It is now recognized that normal effect innervation is necessary for development of the auditory pathway. This study investigated the effect of chronic electrical stimulation of the auditory nerve on the size of cochlear nucleus somata of neonatally deafened kittens. Total 16 kittens were deafened by using kanamycin and ethacrynic acid at 10 days of age and implanted at various ages (60-719 days) with an active intracochlear implant in the left side and some of them chronically and electrically stimulated from ages 98- 665 days. Then the kittens were investigated the soma area of cochlear nucleus and the 2 deoxyglucose (DG) uptake area on the inferior colliculus. The soma area of 2 DG-labeled regions was usually larger than that of the unlabeled regions up to the stimulation starting time of 140 days significantly, but the area of 2 DG labeled regions of the inferior colliculus was larger up to 180 days in either stimulated and unstimulatred kittens. This means that electrical stimulation of the auditory nervous system is very effective even the ages of 140- 240 days and there appears to be optimum age for cochlear implantation.
Expression of glutamate receptors (GluR 1-4, NR1, NR2) was determined in the spiral ganglion cells of KM (kanamycin)-treated rats during 0-8weeks. The GluR expression was compared to that of KM+HGF (hepatocyte growth factor)-treated rats. In the spiral ganglion cells of KM-treated rats, the expressions of GluR2, GluR3, and NR1 were up-regulated at both protein and mRNA levels. In contrast, those of GluRl and NR2 were down-regulated. In the spiral ganglion cells of KM+HGF-treated rats, the expressions of GluR2 and GluR3 were up-regulated at both protein and mRNA levels, while those of NR1, NR2, and GluR1 were downregulated. The expression of HGF receptor (C-MET) was up-regulated at both protein and mRNA levels. These results suggest that rapid and drastic changes in GluR expression may contribute to the plasticity observed in the auditory system after profound hearing impairment.
Four and a half years have passed since cochlear implantation became an authorized treatment with health insurance coverage in Japan. Reviewing clinical courses of 48 implant (Nucleus CI-22M, SPEAK strategy) users from our hospital, the effectiveness of the procedure was discussed. No serious surgical and postoperative complications were experienced in our series. Preoperative evaluation of the candidates, in terms of their cochlear functions and anatomy, is important to make indication. Three-D reconstructed MRI images are very useful to grasp thepathological state of the whole cochlea. Cochlear implant can be a major medical breakthrough for people with profound to severe hearing impairment, even if they are wearing hearing aids. Considering the fact that many hearing aid users are getting better hearing ability with the implants, its indication may be further expanded to less severely impaired listeners.
Indication and rehabilitation for pediatric cochlear implantation are discussed based on the data of seventeen children who received cochlear implants in the authors' implant center.The efficacy of hearing aids and cochlear implants were evaluated by pure tone audiometry, speech perception tests and IT-MAIS, which is an auditory intergration scale for infants and toddlers.All children exhibited significant improvement in their auditory skills, which had not been observed during the preoperative follow-up period using hearing aids.As for rehabilitation, we avoided intensive auditory training, but tried to let them acquire spoken language naturally by playing with them providing various situations with different kind of speech and environmental sounds that may interest them.Although we clearly recommended the auditory oral approach for rehabilitation in pediatric cochlear implant users, final decisions were entrusted to the parents and the local (deaf) school teachers after full explanation of our policy on rehabilitation.
The purpose of this study was to analyse the backgrounds, preoperative evaluations, surgical techniques, and complications in pediatric cochlear implantation in Japan. Questionnaires were sent to 15 institutions performing cochlear implantation more than three cases between 1991 and June, 1998. There was 13 responses (86.7%). One hundred and thirty cases (63boys and 67girls) underwent cochlear implant surgery. Children, who were operated on at 2-5 aged, accounted for 82/130cases (63.1%). Preoperative tests for pediatric candidates including COR, play audiometry, a hearing aid effectiveness, high resolution CT, MRI, and physical & memtal development test were much more important than those for the adult. In a group of 130 children who received Nucleus Mini-22 device in Japan, there were no deaths, no life threatening complications. The incidence of total complications was 6.9%(9/130), 4 major complications and 5 minor complications occured. Revision surgery was performed in 2.3%(3/130). And the incidence of device failure was only 0.77%(1/130).
The outer hair cell is one of two receptor cell types in the organ of Corti. It alone, however, functions as both receptor and mechanical effector. It is currently held that this cell is the basis of the cochlear amplifier. In this presentation, a brief overview is provided on selected aspects of the cell's mechanical activity.
The outer hair cell (OHC) has an important role for the normal function of the cochlea, and the cochlear amplification is believed to be based on OHC electromotility. Although many studies of measuring isolated OHC motility have been done, the whole movement of OHC is still unclear, because most of the measurements have been done by the photodiode technique. In order to understand the shape changes in various points on OHC, the whole movements of OHC were recorded by a high-speed video system when the isolated OHC was whole cell voltage clamped and evoked by low frequency (5Hz) electric stimulus, and displacement of the cell edge and the microbeads attached to the lateral wall of OHC were analyzed by quantifying enhanced grayscale profile shifts in the processed images. The results were as follows: 1. OHC vibrates synchronously in response to the sinusoidal voltage stimuli, and the amplitude of the microbead movements increases with an increase in the distance between the microbead on the cell body and the patch-clamped position. 2. The axial strain in the middle region of OHC is larger than those in the apical and basal regions, and there is no relationship between the patch-clamped position and the strain distribution of OHC. 3. The amplitudes of diameter changes are constant in various points on OHC. 4. There is a possibility that the density of protein motor is largest in the middle region of OHC. However, in order to clarify this possibility, further investigation of measuring the distribution of the OHC axial stiffness from the apical end to the basal end is necessary.
Navigation systems are a new surgical aid with which the surgical site is visualized as a CT or MRI image. Such systems navigate the surgeon to the relative position of the target organ in real time. Four types of systems are now available: mechanical arm system, optical system, electromagnetic system and ultrasonic system. We performed ear surgery using mechanical arm system in 12 patients (7 with cholesteatoma, 1 chronic otitis media, 1 cholesterin granuloma, 1 otosclerosis, 1 acoustic neuroma and 1 congenital aural atresia). We were easily able to detect the position of important organs inside the temporal bone such as the facial canal, semicircular canals, ossicles, the sigmoid sinus, the middle cranial fossa, and the internal auditory meatus. Furthermore, the system was useful in detecting residual inflammatory cellula in patients with well-developed mastoid cells, and in confirming the area of bone removal of obstructed ear canal in the patient with aural atresia. This system ensures targeting with an error of about 2mm. Application of navigation systems to ear surgery should permit safer, sounder operations when attempting reoperation on anatomically ambiguous target organs, surgery on lesions expanding to the organs with risk factors for complications, and in minimally invasive surgery.
A technique of surgical operation and postoperative results for congenital aural stenosis was reported. Generally, the surgical treatment of congenital aural atresia is one of the most difficult otologic surgeries. On the other side, congenital aural stenosis has better postoperative results than congenital aural atresia because of congenital aural stenosis has small stenotic skin of the external auditory canal. But congenital aural stenosis has a atresia bony plate like congenital aural atresia and has insufficience of the external auricular canal skin. Therefore, it is needed a scrupulous care about the hearing improvement in the operation of congenital aural stenosis. Especially the postoperative hearing loss and stenosis of the newly reconstructed external auditory canal due to hypertrophic scar and lateralization of the drum are the main problems. We performed a new operation named the one-stage canaloplasty and tympanoplasty for congenital aural stenosis with successful results.
The purpose of this report is to analyze the degree of inflammation in chronic otitis media (COM) and cholesteatoma at preoperative states. Primary ear surgery was preformed on 299 ears from December 1994 to November 1998 at Hyogo College of Medicine. COM was found in 170 ears (56.8%) and cholesteatoma in 129 ears (43.2%). The types of cholesteatoma included pars flaccida type in 93 ears (72.1%), pars tensa type in 26 (20.2%), and congenital type in 10 (7.7%). Preoperative states were investigated from operative records, regarding chief symptoms, hearing level, surgical methods and intraoperative findings. Results of COM were as follows: ears without otorrhea were found in more than 40%, and ears suffering from continuous otorrhea were less than 15%. Bone conduction hearing levels within 20dB were found in about 45%. Intact ossicular chains were found in about 85%, and tympanoplasty type I and simple underlay myringoplasty were performed in about 85%. Results of cholesteatoma were as follows: bone conduction hearing levels within 20 dB were found in 60% of pars flaccida type, and in 35% of pars tensa type. Ears with intact ossicular chains were found in 50% of pars flassida type, and in 25% pars tensa type. These findings suggested that cases of mild inflammation have recently increased in COM and cholesteatoma.
A 12-year-old girl had a history of intrauterine growth retardation (IUGR), short stature, asymmetry of low limbs, precocious sexual development, fifth finger clinodactily and small mandible. She had bilateral hearing disturbance since birth. We explored the middle ear and recognized absence of the long processes of the incus in both sides. Ossiculoplasty was carried out by incus interposition in both sides and hearing results were satisfactory (before surgery, mean auditory acuity was 71.8dB in the left and 61.7dB in the right, but after sugery 38.3dB in the left and 10dB in the right). About 40 cases Russell-Silver Syndrome have been reported in Japan and more than 200 cases in the world but any case with midlle ear malformation has never been reported.This is the first case accompanied with middle ear malformations.
It is well known that the middle ear diseases such as otitis media with effusion (OME) are very oftenly seen in those who have any anatomical anomaly and/or dysfunction of the Eustachian tube (E. T.). We investigated the gas-ventirating function of E. T. in cleft-palate-infants, with positive pressure loading test, which is one of the tests for evaluating E. T. ventilating function. We have also investigated the influence of palatinoplasty on E. T. ventilating function comparing the pre-and postoperative examination results. The subjects were 84 ears of 42 complete cleft-palate infants, and 25 ears of 13 incomplete cleft-palateinfants. Sixteen ears of 8 cleft-lip infants with normofunctional E. T. were adopted as a control group. We inserted a ventilation tube through the tympanic membrane before palatinoplasties, then both of passive tubo-opening pressure test and continuous endo-tympanic pressure test were performed before and after each operation. As a result, in passive tubo-opening pressure test, “closing failure pattern” was seen in 81.7%(89 of 109ears) of cleft-palate group, while the “normal pattern” was seen in 87.5%(14 of 16 ears) of the control group. In continuous endo-tympanic pressure measurement, “patulous tube pattern” was seen more frequently, and normal pattern was less frequently seen among the cleft-palate group than the control group. We concluded that E. T. of the cleft-palate-infant closes loosely and tends to open easily. There was no significant difference between pre-and postoperative examination results namely passive tubo-opening pressure test and continuous endo-tympanic pressure measurement (Mann Whitney U test and chai square statistics). So we considered that the palatinoplasty does not influenced to the ventilating function of E. T. at least in a short period of time.
Fluid-attenuated inversion recovery (FLAIR) imaging is a technique which faciliates heavily T2-weighted CSF-nulled images by coupling an inversion pulse followed by a long inversion time to a long echo time leadout. FLAIR MR imaging is known to be useful to evaluate pathologic conditions associated with an increase/decrease in protein contents of interstitial fluids. In this study, the endolymphatic sac in two patients having large vestibular aqueduct syndrome (LVAS) was visualized using FLAIR MR imaging. The signals of the endolymphatic sac showed a low intensity in the left side and a high intensity in the right side, suggesting that the protein contents were different between both sides. The result indicated that FLAIR MR imaging is very useful to detect the changes in protein contents in the fluid of the endolymphatic sac and that the protein contents within the left endolymphatic sac is decreased.
The prognosis of sudden deafness in aged patients is thought to be generally poor. However, the reports of sudden deafness focused on aged patients are scanty. We reported our experience of sudden deafness patients over 80 years old. During the past 10 years, there were 11 cases, and this corresponds to 2.3% of the total sudden deafness patients treated during the same period. The outcome of the treatment using steroid was generally poor; 1 case of complete recovery, 1 case of remarkable improvement, 2 cases of slight improvement and 7 cases of no change (criteria defined by the Committee of the Japanese Ministry of Health and Welfare). We speculated that the possible factors which would contribute to this poor prognosis in aged patients are the existence of complications such as hypertension and diabetes mellitus, the decreased hearing of the contralateral ear and poor reserve of recovery in the inner ear. However, we recommend the active treatment even in aged patients by admitting them to the hospital and controlling the complications, because we could expect some possibility of hearing recovery after this active treatment.
This paper presents the temporal bone histopathology of a patient who had benign positional vertigo more than one month before death. The clinical symptoms indicated that this patient had a horizontal semicircular canal variant of benign paroxysmal positional vertigo. However, the main pathological finding was the attachment of a basophilic granular calculus to the cupula of the right posterior canal. The difference between the clinical findings and the temporal bone histopathological findings was thought to stem from the pathogenesis caused by the floating debris in the lateral semicircular canal entering the posterior semicircular canal and attaching to the cupula of the posterior canal while lying in bed. Furthermore, this case indicated that it is difficult to decide the focal side of benign paroxysmal positional vertigo, because there was no clinical findings which indicated that the right ear had a basophilic granular calculus.