Hearing impairment in children after bacterial meningitis: incidence and resource implications

Decrease in Rates of Hearing Loss From Pediatric Bacterial Meningitis Over Time: A Database Review

OBJECTIVES

Bacterial meningitis is a leading cause of acquired sensorineural hearing loss (SNHL). Treatment and prevention of bacterial meningitis have improved over time, but rates of neurologic complications have not been recently studied. The objective here is to present an updated population-based review of hearing loss as a sequela of bacterial meningitis.

METHODS

A retrospective cohort study was conducted between 2010 and 2022 of children discharged with bacterial meningitis, using the Pediatric Health Information System's (PHIS) database. Rates of hearing loss and mortality were evaluated over time.

RESULTS

A total of 6138 children with a primary diagnosis of bacterial meningitis were identified (3520 male [57.3%], mean age 5.8 months [2.0, 61.2]). Of these, 277 (4.51%) were diagnosed with hearing loss. Children with hearing loss were significantly older (23.6 vs. 5.3 months, p < 0.01), but differences in gender, race, or ethnicity had no association with hearing loss. Streptococcus pneumoniae, Hemophilus influenzae, and Neisseria meningiditis were associated with significantly higher rates of hearing loss than other etiologies (p < 0.01). Children with hearing loss had a higher rate of receiving dexamethasone than children without hearing loss. Overall mortality rate was 2.1%. Hearing loss and mortality demonstrated significant decreases over the study period.

CONCLUSION

Hearing loss remains a common sequela of bacterial meningitis despite widespread uptake of vaccines for preventing S. pneumoniae, H. influenzae, and N. meningitidis. Dexamethasone was not associated with decreased rates of hearing loss in this cohort. From 2010 to 2022, there was a significant decrease in overall rates of mortality and hearing loss for children with bacterial meningitis.

LEVEL OF EVIDENCE

Level 3: retrospective case-control series Laryngoscope, 2024.

Birth weight discordance in very and extremely preterm twins and the risk of neonatal hearing loss

OBJECTIVE

Birth weight (BW) discordant twins have an increased risk of mortality and morbidity. We aimed to study the effect of BW discordance on the risk of neonatal hearing loss (NHL) in very and extremely preterm twins.

STUDY DESIGN

Results of the nationwide newborn hearing screening program in Dutch Neonatal Intensive Care Units and diagnostic examination were centrally registered between 2003 and 2021 and included in this study. We selected twins and singletons with a gestational age (GA) 24- < 32 weeks. Logistic regression analyses were applied to study the effect of BW discordance on the risk of NHL adjusted for BW, GA and sex. Singletons and concordant twins, defined as a BW discordance of ≤20 %, were used as two reference groups. BW discordance was further categorized as medium (>20-30 %) and high (>30 %).

RESULTS

In total, 3430 twins (2694 concordant, 428 medium and 308 high BW discordant), and 23,114 singletons were available. Smaller newborns of high BW discordant twins showed an increased risk of NHL compared to singletons (adjusted odds ratio with 95 % confidence interval was 3.56 (2.26-5.60)). Also, smaller newborns of medium and high BW discordant twins showed an increased risk of NHL compared to concordant twins (adjusted odds ratio with 95 % confidence interval were 1.97 (1.13-3.44) and 4.17 (2.56-6.82), respectively). No other statistically significant differences were found.

CONCLUSION

BW discordance increased the risk of NHL in the smaller of the twin born very or extremely preterm. This risk increased as the weight difference increased.

Predicting Parameters for Audiological Complications in Pediatric Patients Affected by Meningitis

Objective Meningitis is one of the most common causes of acquired sensorineural hearing loss in childhood. The aim of this study was to identify parameters predicting long-term audiological complications in meningitis.

Methods Patients under 18 years admitted to the Bambino Gesù Pediatric Hospital between March 2001 and February 2019 with a diagnosis of meningitis entered the study. Audiological complications had been investigated during hospitalization and at follow-up.

Results During the study period, 425 patients were enrolled. Sensorineural hearing loss was observed in 48 patients (11.3%). Multivariate analysis has shown that female gender predisposes to the development of permanent hearing loss after meningitis. Hearing impairment was associated with pneumococcal etiology (p < 0.001), lethargy (p = 0.027), reduced cerebrospinal fluid glucose level (26.18 mg/dL, p = 0.004), increase in both C-reactive protein (17.77 mg/dL, p = 0.001), and erythrocyte sedimentation rate (106.3 mm/h, p = 0.004). At follow-up, 19 patients had a persisting hearing damage, 7 recovered their hearing capacity and 20 were lost to follow-up. Among patients with permanent hearing damage, treatment was necessary in 16 patients. In details, 6 patients required external hearing aids and 10 patients required a cochlear implant.

Conclusions Female gender, lethargy at onset, reduced cerebrospinal fluid glucose level, increased inflammation index, and pneumococcal etiology are correlated with sensorineural hearing damage in meningitis patients.

Hearing impairment after acute bacterial meningitis in children

OBJECTIVE

To determine the incidence of hearing loss after acute episode of meningitis in children.

METHODS

A descriptive study carried out in the Department of Pediatric Medicine of The Children's Hospital Lahore, Pakistan from January 2014 to July 2016. A total of 175 children one month to 13 years of age admitted with diagnosis of meningitis were included. Complete blood count, CSF cytology, biochemistry and culture sensitivity were sent. CT scan brain was done if required. Hearing assessment was done two weeks after admission using otoacoustic emissions in the patients having normal tympanogram. Hearing impairment was classified as sensorineural if otoacoustic emissions were absent while tympanometry was normal.

RESULTS

Of 175 children, 58% were males and 42% were females. Mean age was 2.1 years. Orientation as assessed by Glasgow comma scale (GCS) was normal in 63% while 5% had GCS<8 and 32% had GCS between 8 and 15. Signs of meningeal irritation were seen in 58% while focal signs only in 4%. In 15 % cases CT scan was done, out of which 73% showed abnormal findings. Otoacoustic emissions were absent in 22% of cases. Risk factors of hearing deficit were stay duration of more than 10 days (p=0.04), low GCS at presentation (p=0.009) and meningitis with complications (p=0.008).

CONCLUSION

The frequency of hearing loss is 22% following acute episode of meningitis which necessitates the need for implementation of screening assessment after meningitis in Pakistan. Prolonged stay, low GCS and complicated meningitis are risk factors for hearing impairment.

Hearing Impairment Among Children Referred to a Public Audiology Clinic in Gaborone, Botswana

Objective. To describe and quantify hearing impairment among children referred to the audiology clinic in Princess Marina Hospital, a public referral hospital in Botswana. Methods. In a retrospective case series, we reviewed medical records of children aged 10 years and younger whose hearing was assessed between January 2006 and December 2015 at the audiology clinic of Princess Marina Hospital in Gaborone, Botswana. Results. Of 622 children, 50% were male, and median age was 6.7 years (interquartile range = 5.0-8.3). Hearing impairment was diagnosed in 32% of clinic attendees, comprising sensorineural (23%), conductive (25%), and mixed (11%) hearing loss, while 41% of children with diagnosed hearing impairment did not have a classification type. Hearing impairment was mild in 22.9%, moderate in 22.4%, severe in 19.4%, profound in 16.9%, and of undocumented severity in 18.4%. Children younger than 5 years were 2.7 times (95% confidence interval = 1.29-5.49; P = .008) more likely to be diagnosed with sensorineural hearing impairment compared with those older than 5 years. By contrast, children older than 5 years were 9.6 times (95% confidence interval = 2.22-41.0; P = .002) more likely to be diagnosed with conductive hearing loss compared with those under 5 years. Conclusion. Hearing impairment was common among children referred to this audiology clinic in Botswana. Of those with hearing impairment, more than a third had moderate or severe deficits, suggesting that referrals for hearing assessments are not occurring early enough. Hearing awareness programs individually tailored to parents, educators, and health care workers are needed. Neonatal and school hearing screening programs would also be beneficial.

Risk Factors for Hearing Loss after Pediatric Meningitis in Japan

Objectives

We sought to identify predictors for hearing loss in Japanese children with meningitis.

Methods

We analyzed 155 cases of pediatric meningitis without other entities causing hearing loss in children admitted to Saitama Children's Medical Center between 1990 and 2005 for potential risk factors for hearing loss, using multiple logistic regression. Auditory brain stem response tests were performed to evaluate hearing loss.

Results

Of 155 children, 35 (23%) developed hearing loss (21 unilaterally and 14 bilaterally). Profound hearing loss (greater than 90 dB normal hearing level) occurred in 15 patients (9.7%; 4 unilaterally and 11 bilaterally). Of 112 patients with positive cerebrospinal fluid cultures, 27 (24%) developed hearing loss and 13 (12%) showed profound loss. Of 22 patients with Streptococcus pneumoniae meningitis, 11 (50%) developed hearing loss and 7 (32%) showed profound loss. Of 54 patients with Haemophilus influenzae meningitis, 11 (20%) developed hearing loss and 4 (7.4%) showed profound loss. High serum C-reactive protein levels and cerebrospinal fluid cultures positive for Streptococcus pneumoniae were identified as significant risk factors for hearing loss.

Conclusions

A high serum C-reactive protein level was first identified as a risk factor for hearing impairment after pediatric meningitis.

Asymmetric and unilateral hearing loss in children

Asymmetric and unilateral hearing losses in children have traditionally been underappreciated, but health care practitioners are now beginning to understand their effect on development and the underlying pathophysiologic mechanisms. The common wisdom among medical and educational professionals has been that at least one normal-hearing or near-normal-hearing ear was sufficient for typical speech and language development in children. The objective of this review is to illustrate, to the non-otolaryngologist, the consequences of asymmetric and unilateral hearing loss in children on developmental and educational outcomes. Etiology, detection, and management are also discussed. Lastly, implications for further research are considered.

Profound childhood hearing loss in a South Africa cohort: risk profile, diagnosis and age of intervention

OBJECTIVE

To describe profound childhood hearing loss in a South African population of pediatric cochlear implant recipients in terms of risk profile, and age of diagnosis and intervention.

METHODS

A retrospective review of patient files for 264 pediatric cochlear implant recipients from five cochlear implant programs was conducted. Data was captured from 264 eligible subjects, of which all were implanted between 1996 and 2013 and PCEHL was confirmed under the age of 5 years old. Data collected included demographical information, risk factors from case histories, diagnostic test procedures conducted, diagnosis (type, onset and degree of hearing loss) and documented ages of caregiver suspicion, initial diagnosis and intervention.

RESULTS

Risk factors for permanent childhood hearing loss were present in 51.1% of cases, with the most prevalent risks being NICU admittance (28.1%), family history of childhood hearing loss (19.6%) and prematurity (15.1%). An associated syndrome was diagnosed in 10% of children and 23.5% presented with at least one additional developmental condition. Hearing loss for most (77.6%) children was confirmed as congenital/early onset, while 20.3% presented with postnatal onset of hearing loss. ANSD was diagnosed in 5% of children, with admittance to NICU (80%) and hyperbilirubinemia (50%) being the most prevalent risk factors for these cases. Hearing loss was typically diagnosed late (15.3 months), resulting in delayed initial hearing aid fitting (18.8 months), enrollment in early intervention services (19.5 months) and eventual cochlear implantation (43.6 months).

CONCLUSION

Most prevalent risk factors in profound childhood hearing loss were admittance to NICU, family history and prematurity. Diagnosis and intervention was typically delayed predisposing this population to poorer outcomes.

Risk Factors for Hearing Loss in Children following Bacterial Meningitis in a Tertiary Referral Hospital

Objective. This study aimed to examine hearing function in children admitted with bacterial meningitis to determine the risk factors for sensorineural hearing loss. Setting. The study was conducted in the audiology unit and paediatric wards of Kenyatta National Hospital. Subjects and Methods. The study involved 83 children between the ages of six months and twelve years admitted with bacterial meningitis. The median age for the children examined was 14. On discharge they underwent hearing testing to evaluate for presence and degree of hearing loss. Results. Thirty six of the 83 children (44.4%) were found to have at least a unilateral mild sensorineural hearing loss during initial audiologic testing. Of the children with hearing loss, 22 (26.5%) had mild or moderate sensorineural hearing loss and 14 (16.9%) had severe or profound sensorineural hearing loss. Significant determinants identified for hearing loss included coma score below eight, seizures, cranial nerve neuropathy, positive CSF culture, and fever above 38.7 degrees Celsius. Conclusions. Sensorineural hearing loss was found to be highly prevalent in children treated for bacterial meningitis. There is need to educate healthcare providers on aggressive management of coma, fever, and seizures due to their poor prognostic value on hearing.

Independent validation of an existing model enables prediction of hearing loss after childhood bacterial meningitis

OBJECTIVE

This study aimed external validation of a formerly developed prediction model identifying children at risk for hearing loss after bacterial meningitis (BM). Independent risk factors included in the model are: duration of symptoms prior to admission, petechiae, cerebral spinal fluid (CSF) glucose level, Streptococcus pneumoniae and ataxia. Validation helps to evaluate whether the model has potential in clinical practice.

STUDY DESIGN

116 Dutch school-age BM survivors were included in the validation cohort and screened for sensorineural hearing loss (>25 dB). Risk factors were obtained from medical records. The model was applied to the validation cohort and its performance was compared with the development cohort. Validation was performed by application of the model on the validation cohort and by assessment of discrimination and goodness of fit. Calibration was evaluated by testing deviations in intercept and slope. Multiple imputation techniques were used to deal with missing values.

RESULTS

Risk factors were distributed equally between both cohorts. Discriminative ability (Area Under the Curve, AUC) of the model was 0.84 in the development and 0.78 in the validation cohort. Hosmer-Lemeshow test for goodness of fit was not significant in the validation cohort, implying good fit concerning the similarity of expected and observed cases. There were no significant differences in calibration slope and intercept. Sensitivity and negative predicted value were high, while specificity and positive predicted value were low which is comparable with findings in the development cohort.

CONCLUSIONS

Performance of the model remained good in the validation cohort. This prediction model might be used as a screening tool and can help to identify those children that need special attention and a long follow-up period or more frequent auditory testing.

Effectiveness of targeted surveillance to identify moderate to profound permanent childhood hearing impairment in babies with risk factors who pass newborn screening

OBJECTIVE

To examine the effectiveness of targeted surveillance for the identification of moderate-profound PCHI in babies who pass the newborn hearing screen in England and have risk factors.

DESIGN

Retrospective analysis.

STUDY SAMPLE

2,307,880 children born 01/04/06-30/09/09 in England.

RESULTS

Overall the prevalence for all PCHI in children with risk factors who pass newborn hearing screening is 1.49/1000. The risk factors with the highest prevalence are (1) Syndrome (other than Down's) associated with a hearing loss; (2) NICU with refer in both ears at OAE and pass in both ears at AABR; (3) Craniofacial anomaly; (4) Down's syndrome; (5) Congenital infection.

CONCLUSION

Targeted surveillance for children who pass the screen and have the risk factors 1-5 listed above will be retained within the English NHSP; targeted surveillance for children who pass the screen and have other risk factors is not effective and has been discontinued.

Cochlear implantation after bacterial meningitis in infants younger than 9 months

Objective. To describe the audiological, anesthesiological, and surgical key points of cochlear implantation after bacterial meningitis in very young infants. Material and Methods. Between 2005 and 2010, 4 patients received 7 cochlear implants before the age of 9 months (range 4-8 months) because of profound hearing loss after pneumococcal meningitis. Results. Full electrode insertions were achieved in all operated ears. The audiological and linguistic outcome varied considerably, with categories of auditory performance (CAP) scores between 3 and 6, and speech intelligibility rating (SIR) scores between 0 and 5. The audiological, anesthesiological, and surgical issues that apply in this patient group are discussed. Conclusion. Cochlear implantation in very young postmeningitic infants is challenging due to their young age, sequelae of meningitis, and the risk of cochlear obliteration. A swift diagnostic workup is essential, specific audiological, anesthesiological, and surgical considerations apply, and the outcome is variable even in successful implantations.

Adolescent development of psychosis as an outcome of hearing impairment: a 10-year longitudinal study

BACKGROUND

It has long been acknowledged that hearing impairment may increase the risk for psychotic experiences. Recent work suggests that young people in particular may be at risk, indicating a possible developmental mechanism.

METHOD

The hypothesis that individuals exposed to hearing impairment in early adolescence would display the highest risk for psychotic symptoms was examined in a prospective cohort study of a population sample of originally 3021 adolescents and young adults aged 14-24 years at baseline, in Munich, Germany (Early Developmental Stages of Psychopathology Study). The expression of psychosis was assessed at multiple time points over a period of up to 10 years, using a diagnostic interview (Munich Composite International Diagnostic Interview; CIDI) administered by clinical psychologists.

RESULTS

Hearing impairment was associated with CIDI psychotic symptoms [odds ratio (OR) 2.04, 95% confidence interval (CI) 1.10-3.81], particularly more severe psychotic symptoms (OR 5.66, 95% CI 1.64-19.49). The association between hearing impairment and CIDI psychotic symptoms was much stronger in the youngest group aged 14-17 years at baseline (OR 3.28, 95% CI 1.54-7.01) than in the older group aged 18-24 years at baseline (OR 0.82, 95% CI 0.24-2.84).

CONCLUSIONS

The finding of an age-specific association between hearing impairment and psychotic experiences suggests that disruption of development at a critical adolescent phase, in interaction with other personal and social vulnerabilities, may increase the risk for psychotic symptoms.

The influence of post-meningitic obliteration and ossification of the cochlea on cochlear microphonics

Cochlear microphonics are electrical stimulus responses of the inner ear. They are generated by mechanical displacement of the hair cells caused by acoustic stimulation and can be recorded from the cochlear promontory via a needle electrode. In individuals with post-meningitic deafness, fibrous obliteration or ossification of the cochlea may occur. The aim of the present investigation was to establish whether obliteration or ossification leads to any alteration in the extent to which cochlear microphonics can be recorded (as compared with that in patients with a fluid-filled cochlea whose deafness was not post-meningitic), as an indication of changes in the mechanical displacement of the remaining hair cells. Cochlear microphonics in 15 individuals with proven obliteration or ossification of the cochlea were compared with those in 15 control subjects (deaf individuals whose hearing loss was not post-meningitic, and who had a fluid-filled cochlea). Our findings reveal no statistically significant differences between the two groups in the degree to which cochlear microphonics can be recorded. This study does not demonstrate evidence of a change in this property due to ossification or obliteration of the cochlea.

Global and regional risk of disabling sequelae from bacterial meningitis: a systematic review and meta-analysis

Few data sources are available to assess the global and regional risk of sequelae from bacterial meningitis. We aimed to estimate the risks of major and minor sequelae caused by bacterial meningitis, estimate the distribution of the different types of sequelae, and compare risk by region and income. We systematically reviewed published papers from 1980 to 2008. Standard global burden of disease categories (cognitive deficit, bilateral hearing loss, motor deficit, seizures, visual impairment, hydrocephalus) were labelled as major sequelae. Less severe, minor sequelae (behavioural problems, learning difficulties, unilateral hearing loss, hypotonia, diplopia), and multiple impairments were also included. 132 papers were selected for inclusion. The median (IQR) risk of at least one major or minor sequela after hospital discharge was 19.9% (12.3-35.3%). The risk of at least one major sequela was 12.8% (7.2-21.1%) and of at least one minor sequela was 8.6% (4.4-15.3%). The median (IQR) risk of at least one major sequela was 24.7% (16.2-35.3%) in pneumococcal meningitis; 9.5% (7.1-15.3%) in Haemophilus influenzae type b (Hib), and 7.2% (4.3-11.2%) in meningococcal meningitis. The most common major sequela was hearing loss (33.9%), and 19.7% had multiple impairments. In the random-effects meta-analysis, all-cause risk of a major sequela was twice as high in the African (pooled risk estimate 25.1% [95% CI 18.9-32.0%]) and southeast Asian regions (21.6% [95% CI 13.1-31.5%]) as in the European region (9.4% [95% CI 7.0-12.3%]; overall I(2)=89.5%, p<0.0001). Risks of long-term disabling sequelae were highest in low-income countries, where the burden of bacterial meningitis is greatest. Most reported sequelae could have been averted by vaccination with Hib, pneumococcal, and meningococcal vaccines.

The risk of sequelae due to pneumococcal meningitis in high-income countries: a systematic review and meta-analysis

OBJECTIVES

To determine the risk of various kinds of sequelae in survivors of meningitis due to Streptococcus pneumoniae, as well as the influence of co-factors such as study design, study population and treatment on this risk.

METHODS

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from 1 September 1991 to 18 June 2009 for original articles on pneumococcal meningitis sequelae. Prevalence of sequelae was pooled using random effects meta-analysis. Studies were appraised for the influence of referral bias, external validity of study populations, testing procedure and publication bias.

RESULTS

Data were extracted from 63 studies involving 3408 pneumococcal meningitis survivors. The pooled prevalence of any reported sequelae from 48 studies was 31.7% (95% confidence interval 27.2-36.3%) using a random effects model (Cochran-Q = 277, p < 0.01). Differences in studies due to design, study population and treatment were not significant. The pooled prevalence of hearing loss, seizures, hydrocephalus, spasticity/paresis, cranial nerve palsies and visual impairment was 20.9% (17.1-24.7%), 6.5% (3.3-9.7%), 6.8% (3.3-10.2%), 8.7% (6.4-11.0%), 12.2% (5.3-19.1%) and 2.4% (0-5.7%) respectively.

CONCLUSIONS

The burden of sequelae due to pneumococcal meningitis remains high in the reviewed studies.

Hearing impairment in childhood bacterial meningitis is little relieved by dexamethasone or glycerol

OBJECTIVE

Several studies have evaluated dexamethasone for prevention of hearing loss in childhood bacterial meningitis, but results have varied. We compared dexamethasone and/or glycerol recipients with placebo recipients, and measured hearing at 3 threshold levels.

METHODS

Children aged 2 months to 16 years with meningitis were treated with ceftriaxone but were double-blindly randomly assigned to receive adjuvant dexamethasone intravenously, glycerol orally, both agents, or neither agent. We used the Glasgow coma scale to grade the presenting status. The end points were the better ear's ability to detect sounds of >40 dB, >or=60 dB, and >or=80 dB, with these thresholds indicating any, moderate-to-severe, or severe impairment, respectively. All tests were interpreted by an external audiologist. Influence of covariates in the treatment groups was examined by binary logistic regression.

RESULTS

Of the 383 children, mostly with meningitis caused by Haemophilus influenzae type b or Streptococcus pneumoniae, 101 received dexamethasone, 95 received dexamethasone and glycerol, 92 received glycerol, and 95 received placebo. Only the presenting condition and young age predicted impairment independently through all threshold levels. Each lowering point in the Glasgow scale increased the risk by 15% to 21% (odds ratio: 1.20, 1.21, and 1.15 [95% confidence interval: 1.06-1.35, 1.07-1.37, and 1.01-1.31]; P = .005, .003, and .039) for any, moderate-to-severe, or severe impairment, respectively. Each increasing month of age decreased the risk by 2% to 6% (P = .0001, .0007, and .041, respectively). Neither dexamethasone nor glycerol prevented hearing loss at these levels regardless of the causative agent or timing of antimicrobial agent.

CONCLUSIONS

With bacterial meningitis, the child's presenting status and young age are the most important predictors of hearing impairment. Little relief is obtained from current adjuvant medications.

Pathology of the vestibulocochlear nerve

Imaging of the vestibulocochlear nerve has evolved dramatically over the past few decades. The imaging specialist now is involved in the diagnosis of far more diagnostic entities than ever before. With this increased involvement comes the responsibility to increase collective knowledge regarding the pathophysiology of these diagnostic entities. This article is organized in a conventional way and covers congenital deformity of the internal auditory canal, neoplastic and pseudoneoplastic lesions, with special detailed emphasis on schwannoma of the eight cranial nerves (acoustic neuroma), nonneoplastic IAC/CPA pathology, including vascular loops, and numerous additional differential diagnostic entities, with particular emphasis on non-neoplastic meningeal disease. Lesions of the auditory pathway and an overview of cochlear implant surgery are also included in this discussion.

Etiologic and audiologic evaluations after universal neonatal hearing screening: analysis of 170 referred neonates

OBJECTIVE

The goal was to clarify the audiologic aspects and causes of congenital hearing loss in children who failed universal neonatal hearing screening.

METHODS

A prospective analysis of 170 consecutive records of neonates referred to a tertiary center after universal neonatal hearing screening failure, between 1998 and 2006, was performed. The data presented here represent the equivalent of approximately 87000 screened newborns. The screening results were validated with a clinical ear, nose, and throat examination and electrophysiological testing, including diagnostic auditory brainstem response, automated steady state response, and/or behavioral testing. A diagnostic evaluation protocol for identification of the cause of the hearing loss was also implemented, in collaboration with the departments of genetics and pediatrics.

RESULTS

Permanent hearing loss was confirmed in 116 children (68.2%). Bilateral hearing loss was diagnosed in 68 infants (58.6%) and unilateral hearing loss in 48 infants (41.4%). Median thresholds for the neonates with confirmed hearing loss were severe in both unilateral and bilateral cases, at 70 dB nHL and 80 dB nHL, respectively. In 55.8% of those cases, no risk factors for hearing loss were found. In 60.4%, the initial automated auditory brainstem response diagnosis was totally in agreement with the audiologic evaluation results. In 8.3% of the cases, however, a unilateral refer result was finally classified as bilateral hearing loss. An etiologic factor could be identified in 55.2% of the cases. Of the causes identified, a genetic mechanism was present in 60.4% of the cases, peripartal problems in 20.8%, and congenital cytomegalovirus infection in 18.8%.

CONCLUSIONS

An etiologic factor could be identified for nearly one half of the children with confirmed congenital hearing loss referred through a universal hearing screening program.

Causation of permanent unilateral and mild bilateral hearing loss in children

Children with permanent unilateral or mild bilateral hearing loss have been a focus of concern by audiologists, educators, and physicians for at least 2 decades. These children are known to be at risk for psychoeducational difficulties. However, despite this concern, little has been learned about the causative factors of these hearing losses and how those factors might be contributing to child development. This review of known causes of permanent unilateral and mild bilateral hearing loss in children is meant to draw attention to the importance of the search for etiologic factors. That is, the identification of the hearing loss should not signal the end of the diagnostic process but, rather, the beginning of a search for causation. With the combined efforts of audiologists, otolaryngologists, pediatricians, geneticists, and other medical professionals, we may enhance our understanding of the primary causes of unilateral and mild bilateral hearing loss and, perhaps, create links between causative factors and psychosocial and psychoeducational outcomes.

Sensorineural hearing loss in children

During the past three to four decades, the incidence of acquired sensorineural hearing loss (SNHL) in children living in more developed countries has fallen, as a result of improved neonatal care and the widespread implementation of immunisation programmes. The overall decrease has been accompanied by a relative increase in the proportion of inherited forms of SNHL. The contribution made by one gene in particular, GJB2, to the genetic load of SNHL has strongly affected the assessment and care of children with hearing loss. These changes in the incidence of SNHL have not been seen in children living in less developed countries, where the prevalence of consanguinity is high in many areas, and both genetic and acquired forms of SNHL are more common, particularly among children who live in poverty. Focused genetic counselling and health education might lead to a decrease in the prevalence of inherited SNHL in these countries. Establishment of vaccination programmes for several vaccine-preventable infectious diseases would reduce rates of acquired SNHL. Although the primary purpose of such programmes is the prevention of serious and in many cases fatal infections, a secondary benefit would be a reduction in disease-related complications such as SNHL that cause permanent disability in survivors.

Evidence of Subtle Auditory Deficit in a Group of Patients Recovered from Bacterial Meningitis

OBJECTIVES

Sensorineural hearing loss of greater than 30 dB hearing loss occurs in up to 30% of patients after acute bacterial meningitis. This study investigated whether postbacterial meningitic patients with no apparent clinical sensorineural hearing loss had any evidence of more subtle subclinical cochlear deficit.

DESIGN

Prospective case-controlled clinical trial.

SETTING

Departments of Otolaryngology in Leicester and Nottingham, England, UK.

PATIENTS

Fifty-eight controls and 20 postbacterial meningitic patients aged between 18 and 38 years were screened by a questionnaire and tympanometry to exclude hearing loss attributable to other causes. All participants fell below the 90th percentile pure-tone audiometry threshold of the Lutman and Davis UK data sets.

MAIN OUTCOME MEASURES

In both ears, standard (0.25-8 kHz) pure-tone audiometry, high-frequency pure-tone audiometry (10-16 kHz), and distortion product otoacoustic emissions at 2, 4, and 6 kHz were measured.

RESULTS

Mean thresholds over the range of standard pure-tone audiometry (analyzed independently) for the postbacterial meningitic patients were significantly elevated at most frequencies (p < 0.05-p < 0.001) between 4 and 7 dB in both ears above control group values. There was no evidence of significant high-frequency threshold elevation (10-16 kHz). The mean iso-distortion product values at 2, 4, and 6 kHz were elevated in both ears in the meningitis group; significantly so (p < 0.05-p < 0.01) at all three frequencies in the right ear and at 4 kHz in the left.

CONCLUSIONS

Postbacterial meningitic patients with hearing below the 90th percentile range had a slight but significant subclinical threshold elevation over the standard pure-tone audiometry. This may reflect a real effect of the infection at the level of the cochlea, or it may be attributable to a mild residual cognitive defect. The moderate increases in iso-distortion product values are more likely to be real and reflect an effect on outer hair cell function in response to lower stimulus intensities.

Hearing loss at school age in survivors of bacterial meningitis: assessment, incidence, and prediction

OBJECTIVES

To establish the incidence of sensorineural hearing loss in children who survived non-Haemophilus influenzae type B (Hib) bacterial meningitis, to highlight the actual percentage whose hearing was evaluated, and to develop a prediction rule to identify those who are at risk of hearing loss.

METHODS

In 1999, we compiled a cohort of 628 school-aged children who were born between January 1986 and December 1994 and had survived non-Hib bacterial meningitis between January 1990 and December 1995. Presence of sensorineural hearing loss (>25 dB) was determined, based on information from questionnaires and medical records. Potential risk factors for hearing loss were obtained from medical records; independent predictors were identified using multivariate logistic regression analysis, leading to the formulation of a prediction rule.

RESULTS

The incidence of hearing loss was 7%. The hearing of 68% of the children was evaluated as part of their routine follow-up after bacterial meningitis, resulting in the detection of 75% of the cases of hearing loss. The remaining 25% were detected after this follow-up had ended. Using a prediction rule based on 5 factors-duration of symptoms before admission >2 days, absence of petechiae, cerebrospinal fluid glucose level <or=0.6 mmol/L, Streptococcus pneumoniae, and ataxia-62% of the postmeningitic children were selected as being at risk. All cases of hearing loss were in this at-risk group.

CONCLUSIONS

Hearing loss can be predicted satisfactorily. When the hearing of children who are predicted to be at risk is tested as part of their routine follow-up, no children with hearing loss need be missed.

Newborn hearing screening: tobramycin and vancomycin are not risk factors for hearing loss

OBJECTIVE

To investigate the chance of detecting hearing loss with neonatal hearing screening in relation to exposure to tobramycin and vancomycin.

STUDY DESIGN

Automated auditory brainstem response (A-ABR) hearing screening was performed in all neonates with at least one risk factor. Data on drug administration were abstracted from patient files. Exposure to these drugs was related to the result of hearing screening. In patients failing hearing screening, exposure to ototoxic medication was assessed in the light of other risk factors for hearing loss.

RESULTS

Six hundred twenty-five patients were analyzed; 45 neonates failed hearing screening. Tobramycin, vancomycin, and furosemide were used in 508, 130, and 174 patients, respectively. Exposure to vancomycin, tobramycin, or furosemide or a combination, defined in terms of treatment duration, total dose, or serum concentrations of antibiotics, was not related to failure to pass A-ABR screening. Ototoxic medication was not the most probable risk factor in any of the patients with serum concentrations outside the therapeutic range.

CONCLUSIONS

Routine therapeutic drug monitoring of vancomycin and tobramycin in neonates for ototoxicity reasons is not helpful in detecting patients at risk for clinically important hearing loss in the 2- to 4-kHz range. A longer period of audiometric follow-up is needed to determine any long-term effects.

The value of enhanced magnetic resonance imaging in the evaluation of endocochlear disease

BACKGROUND

Gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear.

STUDY DESIGN

Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000.

RESULTS

Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification.

CONCLUSION

Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management.

Otoacoustic emissions as a screening test for hearing impairment in children recovering from acute bacterial meningitis

OBJECTIVES

To study the efficacy of otoacoustic emissions (OAEs) as a screening test for hearing impairment in children with acute bacterial meningitis. Hearing tests were performed before discharge from the hospital in an attempt to improve coverage and avoid delays in the diagnosis of postmeningitic hearing loss.

METHODS

Children with bacterial meningitis were recruited from 21 centers. In the 48 hours before discharge from the hospital, all patients underwent a thorough audiologic assessment consisting of transient evoked OAEs, auditory brainstem responses (ABRs), otoscopy, and tympanometry. Hearing loss was defined as ABR threshold >/=30 dB. The results of OAE screening were compared with the gold standard of ABR threshold.

RESULTS

Of 124 children recruited, we were able to perform both OAEs and ABRs on 110 children. Seven (6.3%) of the 110 children had ABR threshold >/=30 dB; 2 had sensorineural hearing loss and 5 had conductive hearing loss. At follow-up, hearing loss persisted in both cases of sensorineural hearing loss and no new cases were identified. All 7 children with hearing loss failed the OAE screening test. Ninety-four children with normal hearing thresholds passed the test, and 9 failed. Thus, the screening test had a sensitivity of 1.00 (95% confidence interval, 0.59 to 1.00), a specificity of 0.91 (0.85 to 0.97), a positive predictive value of 0. 44 (0.20 to 0.70), and a negative predictive value of 1.00 (0.96 to 1.00).

CONCLUSIONS

OAE screening in children recovering from meningitis was found to be feasible and effective. The test was highly sensitive and reasonably specific. Inpatient OAE screening should allow early diagnosis of postmeningitic hearing loss and prompt auditory rehabilitation.

Epidemiology of permanent childhood hearing impairment in Trent Region, 1985-1993

This retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in children born between 1985 and 1993 and resident in Trent Health Region, achieved an ascertainment of 92.9% of that expected from previous studies and 100% for the subset of children born between 1985 and 1990. The prevalence rate of all permanent hearing impairment > or = 40 dB HL for the birth cohort 1985-90 is 133 (95% confidence interval, (ci) 122-145) per 100,000 live births (1 in 750). Sixteen per cent of PCHI were postnatally acquired, late-onset or progressive impairments. Excluding these, the prevalence rate for congenital impairments is 112 (ci 101-123) per 100,000 (1 in 900). The rate for profound impairments > or = 95 dB HL is 24 (ci 20-30) per 100,000 live births (1 in 4150). Prevalence was increased sixfold for children with a history of neonatal intensive care and 14-fold for children with a family history, compared with children with no risk factors. A more than two-fold increase in prevalence was seen in Asian children. For the congenitally-impaired children born between 1985 and 1990, 29% had a stay in neonatal intensive care > or = 48 hours, 30% had a family history of permanent childhood hearing impairment, and 12% had a cranio-facial abnormality (CFA). Over 59% were potentially detectable by a targeted neonatal screening programme using these three high-risk factors. For 1985-1993, the overall yield of the targeted neonatal screening programmes available in three of the 11 health districts was 15% but increased over time. The overall yield from the Health Visitor distraction test was 30% but lower in districts with neonatal screening programmes. Only 59% of children had a stated aetiology, classified by time of onset into genetic, including syndromes and CFA (41%), pre- or peri-natal (10%), post-natally acquired (6%), and uncertain onset (2%). Just under 40% of the children were said to have another clinical or developmental problem, about half of whom had at least two additional problems. The median age at referral, confirmation of the impairment, prescription of the hearing aid and fitting of the hearing aid were, respectively, 10.4 months, 18.1 months, 24.4 months and 26.3 months. A more severe impairment was associated with earlier age. Small improvements in the median age of hearing aid prescription and fitting were seen over time. Twenty-five per cent of children were referred for genetic counselling, the proportion increasing systematically with the severity of the impairment. Based on evidence of the yield from hearing screens we suggest a wider implementation of neonatal screening and further consideration of the role of the health visitor distraction test in the identification of children with PCHI. To facilitate further assessment of services for hearing-impaired children we suggest implementation of a co-ordinated shared list of children with permanent hearing impairment on a region-wide basis to provide adequate numbers for comparison over time, and the routine collection of a minimum set of data for each child.

Acute otitis media and otitis media with effusion in children with bacterial meningitis

Acute otitis media and otitis media with effusion (OME) have often been observed in children with bacterial meningitis. OME has also been proposed as the mechanism of reversible hearing loss after meningitis. In this controlled study, children with acute bacterial meningitis were studied using auditory brainstem responses (ABR), otoacoustic emissions, tympanometry and otoscopy. An age- and sex-matched control was recruited for each patient and the incidence of acute otitis media and OME was compared between the two groups. One hundred and twenty-four children with meningitis were studied. Ninety-two children (74 per cent) had meningococcal meningitis. Five patients (4 per cent) had conductive hearing loss (ABR threshold > or = 30 dB HL) at the time of discharge from hospital. None of the patients or controls had acute otitis media. Patients and controls were well matched for risk factors for OME and the prevalence of middle ear effusion in patients and controls was 7.2 per cent and 11.3 per cent respectively. The relative risk of OME in the children with meningitis was 0.64 (95 per cent confidence interval 0.29 to 1.42). After nine months, three of the five children with meningitis and conductive hearing loss had regained normal hearing. In contrast to previous reports, there was no relationship between bacterial meningitis and acute otitis media or OME in this study. Nevertheless, coincidental conductive hearing defects were identified as the cause of reversible hearing loss in three patients.

Prevalence and etiology of bilateral sensorineural hearing impairment in a Finnish childhood population

A retrospective study was performed on the prevalence and etiology of bilateral sensorineural hearing impairment (> 25 dB at 0.5-4 kHz in the better ear) among children born 1974-1987 in a province of eastern Finland. A total of 98 children with hearing impairment were identified, which gave a prevalence of 2.1 per 1000 live births. This prevalence was higher than reported form most of other developed countries but slightly lower than reported from Sweden. A slight decline from the prevalence of 2.3 per 1000 in the 1970s to the prevalence of 1.9 per 1000 in the 1980s was observed. Contrary to several earlier studies, no male predominance was noted, there were even slightly more females than males (52 vs. 46). Etiology of the hearing loss was estimated to be genetic in 41%, congenital nongenetic in 13%, delayed-onset nongenetic in 16% and remained unknown in 30%. On average, children with a congenital disorder had more severe hearing impairment than those with delayed-onset hearing loss, e.g. 31% of the former patients had profound (> 95 dB) hearing loss compared to 6% of the latter. A very gratifying finding was that no case of congenital hearing impairment caused by maternal rubella was identified after 1982, obviously due to general vaccinations. Also, a decline in cases of hearing loss attributed to perinatal and neonatal complications was observed.

[Hearing findings in subjects after meningitis]

INTRODUCTION

It was proposed to ascertain the occurrence of individuals who present hearing loss, due to contracting meningitis, as well as to characterize the diagnosed loss as far as the type, degree and the audiometric configuration are concerned.

MATERIAL AND METHOD

The methodology used comprised a survey of 949 references of patients attended at the Hearing Disturbance Center of the HPRLLP/USP, in order to select those who presented hearing loss after meningitis and, from the analysis of the hearing evaluation to which they were submitted, achieve the proposed goal.

RESULTS AND CONCLUSION

The results indicated a 6.2 percent occurrence as regards hearing loss due to meningitis in relation to other causes and the characteristic of this hearing loss was predominantly sensorineural, symmetrical, al linear and to a profound degree.

Evaluation of hearing loss with auditory brainstem responses in the early and late period of bacterial meningitis in children

The hearing function of 50 children with bacterial meningitis was evaluated at the second and 10th days, and eight weeks after admission with auditory brain system responses (ABR) to investigate whether meningitis causes hearing loss. Normal values were obtained in all tests from both ears of 24 patients (48 per cent). Twelve patients (24 per cent) had temporary, and seven (14 per cent) patients had persistent mild degree hearing loss. Severe hearing loss was detected bilaterally in five (10 per cent) patients and unilaterally in two (four per cent) patients. Patients, with other complications such as subdural effusion, convulsion, brain oedema and paralysis were found to have a higher incidence of hearing loss. We observed that patients treated with dexamethasone had 7.7 per cent persistent hearing loss, 11.6 per cent mild hearing loss, 34.6 per cent transient hearing loss, but in the group who did not receive dexamethasone there was 19.2 per cent persistent hearing loss, 15.3 per cent mild hearing loss and 11.6 per cent transient hearing loss. There were other significant differences between the two groups in restoration of normal body temperature, the CSF/plasma glucose concentration ratio was elevated, CSF (cerebro-spinal fluid) protein concentration was decreased and the cell count in the CSF was decreased in the dexamethasone group, significantly more than the group who were not receiving dexamethasone. The hearing loss tended to be more frequent among younger children.

Cochlear implantation after bacterial meningitis: the dangers of delay

A case is described of a child of 2.6 years who developed total deafness after acute bacterial meningitis. Rapid obliteration of the cochleas due to osteoneogenesis led to limited cochlear implantation. The case is made for fast tracking these children to cochlear implant teams before neoossification becomes established.

Management and outcome: children fitted with hearing aids in Ireland

The Republic of Ireland has a total population of 3.5 million people, mainly rural or in small towns, a rapidly declining birthrate during 1984 to 1991, and a geographically stable children's population. A unified Audiology Service is provided by the National Rehabilitation Board for the fitting of hearing aids to all children deemed to require them. The current study outlines a database analysis of all children fitted with hearing aids for the first time in 1984 or 1991. Follow-up information on the status (in 1991-1992) of those fitted in 1984 was obtained, with regard to hearing loss, schooling and changes in aiding. Data on severe/profound losses in particular, and the trends in service provision are examined. Similar numbers of children were fitted with hearing aids in the two years sampled, even though the overall degree of hearing loss amongst this population had fallen.

Hearing assessment after meningitis and meningococcal disease

A method to increase audiology referral after meningitis or meningococcal disease was audited in 89 children. A standardised proforma increased referrals from 78% to 96% over a two year period. However, only 73% of children had a hearing test. The major reason for hearing not being tested changed from non-referral to non-attendance.

Children who could benefit from a cochlear implant: a European estimate of projected numbers, cost and relevant characteristics

The incidence of profound hearing impairment by the age of 5, derived from a number of retrospective studies in the UK (population about 58 million; birth rate 14/1000), is estimated to be about 300 per annual birth cohort in the 1990s. This estimate includes 80 children who might be expected to acquire deafness in those first 5 years. Projected to Europe as a whole (population 511 million; birth rate 12/1000) this would mean a population who should be considered as potential cochlear implant patients of some 2268 children, given a variety of assumptions. At a take-up rate of 25% for both congenital and acquired cases of profound hearing impairment this would imply a European-wide expenditure of the order of 17 pounds m/p.a. on hardware and associated rehabilitation programmes. The need for such programmes is explored, in the context of strategies of early identification of hearing impairments.

The causes of profound hearing impairment in a school for the deaf--a longitudinal study

The study was aimed towards an evaluation of the causes of hearing loss in children attending the School for the 'Deaf' in Copenhagen in 1993-4 in comparison to causes evaluated 10 and 40 years previously (Arnvig, 1953; Holten and Parving, 1985). The 124 children attending the school in 1993 represent 0.04% of the age-matched target population of 312,715. A more detailed evaluation of two comparable cohorts born in 1969-77 and 1979-87 demonstrates a significant increase of children attending this type of school from 0.03% to 0.05% within a 10-year period, while a comparison between 1953 and 1993 demonstrates a reduction from 0.07% to 0.04%. The longitudinal evaluation of the causes of hearing loss showed a significant increase in the frequency of congenital inherited hearing impairment from 29% (1953) through 33% (1983) to 43% (1993), whereas a significant reduction of about 17% in the frequency of acquired deafness due to chronic otitis media was found. Between 1953 and 1993 a minor reduction (2%) in post-meningitic acquired hearing impairment was found, between 1953 and 1983 there was a significant increase in prenatal infections, compared with a decrease of 6% between 1983 and 1993. It is concluded that significant changes are found both in the prevalence of children referred to the school and in the factors causing severe to profound hearing impairment in children. Continuous recording of, and improvement in, diagnostic classification is necessary to obtain preventive measures.