Meningitis

Meningitis is the inflammation of the membranes (meninges) that cover the brain and spinal cord. It is a serious condition and can be life threatening. Infective organisms such as viruses, bacteria and fungi most often cause it. Drugs can also cause it. Aseptic meningitis is meningitis without a proven bacterial cause.

The incidence of meningitis is estimated at 4 per 100 000 per year. It is the highest in children and in children less than 1 year the incidence is 70 per 100 000 per year. In South Africa HIV and immunocompromised patients are at higher risk for developing meningitis and associated hearing loss.

One of the serious complications of specifically bacterial meningitis is hearing loss. This can occur in 30 % of patients. In 4% of patients the hearing loss will be profound and so bad that only a cochlear implantation will be an option to restore some hearing. Virus meningitis usually lasts two weeks and the hearing loss most often reversible.

Overall, the incidence of bacterial meningitis seems to decline in response to vaccination schedules. Unfortunately it still occurs, sometimes in outbreaks and often with different strains of bacteria.

In patients with bacterial meningitis the bacteria and inflammation spread to the cochlea of the inner ear causing hearing loss. This may lead to scar tissue formation and in some unfortunate patients new bone formation (ossification). This obstruction of the cochlea is critical. When this has happened it makes cochlear implantation very difficult and even impossible. It is therefore critical that all patients with meningitis must have their hearing tested within one week of onset. It is also strongly advised to start antibiotics and cotricosteroids as soon as possible after diagnosis, as this can prevent the ossification.

Hearing loss can also occur due to involvement of the nerve and it is therefore strongly advised to monitor the hearing for at least up to one year after the onset of meningitis. Hearing loss is not noticed in up to 35% of patients and especially in young children this may lead to a critical delay in speech and language development. For partial hearing loss hearing aids are indicated.

Meningitis can also lead to vestibular problems and impairment of balance. This is often the case in tuberculosis meningitis where the drugs used can lead to ototoxicity and vestibulotoxisity.

It cannot be stressed enough that if any of your family or friends are diagnosed with meningitis that their hearing be assessed as early on as possible. They should be followed up for at least one year.

Make it your duty to ensure that this happens.

Open cochlea

Open cochlea (white asterisk).

Cochlear implant in patent cochlea

Cochlear implant in open cochlea (white asterisk).

Meningitis causing blocked cochlea

Meningitis causing blocked cochlea (black asterisk)

Further reading

Meningitis – The Basics

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South African statistics on communicable diseases

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South African vaccination schedule

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Paediatric Meningitis and Hearing Loss in a Developing Country

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Dutch screening program for hearing loss in bacterial meningitis

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