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Diagnosis of Meningitis

Meningitis is an inflammation of the meninges, the membranes that surround the brain and the spinal cord. It is a relatively common illness, one that could be fatal if untreated. It can affect people of all ages, but infants, children and adolescents are particularly susceptible. Prompt diagnosis is important to prevent significant morbidity and mortality.

  1. Facts

    • The meninges (also called leptomeninges) are a thin layer of tissue that surrounds the brain and the spinal cord.

    Types

    • Microbial agents cause most cases of meningitis. These include viruses like arboviruses; bacteria like Escherichia coli, Group B Streptococcus and Neisseria meningitidis; and fungi like Candida albicans. Chemicals can also cause it, as well as some drugs like the sulfa drugs.

    Features

    • Meningitis can present different signs and symptoms. The most common symptoms are headache, neck stiffness, vomiting and photophobia (bright light bothering the eyes). Newborns and infants can present with nonspecific symptoms like bulging fontanel, irritability and lethargy. Almost all patients also present with fever.

    Identification

    • Physical signs and symptoms can help with the diagnosis. Inflammation of the meninges causes neck stiffness. This can be elicited by two tests: the Kernig and Brudzinski signs. Kernig's sign occurs when a healthcare provider flexes the patient's hip 90 degrees then extends the knee, eliciting pain in the neck. Brudzinski's sign occurs by flexing the patient's neck, causing flexion of the patient's hips and knees.

    Considerations

    • Ultimately, performing a lumbar puncture is necessary to make the diagnosis of meningitis. An increase in white blood cells, which fight infection, in the spinal fluid is indicative of meningitis. Different types of meningitis can produce different changes in the spinal fluid: bacterial meningitis causes a higher increase in the number of white blood cells than viral meningitis; bacterial meningitis results in a low level of glucose in the fluid (about 30 percent of serum glucose), but in viral meningitis the spinal fluid glucose level is usually normal and viral meningitis usually shows a high level of protein in the spinal fluid.

    Warning

    • If a patient shows signs of meningitis, empirical treatment should begin before confirmation of diagnosis.

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