Eustachian tube function during pregnancy.

The upper respiratory mucosa has been reported to react to sex hormones in both physiological and pathological conditions. The present study was specifically aimed to determine the influence of high levels of oestrogen on Eustachian tube function. Fifty-three healthy, pregnant women were prospectively evaluated for Eustachian tube function during pregnancy. Eustachian tube function was found to be highly variable in different women, and in the same woman at different stages of pregnancy. We did not find a specific trend in Eustachian tube function with increasing oestrogen levels as encountered during pregnancy.

White noise does not induce fetal sleep.

White noise has been shown to induce sleep in newborns. We sought to examine whether this type of sound will also induce a quiet state in the fetus. Twenty-two fetuses at 36-41 weeks of gestation were exposed to white noise during an active state. The sound was delivered for 5 min at an intensity of 100 dB. No significant change in fetal activity was noted following the sound.

Effect of estrogen on eustachian tube performance.

Changing levels of sex hormones have been previously associated with clinical symptoms due to alterations of the respiratory mucosa. Aural manifestations, however, have not yet been studied in this regard. Eustachian tube swallow test and blood levels of estrogen were evaluated daily in 25 women undergoing induction of ovulation. Most women showed a near stable eustachian tube performance over a wide range of estrogen levels, particularly in the physiologic range. However, there is a moderate decrease in eustachian tube function with increasing estrogen levels in some women, manifested mainly at levels beyond that of the normal menstrual cycle.

Auditory brainstem evoked potentials in evaluating the efficacy of surgical ventilation of the middle ear.

Conductive hearing loss in children is most commonly associated with Secretory otitis media (S.O.M.). Since auditory brainstem evoked potentials (ABEP) reflect conductive damage in prolonged peak latencies, the present study evaluated the efficacy of surgery for ventilating the middle ear, by comparing changes in peak latencies. These changes were compared in 4 groups of children (4-12 years old): children with S.O.M. in the past, who recovered as a result of conservative treatment; children with S.O.M. in the past, who had been operated on with insertion of ventilation tubes (V.T.); children with S.O.M. in the past, who had been operated on and who still had V.T. at the time of study, and a control group with healthy ears. In all, 183 ears were tested. The results indicate that there is no significant audiometric and electrophysiological difference between the groups who recovered with or without V.T.

Auditory brainstem evoked potentials in insulin-dependent diabetics with and without peripheral neuropathy.

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 33 insulin-dependent diabetes mellitus (IDDM) patients (17 with diabetic peripheral neuropathy and 16 without) as well as from 20 normals. Pure-tone audiometry, speech reception threshold and discrimination were also evaluated. Sub-clinical pure-tone threshold elevation was observed for IDDM patients with neuropathy. Pure-tone thresholds of IDDM patients without neuropathy were not significantly different from those of normals. ABEP abnormality (at 10/sec click rate) was observed in 31% of IDDM patients with neuropathy, rising to 44% when 55/sec click rate measures were included. Abnormalities included bilateral and symmetrical peak-latency prolongations for all waves, greater for the later waves, and prolongation of V-I and V-III interpeak latency differences, all at 10/sec, and only prolonged peak latency for I at increased rate. Abnormalities coincided with microangiopathy and peripheral neuropathy. The incidence of ABEP abnormality for IDDM patients without neuropathy was only 12%, unilateral and sporadic in nature. As a group, IDDM patients with neuropathy had significantly prolonged IV and V peak-latencies, compared with the normals, or with the IDDM patients without peripheral neuropathy. In contrast, IDDM patients without neuropathy resembled the normals in all respects. ABEP have proven useful in understanding the variety of pathologies underlying the clinical manifestation of diabetes.

Auditory brainstem evoked potentials in asymptomatic lead-exposed subjects.

Auditory Brainstem Evoked Potentials (ABEP) were recorded from 29 adults and children, accidentally exposed to lead through food until approximately a year prior to this study. ABEP were recorded in response to 75 dBHL clicks presented at rates of 10/sec. and 55/sec. Average values were calculated for peak latency and for interpeak latency differences. Average values of the effect of increasing stimulus rate were calculated as well. Similar values were calculated for normative child and adult control groups. IPLD(I-III) showed the most significant and recurring results, with longer intervals in lead-exposed children compared with their control group. Increasing stimulus rate, on the other hand, affected the adult lead-exposed subjects more than the children. These results may imply an impairment of the peripheral portion of the auditory system with axonal and myelin involvement. ABEP is suggested as a sensitive detector of subclinical lead exposure effects on the nervous system.

Simulation of the spatial distribution of muscle fibres in human muscles.

A composite muscle cross section model was simulated on a VAX 780 computer. The various motor unit territories in the cross section area were circular, partially overlapping each other. The radii of the territories of the motor units, their centres, and the number of muscle fibres in each motor unit were treated as random variables. Two different models were generated, one with a uniform distribution of the fibres in the motor unit territories, and the other with a normal distribution of the fibres. An algorithm for simulation of fibre density measurements was written, and the effects of varying the parameters of the model on fibre density measurements were investigated. The results of the computer simulation were in agreement with analytical and laboratory findings.

Applications of auditory evoked potentials to evaluate hearing disorders: assets and limitations.

A variety of auditory evoked potentials for audiometric use are briefly reviewed and their assets and shortcomings discussed. Auditory brainstem evoked potentials provide the most audiometric parameters per patient evaluation time. Illustrative case reports are summarized to demonstrate the assets and pitfalls in evoked potential audiometric evaluations. Frequency contents of the stimulus used to evoke the potentials, the normative values for parameters evaluated, and the notion that the potentials reflect only the functioning of their generators must be constantly borne in mind. The primary concern must be the patient's welfare, and unnecessary procedures should be avoided.

Auditory brainstem evoked potentials in blast injury.

Blast injury typically consists of a mixed conductive and sensorineural hearing loss. The sensorineural component includes temporary as well as permanent threshold elevations. Auditory brainstem evoked potentials (ABEP) are sensitive to functional changes in various levels along the auditory pathway. ABEP were recorded from 37 survivors of blasts and latency measures were correlated with clinical findings. Prolongation of peak latencies was correlated with the conductive component of blast-induced hearing loss, as well as with the TTS component of the sensorineural impairment. No central effects of blast on the auditory system were detected. In addition to their objectivity, ABEP hold the promise of differentiating between the permanent and temporary effects of blast on hearing.

Early identification of deaf babies and children in northern Israel.

Mass screening for hearing loss is established in Israel early in the first year of life, in the free Mother and Child Welfare Clinics, leading to early detection and rehabilitation of almost all the deaf babies. At risk newborns are tested within the first three months of age. Impedance audiometry should be widely implemented in pre- and early school screenings, to detect the minor conductive hearing losses.

Semi-objective method for auditory mass screening of neonates.

An instrument called the Accelerometer Recording System (ARS) was developed for graphically recording responses of neonates to auditory stimulation. Its main component, is an accelerometer, which picks up vibrations of the crib, caused by the response movements of the infant. In a pilot study with 400 newborns, a distinct record was registered in all but seven. The ARS seems to offer a semi-objective test procedure which is short, simple and reliable. It promises to be a valid test method for mass screening of newborns for early detection of profound hearing loss.