Meningitis

The membranes that surround the brain are known collectively as the meninges. Inflammation of the meninges (meningitis) should always be considered as a diagnosis for anyone with an altered mental status.

Causes
Meningitis occurs when the meninges get infected with an organism. Most cases of meningitis are either caused by a bacteria or virus.

Signs and Symptoms
Fever, neck stiffness and altered mental status are the most common signs and symptoms. The patient may be lethargic, confused, or even unconscious. OVen they complain of headache, intolerance to light (photophobia), nausea and vomiting. Occasionally they may also have a seizure.

Symptoms usually develop rapidly, and so the patient can become very sick over a period of just a few hours. If bacterial meningitis is not treated rapidly then it can cause permanent dysfunction, or may lead to death. Viral meningitis usually has a good recovery even without specific treatment, and rarely causes death. 

Investigations
Lumbar puncture should be performed and the cerebrospinal fluid (CSF) sent to the laboratory. Analysis of the cerebrospinal fluid (CSF) helps identify whether the cause is due to a bacteria or virus or other organism.

A CT scan of the head is required if there is suspicion of brain tumor or raised intracranial pressure, as lumbar puncture may be contraindicated in these circumstances.

Routine bloods should be taken. A blood glucose should be checked on anyone with altered mental status. Blood culture is used to determine whether there is infection in the blood stream.

The patient’s level of consciousness must be closely monitored, as bacterial meningitis can cause rapid deterioration leading to death.

Treatment
If bacterial meningitis is suspected, then intravenous antibiotics must be commenced immediately, before the results of the lumbar puncture are available. If lumbar puncture will be delayed, then antibiotics must be commenced prior to lumbar puncture.

If the patient is unconscious then an open airway must be maintained, and oxygen administered as required. Any seizures must be treated as required. Steroids (such as Dexamethasone) can be given to decrease neurological dysfunction of the patient if they recover.

Viral meningitis is mostly a benign disease, requiring only supportive care, such as analgesia and intravenous fluids.

Some types of meningitis can be spread by respiratory droplets from one person to another. Therefore, protective measures must be taken when caring for these patients, such as wearing gloves and mask, and thorough washing of hands. Family and friends that have had close contacts with the patient with bacterial meningitis may require oral antibiotics to prevent them from contracting the disease.