What is this condition?
In this disorder, the brain and the spinal cord meninges become inflamed, usually as a result of bacterial infection. Such inflammation may involve all three meningeal membranes: the dura mater, the arachnoid, and the pia mater. The prognosis is good and complications are rare, especially if the disease is recognized early and the infecting organism responds to antibiotics. However, the death rate in untreated disease is 70% to 100%. The prognosis is poorer for infants and elderly people.
What causes it?
Meningitis is almost always a complication of another bacterial infection: bacteremia (especially from pneumonia, pus in a body cavity, osteomyelitis, or endocarditis), sinus or middle ear infection, encephalitis, myelitis, or brain abscess.
This disorder may also follow skull fracture, a penetrating head wound, lumbar puncture, or ventricular shunt insertion. Aseptic inflammation of the brain and spinal cord membranes also may result from a virus or other organism. Sometimes, no causative organism can be found. Inflammation of the brain and spinal cord membranes may progress to congestion of adjacent tissues and destroy some nerve cells.
What are the symptoms of Meningitis?
The cardinal symptoms of this disorder are the same as those of infection (fever, chills, malaise) and of increased intracranial pressure (headache, vomiting and, rarely, swelling of the optic disk). Signs of meningeal irritation include rigidity at the nape of the neck, involuntary knee flexion when the neck is passively flexed, inability to extend the leg completely when sitting, exaggerated and symmetrical deeptendon reflexes, and backward arching of the back and extremities so that the body rests on the head and heels.
Other symptoms are irregular heartbeats, irritability, extreme sensitivity to light, double vision and other visual problems, and delirium, deep stupor, and coma.
An infant may show signs of infection and is often fretful and refuses to eat. Such an infant may vomit a great deal, leading to dehydration.
As this disease progresses, twitching, seizures (in 30% of infants), or coma may develop. Most older children have the same symptoms as adults. In the subacute form, onset may be gradual.
How is it diagnosed?
A lumbar puncture (spinal tap), showing typical cerebrospinal fluid findings, and certain physical exam findings usually establish this diagnosis. The fluid may appear cloudy or milky white, depending on the number of white blood cells present. Protein levels in cerebrospinal fluid tend to be high; sugar levels may be low. (In subacute disease, fluid findings may vary.) Cerebrospinal fluid culture and sensitivity tests usually identifY the infecting organism unless it's a virus.
To help determine the major sites of infection, the doctor will take cultures of the blood, urine, and nose and throat secretions; a chest X-ray; and an electrocardiogram. An abnormally high level of white blood cells and electrolyte abnormalities also are common. Computed tomography (commonly called a CAT scan) can rule out brain hematoma, hemorrhage, or tumor.
How is it treated?
To treat this disorder, the person receives appropriate antibiotic therapy and vigorous supportive care. Usually, intravenous antibiotics are given for at least 2 weeks, followed by oral antibiotics. Such antibiotics include Bicillin, Omnipen, or Nafcil. However, if the person is allergic to penicillin, Chloromycetin or Kantrex may be given. Other drugs include a cardiac glycoside such as Lanoxin to control irregular heartbeats, Osmitrol to decrease brain swelling, an anti seizure drug (usually given intravenously) or a sedative to reduce restlessness, and aspirin or Tylenol (or another acetaminophen product) to relieve headache and fever.
Supportive measures include bed rest, reduction of body temperature, and measures to prevent dehydration. The person must be isolated if the nasal cultures are positive for certain organisms. Of course, treatment includes appropriate therapy for any coexisting conditions, such as pneumonia.
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