The development of new techniques for studying synaptic interactions between nerve cells have affected the way in which we think about the synapses of the inner ear. The synapse of the inner hair cell is the first relay on the pathway through from the cochlea to the brain, and any disorders of its working present as a neuropathy. This short review summarizes some of the relevant background to understand the design of new experiments to uncover the working of this synapse. Using imaging methods the ribbon synapse of the inner hair cell can be studied in semi-intact systems of the organ of Corti. Exploiting a unique property of the cell biology of hair cells, the fluorescent membrane dye FM1-43 can be trafficked down to label synaptic vesicles at the basolateral end of the cell. The experiments identify functional properties of the hair cell ribbon synapse, where the neurotransmitter is packaged in vesicles and released rapidly and over long periods with relatively little fatigue. The technique may also clarify the roles of two new auditory neuropathy genes, pejvakin and otoferlin.
Immune mechanism has been postulated as one of the possible pathoetiology for Meniere's disease, since it is clinically well known that some patients with Meniere's disease show remarkable recovery from fluctuated and repeated sensorineural hearing loss or vertigo by systemic application of corticosteroid. However, there still has been a distance between the clinical entity and the basic knowledge of anatomy and immunology obtained so far. Moreover, little is known about bone marrow-derived cells or immune-competent cells in the vestibule on the basis of experimental research. In this study, we studied the distribution and phenotypes of bone marrow-derived cells in the vestibule using bone marrow-chimeric mice, in which bone marrowderived cells were visualized with green fluorescence. In order to make bone marrow-chimeric mice, bone marrow was obtained from GFP mice with green fluorescence expressed in every cell in the body. Adult C57 BI/6 mice received systemic irradiation to ablate their own bone marrow, and then were systemically applied bone marrow derived from GFP mice. Three month after bone marrow transplantation, the inner ears were collected and processed for cryostat sections. The specimens were studied with a fluorescent microscope. In the endolymphatic sac, bone marrow-derived cell were found in the epithelial layer and lumen of the sac, as previously reported, and most of these cells exhibited the phenotype of macrophage. In contrast, bone marrow-derived cells were observed being limited within the stroma in the vestibular ganglion or underneath the sensory epithelia of the utricle, saccule, and ampullae of semicircular canals. Immunohistochemical study demonstrated that more than 70% of bone marrow-derived cells in the vestibule showed the phenotype of macrophage. These results proved that bone marrow-derived cells exist mainly as vestibular macrophages in the stroma underneath the vestibular sensory epithelia, even when without damage. It is also indicated that the vestibular macrophages appeared to be novel constitutive cells in the vestibule, and would have a potential to be a therapeutic target in vestibular disorders.
A retrospective analysis was performed about the utility of adenoidectomy for otitis me di a with effusion (OME) in the schoolchildren. 92 ears of 92 patients from 7 to 12 years old were enrolled who went ventilation tube insertion for OME between January 1982 and December 2003. Patients were classified into two groups: 1) the adeno idecoto my group in which adenoidectomy was performed a t the time of tube insertion and 2) the tube group in which o nl y tube insertion was performed without adenoidectomy. Furthermore, each group was classified in more than 18 months (18M≤group) and less than 18 months (18M>group) according to the duration of tube placement. The outcome after tube removal was classified in “good” and “recurrence”. Furthermore, of these 9 2 patients, the relationship between the Eustachian tube (ET) function and the outcome after tube removal was examined in 21 ears of 21 patients who underwent sonotubometry. Of these 21 patients, the relationship between the ventilation function by the transmucosal gas exchange in the middle ear and the outcome after tube removal was examined in 13 ears of 13 patients who underwent the middle ear total pressure (MET P) measurement. In 52 patients of the adenoidectomy group, 18M≤s and 18M>included 39 and 13 patients, respectively. In the adenoidectomy group, the numbers of “recurrence” were 3 patients (7.7%) and 1 patients (7.7%) in 18M≤s group and 18M>group, respectively, showing no statistically significant difference between the two groups. In 40 patients of the tube group, 18Ms and 18M>included 25 and 15 patients, respectively. In the tube group, the numbers of “recurrence” were 4 patients (16.0%) and 9 patients (60.0%) in 18M s and 18M>, respectively, showing significantly much “recurrence” in 18M>(p<0.01). These results suggested that adenoidectomy has an effect to improve OME in the early stage less than 18 months. In 18M≤ group, there was no statistically significant in the “recurrence” between the adenoidectomy group and the tube group. This result suggested that the tube placement more than 18 months hardly showed the effect of adenoidec tomy. On sonotubometry, 11 of 17 patients in “good” showed a good ET function, but all of 4 patients in “recurrence showed poor ET function. On METP measurement, all 2 patients of recurrence” withpoor ET function showed a tendency that the maximum MET P was low; on the other hand, all 4 patients of “good” with poor ET function showed a tendency that the maximum METP was high. These results showed that it is important to improve either of ET function or transmucosal ventilation function to become “good”.
Ten cases of auditory ossicular malformation were operated on at the Department of Otolaryngology, Hyogo College of Medicine from 2004 to 2006. Their mean age was 19. 9 years. Deformities of the external meatus and otoscle ro si s were excluded. The stape di al reflex appeared in three ears. Defects in the incudostapedial joint was found in 4 ears (40%), fixation of the malleus and incus in 2 (20%), fixation of the stapes in 2 (20%), and multiple malformations in 2 (20%). Ossicular reconstructions were performed with type I (1 ear), modified type II (1 ear), modified type 111 (2 ears), modified type N (2 ears). Total stapedectomy with malleus attachment was performed in 2 ears. Exploratory tympanotomy without ossicular reconstruction was performed in 2 ears. Hearing improvement was achieved in 7 out of 8 ears (87. 5%) with exception of 2 exploratory tympanotomy cases. High rate of hearing improvement encouraged us to operate on auditory ossicular malformation. However, we should consider that because of their way of life, only exploratory tympanotomy without ossicular reconstruction should be recommended in some cases.
We performed cochlea implant in a patient with cochlear otosclerosis presenting bilateral facial spasm on preoperative promontory stimulation test (PST). Facial spasm due to the stimulation by implanted electrode is one of the complications after cochlear implantation in cochlear otosclerosis or otospongiosis. We successfully prevented the facial spasm by using the self curling electrode (Cochlea Nucleus 24 Contour) and hydroxyapatite (BIOPEX (R)) for prevention of the current flow stimulation of the facial nerve.
A 11 year-old boy complained of a headache, fever, swelling of the left orbit, and otalgia. He was diagnosed acute otitis media. CT scan showed an intracranial abscess, left otitis media and left mastoiditis. Although he was treated with intravenous antibiotics, his consciousness was getting cloudy. Therefore mastoidectomy and craniosurgical drainage were performed. Although otogenic intracranial complication is rare, it can still become serious condition. It is important to examine head CT and MRI scanning with change of patient's condition, and to perform suitable treatment for each case.
A 10-year-old girl was found a speech delay by her mot he r at age of 4 years. A local ENT physician diagnosed of bilateral congenital auditory stenosis and referred her to our hospital for further evaluation. At that time CT revealed no anomalies of the middle and inner ear, and auditory brain stem response and play audiometry showed the threshold of 60 dB in both ears. Hearing aids were fitted for her ears, thereafter she was followed up in our hospital and by the referring physician. Since January 2004, otorrhea in both ears was repeatedly observed. On March 2007, she hospitalized for surgery. On the day of admission, the size of bilateral external auditory canals was like a pin-hole. Pulsating otorrhea was observed in the left ear. CT revealed the bony stenosis of bilateral external auditory canals, and soft tissue density in the tympanic cavity to antrum and bone destruction at the promontory in the left ear. Three days after her hospitalization, she underwent planned staged tympanoplasty and meatoplasty in the left ear. Cholesteatoma filled in the tympanic cavity and cochlear fistula was found at the promontory. After the operation, she had neither vertigo nor hearing loss in bone conduction. Most of inner ear fistula in the cases with cholesteatoma are found on the lateral semicircular canal, but cochlear fistula is rare. Cholesteatoma stored at the lateral side of the promontory might have destructed bone over the cochlear and made a fistula in this patient. Any patient with congenital auditory stenosis who has repeating infection should have the surgical intervention as soon as possible.
A 45-year-old man presented with complaints of right hearing loss, otorrhea, and headache. The right eardrum was perforated, and an inflammatory polyp was present in the middle ear, and the posterior wall of the external auditory canal was partially destructed. CT scan revealed a large mass measuring 60×55×55 mm in the posterior fossa. The mass was found to be a cholesteatoma and it was subsequently removed. The eardrum and external auditory canal was reconstructed with fascia and cartilage, and the surgical defect was obliterated with adipose tissue. The postoperative course was uneventful, and to date there has been no recurrence of the chole st eato ma. Initially, we considered that this cholesteatoma must be acquired, in view of the perforation of the eardrum. However, there was no cholesteatoma in the tympanic cavity, but the cholesteatoma destroyed mainly the mastoid air cells and extended i nt o the posterior fossa. Therefore, this was probably a case of congenital cholesteatoma. It was difficult to decide how to reconstruct the posterior wall of the external auditory canal, however, we selected the closed method in order to minimize the risk of infection.