Reflex contraction of the stapedius muscle elicited by unilateral electrical stimulation by using Hilger facial nerve stimulator of the external auditory meatus, was studied in persons of normal hearing and patients with various types of hearing impairment. The reflex of the stapedius muscle was observed by impedance meter (Madsen ZO 70), and it was recorded quantitatively by continuous tracing on a level recorder. In normal ears, the threshold of electrocutaneous stapedius reflex (average 1-mA) and uncomfortable level of electrocutaneous stimulation (average 5mA) were measured respectively. Even in severe perceptive hearing loss with no acoustic stapedius reflex, the electrocutaneous reflex was obtained. In otosclerosis verified by operation, an electrocutaneous reflex was not obtained. And the electrocutaneous stimulation caused no impedance change in patients with unilateral peripheral facial palsy in whom paralysis of the stapedius muscle ascertained by means of acoustic stimulation. Thus it could be concluded that the impedance change is caused by reflex contraction of the stapedius muscle elicited by electrocutaneous stimulation in the external auditory canal. This investigation indicated that stapedius reflex was elicited by the non-acoustic stimulation in humans.
The study was designed to examine the combined toxic effect of DKB, a new semi-synthetic aminoglycoside antibiotic, and diuretics, ethacrynic acid or furosemide, on the cochlea in three groups of guinea pigs and mice. One group received DKB alone, one received ethacrynic acid or furosemide alone, and one received DKB with either of ethacrynic acid or furosemide. DKB was found as much toxic as kanamycin A, but less toxic than gentamicin with regard to toxicity /g/ body weight. Degeneration appeared first in the outer hair cells in the basal turn of the cochlea starting with the increasing of lyosomes, degeneration of mitochondria and resulting in the complete loss of hair cells, but stria vascularis showed little change. No change in the cochlea were observed in 2 days after single administration of DKB, ethacrynic acid or furosemide in both guinea pigs and mice. Mice receiving both DKB and diuretics did not show any change in the cochlea. The harmful effects were shown in guinea pigs, when DKB and ethacrynic acid were combined, more significantly than predicted by simple addition of the effect of each drug. The sever disintegration and loss of outer and inner hair cells and nerve fibers in all turns were observed in this condition. Therefore, it was suggested that a care must be taken when amino glycoside antibiotics and ethacrynic acid are given together in a patient. The toxic mechanism of the interaction of these drugs to the cochlea were discussed from the morphological point of view.
The purpose of this paper is to elucidate the early development in young children with severe hearing impairment. Four girls whose language developed relatively favorably in spite of severe hearing losses of approximately 80dB or more were selected for this purpose. Language education was begun by their mothers who participated in our home training program when the girls were one year and five months old, one year and seven months old, one year and ten months old, and two years and four months old respectively. Data was collected through the use, by their mothers, of special diary to evaluate the psychos logical development and the development of language comprehension as well as verbal and nonverbal expressions, as observed in their deaf children. The results obtained are as follows: 1. The development of language comprehension preceeded the growth of vocabulary in all cases. 2. Pointing or inquisitive behavior emerged between the ages of two years and two years and eleven months. 3. As soon as pointing behavior emerged, vocabulary began to increase rapidly, and infantile words, which previously held only generalized meanings, began to differentiate into individual words with specific meanings. 4. At this time, most mothers commented that their child had found “All things have their own names.” As far as these four cases are concerned, the findings mentioned above suggest the conclusion that there is a critical period for language development in young children with severe hearing impairment. The rationale for this critical period may be explained by Vygotsky's theory that the curve of development of thought and speech, till then separate, meet and join to initiate a new form of behavior in which speech begins to serve the intellect and thoughts begin to be spoken.
Histopathological findings in a case of the metastatic tumor in the temporal bones were reported. The patient had extensive invasion of tumor cells in the internal auditory canal and in the Rosenthal's canal on both sides. The tumor cells infiltrated into the acoustic nerve fibers and replaced the spiral ganglion cells up to the middle turns. The hair cells were missing in the basal turn and a part of the middle turn. The patient's records showed that his hearing was not impaired and he responded well to the inquiries at rounds. This case, as well as experimental and clinical evidences in the literatures, supports the current concept that rather few nerve elements and sensory cells are required to auditory sensation and speech discrimination.
Twenty three children between 4 months and 5 years of age suspected of hearing impairment were tested by brainstem response (BSR) and electroencephalic response audiometry (ERA). We used the chicks as auditory stimuli in BSR and used the tone bursts from 250Hz to 4000Hz in ERA. The response was recognized in 16 cases by ERA and in 11 cases by BSR. The lowest response threshold was at 0dB HL in BSR and at around 60dB in ERA. Nevertheless more frequent response were obtained in ERA than in BSR. The reason of this was thought that the residual hearing at low frequencies would not be recognized by BSR but by ERA. Tone bursts of 250Hz and 500Hz which were used in ERA were useful for testing the residual hearing. The clicks used for BSR were also utilized as auditory stimuli in ERA, and the lower response threshold were obtained as same as in BSR. But the response by chicks in ERA did not show hearing sensitivity at low frequencies.
A computer-controlled system of an automatic audiometry was devised for improving the reliability and the rapidity of the measurement. The system was designed to deal with up to thirty two subjects simultaneously, and the procedure was identical to the current pure tone audiometry. The procedure and test tones were selected by computer software. “Yes or No” respone of every subject was fed back to the computer. It was processed according to the specific criteria in threshold measurement. Audiograms of the respective subjects were displayed on a computer scope or typed out. Some problems were discussed in terms of the practical application of the system in the screening and mass surveys of hearing loss. This system may have some essential features of a stimulus-response control system having multiple input-output channels.
The effect of click repetition rate and intensity on wave V latency, amplitude and probability of wave detection (I-VII) was observed in 10 normal listeners. Click repetition rates of 10, 30, 50 and 70c/s were presented at each of 70, 50 and 30dBHL intensities. Results as follows. 1. Increasing the click rate results in an increase in the latency of wave V (a click rate increase from 10 to 70c/s cause a 0.5msec shift). Also an increase in the click rate results in a decrease in the amplitude and a lowering of the probability of wave detection. 2. Increasing the click intensity results in a shortening of wave V latency (An intensity increase from 30 to 70dBHL results in a 1.4msec shift). Also an increse in the click intensity results in an increase in the amplitude and an increase in the probability of detection of all waves. 3. A convienient click repetition rate in the clinical routine examination is 10 to 30c/s.