An increase of acid mucopolysaccharides in the connective tissue in the inner ear in the experimental alloxan diabetic mice was demonstrated by biochemical analysis, and sporadic losses of the outer hair cells and microangiopathy of the stria vascularis in the cochleae were also demonstrated by histopathological methods. The existence of hearing disorders in diabetics which have been clinically experienced, was experimentally clarified.
A woman, aged 56, was admitted to a hospita because of diabetic coma on Jan. 14, 1977, and complained of a gradually progressed hearing loss in both ears without vestibular symptoms after recovering from coma. About three months after attack, audiological examination showed bilaterally symmetrical sensory hearing loss of a severe flat type. Hearing test showed 10 to 20dB deterioration in 3, 4 and 6kHz after peroral taking of 50g. glucose. Vestibular function test showed diminished caloric reaction in both ears. Although her diabetes became well controled, nephropathy and retinopathy (Scott V) were still remained. The following considerations were obtained. 1. It was assumed that circulatory disturbance of the inner ears might be caused by increased viscosity of blood, stagnation of blood stream, tissue hypoxia and subsequent clot in capillary vessels i.e. hemorheologic change. 2. Hearing deterioration observed during the glucose tolerance test was thought to be caused by hyperglycemia.
A case with sensorineural hearing loss and simple goiter (Pendred's syndrome) was reported. The case, whose mother had congenital deaf-mutism with a simple goiter, was a thirteen years old girl who suffered from congenital hearing loss and simle goiter. The thyroid function tests revealed euthyroidism except for 131I up take which showed 46%. Neither hyper- nor hypothyroidism was seen clinically and mental or physical development seemed normal. Pure tone audiogram revealed a high tone hearing loss in her both ears. After a battery of the audiological examinations, the inner ear was suspected as a lesion of the hearing loss. The hearing threshold of this patient showed fluctuation during her clinical course. For past three years, sudden hearing loss ocurred three times, and the first one was idiopathic, the second after viral infection and the third after swimming. In each occasion her hearing threshold was recovered from complete deafness 40dB to in the right ear and from 80dB to 55dB in the left ear within a week.
Pendred's syndrome was originally described by Pendred (1896), as the condition of goiter and profound congenital sensorineural deafness. Fraser et al. (1961) reported the findings in 113 individuals from 72 families. Although the sporadic reports were found in the literature, this condition, particularly from the otological aspect, has not been well described in Japan. The authors reported two cases in three siblings, and both of them had a similar type of rather severe, symmetrical congenital deafness and goiter that developed at the age of 16 (sister) and 11 (brother). Positive recruitment was found in both cases. As the recent characteristic clinical finding appeared in both cases, vertiginous episodes with nausea, vomiting and fluctuant hearing were occurred occasionally. The abnormal vestibular responses were found in the sister.
Cyclic AMP, renin and angiotensin were examined in sixteen patients with sudden deafness and in four patients with fluctuating sensorineural hearing loss. Eight out of sixteen patients of sudden deafness showed an increase in cyclic AMP just after onset of symptom, and this increase seemed to relate to renin value. Other patients of sudden deafness showed no change of cyclic AMP and renin. From these observations, it concluded that renin might be a factor in pathogenesis of acute sensorineural hearing loss.
The purpose of this experiment is to examine pathologic change of the inner ear related to the disturbance of blood circulation due to contraceptives. Twelve guinea pigs (6 males and 6 females) weighing approximately 300g were used. To each animal, 0.1ml of E. P. Hormone (contains 10mg of progesterone and 1mg of estradiol benzoate per 1ml) was injected intra-muscularly daily for 40 days. Pinna reflex was measured by audiometer, made for guinea pig, before and during the administration of the drug, and then the animals were sacrificed. The inner ear was examined histologically. One of the 12 animals showed the pathologic changes of the vacular system of the inner ear. In this animal, hyaline thrombus like dense homogenous materials were frequently found in the capillary lumina of the stria vascularis and plexus cochlearis. These materials were distinctly different from blood clot in the vessels. The spiral organ and spiral ganglion did not indicate any pathologic changes. The tissue was rather well fixed, and postmortem change was minimum. In the vestibular organ, there was no thrombosis. These thrombus like materials were most probably caused by an increase in coagulability of blood which may be induced by E. P. Hormone administration.
The effects of ethacrynic acid, furosemide and bumetanide upon EP in the cochlea were examined using 214 normal guinea pigs. Bumetanide is, by weight, the most potent ototoxic agent followed by ethacrynic acid and then by furosemide. However, taking clinical dosages of these diuretics into consideration, the relative ototoxicity of bumetanide is much smaller than that of other two. It is the authors' impression that ethacrynic acid and bumetanide share the almost common mechanism of action in the inner ear but that of furosemide is slightly different from that of others.
In this study 874 ears of 437 persons aged 45-69 years were tested, and the mean hearing threshold of physically normal group were compared with those of group with various physical disorders such as hypertension, retinal angiosclerosis, hyperglicemia and renal or hepatic insufficiency. Average hearing threshold of physically normal group was slightly better at 8kHz than these of physically abnormal group aged 45-49 years. But in the 50-54 years old group, hearing threshold of normal group was 5 to 7dB better than pathologic one at high tones. These values were statistically significant. In the 55-59 age group, the differences of hearing threshold at high tones became little. In the 60-64 age group, the difference at high tones was also little but at low tones this was similar. At all frequencies, the differences were 5dB at 0.5kHz and 4-7dB at high tones in the 65-69 age group. The further studies in the higher age group could not be accomplished because there were few in this group physically normal persons.
Patients with congenital metabolic diseases and deafness were investigated by auditory brain stem responses and other audiometric methods. The cases consisted of a case of osteogenesis imperfecta, a case of oculocutaneous albinism, two cases of Hunter diseases (Mucopolysaccharidosis II) and three cases of Leucodystrophy. Auditory brain stem responses were estimated by latencies of wave I, V, V-I at 85dB SL of 3kHz click, the latency intensity curve of wave V and threshold of wave V, and the results were compared with pure tone or speech audiometry. The patients with osteogenesis imperfecta, oculocutaneous albinism and Hunter disease showed mixed deafness or sensory neural deafness, however, the features of their auditory brain stem responses were almost similar to those of sensory neural deafness previously reported and no specific findings due to congenital metabolic diseases were found. Although the cases of Leucodystrophy showed moderate sensory neural hearing loss at the early stage of the illness, the auditory brain stem responses revealed a normal wave form and normal threshold, but the slow vertex responses were poor. Therefore, the central deafness due to cortical or subcortical lesions was suspected. Especially one of three cases showed normal auditory response at the onset, but showed wave I alone at his terminal stage, and this fact suggested that there was the advanced lesion toward the brain stem. We want to emphasize that measurements of the latencies of wave I, V, V-I, the threshold and latency-intensity curve of wave V will be helpful to make differential diagnosis of deafness due to the middle ear, cochlea, brain stem and cortical or subcortical disorders.