Hearing Loss Common After Bacterial Meningitis in Kids

HOUSTON, Sept. 20 -- One-quarter to one-third of children infected with bacterial meningitis develop hearing loss, according to investigators here.

The loss may be preventable with the early use of antibiotics, said Carla Marie Giannoni, M.D., of Baylor College of Medicine, and colleagues, on the basis of a retrospective review of case records.

Sensorineural hearing loss was more common among children infected with Streptococcus than Neisseria species, although this difference was not statistically significant, they reported in the September issue of Archives of Otolaryngology -- Head & Neck Surgery. It was associated with greater length of stay, development of seizures, elevated protein levels in cerebrospinal fluid, and decreased glucose levels in CSF.

Three-quarters of patients in the study who did not develop hearing loss after a meningitis infection had received antibiotics before hospital admission, compared with only about a fifth of those who went on to have hearing loss, the authors wrote.

"The exact mechanism of hearing loss in patients with bacterial meningitis is not well understood and is likely due to multiple factors that include direct labyrinth involvement, cochlear neuroepithelial damage, and vascular insult," the investigators wrote. "By identifying children at risk for development of hearing loss, early rehabilitation may lessen long-term adverse outcomes."

The retrospective review of case records was conducted on 171 children admitted to Baylor with cultured-confirmed bacterial meningitis. The children ranged in age from three months to 17 years.

Streptococcus pneumoniae was isolated from 92 patients, and Neisseria meningitidis was isolated from 65. The two organisms accounted for 91.8% of all cases.

The authors found that the clinical presentation differed according to the infectious organism, with pneumococcal meningitis occurring in younger patients, those who presented with a longer history of symptoms, required longer hospitalization, had a greater incidence of seizures, and were more often had concurrent otitis media.

In contrast, children who presented with meningococcal meningitis tended to be of school-age, have a greater elevation in CSF white blood cell count, and had less decrease in CSF glucose.

The overall incidence of hearing loss was 30.6%. Hearing loss occurred in 35.9% of the children with S. pneumoniae infections, compared with 23.9% of those with N. meningitidis infections; this difference was not statistically significant, however.

Among the 134 children who underwent subsequent auditory testing, 41 (30.6%) had at least a unilateral mild sensorineural hearing loss.

Of this group 17 (41.4%) had mild or moderate sensorineural hearing loss, and 29 (58.6%) had severe or profound loss. Nine of the 29 children with severe or profound sensorineural hearing loss had at least a severe bilateral loss.

Among all children with bacterial meningitis, predictors of hearing loss included length of hospital stay (P<0.01), development of seizures (P=0.01), concurrent cranial nerve neuropathy (P<0.01), elevated CSF protein (P=0.04), and decreased CSF glucose (P<0.01). These factors were more strongly correlated with pneumococcal meningitis than with meningococcal infections.

There was also a trend toward a lower incidence of hearing loss among those children who received antibiotics prior to hospital admission, but this difference was not statistically significant, the authors found.

Of the 12 patients with loss who had additional audiologic testing, seven had stable hearing an average of nearly 10 months after initial testing. Four patients who initially had mild unilateral hearing loss had recovered to normal on followup testing, and one patient who had normal hearing during the index hospitalization had a moderate unilateral sensorineural hearing loss 16 months after hospitalization.

The investigators noted that the rate of hearing loss they found is higher than that seen in previous studies. Possible explanations include a higher proportion of critically ill patients seen in their tertiary care center, more virulent pathogens, or a lack of objective baseline audiologic testing in most children, leading to subjective recall of pre-meningitis hearing function, they wrote.