Biomedical subjects

M P Brocaar

Publications and source records attributed to M P Brocaar.

At least 19 recordsLinked to original sources

PubMed2004

Prenatal exposure to polychlorinated biphenyls and breastfeeding: opposing effects on auditory P300 latencies in 9-year-old Dutch children.

Effects of perinatal exposure to polychlorinated biphenyls (PCBs) on auditory P300 latencies and amplitudes were evaluated in children from a Rotterdam cohort. From this cohort of healthy, term babies, the 26 lowest and 26 highest prenatally PCB-exposed children from the breastfed and the formula-fed groups (n=104) were invited for P300 assessment when they were 9 years of age. For P300 assessment an auditory simple odd-ball paradigm was used. In the 83 participating children, 60 assessments (32 males, 28 females) satisfied the measurement criteria and were included in the data analyses. After adjusting for confounding variables, children with high prenatal exposure were found to have longer P300 latencies than children with low prenatal exposure. Lactational exposure to PCBs through breastfeeding milk was not related to P300 latencies. P300 latencies were shorter in children breast-fed for at least 16 weeks than in children breastfed for 6 to 16 weeks and formula-fed children. P300 amplitudes were not related to perinatal PCB exposure nor breastfeeding. Results of this exploratory study suggest that prenatal exposure to environmental levels of PCBs and related compounds delays mechanisms in the central nervous system that evaluate and process relevant stimuli, whereas breastfeeding accelerates these mechanisms.

Adult↗

PubMed2001

Analysis of hearing loss after shunt placement in patients with normal-pressure hydrocephalus.

OBJECT: Following shunt placement for treatment of normal-pressure hydrocephalus (NPH), several patients suffered hearing loss. The authors undertook a study to analyze this outcome. METHODS: Sixteen patients in whom NPH was diagnosed were treated by placement of a ventriculoperitoneal shunt. Their hearing was assessed pre- and postoperatively by using pure tone audiometry. Two thirds of the ears tested showed a postoperative hearing loss of more than 10 dB. Recovery of the hearing loss occurred 6 to 12 weeks after shunt placement in 75% of the ears examined. CONCLUSIONS: Although shunt insertion for treatment of NPH results in a decrease in hearing, most of the loss can be recovered.

Aged↗

PubMed1995

The click-evoked oto-acoustic emission, c-EOAE, in preterm-born infants in the post conceptional age range between 30 and 68 weeks.

Click-evoked otoacoustic emissions (cEOAEs) were repeatedly recorded in an operational sample of 144 very low birth weight (VLBW) infants. A subgroup of 22 was composed of all those babies in which at least 4 recordings were successfully done. The mean birth weight of this group was 1040 g, and the mean duration of assisted ventilation was 17 days. The OAE-recordings were done in the post conceptional age (PCA) range between 30 and 68 weeks. In relation to ear function screening it was shown that the EOAE was present in 95% of the ears at least once at any age, while it was present in all recordings in only 34%. From a longitudinal analysis of the recordings per infant it appeared that: (1) the OAE recorded was already present in one infant at the PCA of 29.4 weeks; (2) in most infants the level of the OAE varies strongly between recordings; (3) in each infant the OAE-level shows an increase with age, on average this growth amounts to 10 dB between the PCAs of 31 and 42 weeks; (4) there is no clearcut difference in the growth of high- and low-frequency components of the EOAE.

Acoustic Stimulation↗

PubMed1994

Virilization of the voice in post-menopausal women due to the anabolic steroid nandrolone decanoate (Decadurabolin). The effects of medication for one year.

In a prospective study the effects on the voice of nandrolone decanoate super-imposed on cyclical hormonal replacement therapy (HRT) given to post-menopausal women suffering from a severe form osteoporosis were compared with the effects of HRT alone. Comparing the experimental group with the control group, after one year of medication in the experimental group a higher percentage of patients had: a lower fundamental frequency during speech, a loss of high frequencies and an increase in voice instability and creakiness. The lowering of the frequencies and the increase of instability can be explained by histological changes in the vocal cords and by problems in the adaptation to these histological changes.

Aged↗

PubMed1993

Aspects of spontaneous otoacoustic emissions in healthy newborns.

Spontaneous otoacoustic emissions (SOAEs) are pure-tone like signals, spontaneously present in the ear canal. In normal adult ears the prevalence of SOAEs is reported to be 30-70%, probably depending on the noise floor of the recordings. In infant studies, results on the SOAE prevalence are rare. SOAEs as well as evoked otoacoustic emissions (EOAEs) were recorded in healthy newborns. Their ages varied between 1 and 10 days. The recordings were done with commercially available equipment in a separate not sound treated room of the obstetric department. The prevalence of SOAEs was 78%, which is higher than previously reported for adults as well as healthy newborns. The prevalence was not significantly different between left and right ears, or genders. The number of emissions per emitting ear amounted on average 5.5. The median number of SOAEs in boys (3.3) is significantly lower than in girls (4.6). The SOAE levels were between -2 and 42 dB SPL. The mean level per emitting ear was 8.0 dB SPL and not significantly different between right and left ears or genders. However, the level of the strongest emission per emitting ear was significantly higher for right than for left ears. In contrast with adults most of the emissions (70%) are at frequencies above 2 kHz. Comparing the levels of the EOAEs between ears with and without SOAEs we found a statistically significant higher EOAE level in ears with SOAEs. This supports our previous hypothesis that the higher EOAE level found in healthy newborns is partly due to the more frequent presence of stronger SOAEs in healthy newborns.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked Potentials, Auditory, Brain Stem↗

PubMed1993

Frequency-specific aspects of the auditory brainstem response threshold elicited by 1000-Hz filtered clicks in subjects with sloping cochlear hearing losses.

The frequency specificity of the ABR threshold evoked by a 1000-Hz filtered click was determined in subjects with sloping cochlear hearing losses, both high- and low-frequency in character. The results show that the ABR threshold evoked by this stimulus is low-frequency specific. The standard error in estimating the 1000-Hz pure-tone threshold (PTT) is 10.4 dB, which equals that for estimating the 3000-Hz PTT from the routinely used click-evoked ABR threshold. The ABR threshold evoked by a 1000-Hz filtered click can therefore be regarded as an accurate tool to predict the pure-tone hearing loss at 1000-Hz. In comparison with the ABR threshold evoked by a click masked with 1590-Hz high-pass noise, the ABR threshold evoked by a 1000-Hz filtered click has a larger dynamic range, yields a larger number of useful responses and is less time consuming. For clinical low-frequency-specific ABR threshold assessment, the 1000-Hz filtered click is therefore preeminently useful.

Adolescent↗

PubMed1992

Growth of evoked otoacoustic emissions during the first days postpartum. A preliminary report.

Evoked otoacoustic emissions (EOAEs) were recorded twice in 20 ears of 15 newborns. The recordings were performed in a room of the well baby ward, using the ILO88 in its default setting, i.e. with click stimulation. On the first test occasion, the infants were between 3 and 51 h of age, and EOAEs were identified in 10 ears. On the second test occasion, while the infants were at least 1 day older (range 42-107 h), EOAEs were present in all ears. The second EOAE was stronger, so the EOAE appeared to grow in the first days postpartum. This might be due to middle ear clearance of amniotic fluid, shortly after birth. The results of the EOAEs of the second examination were compared with 10 EOAEs in adult ears. The response levels of the newborns were significantly higher than in the adults. The (cross)-correlation peak value of the two tests' waveforms is over 0.75, however sometimes only after filtering around the most pronounced emission frequencies. The study proves that newborns failing the EOAE screen in the first 24 h after birth can pass if retested 1 day later, simply because of growth of EOAE strength.

Acoustic Stimulation↗

PubMed1992

Low-frequency specificity of the auditory brainstem response threshold elicited by clicks masked with 1590-Hz high-pass noise in subjects with sloping cochlear hearing losses.

In this study, the frequency specificity of the ABR threshold to stimulation with a click masked with 1590-Hz high-pass noise was determined in subjects with sloping cochlear hearing losses both high- and low-frequency in character. The results show that the ABR threshold elicited by this stimulus is low-frequency specific. The standard error in estimating the 1,000-Hz pure-tone threshold from the high-pass-noise-masked click-evoked ABR threshold is 10.2 dB which equals that for estimating the 3,000-Hz pure-tone threshold from the routinely used unmasked click ABR threshold. The ABR threshold elicited by a click masked with 1590-Hz high-pass noise can therefore be regarded as an accurate tool to predict the pure-tone hearing loss at 1,000 Hz. However, this method is less suitable for routine clinical testing because of the masking noise needed: the occasional high loudness level adversely affects the response quality and reduces the dynamic range of pure-tone hearing losses to be assessed. A third disadvantage is that determining the masking level electrophysiologically for each ear is time consuming. The search for a method with no or less masking noise should therefore continue.

Acoustic Stimulation↗

PubMed1992

Comparison between the frequency specificities of auditory brainstem response thresholds to clicks with and without high-pass masking noise.

In this study, the frequency specificity of the auditory brainstem response (ABR) threshold to a click masked with 1590-Hz high-pass masking noise is compared with the frequency specificity of the unmasked click-evoked ABR threshold. The ABR threshold to the high-pass-noise-masked click stimulus is low frequency specific and corresponds with the 1,000-Hz pure-tone threshold. Although the ABR threshold to the unmasked click stimulus corresponds with the '3,000'-Hz pure-tone threshold, the frequency specificity seems much less pronounced than that of the low-frequency-specific stimulus. This study shows, however, that this apparent lack of frequency specificity can be attributed to the selection of pure-tone hearing losses. The ABR threshold evoked by an unmasked click stimulus is, therefore, preeminently useful as a high-frequency point of a two-point audiogram. The possible reasons why the ABR threshold evoked by a broad-band stimulus as the unmasked click corresponds with the higher frequencies of the pure-tone audiogram are discussed.

Acoustic Stimulation↗

PubMed1992

Hearing loss in middle-age persons with Down syndrome.

Hearing function of 35 institutionalized persons with Down syndrome, age 35 to 62 years, was assessed by means of otoscopy, impedance audiometry, brainstem evoked response audiometry, and pure tone audiometry. Using brainstem evoked response audiometry, we determined response thresholds for 59 ears, which compares favorably with pure tone audiometry (20 ears). We found hearing losses of 20 dB to over 90 dB in 56 of these ears. Hearing loss should be considered and, whenever feasible, excluded as a contributing factor in social and mental deterioration in middle-age persons with Down syndrome.

Acoustic Impedance Tests↗

PubMed1990

Frequency specificity of the auditory brainstem response elicited by 1,000-Hz filtered clicks.

In normal-hearing subjects and in subjects with a flat cochlear hearing loss, auditory brainstem responses (ABR) were recorded at various levels of a 1,000-Hz filtered click stimulus with and without high-pass filtered masking noise. The difference in latency of the major peak in the ABR for the masked and unmasked condition was zero at the ABR threshold. We regard this as proof of the frequency specificity of the 1,000-Hz filtered click-stimulated ABR threshold. The difference between ABR threshold and the subjective puretone threshold at 1,000 Hz amounted to 19 dB in normal-hearing subjects and to 10 dB in subjects with a flat cochlear hearing loss. This is probably related to loss of temporal integration and an abnormal loudness growth (recruitment).

Acoustic Stimulation↗

PubMed1990

Monaural versus binaural auditory brainstem response threshold to clicks masked by high-pass noise in normal-hearing subjects.

Monaural and binaural auditory brainstem response (ABR) thresholds to clicks masked by high-pass noise with a cut-off frequency of 1,590 Hz were measured in normal-hearing subjects. In sleeping normal-hearing subjects, the 1,000-Hz frequency-specific ABR threshold for binaural stimulation amounted to 12 dB nHL and for monaural stimulation to 18 dB nHL. No significant difference in latency was found between monaural and binaural stimulation. Binaural ABR threshold was 5.5 +/- 1.4 dB (mean +/- SEM) lower than the mean monaural ABR threshold. This difference is statistically significant (Student's t test; p less than 0.005).

Acoustic Stimulation↗

PubMed1990

Residual hearing capacity of severely hearing-impaired subjects.

Speech reception functions (speech reception threshold and maximum discrimination score for phonemes) and auditory functions (hearing threshold, difference limens for intensity and frequency, temporal modulation threshold function, critical ratio and temporal integration) have been investigated in a group of severely hearing-impaired subjects (64 ears, median Fletcher Index of 80 dB). The results were separated into low-, middle- and high-frequency regions. The investigations were intended to describe and quantify the residual hearing capacities and the correlations between the different functions. It was found that the speech functions, the difference limen for frequency, the critical ratio and the time constant of temporal integration deteriorate gradually with increasing hearing loss. These functions show a relatively high mutual correlation in the low-frequency region and considerable scatter in the high-frequency part. The sensitivity for modulations and the difference limen for intensity were least affected. The results revealed that the residual capacity can be described by means of two independent factors: frequency discrimination at the higher frequencies and a decrease in processing efficiency of the system. The latter is dominated by the middle- and low-frequency hearing elements.

Adolescent↗

PubMed1989

Conductive hearing loss assessment in children with otitis media with effusion. A comparison of pure tone and BERA results.

A comparison between pure-tone audiometry and brainstem electric response audiometry was made in 25 children with a conductive hearing loss due to otitis media with effusion. Pure-tone audiometry, including bone and air-conduction thresholds, was recorded using standard procedures. BERA was used to construct a latency-intensity function and from this the conductive hearing loss could be estimated. For all frequencies except for 2000 Hz a good correlation was found between the conductive loss in the pure-tone audiogram and the conductive loss as estimated by BERA. The moderate correlation for 2000 Hz is due to a 'Carhart'-notch-like phenomenon in the pure-tone audiogram.

Audiometry↗

PubMed1989

Brainstem electric response audiometry: estimation of the amount of conductive hearing loss with and without use of the response threshold.

Three aspects of brainstem response audiometry were investigated in the present study. (1) The brainstem response threshold was compared with the pure-tone audiogram in 40 patients with conductive hearing loss. The brainstem response threshold has a one-to-one relationship with the mean of the pure-tone thresholds at 2 and 4 kHz. The correlation coefficient in this comparison is 0.84 and the standard error of the estimate is 8.3 dB. Taking into account corresponding results in cochlear hearing loss [Drift et al.: Audiology 26: 1-10, 1987] it is concluded that the brainstem response threshold provides a good estimate of the amount of peripheral hearing loss, independent of the type of hearing loss. (2) It was shown [Drift et al.: Audiology 27: 260-270, 1988] that different types of peripheral hearing loss can be distinguished reliably with brainstem response audiometry. Parameters relevant for this distinction were the horizontal shift of the latency-level curve (1(L) curve), that of its derivative and the response threshold. In the clinical situation measurement of the response threshold is not always possible due to restlessness of the patient. To simulate this situation we randomly truncated the lower parts of the 1(L) curves of quiet patients. The test group consisted of 22 adult normally hearing subjects, 79 patients with cochlear hearing loss, 40 with conductive hearing loss and 22 with mixed hearing loss. Linear discriminant analysis was applied to the horizontal shift of the 1(L) curve and of its derivative. The brainstem diagnosis 'normal hearing' correctly excludes a conductive hearing loss in 98% of the cases and the brainstem diagnosis 'cochlear hearing loss' does so in 79%. The brainstem diagnosis 'conductive hearing loss' correctly predicts a conductive component of hearing loss in 94% of the cases and the brainstem diagnosis 'mixed hearing loss' does so in 90%. The distinction between cochlear hearing loss and normal hearing is not reliable, neither is the distinction between conductive and mixed hearing loss. (3) The amount of the conductive component of hearing loss can be estimated by the horizontal shift of the 1(L) curve. Statistical comparison with the mean of the air-bone gaps at 2 and 4 kHz gave a correlation coefficient of 0.77, a standard error of the estimate of 9.7 dB, and a slope of the regression line of 0.93. An overestimation of about 7 dB has to be taken into account in case of mixed hearing loss.

Adolescent↗

PubMed1988

Correlations between cis-platinum dosage and toxicity in a guinea pig model.

A guinea pig model was used to study correlations between cis-platinum dosage and level of hearing loss, hair cell loss in the cochlea. Other parameters measured included weight loss and serum urea, creatinine, and cis-platinum levels. The damage to the inner ear expressed as hearing loss and hair cell loss demonstrated a highly positive correlation with the dosage of cis-platinum, and only a moderately positive correlation with the cis-platinum serum levels. Weight loss correlated well with hearing loss.

Animals↗

PubMed1988

Inaccuracies in the measurement of auditory brainstem response data in normal hearing and cochlear hearing loss.

In a test-retest experiment inaccuracies in the measurement of the peak latencies and threshold of the auditory brainstem response were determined for a group with normal hearing and for a group with cochlear hearing loss. The inaccuracy of the auditory brainstem response threshold is less than 4 dB in both groups. The inaccuracy in latency was measured as a function of stimulation level. In both groups the latency inaccuracy of peak V varies from 0.1 ms at levels well above threshold to 0.2 ms near the response threshold. Analysis of variance showed that in subjects with normal hearing the intra- and interindividual variabilities of the peak V latencies contribute about equally to the total variance at all stimulation levels. The implications that these findings have for the determination of the horizontal shift of the latency-intensity curve are discussed.

Adult↗

PubMed1988

Brainstem response audiometry. I. Its use in distinguishing between conductive and cochlear hearing loss.

The auditory brainstem response thresholds and the latency-level curves, l(L)curves, for peak V were determined in 22 subjects with normal hearing, in 40 patients with conductive hearing loss and in 79 patients with cochlear hearing loss. The goal of this study was to investigate the potentials to distinguish between different types of hearing loss on the basis of these auditory brainstem responses. For this purpose the horizontal shift of the l(L) curve, the horizontal shift of its derivative and the latency of peak V at threshold level were plotted against the response threshold. For response thresholds above 30 dB nHL both the horizontal shift of the l(L) curve and the horizontal shift of its derivative give a good separation between cochlear and conductive hearing loss. The combination of the response threshold with the shift of the derivative of the l(L) curve gave a slightly better separation than that of the response threshold with the shift of the l(L) curve itself.

Adolescent↗