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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report on a woman who was diagnosed with branchio-oto-renal (BOR) syndrome after 2 pregnancies complicated by oligohydramnios due to renal hypoplasia and agenesis. Both babies died neonatally of pulmonary hypoplasia. Histopathology of the temporal bones of the second child showed marked immaturity of the middle ear cleft, ossicles, facial nerve and canal, and cochlear nerve. Maternal renal ultrasound study was normal although intravenous pyelography indicated renal hypoplasia. The frequency of BOR syndrome among cases of recurrent fetal renal hypoplasia/dysplasia or agenesis is unknown, and parental renal ultrasonography may not identify a heritable renal defect. Investigations should include a family history, and examination of relatives to look for preauricular pits, lacrimal duct stenosis, and branchial fistulae and/or cysts. Hearing studies and IVP may be indicated.
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PMID:Branchio-oto-renal syndrome: further delineation of an underdiagnosed syndrome. 141 48

Fourty-four cleft palate children consecutively referred to a plastic surgery unit were treated with palate repair at one year of age by one surgeon. The children were not routinely treated with ventilating tubes for middle ear disease. At 3 years of age they were investigated for aural pathology. Also specific antipneumococcal antibody activity was measured and was found to be compatible with the activity found in healthy age-matched control children. In the cleft palate children with no immaturity of the immune system only a slight increase in frequency of acute otitis media was evident. One third of the children had however suffered from long-standing secretory otitis media which can be regarded to be more common than what has been found in the normal population in several epidemiologic studies. At 3-4 years of age 82% of the children had a normal hearing indicating an improvement of the condition.
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PMID:Middle ear disease in cleft palate children at three years of age. 159 56

This study explored further the relationship between peripheral and central auditory maturation on the basis of the auditory brain stem response. Auditory brain stem responses were recorded in preterm infants and adults to rarefaction and condensation click stimuli transduced through insert Tubephones. Infant recordings presented a triphasic waveform preceding wave I similar to that of the cochlear receptor potentials seen with adults during electrocochleography. Wave I latency and amplitude were found to be equivalent to those of adult subjects. Moreover, neither latency nor amplitude variability among infant wave I responses was found to be any greater than adults. Latencies of waves III and V, however, exhibited the expected differences relative to the adult comparison group. When the indirect evidence of cochlear receptor potentials in the infant are viewed adjacent to the observations that their ABR wave I latency, amplitude, and variability were entirely consistent with those of young adults, the data lend strong support for peripheral auditory electromaturity. These data are discussed relative to previously published reports of prolonged wave I latency in the infant which was attributed either to middle ear effects or immaturity of the cochlea and first order VIIIth nerve neurons.
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PMID:Auditory brain stem responses in preterm infants: evidence of peripheral maturity. 272 24

The auditory system of many mammalian species is immature at the time of birth. Peripheral elements, particularly the middle ear and cochlea, account for much of the physiological immaturity observed in central auditory structures. However, there is now considerable evidence that the central pathway undergoes developmental changes that, at least partially, occur in parallel with peripheral development. Auditory nerve fibres and their terminals have been shown to be of smaller diameter and less extensively arborized in neonatal than in adult cats. These factors almost certainly contribute to many of the sluggish physiological properties of neurones in the kitten auditory nerve and cochlear nucleus. At higher levels of the cat auditory system (inferior colliculus, auditory cortex) mechanisms subserving binaural interaction also undergo a period of postnatal development. Recent studies of sound deprivation produced by either deafferentation or a conductive hearing loss have demonstrated that alteration of cochlear output during the immediate postnatal period may change the normal development of the central auditory system.
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PMID:Postnatal development of the mammalian central auditory system and the neural consequences of auditory deprivation. 299 53

The contribution of middle ear immaturities to the development of cochlear microphonic potential (CM) responses was studied throughout the ontogeny of auditory function in the Mongolian gerbil. CM produced by direct mechanical stimulation of the stapes was compared with CM generated by acoustic stimulation of the intact ear at various postnatal ages. The results indicated that during development acoustically generated CM reflects middle ear as well as inner ear maturational factors. With direct stapes driving, CM was first elicited at 10 days after birth (DAB), two days earlier than with acoustic stimulation. Controlling for the contributions of middle ear immaturity, maturation of the inner ear accounted for approximately a 75 dB improvement in CM thresholds between 10 and 18 DAB. Comparisons between the results obtained with the acoustic and stapes driving stimulation protocols suggested that the major maturational changes in the middle ear conduction apparatus occurred between 14 and 16 DAB. This period was associated with the final stages of resorption of middle ear mesenchyme and ossicular ossification. Before 16 DAB, acoustically evoked CM thresholds reflect approximately a 25 dB loss in sensitivity due to middle ear immaturity.
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PMID:Contributions of the middle ear to the development of function in the cochlea. 319 6

A longitudinal study of the Eustachian tube function by different pressure equilibration tests was performed during 11/2-3 years in 44 otologically healthy children, 3-12 years of age. The muscular opening function improved significantly with increasing age. The improvement was most frequent during pre-school ages (3-7 years). Also the tympanometrically measured middle ear pressure, related to the muscular opening function, tended to normalize during the follow-up study. The pressure opening and closing functions, reflecting the tubal closing forces, did not, however, change during the observation time. All the children with poorest muscular opening function at the initial test improved; none developed persistent middle ear disease during the follow-up. Using this standardized exhalation/inhalation test of the pressure equilibrating function of the tube it seems possible to grade the muscular opening function in a valid way. It is argued that the main cause of poor muscular opening function in children is not only due to anatomical differences of the skull base, the tube and peritubal structures but also to the immaturity of the neuromuscular system during childhood.
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PMID:Changes in Eustachian tube function with age in children with normal ears. A longitudinal study. 663 57

Primary afferent activity was recorded from the cochlear ganglion in chicken embryos (Gallus domesticus) at 19 days of incubation (E19). The ganglion was accessed via the recessus scala tympani and impaled with glass micropipettes. Frequency tuning curves were obtained using a computerized threshold tracking procedure. Tuning curves were evaluated to determine characteristics frequencies (CFs), CF thresholds, slopes of low and high frequency flanks, and tip sharpness (Q10dB). The majority of tuning curves exhibited the typical 'V' shape described for older birds and, on average, appeared relatively mature based on mean values for CF thresholds (59.6 +/- 20.3 dBSPL) and tip sharpness (Q10dB = 5.2 +/- 3). The mean slopes of low (61.9 +/- 37 dB/octave) and high (64.6 +/- 33 dB/octave) frequency flanks although comparable were somewhat less than those reported for 21-day-old chickens. Approximately 14% of the tuning curves displayed an unusual 'saw-tooth' pattern. CFs ranged from 188 to 1623 Hz. The highest CF was well below those reported for post-hatch birds. In addition, a broader range of Q10dB values (1.2 to 16.9) may related to a greater variability in embryonic tuning curves. Overall, these data suggest that an impressive functional maturity exists in the embryo at E19. The most significant sign of immaturity was the limited expression of high frequencies. It is argued that the limited high CF in part may be due to the developing middle ear transfer function and/or to a functionally immature cochlear base.
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PMID:Neural tuning characteristics of auditory primary afferents in the chicken embryo. 777 80

The purpose of the present study was to determine the tonotopic map in the chicken cochlea at 19 days of incubation (E19) by obtaining characteristic frequencies (CFs) for primary afferents, labeling the characterized neurons, and documenting their projections to the papilla. The lowest and highest CFs recorded were 188 and 1623 Hz respectively. The embryonic tonotopic map coincided with maps reported for post-hatch chicks. There were no evidence that neurons selective to low frequencies project inappropriately to more basal locations of the embryonic papilla. Linear regression was used to estimate the frequency gradient (b = 0.037 +/- 0.012 In Hz/% [b +/- SEb]) and intercept (In C, where C = 111 Hz) of the semilog plot of frequency versus cochlear position (in % distance from apex). From these estimates the octave distribution was calculated to be 18.7%/octave or 0.58 mm/octave. These quantities were not significantly different from those found in post hatch chickens. We conclude that the tonotopic map of the avian cochlea for CFs between 100 and 1700 Hz is stable and relatively mature from age E19 to post-hatch day 21 (P21). The most striking sign of immaturity in the E19 embryo is the limited range of high CFs. We offer the hypothesis that, between the ages of E19 and P21, improvements in middle ear admittance alone or in combination with functional maturation of the cochlear base may be the principal factors responsible for the appearance of adult-like high CF limits and not an apically shifting tonotopic map.
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PMID:The tonotopic map in the embryonic chicken cochlea. 777 81

Middle ear disease encompasses acute otitis media, recurrent otitis media, and otitis media with effusion. For many children, middle ear disease occurs early in life, is chronic and recurrent and can impair language development and/or school performance. Risk factors for recurrent otitis media include early disease onset, bottle feeding, daycare attendance, exposure to cigarette smoke and immunological defects or immaturity. Antimicrobial therapy in acute otitis media is associated with earlier resolution and a reduction in the frequency of persistent disease and suppurative complications. An antimicrobial agent should be selected according to its activity, tolerability and concentrations achieved in the middle ear. At present, amoxicillin remains the drug of choice for acute otitis media. Antimicrobial prophylaxis is also effective, but only for the duration of therapy. Future challenges for the management of middle ear disease include the treatment of penicillin-resistant Streptococcus pneumoniae, effective prevention of relapses, and the development of a vaccine for S. pneumoniae that has the appropriate serotypes and is immunogenic in young children.
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PMID:New concepts in the pathophysiology and management of middle ear disease in childhood. 886 39

Distortion product otoacoustic emissions (DPOAEs) are thought to be by-products of an active amplification process in the cochlea and thus serve as a metric for evaluating the integrity of this process. Because the cochlear amplifier functions in a level-dependent fashion, DPOAEs recorded as a function of stimulus level (i.e., a DPOAE growth function) may provide important information about the range and operational characteristics of the cochlear amplifier. The DPOAE growth functions recorded in human adults and neonates may provide information about the maturation of these active cochlear processes. Two experiments were conducted. Experiment I included normal-hearing adults and term-born neonates. The 2f1-f2 DPOAE growth functions were recorded for both age groups at three f2 frequencies. Experiment II was an extension of the first experiment but added a subject group of premature neonates. The results of these studies indicate that DPOAE growth functions most often show amplitude saturation and nonmonotonic growth for all age groups. However, premature neonates show monotonic growth and the absence of amplitude saturation more often than adults. Those premature neonates who do show saturation also show an elevated threshold for amplitude saturation relative to adults. In contrast, term neonates are adultlike for most measures except that they show a larger percentage of nonsaturating growth functions than adults. These results may indicate immaturity in cochlear amplifier function prior to term birth in humans. Outer hair cell function and/or efferent regulation of outer hair cell function are hypothesized sources of this immaturity, although some contribution from the immature middle ear cannot be ruled out.
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PMID:Distortion product otoacoustic emission (2f1-f2) amplitude growth in human adults and neonates. 1064 53


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