Cognitive, adaptive, and behavioral characteristics of Williams syndrome.

Williams syndrome is a genetic disorder linked to cognitive and behavioral patterns of varying consistency; this study was conducted to clarify further the strengths and weaknesses of children with Williams syndrome. Fifteen subjects with the characteristic features of Williams syndrome were evaluated using the Stanford-Binet Intelligence Scale for Children, Fourth Edition; the Vineland Adaptive Behavior Scales, Interview Edition; and the Child Behavior Checklist. Cognitive skills ranged from the Moderate Range of Mental Retardation to the Low Average range, with relative strengths in nonverbal and quantitative reasoning. Adaptive skills were delayed, with strengths in communication and socialization. Behaviorally, clinically significant levels of attention problems, borderline-significant levels of social and thought problems, and significantly low levels of social contacts and structured activities were found. In contrast to the findings of many other studies of Williams syndrome, language skills and short-term memory skills were weak. Children with Williams syndrome may present a more evenly developed intellectual profile, with verbal and nonverbal skills being commensurate. In conclusion, a variety of cognitive, adaptive, and behavioral patterns have been shown to be possible in Williams syndrome; therefore, a single predictable cognitive or behavioral phenotype cannot be assumed.

Hearing loss.

Hearing loss may be caused by either a conductive problem, such that the sound waves do not reach the tympanic membrane, ossicles or inner ear, or a sensorineural problem, in which the cochlea and/or auditory nerve are somehow damaged. A combination of the above may also occur. The various causes of hearing loss and the options in treatment will be presented.

Hearing aids.

The first step in the hearing aid fitting and selection process is to determine the patient's hearing disability, motivation, lifestyle, finances, and cosmetic concerns. Most hearing impairments can be helped with a modern hearing aid. With a symmetric hearing loss, a binaural fitting provides the most benefit and should be attempted initially. The binaural fitting may not be successful in cases with large asymmetries in auditory function. The advances in electronic technology, such as the digital hearing aid, are moving faster than the research to determine which is the most effective signal processing method. The near future should yield more significant improvements in hearing aids that will provide a better quality of life of the hearing-impaired population.

Frequency and age-dependent auditory evoked potential thresholds in infants.

Auditory evoked-potential thresholds to 0.5, 4.0 and 10.0 kHz tone pips were measured in 40 normal infants 2-28 wks old and 14 normal hearing adults. Thresholds to 500 Hz tone pips were based upon the steady-state, 40 Hz evoked potential. Thresholds to 4.0 and 10.0 kHz tone pips were based upon the brainstem response. Stimulus intensity was varied in 5-dB steps for threshold search. The greatest difference between infant and adult thresholds occurred at 4.0 kHz. The magnitude of this difference decreased with age; however, differences were still significant up to 28 wks of age. No significant differences were seen at 500 Hz. To the 10.0 kHz stimulus only the youngest (2-4 wk) infants had thresholds that were significantly higher than adults. The reasons proposed to explain these results are complex interactions between immaturity of the conductive mechanism, brainstem pathways, and possibly the cochlea.

An analysis of auditory brainstem responses in infants.

Acoustic brainstem responses (ABRs) were recorded from 148 infants from 4 to 60 weeks of age. 28 subjects returned to the laboratory 3 or more times for additional recordings. Filtered clicks of 1, 2, 4 and 8 kHz were presented at two intensities, 30 and 50 dB HL re the average threshold for a group of young adults. Responses to a broadband click, 50 dB nHL, were also recorded. The latencies of waves I, III and V were measured. Wave I latencies for the 8 kHz filtered click showed no change but those for lower frequencies decreased with age. The latency decreases with age were largest for wave V, and, among the filtered clicks, was largest for the responses to 1 kHz. Best-fitting curves were determined for latency vs. age for each filtered click and for the broadband click. Wave V--Wave I latency differences showed that the rostral conduction time for responses to the 8 kHz FC decreased with age and, for the 1 kHz filtered click (50 dB), remained constant. The early development of basal regions in the cochlea is viewed as insuring the delivery of a wide range of frequencies to rostral segments of the auditory system. The limiting feature of maturation is at rostral sites. The immature auditory system appears to be fully capable of transducing low frequency stimuli, but not high frequencies.

Traumatic hematuria in patients with polycystic kidney disease.

Autosomal dominant polycystic kidney disease (PKD) is the most prevalent hereditary disorder in this country and a common cause of chronic renal failure. Patients frequently present with hematuria as the initial manifestation of PKD. We describe a patient with gross hematuria after blunt trauma who was found to have previously undiagnosed PKD. We review present diagnostic and treatment modalities and suggest potential management strategies for surgeons caring for patients presenting with traumatic hematuria and PKD.

Pass/fail rates for repeated click-evoked otoacoustic emission and auditory brain stem response screenings in newborns.

The click-evoked otoacoustic emission (EOAE) recording procedure is a simple and quick test to perform. Some suggest that the EOAE is a more efficient newborn hearing screening procedure than the auditory brain stem response (ABR). However, one shortcoming of the EOAE is a high false-positive rate in newborns, which is attributed to ear-canal debris. The purposes of this study were to assess the initial pass/fail rates of ABR and EOAE measurements and the effectiveness of repeated EOAE measurements as a method of reducing the false-positive rate. Fifty healthy, low-risk newborns sequentially underwent ABR, repeated EOAE, otoscopy, EOAE, and ABR if necessary. The initial ABR passing rate was 98%, whereas the EOAE passing rate was 61%. The EOAE passing rate improved with each retest and approximated the ABR rate by the fourth test. EOAE failures and the overall level of the EOAE were found to be significantly related to the amount of ear-canal debris. These results indicate that some newborns will require four or more tests before they eventually pass. Further study is needed to determine the overall cost-effectiveness of the EOAE as compared with the ABR before specific recommendations for a universal hearing screening program are proposed.

Occupational hearing conservation.

Chronic exposure to high-intensity noise can produce permanent hearing loss, the amount of which depends on noise intensity, temporal and spectral characteristics, and the length of exposure. OSHA regulates workplace noise exposure in accordance with the Hearing Conservation Amendment of 1983. When noise levels equal or exceed an 85 dBA time-weighted average (TWA), the employer is required to provide annual audiometric screening. When noise levels exceed 90 dBA TWA, the worker's exposure must be reduced by engineering methods, administrative changes, or personal hearing protectors. If a worker demonstrates a standard (significant) threshold shift (10 dB or greater increased average hearing threshold at 2, 3, and 4 kHz in either ear) that is attributed to noise, the worker's exposure must be further reduced by one of the aforementioned methods.

Hearing-aid-processed tone pips: electroacoustic and ABR characteristics.

The auditory brainstem response (ABR) recorded while wearing a hearing aid may supply supplemental information about the benefit and appropriateness of the hearing aid for certain infants. The purposes of this study were (1) to determine the effects of different output limiting circuits on the acoustics of tone-pip stimuli used for ABR recordings and (2) assess how changes in hearing-aid-processed stimuli affect ABR characteristics. Electroacoustic input/output functions to tone-pip stimuli were constructed for three different output limiting circuits (wide dynamic range compression, output compression, and linear with peak clipping) available in a programmable hearing aid. Wave V latency and amplitude functions were then measured to the same stimuli and hearing aid settings in five normal-hearing adults. Electroacoustic results showed that none of the output limiting circuits, including linear peak clipping, were effectively activated by tone pips compared to the hearing aid performance to continuous tones. Aided wave V latency and amplitude functions were asymptotic to high stimulus levels, suggesting that cochlear output was in saturation.

Payments arrangements.

No matter what financial arrangements are made with patients, there is no foolproof method of ensuring payment. As stated earlier, the financial arrangement does not indicate mistrust of the patient, but is a means of communication. If we accept the fact that nearly all patients have full intentions of meeting their financial obligations, the guiding rule should be flexibility. Inflexibility when making financial arrangements may limit the growth of your practice. Sensitivity is an important ingredient in helping to understand and to meet your patient's needs. Many more patients will accept necessary dentistry if they are given the opportunity to select a method of payment with which they are comfortable.

A digital control system for external magnetohydrodynamic modes in tokamak plasmas.

A feedback system for controlling external, long-wavelength magnetohydrodynamic activity is described. The system is comprised of a network of localized magnetic pickup and control coils driven by four independent, low-latency field-programable gate array controllers. The control algorithm incorporates digital spatial filtering to resolve low mode number activity, temporal filtering to correct for frequency-dependent amplitude and phase transfer effects in the control hardware, and a Kalman filter to distinguish the unstable plasma mode from noise.

Properties of the brain-stem response slow-wave component.

A slow-wave component of the brain-stem response recordable to signals at low sensation levels shows some promise for estimating hearing thresholds at low frequencies. This study describes several properties of this slow-wave response (SWR) in 30 normal hearing subjects and examines correlations with psychophysical thresholds. Acoustic signals were tone pips at 0.25, 0.5, 1, 2, and 4 kHz with 3-ms rise-fall times and no plateau. Repetition rate was 40/s. The EEG was filtered at 20 to 1,500 Hz before averaging. Results showed SWR thresholds were on the average about 15 dB higher than behavioral thresholds, however, the range was 0- to 35-dB sensation level. A large decrease in SWR amplitude and a 20-dB increase in threshold could occur in states of deep sleep. The SWR appears to be useful for estimating low-frequency thresholds, but the 35-dB threshold range in normal hearing subjects should be considered when interpreting some SWR results.

Properties of the brain-stem response slow-wave component. II. Frequency specificity.

Frequency specificity of a slow-wave response (SWR) of the brain-stem response (BSR) was measured with a simultaneous masking tuning-curve paradigm. The SWR tuning curves to 250-Hzz tone pips show greatest sensitivity to 350- to 400-Hz maskers. The SWR tuning curves to 500-Hz tone pips are most sensitive to 500- and 600-Hz maskers. Higher-frequency tuning curves show greatest sensitivity when masker frequency is equal to signal frequency. Frequency specificity is preserved to 80-dB sound-pressure level or 55- to 65-dB sensation level. Tone-pip frequencies of 0.5, 1.0, 2.0 and 4.0 kHz appear to be adequate stimuli for eliciting a frequency-specific SWR. The 250-Hzz tone pip does not elicit a frequency-specific SWR and is probably not a useful test frequency under the present recording conditions.

Masking effects on ABR waves I and V in infants and adults.

The effects of high- and low-pass masking on waves I and V of the auditory brain stem response (ABR) were measured in normal infants who were 2-4 weeks old, and in adults. The signal was a 4-kHz tone pip presented at 86 dB peak equivalent sound-pressure level (p.e.SPL). The masking patterns were different for latency and amplitude criteria, and were also different for infants and adults. The largest difference between infants and adults was seen in the wave I data. Low-pass maskers were very disruptive of the infant wave I, while little or no effect was noted on the adult wave I. High-pass maskers were very disruptive of the adult wave I, while less of an effect was measured on the infant wave I. The wave V data were similar between groups. Cochlear regions which contribute most importantly to wave I extend up to one octave above the frequency of the signal in adults, and to one-half octave above the signal frequency in infants. The reasons for the differences found between infants and adults are uncertain. Two possible mechanisms which can explain these data are differences in peripheral auditory sensitivity, and differences in tuning characteristics of the auditory system.

Assessing speech recognition in noise for listeners with a signal processor hearing aid.

Hearing aids with signal processors use advanced circuitry to enhance speech recognition in noise. The effectiveness of these processors has not been well established. The purpose of this study was to evaluate performance on a speech recognition in noise task for listeners wearing a Zeta signal processor aid with the processor turned on and with the processor turned off. In addition, comparisons were made to performance while unaided and aided with a conventional hearing aid. A simple adaptive procedure and a psychometric function were the procedures used. Results for normal-hearing subjects indicate performance was usually better without a hearing aid. Performance when aided was similar for the processor on and the conventional aid. Performance in both of these conditions was clearly better than with the signal processor off. Although results for the hearing-impaired subjects varied widely, there was a trend for better performance with the conventional aid and with the signal processor on than for the signal processor off condition.