Sensorineural hearing loss following acute bacterial meningitis in non-neonates

Hearing impairment after childhood bacterial meningitis dependent on etiology in Luanda, Angola

OBJECTIVE

Childhood bacterial meningitis (BM) damages hearing, but the potential of different agents to cause impairment in developing countries is poorly understood. We compared the extent of hearing impairment in BM caused by Haemophilus influenzae type b (Hib), Streptococcus pneumoniae or Neisseria meningitidis among children aged 2 months to 13 years in Luanda, Angola.

METHODS

Hearing of 685 ears of 351 (78%) survivors among 723 enrolled patients was tested by brainstem-evoked response audiometry on day 7 of hospitalization. The causative agent was sought by cerebrospinal fluid culture, PCR or the latex-agglutination test.

RESULTS

Altogether, 45 (12%) of the survivors were deaf (threshold >80 dB), and 20 (6%) had a threshold of 80 dB. The incidence of any kind of hearing loss, with ≥60 dB, was 34% with Hib, 30% with S. pneumoniae, 19% with N. meningitidis and 33% with other bacteria. Examining all ears combined and using the ≥60 dB threshold, the agents showed dissimilar harm (P=0.005), Hib being the most frequent and N. meningitidis the most infrequent cause. Compared to other agents, S. pneumoniae more often caused deafness (P=0.025) and hearing impairment at ≥60 dB (P=0.017) in infants, whereas this level of hearing loss in older survivors was most commonly caused by Hib (P=0.031).

CONCLUSIONS

BM among children in Angola is often followed by hearing impairment, but the risk depends on the agent. S. pneumoniae is a major problem among infants, whereas Hib is mainly a risk beyond 12 months. N. meningitidis impairs hearing less frequently.

Early prediction of postmeningitic hearing loss in children using magnetic resonance imaging

OBJECTIVE

To determine whether early gadolinium-enhanced magnetic resonance imaging (GdMRI) can reliably detect meningitic labyrinthitis and thereby predict which children are at high risk for hearing loss. Permanent sensorineural hearing loss (SNHL) remains a common sequela of bacterial meningitis, and early diagnosis of the associated suppurative labyrinthitis can be difficult, especially in critically ill, sedated patients and young children.

DESIGN

Retrospective cohort study.

SETTING

Tertiary pediatric hospital.

PARTICIPANTS

Twenty-three survivors of bacterial meningitis (median age, 15 months [range, 3 months-14 years]) who had undergone brain GdMRI during the acute disease and had subsequent ear-specific audiometric data.

MAIN OUTCOME MEASURE

Blinded to disease and outcome, a neuroradiologist rated the relative enhancement of each cochlea on T1-weighted images using a 4-point scale. Scores were then correlated with the degree of hearing loss on subsequent testing.

RESULTS

Sensorineural hearing loss occurred in 15 of 46 ears (8 of 23 patients). Enhancement on GdMRI was detected in 13 of the 15 ears that later developed SNHL but was absent in all 31 unaffected ears. Thus, GdMRI was 87% sensitive and 100% specific for predicting which ears would develop permanent SNHL. In the subgroup with pneumococcal meningitis (n = 15), GdMRI was 100% sensitive and 100% specific. Labyrinthine enhancement was detectable as early as 1 day after diagnosis.

CONCLUSION

Gadolinium-enhanced MRI detected meningitic labyrinthitis at early stages and accurately predicted which patients would later develop hearing loss.

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.

Predictors of long term neurological outcome in bacterial meningitis

OBJECTIVE

To study the long-term neurological and developmental outcome and the clinical and laboratory predictors of sequelae in children with acute bacterial meningitis (ABM).

METHODS

Detailed clinical and demographic data was retrieved from the medical records of study children. Subsequently they were followed up for a minimum of 12 months after discharge for development, neurological and hearing assessment. All sequelae were identified and divided into minor or major. For analysis data was divided into 2 groups those with sequelae and without sequelae at follow-up. Statistical analysis was done using SPSS version 10.00 and Epi Info version 2000.

RESULTS

61 boys and 19 girls, a mean age of 31.4 +/= 41.9 months at the time of ABM, were included in the study. Of these 62.5% children were infants. Mean age at follow-up was 58.6 +/= 47.2 months. Sequelae were observed in 32 (40%) children (8 (10%) minor and 24 (30%) major). Mean social quotient at follow-up was 92.8 +/= 32.6. Developmentally 22 (37.9%) children were normal and 20 (34.5%) had global delay. Seizures (P=0.015), cranial nerve palsy (P=0.0065), abnormal deep tendon reflexes (P=0.002), Glasgow coma scale score (GCS) < 8 (P = 0.044) at admission, a CSF culture positive for bacteria and abnormal findings on ultrasonography or computed tomography of head at admission had significant association with sequelae at follow-up. All children (7/7) who had infarct on CT scan (P=0.001) and 12 (80%) of 15 patients who had hydrocephalus (OR - 9.0, 95% CI - 2.03-45.6, P=0.001) diagnosed on CT scan developed severe sequelae. On multiple regressions GCS score <8, presence of cranial nerve palsy and abnormal deep tendon reflexes were independent predictors of sequelae.

CONCLUSION

Neurological and audiological sequelae and global developmental delay may be seen in about one third of survivors of bacterial meningitis. GCS score <8, presence of infarct or cranial nerve palsy, or hydrocephalous on CT/ ultrasound at admission may help in identification of children most likely to need long term follow up and rehabilitation.