It is known that characteristic frequency (CF) distribution of cochlea is quite wide. It is also said that the basilar membrane (BM) configuration is complex and the BM plays an important role in its frequency selectivity. However, the relationship between the CF distribution of the cochlea and the BM configuration is not clear. Therefore, in this paper, the internal structures of the guinea pig cochlea, especially the BM configuration, were reconstructed and measured by using a computeraided three-dimensional reconstruction system. Then the influence of the BM configuration on its frequency characteristics was discussed. The results were as follows:
1. Both the cross sectional area of the scala vestibuli and that of the scala tympani decreased with an increase in the distance from the basal turn towards the apical turn. However, decreasing rate of the cross sectional area of the scala tympani was larger than that of the scala vestibuli In the lower basal turn, the cross sectional area of the scala tympani was larger than that of the scala vestibuli, and in the lower apical turn, the cross sectional area of the scala vestibuli was larger than that of the scala tympani. On the contrary, the cross sectional area of the scala media was nearly uniform throughout the entire length of the cochlea.
2. The width of the BM increased and its thickness decreased with an increase in the distance from the basal turn towards the apical turn.
3. Although the BM configuration had some influence on its frequency characteristics, the wide CF distribution of the cochlea could not be explained only by its configuration change along the length of the cochlea. The changes of the density and Young's modulus of the BM and those of the cross sectional area of the scala vestibuli and scala tympani were estimated to affect the frequency characteristics of the BM.

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Twentytwo cases of middle ear cholesteatoma underwent staged tympanoplasty by 3 surgeons with operative experience of less than 200 tympanoplasties from 1983 to 1990, and 22 cases by one surgeon with operative experience of more than 200 tympanoplasties from 1991 to 1995. Residual cholesteatomas were found in 41% at the second-stage operation between '83 and '90 and in 23% between '91 and '95, suggesting an importance in the skill of the surgeon for decreasing residual cholesteatoma.
After the staged tympanoplasty with mastoid obliteration, 71% of the cases showed no attic retraction, 23% showed mild attic retraction and only one case (6%) had a small retraction pocket in pars tensa with a non-visible part. After the staged operation without mastoid obliteration, on the other hand, 17% of the cases showed no attic retraction, 29% showed mild attic retraction and 54% showed severe attic retraction pockets including 2 cases of recurrent cholesteatoma.
From the present study, the following conclusions were obtained:(1) If there is a possibility that cholesteatoma has not been completely removed, staged tympanoplasty should be performed to prevent residual cholesteatoma.(2) When a severe retraction pocket is found in the second stage or there are granulation tissue or cholesteatoma around the tympanic isthmus, mastoid obliteration is useful for preventing the attic retraction pocket and recurrent cholesteatoma.

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Cholesterol granulomas of six patients were investigated electron-micloscopically. Non-ciliated cells in cholesterol granuloma had a round surface and they formed mulitiple layers. Some small pores were seen between cell membranes, and there were numerous lipoid granules in cytoplasm of the mucosa and in subcutaneous tissue. Lipid granules were secreted at the cell membrane surface with apocrine secretion or were seen escaping from the small pores between cells due to laceration. These lipid substances accumulated together in the mastoid air cells and formed cholesterol crystals. This phenomenon was observed especially around microvessels. Ciliated cells had degenerated and their cilia had decreased in number. Shorter and adherent of cilia were also found.
These observations lead us to conclude that cholesterol granulomas caused by pathological changes in the mucosa of the mastoid air cell system. It also seemed apparent that reducing pathological mucosa in the mastoid portion is very important in clinical therapy.

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In 17 ears with adhesive otitis media, 9 men and 8 women, aged 5 to 57 years, postoperative hearing results and the condition of the tympanic membrane were analyzed. Fifteen ears were operated on by one stage procedure and two ears were operated on by two staged procedure and folowed over 12 months after operation.
Overall success rates in hearing results according to the criteria of Clinical Otology Japan (1987) were 58.8% at the latest follow-up, but no ear with remarkable hearing improvement was obtained postoperatively.
In 8 out of 17 ears, postoperative anatomical troubles, such as re-retraction and re-adhesion of the tympanic membrane, otitis media with effusion and iatrogenic cholesteatoma were developed.
Further technical improvements, such as two stage procedure with mucosal graft to the promontory and mastoid obliteration may be desired to obtain better functional and anatomical results in surgical treatment for adhesive otitis media.

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The purpose of this study is to find the principles of treatment of aural polyps by clinical and histopathological investigation of 16 cases with aural polyps. Otological diagnosis of nine cases were cholesteatoma, two chronic otitis media without cholesteatoma, two myringitis granulosa, two subacute otitis media and one keratosis obturans. Aural polyps in two cases of subacute otitis media disappeared by conservative treatment, while one of miringitis granulosa and keratosis obturans needed polypectomy and other 12 cases were underwent mastoid surgery.
The aural polyps which contains keratin debris indicated possible existence of underlying cholesteatoma, however the aural polyps without keratin cannot be excluded of possibility of underlying cholesteatoma. Therefore the decision of therapeutic measures of cases with auralpolyps should be made from the results of various diagnostic methods, especially otoscopy, conventional X-ray, CT scan, histopathological investigation. Observation of the conservative treatment is also important for the final decision making.

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Actinomycosis is a chronic purulent granulomatous disease caused by actinomyces, especially, actinomycosis of the tympanomastoid region is very rare.
A 14-year-old man presented with a complaint of persistent discharge from the right ear, and the diagnosis of actinomycosis was made during surgery because of a yellow-green mass throughout the mastoid and actinomyces with characteristic “Sulfur granules”.

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Otomassage has been widely used to treat Eustachian tube dysfunction and secretory otitis media (SOM) in Japan over the past years. The effect and influence of otomassage on the middle ear, however, has scarcely been investigated.
We investigated the influence of the otomassage on the middle ear system by tympanogram. This study included 15 adults (15 ears) with normal tympanograms and 34 patients with SOM. These 34 patients, ranging in age from 3 to 74 years old, were composed of 14 cases (17 ears) with B type tympanograms and 20 cases (20 ears) with C type tympanograms. We examined the changes in the middle ear pressure (MEP) and static compliance (SC), by comparing the tympanograms taken before with those taken after otomassage.
In the normal ears, significant increase of SC (p<0.005) was found after otomassage, although no significant change was observed in the middle ear pressure. On the other hand, both MEP and SC did not significantly change in any SOM case.
It is supposed that otomassage may yield an exhaust from the middle ear cavity even in SOM, because the volume displacement of the ear drum produced by otomassage causes, calculated in the flaccid ear drum and/or small middle ear cavity, an increase in MEP which may exceed the average passive opening pressure of the Eustachian tube in SOM cases.

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Although various researches on frequency characteristics of middle ear after tympanoplasty using an artificial ossicle or conchal cartilage as a prosthesis of the ossicle have been performed, their main concerns were the effects of the size, shape and weight of the prosthesis on frequency characteristics of middle ear. It is also important to analyze mechanical properties of the prosthesis of the ossicle, because they affect the frequency characteristics of the middle ear. Therefore, in this paper, mechanical properties of cartilage and dense hydroxyapatite of which the artificial ossicle is made are investigated by using mechanical testing machine. The results are as follows;
1. Cartilage of the external ear is stiffer than other soft tissues in low strain range. Therefore, the external ear cartige will be reasonable substitute for a prosthesis of an ossicle.
2. As dense hydroxyapatite is heavier and stiffer than an original ossicle, an artificial ossicle made from porus hydroxyapatite with low rigidity will be better than that made from dense hydroxyapatite.

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Cerebrospinal fluid (CSF) from 17 patients with peripheral facial palsy was analyzed for IgG antibodies to varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV-1).
In 3 of 11 patients who were initially considered to have Bell's palsy, later the diagnosis was changed to zoster sine herpete. In one of these 3 patients, serum antibody to VZV showed a significant rise in titer between the first and second examinations (after 10-14 days). In 2 of them, CSF antibody to VZV was positive, and CSF cell counts and protein concentration were increased above the normal range.
Of 6 patients with Hunt's syndrome, CSF cells were increased above normal in 4 and CSF antibody to VZV was positive in 3.
No patients with Bell's palsy or zoster sine herpete had positive CSF antibody for HSV-1.
In conclusion, examination of the CSF is sometimes useful to distinguish zoster sine herpete from Bell's palsy.

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MEM-mediated anti-masking effects, which is one of the possible function of MEMs, was examined in a patient with synkinetic stapedial contraction. Thresholds for 1kHz tone (signal) were recorded in several levels of low frequency maskers (250, 500Hz) by Bekesy audiometry. Detection thresholds for 1kHz tone in the background masker were considerably improved during the facial mimetic contraction, which caused the stapedial contraction. These antimasking effects were observed at masker levels above or below the sound level of thresholds for acoustic reflex. In other words, in the respect of effective MEM-mediated anti-masking in the actual condition, it seems to be necessary that MEMs could contract during the signal perception in masking tones, even if the sound level of masker was below the thresholds of acoustic reflex. Therefore, compliance of the tympanic membrane was measured during the task of signal perception in masker in three healthy subjects. However, no stapedial contraction during such a task was observed. Possible significance of middle ear muscles in the respect of anti-masking effects was discussed.

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We analyzed 547 patients (555 ears) with idiopathic sudden hearing loss who visited our clinic within 8 days after the onset. Patients were divided into 8 groups according to the days between the initial visit and the onset. Initial hearing levels, distribution of thresholds, types of audiogram, hearing recoveries were investigated in those groups.
The results were as follows:
1) There were no significant differences between 8 groups regarding the thresholds at 500Hz, 4000Hz and averaged five-frequency thresholds in the initial audiograms.
2) In the distribution of thresholds at 500Hz and 4000Hz of the initial audiograms, the groups within five days showed broad distribution. Whereas, the high population in the range between 60 and 80 dB can be observed in the groups after six days.
3) Regarding the types of initial audiogram, high population was seen in flat and upward slope types in all groups. However, in the groups after six days the distribution slightly moved toward the down slope type. In the ultimate audiograms, flat and down slope types were frequently seen in all groups.
4) There was no significant difference between 8 groups regarding the hearing recovery rates of averaged five-frequency thresholds.

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The characteristics of tinnitus in patients with unilateral acoustic neuroma were investigated by tinnitus test (Pitch match test, loudness balance test) and tinnitus test with glycerol loading. The following results were obtained:
1. In preoperative tinnitus, the incidence of onomatopoeia, which is seldom used spontaneously in tinnitus, tended to be higher than that in tinnitus without hearig loss and tinnitus associated with cochlear deafness.
2. On the preoperative tinnitus test, the incidence of tinnitus identified by band noise or white noise (noise tinnitus) was much higher than that of tinnitus without hearing loss or tinnitus associated with cochlear deafness. The incidence of noise tinnitus was much higher than that of tinnitus occuring after the surgery.
3. The results of preoperative tinnitus test by glycerol-loading suggested that cochlear factors were involved in the preoperative onset of tinnitus in patients with acoustic neuroma.

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Patient 1 was a 11-month-old boy who was born with bilateral severe hearing loss accompanied with persistent ductus arteriosus, pulmonary stenosis, cataract, and mental retardation. His mother was vaccinated against rubella at the age of 14. As signs or symptoms suggesting rubella infection were not seen during gestation, latent infection of rubella was suspected.
Patient 2 was a 3-month-old boy who was born with bilateral deafness, persistent ductus arteriosus, cataract, and mental retardation. His mother also received rubella vaccination. Characteristic eruptions suggesting rubella infection was seen at the second months of gestation.
Incidence of CRS in spite of their mothers' vaccination of rubella is probably due the fact that the titer of serum antibody acquired by vaccination decreases year by year, and therefore, vaccination is no longer effective in some cases to prevent maternal infection more than 10 years later.

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The managements for severe Meniere's disease (MD) is to accept the presence of the endolymphatic hydrops while attempting to eliminate vertigo itself. For this purpose, either vestibular neurectomy (VN) or streptomycin perfusion (SMP) of the horizontal semicircular canal has been performed to MD patients in our department. Excellent auditory results were confirmed after VN treatment, while hearing became worse after SMP treatment.
In the present study, auditory function (pure tone audiogram: PTA) after the SMP of five MD patients with intractable vertigo was evaluated. SM at a concentration of 25 (n=2) or 50 (n=3)μg/ml was applied into the horizontal semicircular canal. In three cases, the intensive treatment with intravenous injection of methylpredonisolone (total 500mg) or defibrase (40 unit) was followed after SMP.
In 4 cases out of 5 MD patients operated, the avaraged PTA thresholds (at 500, 1000, and 2000 Hz) were elevated to 110 dB after SMP. In two cases, who received 25μg/ml SM andthe intensive treatment with methylpredonisolone or defibrase, the averaged PTA thresholds recoverd from 110dB to 77dB and 84dB after three months (58dB, 64dB before SMP). In other two cases, 50μg/ml SM was applied. One case received the intensive treatment and another case received no treatment.
In both cases, the PTA thresholds showed a relative slow recovery during next three months and recoved from 110dB and 102dB to 100dB and 96dB. In all cases, the recovery was most prominent in the middle frequency, while much less in the lower and higher frequencies.
These results suggest that the auditory impairment after SMP would be reversible and the recovery of auditory function could be accelerated by the intensive treatment with methylpredonisolone or defibrase just after SMP.

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Four cases of carcinoma of the external auditory canal treated in the period from 1990 to 1995 are presented. Patients' ages ranged from 46 to 71 years. Three cases were male and one was female. All cases had squamous cell carcinoma. As the tumor invaded deeply in the bony external meatus in all cases, these patients were treated with total en block resection of the external auditory canal involved the tympanic membrane, malleus, incus, combined with postoperative radiotherapy. All patients are still alive without reccurence of tumor
In addition, the literatures on carcinoma of the external auditory canal in Japan were reviewed. Mean patient age was 55.8 years old, ranging from 15 to 81 years. There were 54 ears of squamous cell carcinoma, 16 ears of adenoid cystic carcinoma, 2 ears of malignant melanoma, 1 ear of adenocarcinoma, 1 ear of basal cell carcinoma. The 5-year survival rate by Kaplan-Meier's method was 54.8%.

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