The etiology of neurosensory hearing defects in preterm infants

Noise or sound management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to different types of stress, including sounds of high intensity. The sound levels in NICUs often exceed the maximum acceptable level recommended by the American Academy of Pediatrics, which is 45 decibels (dB). Hearing impairment is diagnosed in 2% to 10% of preterm infants compared to only 0.1% of the general paediatric population. Bringing sound levels under 45 dB can be achieved by lowering the sound levels in an entire unit; by treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled; or by reducing sound levels at the individual level using earmuffs or earplugs. By lowering sound levels, the resulting stress can be diminished, thereby promoting growth and reducing adverse neonatal outcomes. This review is an update of one originally published in 2015 and first updated in 2020.

OBJECTIVES

To determine the benefits and harms of sound reduction on the growth and long-term neurodevelopmental outcomes of neonates.

SEARCH METHODS

We used standard, extensive Cochrane search methods. On 21 and 22 August 2023, a Cochrane Information Specialist searched CENTRAL, PubMed, Embase, two other databases, two trials registers, and grey literature via Google Scholar and conference abstracts from Pediatric Academic Societies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs in preterm infants (less than 32 weeks' postmenstrual age (PMA) or less than 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or stepdown unit. We specified three types of intervention: 1) intervention at the unit level (i.e. the entire neonatal department), 2) at the section or room level, or 3) at the individual level (e.g. hearing protection).

DATA COLLECTION AND ANALYSIS

We used the standardised review methods of Cochrane Neonatal to assess the risk of bias in the studies. We used the risk ratio (RR) and risk difference (RD), with their 95% confidence intervals (CIs), for dichotomous data. We used the mean difference (MD) for continuous data. Our primary outcome was major neurodevelopmental disability. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included one RCT, which enroled 34 newborn infants randomised to the use of silicone earplugs versus no earplugs for hearing protection. It was a single-centre study conducted at the University of Texas Medical School in Houston, Texas, USA. Earplugs were positioned at the time of randomisation and worn continuously until the infants were 35 weeks' postmenstrual age (PMA) or discharged (whichever came first). Newborns in the control group received standard care. The evidence is very uncertain about the effects of silicone earplugs on the following outcomes. • Cerebral palsy (RR 3.00, 95% CI 0.15 to 61.74)and Mental Developmental Index (MDI) (Bayley II) at 18 to 22 months' corrected age (MD 14.00, 95% CI 3.13 to 24.87); no other indicators of major neurodevelopmental disability were reported. • Normal auditory functioning at discharge (RR 1.65, 95% CI 0.93 to 2.94) • All-cause mortality during hospital stay (RR 2.07, 95% CI 0.64 to 6.70; RD 0.20, 95% CI -0.09 to 0.50) • Weight (kg) at 18 to 22 months' corrected age (MD 0.31, 95% CI -1.53 to 2.16) • Height (cm) at 18 to 22 months' corrected age (MD 2.70, 95% CI -3.13 to 8.53) • Days of assisted ventilation (MD -1.44, 95% CI -23.29 to 20.41) • Days of initial hospitalisation (MD 1.36, 95% CI -31.03 to 33.75) For all outcomes, we judged the certainty of evidence as very low. We identified one ongoing RCT that will compare the effects of reduced noise levels and cycled light on visual and neural development in preterm infants.

AUTHORS' CONCLUSIONS

No studies evaluated interventions to reduce sound levels below 45 dB across the whole neonatal unit or in a room within it. We found only one study that evaluated the benefits of sound reduction in the neonatal intensive care unit for hearing protection in preterm infants. The study compared the use of silicone earplugs versus no earplugs in newborns of very low birth weight (less than 1500 g). Considering the very small sample size, imprecise results, and high risk of attrition bias, the evidence based on this research is very uncertain and no conclusions can be drawn. As there is a lack of evidence to inform healthcare or policy decisions, large, well designed, well conducted, and fully reported RCTs that analyse different aspects of noise reduction in NICUs are needed. They should report both short- and long-term outcomes.

Negative Effects of Noise on NICU Graduates' Cochlear Functions

To evaluate the adverse effects of noise on hearing. Methods: Thirty-two infants that had been admitted to neonatal intensive care unit (NICU) and 25 healthy controls were included in this study. Noise levels were recorded continously during the hospitalization period. Results: All healthy controls passed the hearing screening tests before discharge and on the sixth-month follow up. Hospitalized infants had lower "Distortion Product Auto Acoustic Emission Signal Noise Ratio" (DPOAE SNR) amplitudes (dB) at five frequencies (1001, 1501, 3003, 4004, 6006 Hz in both ears). DPOAE fail rates at 1001 Hz and 1501 Hz were higher than in hospitalized infants (81.8% and 50.0% vs 20.0% and 4.0%). Infants who failed the test at 1001 and 1501 Hz were exposed to noise above the recommended maximum level for longer periods of time. Conclusion: Hearing tests performed at sixth-months of life were adversely affected in NICU graduates.

Sound reduction management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to stress, including sound of high intensity. The sound environment in the NICU is louder than most home or office environments and contains disturbing noises of short duration and at irregular intervals. There are competing auditory signals that frequently challenge preterm infants, staff and parents. The sound levels in NICUs often exceed the maximum acceptable level of 45 decibels (dB), recommended by the American Academy of Pediatrics. Hearing impairment is diagnosed in 2% to 10% of preterm infants versus 0.1% of the general paediatric population. Noise may cause apnoea, hypoxaemia, alternation in oxygen saturation, and increased oxygen consumption secondary to elevated heart and respiratory rates and may, therefore, decrease the amount of calories available for growth. Elevated levels of speech are needed to overcome the noisy environment in the NICU, thereby increasing the negative impacts on staff, newborns, and their families. High noise levels are associated with an increased rate of errors and accidents, leading to decreased performance among staff. The aim of interventions included in this review is to reduce sound levels to 45 dB or less. This can be achieved by lowering the sound levels in an entire unit, treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled, or reducing the sound levels that reaches the individual infant by using earmuffs or earplugs. By lowering the sound levels that reach the neonate, the resulting stress on the cardiovascular, respiratory, neurological, and endocrine systems can be diminished, thereby promoting growth and reducing adverse neonatal outcomes.

OBJECTIVES

Primary objective To determine the effects of sound reduction on growth and long-term neurodevelopmental outcomes of neonates. Secondary objectives 1. To evaluate the effects of sound reduction on short-term medical outcomes (bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leukomalacia, retinopathy of prematurity). 2. To evaluate the effects of sound reduction on sleep patterns at three months of age. 3. To evaluate the effects of sound reduction on staff performance. 4. To evaluate the effects of sound reduction in the neonatal intensive care unit (NICU) on parents' satisfaction with the care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings, clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp), Pediatric Academic Societies Annual meetings 2000 to 2014 (Abstracts2ViewTM), reference lists of identified trials, and reviews to November 2014.

SELECTION CRITERIA

Preterm infants (< 32 weeks' postmenstrual age (PMA) or < 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or a stepdown unit.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses according to the Cochrane Neonatal Review Group.

MAIN RESULTS

One small, high quality study assessing the effects of silicone earplugs versus no earplugs qualified for inclusion. The original inclusion criteria in our protocol stipulated an age of < 48 hours at the time of initiating sound reduction. We made a deviation from our protocol and included this study in which some infants would have been > 48 hours old. There was no significant difference in weight at 34 weeks postmenstrual age (PMA): mean difference (MD) 111 g (95% confidence interval (CI) -151 to 374 g) (n = 23). There was no significant difference in weight at 18 to 22 months corrected age between the groups: MD 0.31 kg, 95% CI -1.53 to 2.16 kg (n = 14). There was a significant difference in Mental Developmental Index (Bayley II) favouring the silicone earplugs group at 18 to 22 months corrected age: MD 14.00, 95% CI 3.13 to 24.87 (n = 12), but not for Psychomotor Development Index (Bayley II) at 18 to 22 months corrected age: MD -2.16, 95% CI -18.44 to 14.12 (n =12).

AUTHORS' CONCLUSIONS

To date, only 34 infants have been enrolled in a randomised controlled trial (RCT) testing the effectiveness of reducing sound levels that reach the infants' ears in the NICU. Based on the small sample size of this single trial, we cannot make any recommendations for clinical practice. Larger, well designed, conducted and reported trials are needed.

The Effect of Earmuffs on Physiological Parameters in Preterm Infants: A Systematic Review

Noise may cause stress responses such as apnea, hypoxemia, changes in oxygen saturation and augmented oxygen consumption secondary to elevated heart and respiratory rates. Moreover, stress results in increased intracranial pressure, abnormal sleep patterns, hearing impairment, and bronchopulmonary dysplasia, retinopathy of prematurity, intraventricular hemorrhage, periventricular leukomalacia, retardate development and alterations in the neuroendocrine system. Herein, this study aimed to discuss the effects of earmuffs on physiological parameters in preterm infants. The relevant and available peer-reviewed publications from 2012 to 2018 from various databases were analyzed. For the assessment of the studies, the full-text accessible studies were included for analysis. The retrieved documents were analyzed using VOSviewer regarding the geographical distributions of the documents with their numbers and citations, keywords proposed by the researchers. All records with the term "earmuffs OR earmuff" in the "article title, abstract, keywords" were retrieved from different databases. Accordingly, 396 documents containing the word "earmuffs OR earmuff" were recorded. The search was then restricted for publications that contain the words "noise AND nursing AND preterm" in the title and abstracts (TITLE-ABS-KEY (earmuffs OR earmuff)) AND (noise AND nursing AND preterm) (Scopus=390; Web of Science=1, Medline=2; Cochrane=1; Embase=1= Pubmed=1=n=396). After inclusion and exclusion criteria, 7 documents were recorded and then evaluated for the present study. As a conclusion, the effects of earmuffs on physiological parameters of preterm infants have not been clearly understood and reported yet. Along with the present documents, it is not clear that the use of earmuffs reduces stress and provides physiological stability in preterm infants born between approximately 28-32 weeks. The studies with a larger sample size are needed for validation of information reported in the articles analyzed herein.

Auditory Exposure in the Neonatal Intensive Care Unit: Room Type and Other Predictors

OBJECTIVE

To quantify early auditory exposures in the neonatal intensive care unit (NICU) and evaluate how these are related to medical and environmental factors. We hypothesized that there would be less auditory exposure in the NICU private room, compared with the open ward.

STUDY DESIGN

Preterm infants born at ≤ 28 weeks gestation (33 in the open ward, 25 in private rooms) had auditory exposure quantified at birth, 30 and 34 weeks postmenstrual age (PMA), and term equivalent age using the Language Environmental Acquisition device.

RESULTS

Meaningful language (P < .0001), the number of adult words (P < .0001), and electronic noise (P < .0001) increased across PMA. Silence increased (P = .0007) and noise decreased (P < .0001) across PMA. There was more silence in the private room (P = .02) than the open ward, with an average of 1.9 hours more silence in a 16-hour period. There was an interaction between PMA and room type for distant words (P = .01) and average decibels (P = .04), indicating that changes in auditory exposure across PMA were different for infants in private rooms compared with infants in the open ward. Medical interventions were related to more noise in the environment, although parent presence (P = .009) and engagement (P  = .002) were related to greater language exposure. Average sound levels in the NICU were 58.9 ± 3.6 decibels, with an average peak level of 86.9 ± 1.4 decibels.

CONCLUSIONS

Understanding the NICU auditory environment paves the way for interventions that reduce high levels of adverse sound and enhance positive forms of auditory exposure, such as language.

Sound reduction management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to stress, including sound of high intensity. The sound environment in the NICU is louder than most home or office environments and contains disturbing noises of short duration and at irregular intervals. There are competing auditory signals that frequently challenge preterm infants, staff and parents. The sound levels in NICUs often exceed the maximum acceptable level of 45 decibels (dB), recommended by the American Academy of Pediatrics. Hearing impairment is diagnosed in 2% to 10% of preterm infants versus 0.1% of the general paediatric population. Noise may cause apnoea, hypoxaemia, alternation in oxygen saturation, and increased oxygen consumption secondary to elevated heart and respiratory rates and may, therefore, decrease the amount of calories available for growth. Elevated levels of speech are needed to overcome the noisy environment in the NICU, thereby increasing the negative impacts on staff, newborns, and their families. High noise levels are associated with an increased rate of errors and accidents, leading to decreased performance among staff. The aim of interventions included in this review is to reduce sound levels to 45 dB or less. This can be achieved by lowering the sound levels in an entire unit, treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled, or reducing the sound levels that reaches the individual infant by using earmuffs or earplugs. By lowering the sound levels that reach the neonate, the resulting stress on the cardiovascular, respiratory, neurological, and endocrine systems can be diminished, thereby promoting growth and reducing adverse neonatal outcomes.

OBJECTIVES

Primary objectiveTo determine the effects of sound reduction on growth and long-term neurodevelopmental outcomes of neonates. Secondary objectives1. To evaluate the effects of sound reduction on short-term medical outcomes (bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leukomalacia, retinopathy of prematurity).2. To evaluate the effects of sound reduction on sleep patterns at three months of age.3. To evaluate the effects of sound reduction on staff performance.4. To evaluate the effects of sound reduction in the neonatal intensive care unit (NICU) on parents' satisfaction with the care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings, clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp), Pediatric Academic Societies Annual meetings 2000 to 2014 (Abstracts2View(TM)), reference lists of identified trials, and reviews to November 2014.

SELECTION CRITERIA

Preterm infants (< 32 weeks' postmenstrual age (PMA) or < 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or a stepdown unit.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses according to the Cochrane Neonatal Review Group.

MAIN RESULTS

One small, high quality study assessing the effects of silicone earplugs versus no earplugs qualified for inclusion. The original inclusion criteria in our protocol stipulated an age of < 48 hours at the time of initiating sound reduction. We made a deviation from our protocol and included this study in which some infants would have been > 48 hours old. There was no significant difference in weight at 34 weeks postmenstrual age (PMA): mean difference (MD) 111 g (95% confidence interval (CI) -151 to 374 g) (n = 23). There was no significant difference in weight at 18 to 22 months corrected age between the groups: MD 0.31 kg, 95% CI -1.53 to 2.16 kg (n = 14). There was a significant difference in Mental Developmental Index (Bayley II) favouring the silicone earplugs group at 18 to 22 months corrected age: MD 14.00, 95% CI 3.13 to 24.87 (n = 12), but not for Psychomotor Development Index (Bayley II) at 18 to 22 months corrected age: MD -2.16, 95% CI -18.44 to 14.12 (n =12).

AUTHORS' CONCLUSIONS

To date, only 34 infants have been enrolled in a randomised controlled trial (RCT) testing the effectiveness of reducing sound levels that reach the infants' ears in the NICU. Based on the small sample size of this single trial, we cannot make any recommendations for clinical practice. Larger, well designed, conducted and reported trials are needed.

Active noise control for infant incubators

This paper presents an active noise control system for infant incubators. Experimental results show that global noise reduction can be achieved for infant incubator ANC systems. An audio-integration algorithm is presented to introduce a healthy audio (intrauterine) sound with the ANC system to mask the residual noise and soothe the infant. Carbon nanotube based transparent thin film speaker is also introduced in this paper as the actuator for the ANC system to generate the destructive secondary sound, which can significantly save the congested incubator space and without blocking the view of doctors and nurses.

Recommended permissible noise criteria for occupied, newly constructed or renovated hospital nurseries

OBJECTIVE

To base permissible noise criteria for occupied, new nurseries on research findings.

STUDY DESIGN

An interdisciplinary group of clinicians reviewed the literature regarding the effect of sound on the fetus, newborn, and preterm infant and based recommended criteria on the best evidence. An external panel subsequently reviewed the criteria.

RESULTS

The recommended criteria: Patient bed areas and the spaces opening onto them shall be designed to produce minimal ambient noise and to contain and absorb much of the transient noise that arises within the nursery. The overall, continuous sound in any bed space or patient care area shall not exceed: (1) an hourly Leq of 50 dB and (2) an hourly L10 of 55 dB, both A-weighted, slow response. The 1-second duration Lmax shall not exceed 70 dB, A-weighted, slow response.

CONCLUSION

The permissible noise criteria will protect sleep, support stable vital signs, and improve speech intelligibility for many infants most of the time.

Systematic review of the etiology of bilateral sensorineural hearing loss in children

OBJECTIVE

Identification of the etiology of sensorineural hearing loss (SNHL) in children facilitates management and provides important prognostic information. In recent years, the etiology of bilateral SNHL in children has changed due to advances in genetic testing and treatment of perinatal infections. The objective of this study was to determine the frequency of etiologies of moderate-profound bilateral sensorineural hearing loss (SNHL) in children.

METHODS

The English literature was searched in Medline for articles published between 1966 and 2002. The inclusion criteria were studies involving bilateral SNHL >/=40dB in children less than 18 years of age. The studies were required to account for all patients, and provide a breakdown of etiologic factors. Etiologies investigated included genetic and non-genetic (prenatal, perinatal, postnatal). To compare differences between the frequencies of etiologies a two-sample t-test was performed assuming unequal variance. Studies were stratified according to perceived confounders: start date of study, study design, and degree of hearing loss.

RESULTS

Seven hundred and eighty abstracts were screened for relevancy. Forty-three studies satisfied the inclusion criteria. The common etiologies of bilateral SNHL were unknown (41.5%), genetic non-syndromic (27.2%), prenatal (11.5%), perinatal (9.7%), postnatal (6.6%), and genetic syndromic (3.5%). Unknown and Rubella were significantly less frequent etiologies in the more recent studies, while genetic non-syndromic, asphyxia and prematurity were more common. Genetic non-syndromic hearing loss was more frequent in the prospective studies compared to the population and retrospective studies, but this difference was not significant. Genetic non-syndromic hearing loss was more common among patients with profound hearing loss.

CONCLUSION

Accounting for the recent decline in infectious etiologies, the most common causes of bilateral SNHL are unknown (37.7%), genetic non-syndromic (29.2%), prenatal (12%), perinatal (9.6%), postnatal (8.2%), and genetic syndromic (3.2%).

Nongenetic causes of hearing loss

Nongenetic as well as genetic etiologies must be explored in the child with identified hearing loss. Graduates of the neonatal intensive care unit are at increased risk for developing hearing loss due to hypoxia, hyperbilirubinemia, very low birth weight, and ototoxic medications. Although meningitis has decreased in frequency, it is still a risk factor for hearing loss. Cytomegalovirus remains the most common congenital infection and a relatively common etiology of hearing loss, which can be progressive. Preventable causes of hearing loss include those caused by head trauma, noise, and ototoxic medications. Identification of the etiology of hearing loss can facilitate the development of a treatment and management plan.

Noise in the intensive care nursery

THE PARABLE OF THE GARDEN

The problem of juxtaposing noise and premature babies brings to mind the paradoxical situation of my neighhbor’s garden. This garden is an oasis of visual calm, with evergreen bushes sculpted into flowing waves in the traditional Japanese landscape style which alternate serenely with the perfect miniature green seas of the lawn. However, the great paradox here is the noise made by the tools needed to create this tiny paradise. The gas lawn mower is a familiar evil, but the latest laborsaving invention—the leaf blower— makes life as a neighbor hardly worth living while it’s being used. It is the coexistence and contradiction of these opposites that provides the theme for this article on noise in the intensive care nursery.

Etiology of hearing loss in children. Nongenetic causes

Every child with a hearing loss should have an evaluation to determine the cause of hearing loss. This article focuses on the nongenetic origins of hearing loss, the most frequent of which is the neonatal intensive care unit experience, followed by meningitis, cytomegalovirus, and other infections. Preventable causes such as exposure to ototoxic medications and noise are also discussed in this article.

Failure to clinically predict NICU hearing loss

Neonatal intensive care unit (NICU) survivors demonstrate handicapping sensorineural hearing loss up to 50 times more frequently than normal newborns, yet little is known about the etiology of the hearing loss. Theoretically, accurate identification and triage of a particular infant based on a clinical profile would be useful. Forty NICU graduates of The Massachusetts General Hospital were selected for a detailed retrospective chart review evaluating prenatal, perinatal, and NICU medical conditions and treatment. Twenty-three patients identified with hearing loss and 17 infants with normal hearing were compared clinically. Univariate and multivariate analysis was performed on a subpopulation of patients (20 with hearing loss and 16 with normal hearing). A history of ventilation was associated with hearing loss (P = .0023), but this factor was not absolute. No other clinical parameters were convincingly linked to hearing loss. We conclude that reliance on risk factors is an inadequate clinical method to select a patient for a hearing test and that each NICU survivor deserves audiometric evaluation.

Hemiplegic cerebral palsy. Aetiology and outcome

Hemiplegic cerebral palsy (CP) was studied in a retrospective population-based series of 169 cases from the South-western Swedish health care region covering the birth years 1969-78. The purpose was to analyse the prevalence, aetiology and neuro-developmental outcome in children born preterm and at term, and to correlate pathogenetic periods, aetiological factors and clinical parameters to neuroradiology. The prevalence at the ages 6-15 years was 0.66 per 1000. Postnatally acquired hemiplegia, mainly postinfectious, iatrogenic or posttraumatic, constituted 11%. Among term children with congenital hemiplegia (pre and perinatally derived) the aetiology was considered prenatal, mainly circulatory brain lesions and maldevelopments, in 42%, combined pre and perinatal in 9%, perinatal (cerebral haemorrhage, hypoxia) in 16% and untraceable in 34%. The corresponding distribution among preterm children was 29%, 47%, 25% and 6%, respectively. The rate of preterm birth among congenital cases was 24%. Birth asphyxia was shown to be a poor indicator of pathogenetic period, whereas a cascade of postpartum complications suggested perinatal brain damage. Clinical follow-up of 152 children revealed that 50% had mild, 31% moderate and 19% severe motor dysfunction. Stereognostic sense was impaired in 44% of the children (astereognosia in 20%). Additional impairments (mental retardation, epilepsy, impaired vision, hearing and speech, severe behavioural/perceptual problems) were present in 42%. Term children with congenital hemiplegia tended to be more severely affected than preterm children. The resulting total handicap was considered mild in 40%, moderate in 44% and severe in 16%. The prevalence of severe total handicap was highest among postnatal cases. Computerised tomography (CT), performed in 109 congenital cases, was normal in 26%, showed unilateral ventricular enlargement in 36% and revealed cortical/subcortical cavities in 20%. In the remaining 18% CT findings were classified as "other". With the classification so far used, correlations between CT findings and aetiologies were unsatisfactory and disappointing. In contrast, CT findings showed a strong correlation with clinical degree of severity and magnitude of associated handicap. As a rule, normal CT implied mild disability and unilateral ventricular enlargement moderate, whereas cortical/subcortical cavities were frequently associated with severe handicap, including mental retardation and epilepsy.

Cause of hearing loss in the high-risk premature infant

Bilateral hearing loss occurred in 9.7% of infants who survived despite very low birth weight (less than or equal to 1500 gm), 16.7% of infants who survived neonatal seizures, and 28.6% of infants who survived both low birth weight and neonatal seizures. All neonates received treatment in a single neonatal intensive care unit between 1976 and 1980. Twenty-two of 36 hearing-impaired children were normal physically and mentally, with IQ scores of greater than or equal to 85. Significant neonatal predictors of hearing loss in high-risk premature infants (less than or equal to 36 weeks gestation), as determined by multivariable testing, were prolonged respirator care, high serum bilirubin concentration, and hyponatremia. Exchange transfusions were associated with a decreased risk of hearing loss.

The very low birth weight infant after discharge from intensive care: anticipatory health care and developmental course

Despite intensive research, the data available on the long-term effects of prematurity on development of the child have not led to clearcut conclusions, particularly when the investigations are based on infant or perinatal factors alone. Previous research does indicate that the infant is "at risk" through school age and that the parents' perception of the child and the harmony between the child and his environment are powerful determinants of outcome. The implications for medical care, however, are clear. The developing low birth weight infant is best served by close medical supervision, particularly during the turbulent early years. Health care should be planned to include ongoing developmental assessment and screening at least through school entrance so that emerging vulnerabilities or deficits may be addressed as early as possible, thus impeding developmental progress minimally. An optimal care plan includes active partnership with the parents in detection of weaknesses, reinforcement of strengths, and formulation of recommendations for behavioral and educational management. For the physician this will require clinical acumen, an understanding of the child within the context of his environment, an attitude of supportive realism and a long view.

The ontogeny of sensory perception in preterm infants

The extra- vs intrauterine development of both visual and auditory cortical evoked response patterns was compared at 33, 37 and 40 weeks conceptional age. The maturation of visual cortical evoked responses is retarded in infants at 37 and 40 weeks conceptional age when born with a gestational age of less than 32 weeks, which thus implies a long extrauterine life span. The maturation of the auditory cortical evoked responses is not influenced by premature exposure to the extrauterine environment. The results are explained on the basis of the particular central nervous system growth spurt periods and a thus defined vulnerable period of different brain structures.