Other causes of meningitis - Infections of the nervous system

Other causes of meningitis

Definition

In some cases of clinical meningitis, initial investigations may demonstrate meningeal inflammation but routine blood and CSF cultures are negative.

Aetiology

The differential diagnosis for these cases of ‘aseptic meningitis’ is wide (see Table 7.6).

Investigations/management

In many cases of aseptic meningitis, the diagnosis is of a selflimiting, benign viral meningitis. However, it is important to consider these other causes, particularly if the patient does not improve. Further investigations may include:

·        CT/MRI scanning of the brain and sinuses.

·        Repeated lumbar punctures, including further fluid for cytology, specific CSF antibody. titres, e.g. for mumps, and PCR for, e.g. TB, HSV, enterovirus.

·        CSF staining for acid-fast bacilli, fungi.

·        TB cultures, viral cultures and fungal cultures (although these take days to weeks).

·        Serum serology (acute and convalescent samples).

·        HIV testing.

If it is not clear whether the process is bacterial or viral, antibiotics may be given empirically whilst awaiting further investigation.