Meningitis Health Article

Diagnosis

A number of techniques are used when examining a person suspected of having meningitis to verify the diagnosis. Certain manipulations of the head (lowering the head, chin towards chest, for example) are difficult to perform and painful for a person with meningitis.

The most important test used to diagnose meningitis is the lumbar puncture (commonly called a spinal tap). Lumbar puncture (LP) involves the insertion of a thin needle into a space between the vertebrae in the lower back and the withdrawal of a small amount of CSF. The CSF is then examined under a microscope to look for bacteria or fungi. Normal CSF contains set percentages of glucose and protein. These percentages will vary with bacterial, viral, or other causes of meningitis. For example, bacterial meningitis causes a greatly decreased percentage of glucose in the CSF because the bacteria are essentially consuming or "eating" that glucose and using it for their own nutrition and energy production. Normal CSF should contain no infection-fighting cells (white blood cells), so the presence of white blood cells in CSF is another indication of meningitis. Some of the withdrawn CSF is put into special lab dishes to allow growth of the infecting organism, which can then be identified more easily. Special immunologic and serologic tests may also be used to help identify the infectious agent.

In rare instances a lumbar puncture cannot be performed because of the amount of swelling and pressure within the skull (intracranial pressure). This pressure is measured immediately upon insertion of an LP needle. If it is found to be high, no fluid is withdrawn because doing so could cause herniation of the brain stem. Herniation of the brain stem occurs when the part of the brain connecting to the spinal cord is thrust through the opening at the base of the skull into the spinal canal. Such herniation will cause compression of those structures within the brain stem that control the most vital functions of the body (breathing, heart beat, consciousness). Death or permanent debilitation follows herniation of the brain stem.

Treatment

Antibiotic medications (forms of penicillin and cephalosporins, for example) are the most important elements of treatment against bacterial meningitis. Because of the effectiveness of the blood-brain barrier in preventing passage of substances into the brain, medications must be delivered directly into an affected person's veins (intravenously, or IV), at very high doses. Antiviral drugs (acyclovir) may be helpful in shortening the duration of viral meningitis, and antifungal medications are also available.

Other treatments involve decreasing inflammation (with steroid preparations) and paying careful attention to the balance of fluids, glucose, sodium, potassium, oxygen, and carbon dioxide in a person's system. People who develop seizures will require medications to halt the seizures and prevent their return.

Prognosis

Viral meningitis is the least severe type, and persons usually recover with no long-term effects from the infection. Bacterial infections, however, are much more severe, and rapidly progress. Without very rapid treatment with the appropriate antibiotic, an infection can swiftly lead to coma and death, often in less than 24 hours. While death rates from meningitis vary depending upon the specific infecting organism, the overall death rate is just under 20%.

The most frequent long-term effects of meningitis include deafness and blindness, which may be caused by the compression of specific nerves and brain areas responsible for the senses of hearing and sight. Some people develop permanent seizure disorders, requiring life-long treatment with antiseizure medications. Scarring of the meninges may result in obstruction of the normal flow of CSF, causing abnormal accumulation of CSF. This may be a chronic problem for some people, requiring the installation of shunt tubes to drain the accumulation on a regular basis.

Health care team roles

Family physicians, pediatricians, emergency physicians, or internists usually make the initial diagnosis of meningitis. Laboratory technicians identify organisms that cause meningitis. Nurses and other hospital staff provide supportive care, and patient and family education. Occasionally, physical therapists are needed to help the patient recover lost muscle functioning.

Prevention

Prevention of meningitis primarily involves the appropriate treatment of other infections an individual may acquire, particularly those known to seed to the

meninges (such as ear and sinus infections). Preventive treatment with antibiotics is sometimes recommended for those in close contacts with an individual who is ill with meningococcal or H. influenzae type b meningitis. A meningococcal vaccine is sometimes recommended to individuals traveling to very high risk areas. A vaccine for H. influenzae type b is now given to babies as part of the standard array of childhood immunizations.