPI) for the first patient group with mixed results. Imaging analysis was then performed using 1-mm thin-slice non-EPI combined with magnetic resonance cisternography in a second group. The resulting image was then processed using color mapping to create a CMFI that enhanced cholesteatoma visualization. A second non-EPI was also performed on the third group, incorporating a T1-weighted image (T1WI) to reduce false-positives. MAIN OUTCOME MEASURE(S): Preoperative findings from EPI, non-EPI/CMFIs, and non-EPI/T1WI-enhanced CMFIs were compared with intraoperative findings. The positive predictive value and negative predictive value were also evaluated for each group. RESULTS: Both the positive predictive value and negative predictive value obtained from the CMFIs were high in all areas of the middle ear, and CMFI facilitated accurate detection of the anatomic location of cholesteatomas of 3 mm or larger. The incidence of false-positives was further reduced in the final 18 patients by performing T1WI to distinguish between cholesteatomas and cholesterin granulomas. CONCLUSION: CMFI combined with T1WI is a reliable diagnostic modality for evaluating the anatomic location of cholesteatomas 3 mm or larger and determining whether transcanal endoscopic ear surgery is indicated for treatment in such cases.

Office-based endoscopic procedure for diagnosis in conductive hearing loss cases using OtoScan Laser-Assisted Myringotomy.

OBJECTIVES/HYPOTHESIS: In conductive hearing loss (HL), even though preoperative examinations including audiometry, tympanometry, and computed tomography (CT) scan are applied, exploratory tympanotomy is necessary to make an exact diagnosis of ossicular interruption and stapes fixation. Precise preoperative diagnosis would be useful for patient counseling, surgical indications, and planning. The advantages of office-based OtoScan laser-assisted myringotomy (LAM), which makes a circular and non-hemorrhagic perforation, prompted us to investigate other uses of LAM in addition to ventilation and drainage of the tympanic cavity. To make presurgical diagnosis in conductive HL, endoscopes with an outer diameter of 1.7 or 1.9 mm were used to inspect the middle ear pathology through perforations with a diameter of 2 mm made by LAM. METHODS: In the outpatient clinic, a circular perforation with a diameter of 2 mm was made in the tympanic membrane with LAM. An endoscopic view of the ossicular chain through a 70degrees angled tip endoscope held immediately to the outer side of the perforation was obtained to diagnose conduction disturbance loci in conductive HL cases. RESULTS: Ossicular chain abnormalities were easily and safely detected by clean endoscopic views obtained through a nonhemorrhagic circular perforation. When necessary, insertion of the tip of the endoscope into the tympanic cavity provided additional views of epitympanum. CONCLUSION: We suggest that transtympanic endoscopy through the perforation made by LAM is an effective and safe office-based procedure for diagnosis in conductive HL cases and could be an alternative procedure to replace exploratory tympanotomy.

[Prediction of Japanese cedar pollen emission in a snowy area--surveillance in Hirosaki City].

Japanese cedar is the most common pollinosis allergen in Japan. Predictions of total pollen counts and the first 2 or more days of the Japanese cedar pollen season are beneficial to patients. We developed predictive methods for those 2 factors in Hirosaki. We conducted an atmospheric Japanese cedar pollen survey from 1996 to 2002 in Hirosaki and compared yearly data with the male flowering index counted in 50 cedar trees in the preceding autumn. The male flowering index correlated highly positively with total cedar pollen counts in regression analysis, indicating its usefulness in predicting total pollen counts. Although the number of days from January 1 to the first day of continuous pollen emission showed no correlation with the cumulative maximum temperature during these days, the number of days from the day of first detection of pollen emission (minimum of 1 particle per sq. cm) to the first day of continuous pollen emission correlated highly with the cumulative maximum temperature and cumulative amount of snowfall on these days, suggesting that it is possible to predict the first day of continuous pollen emission by the cumulated daily maximum temperature after the day of first detection of pollen emission.

Autologous serum eardrops therapy with a chitin membrane for closing tympanic membrane perforations.

OBJECTIVE: Office treatment for chronic tympanic membrane (TM) perforations has limitations, and alternative methods to myringoplasty are sometimes needed. Serum lacks antigenicity and contains a large variety of growth factors known to modulate proliferation of various tissues to promote wound healing effects. Our purpose was to evaluate the feasibility of autologous serum eardrops therapy with a chitin membrane for closing TM perforations. INTERVENTION: In the outpatient clinic, the perforation margin was cauterized with silver nitrate, and the perforation was covered with a chitin membrane. Patients were instructed to apply autologous serum eardrops daily. Patients were examined every 2 weeks, and the procedure was repeated. RESULTS: We treated 19 sequential patients with chronic TM perforation in 1 ear between October 2005 and September 2007. Closure of the TM was achieved in 11 (58%) of 19 ears, and reduction of the perforation size was observed in 2 ears (11%). Closure rates for small, medium, and large perforations were 57 (8 of 14), 0 (0 of 1), and 75% (3 of 4), respectively. Closure rates for perforations attributable to intratympanic dexamethasone treatment, after myringoplasty and chronic otitis media were 67 (2 of 3), 67 (2 of 3), and 54% (7 of 13), respectively. Time for closure took from 15 to 175 days, with an average of 68 days (5.9 clinic visits). During autologous serum eardrop therapy with a chitin membrane, no remarkable side effects in the treated ears were observed. Measurement of the concentration of the epidermal growth factor, transforming growth factor beta1, fibronectin, and interleukin 6 in the serum showed no decrease in 14 days, suggesting activity remained stable in that period. CONCLUSION: Autologous serum eardrops therapy with a chitin membrane, which requires no surgical intervention, was found to be a promising office-based technique for the closure of chronic TM perforations because of its ease, safeness, and feasibility. However, additional studies are needed to independently analyze the specific benefits of the serum drops and the chitin membrane.

Leupeptin, a calpain inhibitor, protects inner ear hair cells from aminoglycoside ototoxicity.

Inner ear hair cells play a major role in the auditory pathway that converts sound stimulation into electrical signals, and then into a neural code. However this function is often lost by aminoglycoside ototoxicity. The injury of inner ear hair cells from aminoglycoside treatment is considered apoptosis, and caspase is an important participant in the apoptosis pathway in many organs. It has been reported that calpain, a calcium-dependent protease, is essential for mediation and promotion of cell death. The purpose of the present study was to investigate effects of caspase and calpain inhibitors on the inner ear hair cells after aminoglycoside treatment, and to explore the cell death pathway. Cochlea explant cultures were prepared from mice of postnatal 6 days, cultured with neomycin and/or protease inhibitors, and then stained with phalloidin-fluorescein isothiocyanate (phalloidin-FITC), which was used as a marker to identify surviving hair cells. We demonstrated that neomycin (0.1-1 mM) reduced the number of outer hair cells in a dose-dependent manner. Furthermore, we showed that leupeptin, a calpain inhibitor, significantly protects against the neomycin-induced loss of outer hair cells, whereas a caspase inhibitor was effective only against a lower concentration of neomycin (0.2 mM). Using the TdT-mediated dUTP-biotin nick and labeling method, we also found that a calpain inhibitor, but not a caspase inhibitor, prevents apoptotic DNA fragmentation after treatment with 1 mM neomycin. These results suggest that calpain, rather than caspase, may be responsible for apoptosis induced by aminoglycoside. Thus, leupeptin may prevent hearing loss from aminoglycoside ototoxity.