Hideichi Shinkawa

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.

NMDA (NMDAR1) and AMPA-type (GluR2/3) receptor subunits are expressed in the inner ear

&NA; Using receptor subunit‐specific antibodies, the cellular localization of NMDA and AMPA type glutamate receptor subunits was studied within the rodent (rat, guinea pig) and non‐human primate (monkey) inner ear. In the spiral and vestibular ganglion, almost all cells were immunoreactive for the NMDAR1 subunit and the AMPA type receptor subunit GluR2/3. This indicates that both NMDA and non‐NMDA type glutamate receptors may be co‐distributed in the primary afferent neuronal components, and are possibly involved in neurotransmission in the primary auditory and vestibular systems. This study also indicated the possible localizations of glutamate receptors in the nonneuronal cells in the inner ear, suggesting that some nonneuronal cells may also have the ability to mediate glutamate signalling.

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.

Three familial cases of hearing loss associated with enlargement of the vestibular aqueduct.

The present report describes three familial cases of recessive hearing loss associated with enlargement of the vestibular aqueduct (EVA). Six siblings from three families showed EVA. The common characteristic of these patients was the presence of congenital, high-frequency, fluctuating sensorineural hearing loss. These cases suggest that EVA may be a useful discriminator between different types of recessive hearing loss.

Expression of NMDA receptor subunit mRNA in the vestibular ganglion of the rat and guinea-pig

The expression of NMDA R1 receptor mRNA in the rat and guinea-pig vestibular ganglion was examined using in situ hybridization histochemistry. Most of the ganglion cells of both species were strongly labelled, supporting the view that NMDA-type glutamate receptors may be involved in the vestibular afferent neurotransmission.

Positive intratympanic pressure in the morning and its etiology.

Intratympanic pressures were measured by tympanometer in forty ears free from disease. In the recumbent position, the first tympanogram was obtained in the morning at awakening, before swallowing. The second pressure measurement was performed in the upright position after swallowing and chewing. Twenty-two ears showed positive pressure in the middle ear before swallowing and decreased pressure after swallowing. The present results revealed no evidence of continuous gas absorption from the middle ear during sleep. The other experiment demonstrated that raising of the PCO2 level by hypoventilation increased the pressure in the middle ear. The results suggested indirectly a diffusion of carbon dioxide to the middle ear cavity from its surrounding tissue. The intratympanic pressure seems limited in part to the partial pressure gradient of gases between the middle ear cavity and its surrounding tissue when ventilation through the Eustachian tube is impaired.

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 &bgr;1, 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.

Correlated expression of glutathione S-transferase-π and c-Jun or other oncogene products in human squamous cell carcinomas of the head and neck : Relevance to relapse after radiation therapy

The expression of glutathione S‐transferase (GST)‐π and four oncogene products, c‐Jun, c‐Fos, c‐H‐Ras, and c‐Myc, in human squamons cell carcinomas of the head and neck was investigated immunohistochemically before and after radiation therapy, to examine whether these oncogene products might be involved in GST‐π expression, and also to examine the relationship between their expression and therapeutic response. Clinical response to radiation was evaluated in terms of both tumor regression and relapse over two‐year follow‐up periods. The overall positive rates in 83 carcinoma specimens before therapy were 60.2% for GST‐π and 28.9–51.8% for the individual oncogene products, the positive rates for the oncogene products being higher in GST‐π‐positive than in GST‐π‐negative cancers. c‐Jun was most highly correlated with GST‐π expression. Following radiation, the expression of GST‐π and the oncogene products was altered in about a half of 30 patients. Eleven of the 18 patients who exhibited prior positivity for GST‐π showed negative conversion, while 4 of the 12 patients with prior negativity demonstrated positive conversion. In most cases, changes in c‐Jun staining coincided with those in GST‐π. Regarding clinical response to radiation therapy, the positive rates for GST‐π and c‐Jun before radiation were higher in the residual cancer or relapse cases than in the group showing complete response without relapse. Examination of 26 patients with laryngeal cancer revealed that relapse occurred more frequently in cases exhibiting positive reactions for GST‐π,c‐Jun, or c‐H‐Ras. These results suggest a direct link between c‐Jun and GST‐π in head and neck cancers before and after radiation. Although GST‐π and the oncogene products can be influenced by radiation, GST‐π and c‐H‐Ras expression may be a risk factor for relapse of laryngeal cancer.

Localization of γ-aminobutyric acid a receptor subunits in the rat spiral ganglion and organ of corti

n -Aminobutyric acid (GABA) is thought to be the major inhibitory neurotransmitter in the central nervous system. Although it is distributed in the olivo-cochlear bundles, which constitute the mammalian cochlear efferent system, its function in the cochlea is still obscure. In this study, we investigated the localization of GABAa receptor subunits ( f 1-6, g 1-3, n ) in the rat cochlea in order to determine the role of GABA in the cochlea. Most spiral ganglion cells were intensely immunolabeled with all the anti-GABAa receptor subunit antibodies. In the organ of Corti, punctate immunoreactivities were observed in inner hair cell regions corresponding to the distribution of GABA. These data suggest that GABAa receptor was present in afferent nerve terminals in inner hair cell regions, and that GABA regulated afferent nerve transmission contacting efferent nerve endings by means of the axo-dendritic synapse function.

Evaluation of attic retraction pockets by microendoscopy.

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.