Reversed reflexes (RR) by ipsilateral stimulation were observed in 40 patients who showed no stapedius reflex by a contralateral stimulation. The cause of RR phenomenon is unknown, but there are at least two possibilities. The one possibility is purely due to artefact and the other is the result of the middle ear muscles. Electrocutaneous stimulation caused no RR in the present cases. This finding supports a view that the RR is not referable to the stapedius muscle contraction. Contralateral stimulation caused no impedance change in patients with unilateral and bilateral peripheral facial palsy involving the stapedius muscle. When ipsilateral stimulation caused the RR in patients with bilateral facial palsy involving the stapedius muscle or in patients with acoustic tumor, simultaneous contralateral reflex was not observed. This result indicates that the RR is not related to the tensor tympani muscle contraction in the startle reaction. Thus it is concluded that the RR is not caused by reflex contraction of the middle ear muscles, but caused purely due to artefact.
To elucidate the importance of Ca++ for cochlear function and brain stem response, we investigated the patients with disorders of the thyroid and parathyroid glands using simultaneous recording of AP and ABR. The results obtained were as follows, 1) AP (N1) showed a prolongation in latency when Ca++ level was low in blood. 2) ABR showed no prolongation in latency of V wave and no remarkable change in I-V intervals. 3) Three of nine patients showed fluctuation of AP (N1) latency and variability of AP (N1) amplitude, as Ca++ levels were fluctuated 4) The results of AP and ABR suggested that Ca++ plays an important role in cochlear organ and in controlling the receptive function of the sensory hair surface.
The purpose of this study was to examine learning effects with repeated administration of a Japanese mono-syllable intelligibility test. The subjects were 10 junior and high school students with sensorineural hearing loss. The test was conducted 10 times, once every consecutive day. The results showed marked improvement over trials in 5 out of 6 subjects who scored more than 20 percent correct in the initial test. The intelligibility scores improved 15-20 percent by the 6th testing, and slight changes were observed afterwards. The subjects who scored less than 10 percent correct in the initial test remained almost the same throughout the practice. It was pointed out that we had to be very careful in using a mono-syllable intelligibility test for evaluation of functions of hearing aids, and of auditory training results.
Scalp distributions of slow vertex response (SVR) and middle latency response (MLR) were studied in normal human subjects by computed mapping. The 12 responses elicited by 12 electrodes on the scalp were analyzed automatically with Topography System 500 (Sanei Sokki Co. Ltd). The peak to the baseline amplitude of each component of the responses were calculated, and the distribution of the relative voltage value spread upon the scalp was mapped on the CRT. The maximal amplitude areas of P1 components were tended to distribute over the fronto-central scalp regions. The N1 components were distributed maximally over the frontal head regions. The P2 components were localized upon the central regions. The P0 components were tended to dislocate to the contra-stimuli side from the central regions. The Na components showed no stability. The Pa components were distributed maximally over the centrofrontal regions.
Brain electrical activity mapping of ABR components were studied in normal hearing subjects. The scalp distributions of the highest electrical activity of ABR components on the scalp were as follows: 1) The highest electrical activity of the wave 1 was most significantly detected on the parietal to the ipsilateral occipital area. 2) For the wave 3, the highest area was not uniform, however they tended to distribute to the contralateral hemisphere. 3) The wave 5 revealed the high amplitude area at the parietal portion (fairly contralateral). Topographical display of ABR may have its applicability to the topographical diagnosis of the central lesions.
The experiments were performed on following three groups of guinea pigs with normal Preyer reflex. Group 1 animals were fed with diet containing 2% aluminum chloride and given daily intraperitoneal injections of 0.5% elemental aluminum solution prepared by aluminum lactate. Group 2 animals were given 2-3 times a week intraperitoneal injections of the same solution used in group 1. Group 3 animals were untreated by aluminum (control). The following results were obtained; 1) In group 1, group 2, aluminum treated groups, it was observed that the time course of decline of EP by anoxia delayed significantly compared with group 3 (control). 2) Serum aluminum concentrations in group 1 and 2 elevated 100 times of control. 3) Serum inorganic phosphorus concentrations of group 1 and 2 were decreased significantly. 4) Blood ATP level of group 1 also decreased significantly. The delay of decline time course of EP by anoxia in the aluminum treated animals might be caused by the inhibition of Na-K-ATPase by aluminum in vivo.
Effects of analog high-pass filtering were compared with those of digital filtering on the auditory middle resposes (AMR) from 9 adults and 16 young children with normal hearing. Analog high-pass filtering exerted several pronounced effects on the AMR waveforms in both adults and young children, such as suppression of Po (ABR), enhancement of Nb, enhancement or emergence of Pb, latency decrement for Pa and the later components. The effects seemed to be greater on the responses from the young children than those from the adults. Mean peak latencies for Na2, Pa and Nb in the young children were significantly longer than those in the adults for both digital and analog filtered responses with a passband at 20-200Hz. Mean peak latencies for Pa and Nb in the analog filtered responses were significantly shorter than those in the digital filtered responses for both adults and young children. This shortening of the Pa and Nb latencies by analog filtering was significantly greater in the young children than in the adults. In spite of the greater effects of analog filtering on the AMR for the young children compared to the adults, substantial differences between the adults and the young children still existed in the waveforms of the analog high-pass filtered responses at 20Hz.
Under sodium pentobarbital anesthesia (25-35mg/kg I. P), serum, cerebrospinal fluids (CSF), perilymph from the scala tympani and from the scala vestibuli and endolymph from the scala media were collected from normal guinea pigs after intravenous injection of Glycerol (1.0ml/kg) was administered. Sodium and potassium concentrations were assessed using microflame photometry. Increase in sodium concentration was found in CSF and perilymph in the scala tympani, while no significant change was observed in serum, the scala vestibuli and endolymph in the scala media. Increase in potassium concentration was found only in the scala vestibule. The increase of sodium was considered as a result of the dehydration process caused by Glycerol as the osmotic agent. On the other hand, the potassium increase found in the scala vestibuli was thought as a result of the leakage from the scala media.
ABR audiometry by frequency specific stimuli was performed to 24 normal ears and 13 hearing impaired ears. Comparing pure tone audiograms with ABR audiograms, it was found that thresholds of ABR were 30dB at 0.5kHz, 20dB at 1kHz, 10dB at 2kHz and 0dB over 4kHz. It has been said that a hearing level can not be determined only by ABR, because of the difficulties of standarizing acoustic stimuli and the difference of quality of speakers or amplifiers, etc. However, ABR audiometry can be applied in clinical use most correctly and easily after those thresholds are established. It is important to establish those thresholds based on all problems such as acoustic stimuli, test equipments, recording filters, in each institution using ABR audiometry.