Cell cultures of fetal inner ear sensory epithelial cells have not been established because of difficulties inisolating a sufficient number of cells required. We succeeded in establishing a culture system. Embryonic day 12 rat otocysts were dissociated mechanically, and plated in serum-free media with epidermalgrowth factor (EGF). Seven days in vitro, epithelial-like cells survived and formed colonies, whilemesenchymal cells and Schwann cells mostly died. These colonies expressed cytokeratin that is an epithelialcell marker and nestin that is a neural stem cell marker. These results suggest that EGF-responsive fetalotocyst cells are undifferentiated sensory epithelial cells.
It is known that the efferent nerve fibers in the cochlea are either sympathetic or cholinergic and eachfiber distributes to the vessel wall of the modiolus, osseous spiral lamina and the outer hair cells, respectively.The cholinergic fibers innervates to the outer hair cells can modulate the active mechanism in the cochlea.The function of the sympathetic system remains unclear.In this study, we compared the distribution of thecholinergic terminal and noradrenergic fibers between those in the neonatal and adult rat cochlea.Mosttyrosine hydroxylase (TH) positive fibers in the cochlea disappeared after superior cervical ganglionectomy.VAT (vesicular acetylcholine transporter) immunoreaction could be found at the outer hair cells whichwere identified as 3 rows.Compared with the neonatal rat, the number of TH-immunoreactive fibers in theadult rat decreased in the cochlea, especially in the modiolus.No difference in VAT reaction was foundbetween the neonatal and adult rats.Moreover, to elucidate one of functions of the sympathetic system inthe cochlea after ipsilateral superior cervical ganglionectomy at neonatal stage, we examined the hearingchanges of both sides using the auditory brainstem response (ABR).The latency of wave I in the sympathectomyside was longer than that in the control side.We speculated that development is different foreach efferent fiber in the cochlea.Furthermore, fibers from the superior cervical ganglion influence thedevelopment of hearing.
The purpose of this study is to evaluate the predictive value of universal screening programs with a hospital-based study held in Japan. 2843 new born babies born between 1998 and 2000 were examined by automated ABR. Twenty three of them (0.8%) were referred for further evaluation of their audiologic features.Finally, 7 hearing-impaired children were identified. The qualification rate was 99.2% and predictive valueof positive test was 30.4% in total population. In low-risk populations, the qualification rate and predictivevalue of positive test were 99.6% and 30%, respectively. Educational interventions were immediately conductedin the center for hearing impaired children, Okayama (Kanariya Gakuen). Preliminarily, early-identifiedchildren demonstrated relatively better developmental quotients including language and cognitive development, comparing with later identified children with hearing impairment. Education system for early-identifiedchildren with hearing impairment is indispensable for the establishment of the nation-wide universalscreening system in Japan.
The authors have developed a simulation software of practical masking in pure-tone audiometry fortraining audiologists. The trainee can choose a subject out of 20 audiograms with various hearing loss storedin a personal computer, and determine bilateral air and bone conduction hearing thresholds by changing signaland noise levels and monitoring the “subject's response”. The subject's response is determined from calculationabout the audibility of the test tone in either ear in the presence of masking noise, under the conditionof the air and bone conduction hearing thresholds of the subject. Test situations such as frequency, signaland noise levels, subject's response and measured thresholds are illustrated in the audiogram on the display.The software also can demonstrate masking procedure for the subject according to two methods;plateau searching and simultaneous changing levels of masking and test sounds. In each step of the demonstration, the decision based on the subject's response and the guide to the next step are presented in thetext-box to help learning correct procedure of masking.
In 5 years from May 1993 to Apr 1998 we performed canal wall down tympanoplasty with canal reconstructionmethod using auricular cartilage on 102 ears with fresh cholesteatoma and 58 cases of them wereattic cholesteatoma. An original approach by using the auricular cartilage to prevent retraction pocket wascarried out at the attic reconstraction. In 58 cases, 33 cases were carried out by single-stage surgery and remain 18 cases were carried out bystaged surgery. We examined 58 ears with attic cholesteatoma about postoperative results and aeration in the attic andmiddle ear cavity by CT. After we followed them over 2 years, we could evaluated 43 cases out of 58 about postoperative aerationby CT. Respectively good aeration was seen in 40 cases out of 43 (93%) in the middle ear cavity and in 23cases out of 43 (53%) in the attic. Respectively the rate of success of hearing was 100% in Tympanoplasty type 1, 73% in type 3-C, 50% inthe case of first-stage surgery→type 3-C, 50% in the case of first-stage surgery→type 4-C. As a whole thesuccess of hearing was 71% in attic cholesteatoma totally. There was no evidence of perforation in ear drum in all cases and residual cholesteatoma, but in only onecase showed recurrence. We think that our method is more useful to reconstruct the attic and middle ear with good aeration andto prevent postoperative retraction pocket and recurrence.
It has been reported that an otospongiotic lesion in otosclerosis can be shown as a density-lossarea in computed tomography (CT) of the temporal bone in patients with otosclerosis. Using CT, we evaluated the presence of otospongiotic lesion in 42 ears with otosclerosis and analyzed the relationshipbetween CT and audiometric findings. We found otospongiotic lesions in 21 ears (50%).Bone conduction thresholds were significantly increased in ears with otospongiotic lesions comparedto those without. No significant difference was observed in bone conduction thresholds betweenears with lesions around the cochlea and ears with lesions anterior to the vestibule. It suggests thatactive lesions detected on CT may be more readily cause sensorineural deafness.
During middle ear surgery, surgeons often felt if they could assess hearing changes after ossicular reconstructionprocedure under general anesthesia. Twenty-four ears with tympanosclerosis, otosclerosis, dislocationof the ossicles due to head injury, middle-ear malformation and cholesteatoma were monitored with electrocochleography (ECochG) during surgery. Seventeen showed significant enlargement of AP amplitude toa 85dB click stimulus after the ossicular reconstruction, and the postoperative hearing in 16 of them wasfound improved with an average of 15dB or more. In 7 patients who underwent the surgery early in thisstudy, clear ECochG recordings could not be obtained because the hearing in high-frequency tones was worsethan 70dB in 4 and high electrode resistance was observed due to the unstable ball electrode in the remaining3. Two of the 7 patients showed postoperative hearing improvement. We believed that intraope-rativeECochG with needle electrode enabled surgeons to assess the hearing improvement objectively after theossicular reconstruction.
Congenital cholesteatoma sometimes escapes detection because of its silent growth. We report threecases of children who had congenital cholesteatoma associated with cholesterol granuloma. Two of them hadbeen treated as otitis media with effusion before detection of congenital cholesteatoma. In the third case, unilateralhearing loss was found by school screening audiogram. Congenital cholesteatomas grow slowly, but potentially disturb the middle ear ventilation. It might leadto otitis media with effusion and furthermore to cholesterol granuloma. Clinicians must be aware of congenital cholesteatoma, and cholesterol granuloma in a case of persistentotitis media with effusion.
Surfer's ear (exostosis) is a hyperostotic lesion of the external auditory canal caused by a long-termstimulation of cold water. Two rare cases of exostosis of the external auditory canal are reported. A 40-year-old male, professional surfer in Hawaii, had total occlusion of the left and subtotal occlusion ofthe right ear canal. Another patient was a 66-year-old professional diver, with the uncertain hearing loss anddizziness, had subtotal occlusions of the ear canal bone bilaterally and was accompanied by perilymph leakageof the left ear. Surgical treatment through a postauricular skin incision was performed in both cases and the perilymphleakage from the left round window was closed simultaneously in the second case.
In September 1999, a 69-year-old woman was refered to our clinic, complaining of persistent pain of herright ear for 3 months. She received a radical mastoid surgery in her right ear when she was 3 years old, and the detail of this surgery was unknown. At the initial consultation, her ear cavity was well epithelizedand tumor or granuration tissure were not observed. CT imaging showed that a soft tissure density occupyingwhole mastoid cavity destructed the posterior and the lateral wall of the mastoid. In MRI imaging thissoft tissure was enhanced with Gadrinium, and a tumor lesion in the temporal bone was suspected. In November 1999, mastoidectomy was performed for pathological diagnosis, and the diagnosis wascholesteatoma both in frozen section and in permanent HE stainings. In order to resect most of the lesionand to establish the final diagnosis, subtotal tumor resection was conducted in December. Pathologicallymost of the mass consisted of fibrous granulation tissue containing kerarinizing squamous epithelium andthere was no evidence of malignancy. However, in a small amount of sampling from the mastoid cavity, atypical squamous cells with cancer peal were found and final diagnosis of squamous cell carcinoma wasestablished. In this case malignant tumor was clinically suspected but the most part of the tumor was not pathologicallymalignant, and this factor delayed the final diagnosis.
The patulous eustachian tube (ET) has a very characteristic clinical manifestation namely, its symptomsappear when the patient is in seated or upright position, while diminished when the patient is in recumbentposition. In the previous study, we reported the difference of CT imaging of the ET lumen and its surroundingtissues between patulous ET cases and normal control cases. In that study, however, there was apitfall that all CT examinations were performed on subjects in recumbent position, in which few felt symptomsduring the examination. In the present study, we attempted to image the ET and its surrounding tissues in a 76-year-old malewith severe patulous ET in the seated position, by using a newly developed horizontal CT system. A comparisonwas made between the CT findings obtained in the seated position where the patient had symptomsand these in the recumbent position where the patient lacked symptoms of the patulous ET. In the cartilaginous portion, especially from the pharyngeal orifice to the mid-cartilaginous portion of theET, the air space in the ET lumen was larger in the seated position than in the recumbent position. At theisthmus and the tympanic orifice of the ET, however, there was no significant difference in the findings of theair space in the ET lumen between the two positions. We suggest that this method will lead to a better understanding of the pathology of the patulous ET, ifmore patulous ET cases are investigated.
Hemifacial spasm (HFS) is a condition caused by vascular compression (s) of the facial nerve. Althoughspasm of the stapedial muscle causes tinnitus in about one third of patients with HFS, accompanying tinnitusdue to neurovascular compression (NVC) is rare. Here we report a patient with intractable tinnitus due toNVC of the acoustic nerve. A 57-year-old man presented with a 10-year history of right HFS. He had sufferedfrom high-pitched continuous debilitating tinnitus in the right ear for the last several months, duringwhich the HFS had also worsened. The tinnitus had interfered with his reading and other daily activities.The patient had been receiving medication for hypertension for several years, but was otherwise healthy.An audiogram showed an average hearing level of 14dB on both sides. Thin-slice high-resolution T2-weightedMR images or CISS (Fourier transformation-constructive interference in steady state) images showedarterial compression of the facial nerve and another blood vessel crossing the acoustic nerve. Microvasculardecompression surgery for HFS and exploration of the acoustic nerve were performed simultaneously. Aposterior approach to the right cerebellopontine angle revealed a branch of the anterior inferior cerebellarartery (AICA) compressing the facial nerve root exit zone caudally. Another branch of the AICA compressedthe acoustic nerve laterally, creating a severe indentation. Both AICA branches were transposedaway from the nerves using a Teflon (R) sling and Gelfoam (R). Immediately after surgery, the HFS andtinnitus disappeared, and an audiogram taken 5 days postoperatively showed no significant hearing loss.Thin-slice T2-weighted MR images are useful for diagnosing cases of NVC and for guiding the surgicalapproach, although diagnosis of NVC for isolated tinnitus would be difficult by MRI alone because of thereportedly high incidence of false-positive findings. If preoperative high-resolution MR images suggest thepresence of NVC in patients with intractable tinnitus accompanying HFS, intraoperative attempts to identifyand transpose the offending vessels should be considered.
Lyme disease is Borrelia infection that primarily affects the skin with a characteristic rash, erythemamigrans (EM), but recently the neurologic manifestations (Neuroborreliosis) of this disease have beenreported. A 27 year-old woman presented with unilateral acute sensorineural hearing loss and tinnitus in her leftear. These symptoms were progressive. Vision in her left eye has been hampered considerably after threeweeks, and it was diagnosed as post-ocular neuritis. And paralysis of the left side body was developed withina month. Because this patient didn't have a history of tick bite nor skin rash (EM), the diagnosis wasextremely difficult. After taking minocycline hydrochloride to treat atheroma with infection in her left auricle, incidentally the symptoms were improved. Systemic infection was considered and Borrelia burgdorferi serum antibodies was examined. IgM-antibodiesof B. garinii and B. afzelii were detected in her serum, so Lyme disease was diagnosed. The left sensorineuralhearing loss and other symptoms were recovered in some degree after treatment for Lyme disease.After half-year the left sensorineural hearing loss with other neurologic manifestations were recurred, and the periodical observation should be required.