In this review the author presented the diagnostic criteria of immune-mediated sensorineural hearing loss (SNHL) proposed by the Acute Profound Deafness Committee of the Welfare Ministry of Japan and after careful investigation he found some problems in this criteria. Atmpresent, there are no reliable laboratory diagnostic test. Therefore the author thinks that only the diagnostic criteria of steroid-responsive SNHL among the criteria proposed both by the author and the committee is the most significant in the diagnosis of immune-mediated SNHL at present. The clinical features of deafness, pathoetiology, early diagnosis and treatment were also reviewed based on the author's clinical experience.
Patients with bilateral Meniere's disease were investigated for possible immunologic abnormalities. Thirty six cases of bilateral Meniere's disease were examined and compared with 58 cases of unilateral Meniere's disease, 37 of bilateral sensorineural hearing loss and 6 of syphilitic endolymphatic hydrops. Immune activity was assessed using four types of immune parameters:(1) serum immunoglobulin levels (IgG, IgM, and IgA);(2) erythrocyte sedimentation rate (ESR) and C-reactive protein levels (CRP);(3) complement levels (C3, C4, CHSO);(4) autoantibody levels (rheumatoid factor, anti-DNA antibody, and antinuclear antibody). Of 36 patients with bilateral Meniere's disease, 15 patients (41.6%) showed abnormalities in more than 2 parameters of 4 and are assumed to have mild immunologic abnormalities. Helper T cell (CD4) and suppressor T cell (CD8) population were examined in 19 cases out of 36 bilateral Meniere's disease and elevated CD4/CD8 ratio were found in 63.2% of 19 cases. These figures were significantly higher than that of unilateral Meniere's disease and other inner ear diseases. From these results, immunologic involvement may be assumed in about 40-60% of bilateral Meniere's disease. The possible immunologic involvement is well worth investigation in bilateral Meniere's disease.
The pathogenesis of immune-mediated inner ear diseases are not yet clarified. We previously demonstrated that secondary KLH antigen challenge into the endolymphatic sac of guinea pigs resulted in a rapid formation of endolymphatic hydrops associated with attacks of vertigo and fluctuating hearing loss. In order to elucidate the mechanism involved in immune injury to the inner ear, the present study investigated the afferent site of immunocompetent cells into the inner ear and its relation to the distribution of KLH antigen, time kinetics of perilymph CHSO and anti-KLH antibody levels, as well as the expression of intracellular adhesion molecule-1 (ICAM-1) in the inner ear. KLH antigen was only identified in the lumen of the endolymphatic sac, but not in the vestibule or cochlea. A marked cellular migration occurred in the endolymphatic sac, but minor cellular migration was seen in the perilymphatic space in the cochlea and vestibule. The time kinetics of perilymph anti-KLH levels and CHSO levels, as well as the expression of ICAM-1 in the inner ear demonstrated peak at 10 hours-24 hours in good correlation with our previous study of the cellular infiltration in the endolymphatic sac. Strong ICAM-1 expression occurred in the endothelium of the whole inner ear venules, especially in the endolymphatic sac, the spiral modiolar and collecting venules, the suprastrial and inferior part of the spiral ligament, and the spiral limbus. Altogether, these results suggest that chemical mediators as well as cytokines produced within the endolymphatic sac may spread in all the compartments of the inner ear and lead to immune-defense as well as immune-injury of the inner ear.
The inner ears in an experimental animal model were immunohistochemically investigated following induction of immune injury, to clarify the mechanisms of both immune responsesand damages. Labyrinthitis was induced in guinea pigs by inoculation of keyhole limpet hemocyanin (KLH) into the scala tympani of animals which had been systemically sensitized to this antigen. Inflammatory cells, some of which contained KLH, were observed in the scala tympani, spiral modiolar vein (SMV) and its collecting venule (CV) after challenge with KLH. SMV, spiral ligament and spiral limbus were diffusely positive for IgG, although IgG-positive plasma cells were hardly observed. Staining for albumin showed a similar pattern to IgG. Despite these marked changes in the cochlea, the endolymphatic sac showed no increase in number of immunocompetent cells or any other apparent changes. These findings suggest that the inflammatory cells seen in the cochlea in this animal model were mainly due to extravasation from blood vessels rather than infiltration from the endolymphatic sac. These animals showed decreased immunoreactivity for Na, K-ATPase and the gap junction protein connexin26 in the spiral ligament, although the changes in staining for Na, K-ATPase in the stria vascularis were slight. MRL/lpr mice, an autoimmune disease model with hearing impairment, showed slightly reduced staining for connexin 26 in the- spiral ligament. It is possible that immune injury of the spiral ligament could be one of the causes of cochlear dysfunction.
The progress of the technology is expected to occur mainly in the two fields of information and life/medicine. The technology progress in medicine must be made on the basis of the fusion between medicine and engineering. The authors have made various trials by using micro manufacturing technology in order to support medicine from engineering side. For example, (i) micro testing systems to measure the mechanical properties of small living body materials such as eardrum and inner-ear, and (ii) force sensing surgery knives to detect the forces which appear during surgerical operation, are developed and applied to the actual medical operations. In case of a micro testing system, specimen eardrum which is fixed circumferentially is penetrated by a punch of 130gm in diameter under the observation through optical microscope. As the deformation and force are simultaneously measured, local strength and stress-strain relationship can be obtained. In case of a force sensing knife, the force which is actually applied during operation can be detected without any interference caused by the vibration of surgeon's hand through the cancellation performance by accelerometer. From now on, the authors intend to develop “performance to observe”, “performance to handle” and “performance to support micro surgery”. For example, (i) a long focussing depth optical microscope which gives clear magnified vision in air atmosphere regardless of the working depth, (ii) a micro pump which can exhaust viscous body liquid compulsorily to outside, (iii) micro tools for various operations such as picking, cutting and carrying, (iv) a micro sensor to directly detect pressure in cochlea, are now considered to be developed. In order to realize the above subjects, the technology to fabricate and assemble 3-D micro structures in the order of nano/micro-meter is essential. The authors are now developing the working system named as “Nano Manufacturing World (NMW)” for the above purpose.
Measurement of anatomical indices in human temporal bone has been reported only sporadically using high resolution CT. We developed a method for measuring such indices by computer assisted processing of images obtained by high resolusion CT. Intensive measurement of distances between all anatomical points in the entire temporal bone structure became possible with this method.
The authors presented three patients with acquired petrosal dholesteatomas with facial paralysis. Case I was a 40-year-old man with a history of otitis media, whose chief complaint was right facial paralysis. Examination of the right tympanic membrane showed retraction of pars flaccida. Physical examination demonstrated right facial paralysis, right canal paresis (50%) in caloric test, and normal hearing. Petrosal cholesteatoma was diagnosed and the patient underwent total removal of petrosal cholesteatoma via the transmastoid approach, the cavity being obliterated with temporal muscle fascia. The cholesteatoma extended from the region of supratubal recess, the anterior superior area of the anterior semicircular canal to the petrosal portion. The facial nerve was skeletonized and compressed by the cholesteatoma at the labyrinthine portion. Postoperatively, a moderate conductive hearing loss was demonstrated, but facial nerve paralysis recovered almost completely. Follow-up MRI of 10-months after the operation showed no evidence of recurrence. Case 2 was a 43-year-old man with a history of left cholesteatoma for which he underwent an operation 23 years before. His chief complaint was left facial paralysis. Examination demonstrated recurrence of cholesteatoma in his left mastoid cavity, left sided deafness, and left canal paresis. Removal of recurrent cholesteatoma was performed via the transmastoid-translabyrinthine approach, and the cavity was obliterated with fat and temporal muscle fascia. The cholesteatoma exte nded from the region of attic, via the supralabyrinthine route, to the petrous portion. The facial nerve could not be identified because of severe atrophy. Seven months after the operation, he underwent a plastic surgery of cross-face nerve graft for left facial paralysis. And about a year after this first plastic surgery, second plastic surgery of free muscle transplant was done. Case 3 was a 45-year-old man with a history of right hearing loss since childhood, whose chief complaint was right facial paralysis. Examination of right tympanic membrane showed retraction of the pars flaccida. Physical examination demonstrated right facial paralysis and a moderate mixed hearing loss (50dB) in his right ear. A right transmastoid approach was performed, and the operated cavity was obliterated with a temporal muscle flap. The cholesteatoma extended from the region of attic, via the supralabyrinthine route, to the petrous portion. The facial nerve was not exposed. Postoperatively, his facial paralysis resolved almost completely. In this article, we discussed the facial paralysis due to petrosal cholesteatomas- its causes and its treatment. Two of our patients showed excellent return of their facial functions, and one patient needed plastic surgery twice, cross-face nerve graft and free muscle transplantation. We also reviewed the surgical treatment for petrosal cholesteatomas. Various surgical approaches have been utilized; 1) transmastoid-translabyrinthine, 2) middle fossa, 3) suboccipital, 4) transethmoidtranssphenoid, 5) transpalatal-transclival. Decision making of surgical approach depends on extension of cholesteatomas, eighth nerve functions, and so on. It is still controversial whether obliteration of operated cavity should be done or not. We favor obliteration technique because it may prevent cavity infection, and, furthermore, with the advent of MRI, we can now assess the growth of residual lesions or evidence of recurrence. We feel that annual MR imaging follow-up is indicated in cases with obliteration of operated cavity.
A 55-year-old female presented with paraganglioma in the tympanic cavity. She complained of hearing loss in the left ear. Middle ear tumor was diagnosed by high resolution CTscan and MRI. The tumor was completely removed by transcanal tympanotomy. No recurrence of the tumor was confirmed 10 months after surgery. The importance of preoperative imaging method are discussed.
Reversible sensorineural hearing loss associated with erythromycin (EM) therapy has been reported. Previous reports, however, offered little explanation as to the possible mechanism for EM ototoxicity. Some researchers have recently reported evidence to support a central nervous system foci for EM induced hearing loss. In order to clarify the mechanism of EM ototoxicity, the effects of EM lactobionate on the auditory evoked response (ABR) and the middle latency response (MLR) were examined in eight unanesthetized rats. The effects of piperacillin sodium (PIPC) on the ABR and the MLR were also examined in five unanesthetized rats as controls. After intraperitoneal injection of a large amount of EM lactobionate (500mg/kg), the ABR and the MLR were recorded repeatedly using implanted electrodes on the surface of the dura. All waves except the P1 of the ABR (P2, P3, P4 and P5) showed a progressive increase in latency. The interpeak latencies (IPL) Pl-P3, P3-P5, and Pl-P5 also increased gradually. The amplitudes of the Na and the Pa showed a progressive decrease within the MLR. After a period from 30 to 90 minutes following EM injection, the elongated latency of each wave of the ABR shortened. The IPLs were also shortened. And they returned to the values prior to the EM administration in 270 minutes. The Na-Pa amplitude also increased gradually as the latency decreased. With PIPC administration (1g/kg), these latency and amplitude changes were not observed at all. These results suggest that EM influenced the specific auditory pathway between thecochlear nucleus to the early cortical sections, and the non-specific auditory pathway; the brain-stem reticular formation. Care should thus be taken when a high dose of EM has to be given or when the patient is at risk of higher serum concentration caused by renal or hepatic disturbance.
Of 54 patients with acoustic neuroma (AN) treated at our hospital from 1989 to 1995, 17cases showed the initial symptom of sudden hearing loss, and 11cases showed a so-called “valley type” pattern. The bottom frequency of “valley type” audiogram of the patiants with AN was between 1 kHz and 2 kHz, and these patients showed a slight recovery in early stage comparing with patients with Sudden deafness. These findings suggested that it is neccesary to make further audiological and radiological examinations to detect AN in patients with sudden hearing loss with a “valley type” audiogram.