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Biomedical subjects

A L Mansbach

Publications and source records attributed to A L Mansbach.

14 recordsLinked to original sources
PubMed1997

Temporal distortion products (kernel slices) evoked by maximum-length-sequences in auditory neuropathy: evidence for a cochlear pre-synaptic origin.

When special pseudo-random stimuli sequences (maximum length sequences: MLS) are combined with a deconvolution analysis technique, it is possible to derive new evoked potential components that are called kernels. The kernels give a measure of the temporal interactions that take place between the responses to successive stimuli. This may provide an objective neurophysiological test for the exploration of a dimension of hearing which has hitherto been limited to psychophysical methods. Until now, auditory short-latency kernels obtained by the MLS method have been related to the late portion of the brainstem auditory evoked potential (BAEP), suggesting that temporal interactions occur rather late in the auditory pathways. We report 4 children without any BAEP neural components, who all retained isolated cochlear microphonic potentials. Three of them produced click-evoked otoacoustic emissions and two of them demonstrated only moderately impaired audiometric thresholds. This combination of absent BAEP neural components with preserved otoacoustic emissions and cochlear microphonic potential corresponds to a peculiar pattern of auditory dysfunction recently coined "auditory neuropathy'. All 4 children exhibited well-defined kernels at latencies consistent with the microphonic potential. These data indicate that the cochlea itself can generate kernels at a presynaptic level. They open up the question of the identification of the physiological site(s) responsible for the generation of MLS-evoked kernels.

Adolescent↗
PubMed1997

Auditory neuropathy: a report on three cases with early onsets and major neonatal illnesses.

We report 3 children without any brainstem auditory evoked potential (BAEP) neural component who all retained isolated cochlear microphonic potentials as well as click-evoked otoacoustic emissions. Two of them demonstrated only moderately impaired audiometric thresholds. These features correspond to a peculiar pattern of auditory dysfunction recently coined "auditory neuropathy'. In contrast with the published previous cases of auditory neuropathy presenting with an acquired hearing deficit as children or young adults, all 3 children had a history of major neonatal illness and the auditory neuropathy was already demonstrated in the first months of their lives.

Age of Onset↗
PubMed1996

Otogenic thrombosis of the lateral sinus: report of a case in a child.

A case of thrombosis of the lateral sinus complicating the mastoiditis in a five year old boy is presented. This intracranial complication of suppurative otitis media which has become rare since the use of antibiotics, still raises diagnostic and therapeutic problems. The various clinical and paraclinical elements of this rare pathology, its diagnosis and treatment are reviewed.

Anti-Bacterial Agents↗
PubMed1992

[Treatment of cleft lip and palate: long-term results].

Since 1958, 900 children with cleft lip and palate were operated on at the University Hospital Brugmann in Brussels. Until 1981, the children were operated at 6 months for the lip and at 18 months for the palate with two flap palatoplasties. Since 1982, R. Malek's technique and sequence were adopted. The results after 5 years follow-up are analyzed between two groups of 50 and 49 children operated with the two techniques. Growth of the maxillary arch and phonation are well improved in the second group, but no improvement was observed in terms of hearing.

Child, Preschool↗
PubMed1990

[The value of evoked acoustic oto-emissions in pediatric audiology].

The Evoked Otoacoustic Emissions (EOAE) technique seems to be an early detection method of deafness of particular interest for children. In order to verify the hypothesis, we have tested 157 children and compared the results of the EOAE with a complementary audiologic testing.

Audiometry↗
PubMed1989

Comprehensive and interpretative radiology of middle ear malformations.

Radiological aspects of middle ear malformations based on the study of 31 observations should be correlated with the modalities of normal and abnormal morphogenesis. This is particularly the case for malformations of the ossicles, which can be classified according their precise branchial origin. Facial nerve malformations, dysgenesis of the footplate and atresia of the external auditory meatus is discussed in relation to normal events of middle ear morphogenesis. Standard histochemical procedures and study of radioactive sulphur uptake in the mouse embryo permit to characterize some factors of middle ear ossicles formation. Study of correlations between radiological features and experimental results reveal that the important factors are: the chronology of morphogenesis; the organization of branchial structures; the patterns of neural crest cells migration; the influence of environmental factors. Furthermore, teratologic features obtained in animals models can be correlated with human syndromes.

Animals↗
PubMed1985

[Tinnitus].

Explore the source record for details and available documents.

Humans↗
PubMedDate not supplied

A new descriptor of the dual character of the input-output behaviour of the cochlea, with implications for signal-to-noise ratio estimation of brain-stem auditory potentials evoked by alternating polarity clicks.

The signal-to-noise ratio based on a plus-minus average for residual noise estimation has been systematically computed for brain-stem auditory evoked potentials (BAEPs) evoked by alternating polarity clicks from threshold up to 100 dB nHL in subjects with normal cochlear function. The plus-minus averages have exhibited a systematic dual behaviour in close correspondence with the "L" and "H" portions of the latency-intensity functions: from threshold up to 50 dB SL ("L" segment) they faithfully reflect the post-averaging residual noise. From 50 dB SL upwards the plus-minus averages are contaminated by a signal identified as the differential potential between rarefaction and condensation responses. The plus-minus average is therefore an unreliable indicator of the post-averaging residual noise when alternating polarity clicks louder than 50 dB are used. These findings suggest that for intensities corresponding to the "L" (steep) part of the latency-intensity function, when inner hair cell excitation is dependent on active amplification by the outer hair cells, no difference exists between rarefaction and condensation responses. By contrast, once levels at which the inner hair cells can be directly stimulated are reached, responses to rarefaction and condensation clicks become different.

Acoustic Stimulation↗
PubMedDate not supplied

Effects of click polarity on brainstem auditory-evoked potentials in cochlear hearing loss: a working hypothesis.

The rarefaction-condensation differential potential (RCDP) obtained by subtracting brainstem auditory-evoked potentials (BAEPs) to C clicks from those to R clicks has been studied in 32 normal subjects and 31 cases of cochlear hearing loss. In normal subjects, no RCDP was recorded along the lower 30-55 dB of the JV latency-intensity function, thus defining the pre-RCDP range. The pre-RCDP range was always abolished in losses unmasking BAEPs from lower ( < 1 kHz) tonotopic regions. When the BAEP originated from higher ( > 1 kHz) tonotopic regions, the pre-RCDP range was either reduced or abolished. These results led to a working hypothesis based on single-unit data and stating a dual dependence of polarity effects on variables distributed along the tonotopic and intensity dimensions, with respective break-points at 1 kHz, and at the junction of the tip and tail of unit frequency tuning curves. The 1 kHz break-point could represent the upper frequency limit for phase locking in man.

Adolescent↗
PubMedDate not supplied

Auditory neuropathy with preserved cochlear microphonics and secondary loss of otoacoustic emissions.

Auditory neuropathy is defined as absent or severely distorted auditory brainstem responses with preserved otoacoustic emissions and cochlear microphonics. This entity can be found in various circumstances including pre-lingual children. An almost universal characteristic reported from adult patients is the ineffectiveness of traditional hearing aids. Adequate management of pre-lingual cases therefore remains an open problem. This paper describes two pre-lingual children whose follow-up data demonstrated a selective loss of the otoacoustic emissions, whereas the cochlear microphonics remained preserved. In one of the patients, hearing aid fitting as soon as she lost her otoacoustic emissions proved successful. These findings have important implications for the operational definition of the condition, since one must be prepared to encounter cases with absent otoacoustic emissions. The present data also demonstrate that conventional amplification can benefit pre-lingual auditory neuropathy cases, at least once they have lost their otoacoustic emissions.

Adult↗
PubMedDate not supplied

[Control of recurrent ENT infections in children].

Recurrent ENT infections are extremely frequent in children. Actually, early childhood is a period of adaptation to the environment, with low immunologic defences. The hypertrophy of the lymphoid tissue in the Waldeyer ring, which is normal in early childhood, gives a particular picture to these problems. The repercussions of such recurrent ENT infections on the status of the lower respiratory tract, on the stature and weight as on the general well-being of the child, and their potential complications, are sufficient reasons for eradicating them. The various therapeutical means to reach this goal, are described.

Child↗