Delayed deterioration of hearing following bacterial meningitis

Double challenge: cochlear implantation in the only hearing ear with progressive hearing loss following meningitis and vestibular dysfunction after implantation

Objective

Vestibular dysfunction associated with cochlear implantation is rare. It is usually seen in patients with otosclerosis due to spread of electrical activity throughout the demineralized bone. A 17-year old female with progressive hearing loss 2 years after meningitis and vestibular dysfunction in the implanted ear is presented in this study.

Findings

The patient had mild hearing loss in the right ear and total hearing loss on the left side because of complete ossification of the cochlea following meningitis. She had to have cochlear implantation in the right ear because of progression of hearing loss. She had successful implantation but she experienced vestibular dysfunction following activation of cochlear electrodes. Closure of two electrodes caused disruption of auditory programming. Then the patient was subjected to long term vestibular rehabilitation program.

Conclusion

Timing for implantation before the completion of cochlear ossification is crucial not to miss the chance for hearing restoration. However, difficulties in hearing rehabilitation due to extensive ossification can be doubled by vestibular problems triggered by stimulation of the vestibular nerve by cochlear electrodes. Attempts to reduce the balance problem will complicate auditory programming. Vestibular rehabilitation for long term helps to carry on hearing progress.

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.

Neuroprotective effects of brain-derived neurotrophic factor (BDNF) on hearing in experimental pneumococcal meningitis

Bacterial meningitis is still one of the most common causes of acquired profound sensorineural deafness in children despite antibiotic treatment. We investigated the neuroprotective effects of brain-derived neurotrophic factor on hearing function in experimental bacterial meningitis. We implanted stainless steel tubes into both cerebral ventricles of Sprague-Dawley rats aged 21 days. Bacterial meningitis was induced by inoculating a strain of serotype III Streptococcus pneumoniae into the cisterna magna. Six micrograms per day of brain-derived neurotrophic factor (groups 1 and 3) or albumin (groups 2 and 4) was injected into the cerebral ventricles 24 hours after or before infection, respectively, for a duration of 7 days. Additionally, all rats received antibiotic subcutaneous treatment starting 24 hours after infection for 7 days. Brainstem auditory evoked potentials were recorded 24 hours before and 24 hours after infection and after 7 days of treatment with brain-derived neurotrophic factor or placebo and antibiotics, respectively, to determine hearing threshold. Our results showed that the hearing thresholds of animals in each group increased significantly 24 hours after infection compared with the results recorded 24 hours before infection (P < .01). After 7 days of treatment with brain-derived neurotrophic factor, brainstem auditory evoked potential responses recurred in 16 ears when stimulated at 75 dB hearing level in groups 1 and 3. Their hearing thresholds significantly decreased compared with the control group 2 (P < .05) and group 4 (P < .01). However, 13 of 14 ears absent brainstem auditory evoked potential responses could still not be identified at 75 dB hearing level in control groups 2 and 4. The improvement of the hearing thresholds in group 3 (treated before infection) was greater than that of group 1 (treated after infection) (P < .05), but there was no significant difference found between the control groups before and after infection (P > .05). Our study supports the hypothesis that the administration of exogenous brain-derived neurotrophic factor can be effective in preventing or treating hearing loss following bacterial meningitis.

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.

Análise das principais etiologias de deficiência auditiva em Escola Especial "Anne Sullivan"

OBJETIVO: Determinar as principais etiologias de deficiência auditiva em estudantes da Escola de Ensino Especial para surdos "Anne Sullivan" em São Caetano do Sul e comparar com os dados da literatura mundial. FORMA DE ESTUDO: Estudo retrospectivo. MATERIAL E MÉTODO: Cento e trinta e um alunos da escola no ano de 2001 foram avaliados através de análise de seus prontuários, levando-se em conta dados de anamnese com a família, exame físico otorrinolaringológico, avaliação fonoaudiológica e psicológica. RESULTADOS: Dos 131 pacientes, 67 (51%) eram do sexo masculino e 64 (49%) do sexo feminino. A perda auditiva sensorioneural foi a mais encontrada, representando 99% dos casos. Quanto ao grau de disacusia, 65% foi classificado como profundo. Quanto à etiologia, 24% foi classificada como desconhecida e das causas identificáveis a rubéola congênita foi a mais encontrada (22%). Na maioria dos pacientes a suspeita e o diagnóstico foram feitos com 12 meses de idade. CONCLUSÕES: A etiologia não definida foi a mais representativa, seguida pela rubéola, e a idade de diagnóstico predominou entre 12 e 30 meses.