Calcium ions are essential for acoustic transmission in the cochlea. The basis of the calcium metabolism and transport in the cochlea was discussed, and both experimental and clinical evidences that the systemic disturbance in calcium and vitamin D (V. D) induced the cochlear dysfunction were shown. The long-term decrease in the calcium concentration in serum reduced that in perilymph. The N1 response was damaged by the perilymphatic perfusion with low-calcium solution. The hearing impairment was observed in the V. D deficient rat. On the basis of the abovementioned findings, the cochlear dysfunction associated with hypoparathyroidism might be brought about by the metabolic disturbance of calcium in the inner ear fluid secondary to the decrease in serum calcium and/or the direct effect of the decreased V. D upon the cochlea. The latter was supported by the fact that the low level of serum V. D was commonly observed in patients with bilateral sensorineural hearing loss.
The long-term follow up study of hearing was conducted in a steroid-responsive sensorineural hearing loss. The subjects were 21 ears of 16 cases and the mean observation period after start of steroid administration was about 6.4 years. The results obtained were as follows; 1) A positive correlation was found in the course of hearing fluctuation between two consecutive neighboring frequencies of all frequency matchings, between low frequency area and mid frequency area and also between mid frequency area and high frequency area. 2) A course of hearing fluctuation in both ears almost corresponded in 3 out of 5 bilateral cases, while it differed in other 2 cases. 3) The mean frequency in acute attack of hearing change was about once a year in low frequency area and twice a year in mid- and high frequency areas. 4) The mean degree of deterioration and recovery in each acute attack of hearing change was about 20-25dB. 5) The maximum hearing fluctuation during follow up period was calculated in each ear. The mean value was about 35dB in all frequency areas. 6) The difference between initial hearing level and final hearing level during follow up period was found to be minimal. The mean difference was only 6.2dB even in high frequency area which showed the largest difference.
Pure tone audiograms of 123 patients who suffered from various systemic deseases with some otolaryngeal symptoms were examined. The results obtained were as follows; 1) The hearing level less than 30dB was found in 168 ears (68.3%), 30-60dB in 55 ears (22.4%), 60dB or more in 23 ears (9.3%). 2) Most cases of the hearing loss were bilateral disorder with chronic progress. 3) Most cases of severe hering loss were unilateral disorder with acute onset. Relationship between the hearing loss and general condition was not proved in most cases. There were many reports on hearing loss associated with various systemic deseases. but the hearing type was unknows in each disease. It seems that we must analyze the type of hearing loss of each systemic disease.
Eleven patients of sudden deafness with diabetes mellitus were presented. Clinical course of hearing impairement and the relationship between degree and prognosis of hearing impairement and condition of diabetes mellitus were studied. The Clinical courses of sudden deafnesses were almost the same in those with or without diabetes mellitus, but in the patients with diabets mellitus hearing was highly impaired, and in 3 cases hearing loss became worse after the initial examination and reached the maximum within a few days. The correlation of degree of diabetes mellitus and clinical course of hearing loss was not clear. Steroids was useful for the treatment of hearing loss under control of blood sugar level, and the prognosis was not bad.
We studied temporal bone pathology in 4 cases of leukemia with a hearing loss confirmed by pure tone audiometry. They included severe bilateral sudden deafness in 2 cases, slight mixed hearing loss in 1 case, and slight bilateral sensorineural hearing loss in 1 case. Leukemic changes were observed in the temporal bones of all cases. There were leukemic infiltration and bleeding from the internal auditory meatus to the modiolus and cochlea in 2 cases of sudden deafness. Leukemic infiltration to the external auditory meatus and bleeding from the internal auditory meatus to the cochlea seemed to be the cause of hearing loss in the case of mixed deafness. No leukemic change except cellular infiltration into the mastoid, and exudate in the tympanic cavity were observed in the case of sensorineural hearing loss. Our findings show that any leukemic lesions could occur at any sites of temporal bones. Corresponding to the particular sites of lesions, it seems to cause any types of hearing impairment, such as conductive, mixed or sensorineural hearing loss.
Immunological study was performed in 83 patients with sensorineural hearing loss, including 41 patients with idiopathic bilateral sensorineural hearing loss, 7 Meniere's disease, 6 low tone deafness, 6 sudden deafness, 5 unilateral deafness, 11 other fluctuating sensorineural hearing loss, and 7 fixed sensorineural hearing loss. The results were as follows: 1) Circulating immune complex was investigated in 83 patients and high immune complex titers (over normal means+2SD) were found in 41 cases of C1q SP RIA group and in 22 cases of mRF SP RIA group, especially patients of idiopathic bilateral sensorineural hearing loss showed high titers of immune complex on C1q SP assay. 2) Anti-DNA antibody assay showed high titers (over 2 times normal means) in 7 cases. 3) Anti-cardiolipin antibody assay showed high titers (over 2 times normal means) in only 3 cases. 4) Immunoglobulin test were performed in 31 patients and 12 cases showed high titers of IgG. 5) 11 cases (in 37 cases) showed positive antinuclear antibody. But anti-ENA antibody was not demonstrated. 6) Totally in 53 out of 83 cases, immunological abnormalities were demonstrated.
Harada's disease is one of autoimmune disease in which target cells may be melanocyte, and is characterized by a granulomatous uveitis, meningitis symptoms, labyrinthine disorders and depigmentation of the skin. Eleven of 11 patients with Harada's disease were neurotologically studied. Nine of the 11 patients complained of cochlear and/or vestibular symptoms. In 8 of 22 ears sensorineural hearing loss between 20dB and 40dB was observed. In 5 of them a moderate sensorineural hearing loss between 40dB and 60dB was observed. In 2 of the 11 patients Bekesy's audiometry and SISI test showed auditory recruitment. In 5 of the 22 ears electrocochleography was performed but no ear showed enlarged negative SP. One patient who had a low pitched hearing loss indicated negative glycerol test. Equilibrium test was performed in 6 of 11 patients, and they showed peripheral disequilibrium findings. No interrelationship among hearing loss, visual acuity and CSF findings was obtained. These results suggested that inner ear involvement is a common complication in Harada's disease. It was also discussed whether or not the inner ear involvement is related to disorder of the endolymphatic sac in which melanocytes and immunological substances are contained.
Recently immunological mechanisms as a pathogenesis of some sensorineural hearing disorders elucidated. Eleven cases of bilateral sensorineural hearing disorders associated with the known autoimmune disease were investigated. The results obtained were as follows; Of 11 cases, there were rheumatoid arthritis in 3 patients, relapsing polychondritis in 2, Beçet's disease in 1, Harada's disease in 3, aortitis syndrome in 1, mixed connective tissue disease in 1. 1) The features of pure tone audiogram were various in each case. 2) No case presented with vertigo attack or facial nerve palsy. 3) The hearing disorders were most likely due to the inner ear damages. 4) Responsiveness to steroid hormone therapy was various in each case. 5) Responsiveness to steroid hormone therapy was more effective in autoimmune disease with vasculitis than the others. 6) It was supposed that the hearing disorders are a part of systemic disease like autoimmune disease because of the similarity of hearing level in both ears. 7) There were some discrepancies between our cases and those of autoimmune sensorineural hearing loss which McCabe defined, and those of steroid-responsive bilateral sensorineural hearing loss which Kanzaki defined.