Otoacoustic emissions as a screening test for hearing impairment in children

Transient evoked otoacoustic emissions (TEOAEs) are low amplitude sound waves produced by the healthy cochlea. They can be recorded with a microphone in the external ear. TEOAEs are abolished by hearing losses of 30 dB or more. The feasibility of using TEOAEs as a screening test for hearing loss in children was studied. TEOAE recordings were attempted in 56 children attending an audiology clinic. Recordings were possible from both ears in 52 children; of these 104 ears, 32 had hearing deficits of 30 dB or more. Hearing status was compared with the results of six TEOAE screening criteria. All criteria had a sensitivity of 1.00. Four standard TEOAE criteria yielded specificities of 0.46-0.58. Two new criteria derived from analysis of limited frequencies from the TEOAE waveform gave specificities of 0.76 and 0.82. It can be concluded that, when appropriate pass/fail criteria are employed, TEOAEs are a feasible screening test in children.     

Otoacoustic emissions as a screening test for hearing impairment in children.

Transient evoked otoacoustic emissions (TEOAEs) are low amplitude sound waves produced by the healthy cochlea. They can be recorded with a microphone in the external ear. TEOAEs are abolished by hearing losses of 30 dB or more. The feasibility of using TEOAEs as a screening test for hearing loss in children was studied. TEOAE recordings were attempted in 56 children attending an audiology clinic. Recordings were possible from both ears in 52 children; of these 104 ears, 32 had hearing deficits of 30 dB or more. Hearing status was compared with the results of six TEOAE screening criteria. All criteria had a sensitivity of 1.00. Four standard TEOAE criteria yielded specificities of 0.46-0.58. Two new criteria derived from analysis of limited frequencies from the TEOAE waveform gave specificities of 0.76 and 0.82. It can be concluded that, when appropriate pass/fail criteria are employed, TEOAEs are a feasible screening test in children.     

Otoacoustic emissions: A new method to diagnose hearing impairment in children

Otoacoustic emissions (OAEs) are epiphenomena of sensitive, amplifying processes during hearing which can be detected in persons with normal inner ear function. They originate from the cochlea and are interpreted as an energy leakage of cochlear processes, perhaps resulting from active outer hair cell movements. OAEs travel from the cochlea through the middle ear to the external auditory canal where they can be detected using sensitive miniature microphones. Transient evoked (TEOAE) tests allow to otoacoustic emissions non-invasively check the integrity of the cochlea. In the neonatal period, registration of OAEs can be accomplished during natural sleep. In infants and neonates TEOAEs can be used as screening test with a screening level at 30 dB HL in pacdiatric audiology. They are less time consuming and elaborate than auditory brainstem responses (ABR) and they are more sensitive than behavioral tests. TEOAEs are constant over long periods of time and they are reduced or absent due to various adverse influences in the inner ear. These latter characteristics may allow monitoring of the inner ear function over time e.g. during disease and/or during ototoxic therapeutic interventions. Limitations of this new method are due to the fact that TEOAEs are absent in patients with a more than 30 dB HL hearing loss. Thus a hearing threshold cannot be determined. Diseases of the inner ear which are common in early childhood (like otitis media) reduce the transfer of TEOAEs and may wrongly indicate a cochlear hearing disorder. New methods for evaluation and interpretation of TEOAE test results are currently developed which may allow to circumvent this problem. When used by an experienced examiner who is aware of the possibilities as well as of the limitations of this new method, registration of TEOAEs is a promising new tool which complements our current-armamentarium to diagnose hearing disorders in children.     

Auditory profile in children recovering from bacterial meningitis

In the present study BERA profile of 30 post-meningitic children was compared with 15 normal children of the same age and it was observed that 36.6% children in the age range of 6 months to 36 months were found to have varying degree of sensorineural deafness. Severe bilateral sensorineural hearing loss (>80 dB) was observed in 6.6% children and moderate (40–80 dB) hearing loss in 30% of children. Abnormalities were bilateral in both the samples of children with severe hearing loss (>80 dB) whereas among 9 children who had moderate hearing loss abnormalities were bilateral in one patient and unilateral in the remaining 8 children. A relationship between higher incidence of sensorineural deafness and younger age of children, and occurence of seizures during meningitis were noted. But no relationship was observed with either sex, hydrocephalus, subdural effusion or with low CSF sugar and high CSF proteins.     

Sensorineural hearing loss following acute bacterial meningitis in non-neonates

OBJECTIVE: Sensorineural hearing loss (SNHL) is an important sequelae of acute bacterial meningitis (ABM) in children. This study was undertaken to determine the incidence of SNHL following meningitis in non-neonates and its correlation with various factors. METHODS: Children between the ages of 1 month and 12 years with ABM admitted in a teaching hospital over a period of 18 months were enrolled. Detailed history was taken, clinical examination performed and cerebrospinal fluid analyzed at commencement of therapy, 48 hours later and at the end of treatment. On discharge brainstem evoked response audiometry (BERA) was recorded. Data were analyzed using appropriate statistical tests. RESULTS: Out of 32 children enrolled, 9 (28.1%) developed SNHL, bilateral in 21.9% and unilateral in 6.2%. Among hearing impaired subjects, 11.2% had mild while 44.4% each had moderate and profound hearing loss. Age, presence of vomiting, altered sensorium seizures and aminoglycoside usage were not significantly different in those with and without SNHL, but the total duration of fever was (p<0.05). There was significantly higher protein content and neutrophils in the second CSF sample of those with SNHL. CONCLUSION: There is a greater than 50% probability of the child developing SNHL if neutrophil percentage in the second CSF is 80% or more. Since the overall risk of SNHL is significant in children with meningitis, it is recommended that BERA be recorded in all, so that early intervention may be possible.     

Sensorineural hearing loss following acute bacterial meningitis in non-neonates

Objective : Sensorineural hearing loss (SNHL) is an important sequelae of acute bacterial meningitis (ABM) in children. This study was undertaken to determine the incidence of SNHL following meningitis in non-neonates and its correlation with various factors.Methods : Children between the ages of 1 month and 12 years with ABM admitted in a teaching hospital over a period of 18 months were enrolled. Detailed history was taken, clinical examination performed and cerebrospinal fluid analyzed at commencement of therapy, 48 hours later and at the end of treatment. On discharge brainstem evoked response audiometry (BERA) was recorded. Data were analyzed using appropriate statistical tests.Results : Out of 32 children enrolled, 9 (28.1%) developed SNHL, bilateral in 21.9% and unilateral in 6.2%. Among hearing impaired subjects, 11.2% had mild while 44.4% each had moderate and profound hearing loss. Age, presence of vomiting, altered sensorium seizures and aminoglycoside usage were not significantly different in those with and without SNHL, but the total duration of fever was (p <0.05). There was significantly higher protein content and neutrophils in the second CSF sample of those with SNHL.Conclusion : There is a greater than 50% probability of the child developing SNHL if neutrophil percentage in the second CSF is 80% or more. Since the overall risk of SNHL is significant in children with meningitis, it is recommended that BERA be recorded in all, so that early intervention may be possible.     

Neonatal screening for hearing impairment

Over the last 25 years, technological developments have facilitated the implementation of neonatal screens for hearing impairment. Restricting tests to 10% of the cohort with risk factors enables detection of around 40% of congenital impairments. Critical review has therefore recommended universal screening targeting for identification all neonates with moderate or worse impairment. Both oto-acoustic emission and auditory brainstem response (ABR) recording make this possible. The emission test is very sensitive to mild impairments. Specificity critically depends upon the age of maternity testing, but a false positive rate of 8% at discharge is typical. This is reduced to <1% by implementing a second outpatient test, or an ABR before discharge. Both tests are required to identify auditory neuropathies. Widespread implementation will follow pilot trials that are currently being undertaken. The accurate assessment of screen positives, and appropriate habilitation for those identified, is also required. These needs are complex, and require further study if universal screening is to become routine.     

Differentiating acute bacterial meningitis from acute viral meningitis among children with cerebrospinal fluid pleocytosis: a multivariable regression model

BACKGROUND: Although accurate models for predicting acute bacterial meningitis exist, most have narrow application because of the specific variables selected for them. In this study, we estimate the accuracy of a simple new model with potentially broader applicability. METHODS: On the basis of previous reports, we created a reduced multivariable logistic regression model for predicting bacterial meningitis that relies on age (years) (AGE), cerebrospinal fluid (CSF), total protein (TP) and total neutrophil count (TNC) alone. Data were from children ages 1 month-18 years diagnosed with acute enteroviral or bacterial meningitis whose initial CSF revealed >7 white blood cells/mm. A fractional polynomial model was specified and validated internally by the bootstrap procedure. The area under the receiver operating characteristic curve (discrimination: criterion standard, >0.7), the Hosmer-Lemeshow deciles-of-risk statistic (calibration: criterion standard, P > 0.05) and sensitivity-specificity pairs at prespecified probability thresholds of the model were computed. RESULTS: We identified 60 children with bacterial meningitis and 82 with enteroviral meningitis. At an area under the receiver operating characteristic curve of 0.97, our model represented by the equation: log odds of bacterial meningitis = 0.343 - 0.003 TNC - 34.802 TP + 21.991 TP - 0.345 AGE, was highly accurate when differentiating between bacterial and enteroviral meningitis. The model fit the data well (Hosmer-Lemeshow statistic; P =[r] 0.53). At probability cutoffs between 0.1 and 0.4, the model had sensitivity values between 98 and 92% and specificity values between 62 and 94%. CONCLUSIONS: Among children with CSF pleocytosis, a prediction model based exclusively on age, CSF total protein and CSF neutrophils differentiates accurately between acute bacterial and viral meningitis.     

Sequelae of acute bacterial meningitis in children treated for seven days

The sequelae of acute bacterial meningitis in children who were treated with ampicillin or chloramphenicol for seven days during the period January 1979 to June 1983 were assessed prospectively. The 235 patients (117 boys and 118 girls) ranged in age from four days to 18 years (mean 26.4 months). Haemophilus influenzae type b was isolated in 70% of patients, Streptococcus pneumoniae in 20%, and Neisseria meningitidis in 10%. The mortality rate was 6.4%. No relapses occurred. Of the 220 survivors, 171 had neurologic psychometric, audiologic, and ophthalmologic assessments performed for a minimum of 1 year following their illness. One hundred thirty-six (80%) children had no detectable sequelae; 20% had mild to severe handicaps. The frequency of sequelae was greatest among children with S pneumoniae meningitis (57%) and least among children with N meningitidis (0%). The sequelae observed included: sensorineural hearing loss (12.9%), developmental delay (5.3%), speech defect (4.7%), motor defect (3.0%), hydrocephalus (1.7%), and seizure disorder (1%). The frequency of observed sequelae among these patients is similar to that previously reported in children treated for ten to 14 days. Our findings indicate that seven days of intravenous antibiotic therapy is adequate for the treatment of bacterial meningitis in children.     

Otoacoustic emissions (OAE) in paediatric hearing screening--the Singapore experience.

Early identification and rehabilitation of hearing impairment is important for development of language in affected children. Behavioural audiological tests in children are unreliable. Brainstem auditory evoked response (BAER) although a reliable objective test, is difficult to perform. Otoacoustic emissions (OAE) is now thought to be a more practicable screening modality. A study to compare the use of OAE and BAER in the paediatric population was thus undertaken. 100 children underwent OAE and BAER screening in SGH from August 1991 to February 1992. OAE was equally effective when compared with the BAER in testing for passed or failed subjects (p < 0.05, X2 = 4.9). The sensitivity and specificity of OAE with respect to BAER was 95% and 93% respectively. Mean test time was 3.1 minutes for OAE and 28.6 minutes for BAER. Success rate for OAE was 100%. We therefore conclude that OAE is a feasible alternative to the BAER as a hearing screening modality.     

Unilateral hearing impairment in children

An overview and update are offered on difficulties experienced by children with monaural sensorineural deafness. It is the general consensus that children with unilateral hearing loss experience few, if any, communication and/or educational problems. The medical and educational status of a group (N = 60) of children with unilateral, hearing impairment are described. In addition, the auditory, linguistic, and behavioral manifestations of unilateral hearing impairment were studied in considerable detail for a subsample of these 60 children. The results revealed that approximately one third of the children with unilateral hearing loss had failed at least one grade. Nearly 50% of the group had either failed a grade and/or needed resource assistance in the schools. The small subsample of children with unilateral hearing loss performed much poorer than a matched group of children with normal hearing on both a localization and a syllable recognition task. Finally, the data on behavioral and linguistic manifestations of monaural hearing loss indicate that children with unilateral hearing impairment are experiencing more problems than previously supposed.     

Capillary microhematocrit measurement as a screening test for anemia in children

The spectrophotometric measurement of hemoglobin performed with a well standardized instrument using venous blood is widely accepted as a reference standard for anemia. In developed countries automated electronic counters are used instead. However, this method of determining anemia is not practical for screening in developing countries as it requires special skill or expensive equipment to obtain the specimen or to perform the test. The primary objective of this study was to determine the feasibility of using capillary microhematocrit measurement as a screening test for anemia. The 104 patients examined ranged in age from 6 months to 6 years; 65 were males and 36 females. Sixty one of the 104 cases (58.7%) were below 2 years of age and the other 43 cases (41.5%) were older than 2 years. Hemoglobin values ranged from 2.7-13.5 g/dl and capillary microhematocrit ranged from 9-41%. Analysis of the result showed a significant correlation between the capillary microhematocrit values and the capillary hemoglobin values (r = 0.99 and p less than 0.001). The sensitivity of the microhematocrit method for detecting anemia was 91.11% and the specificity was 89.83%. The predictive value for a normal (negative) microhematocrit was 92.98% and the predictive value for a low (positive) microhematocrit was 87.23%. We conclude from this study that the capillary microhematocrit measurement method can be appropriately used as a screening test for anemia.