– An infection and inflammation of the meninges of the brain and spinal cord resulting in altered neurologic function.
Causes and Incidence
Bacterial meningitis can be caused by any number of bacteria, but 80% of cases are caused by one of three strains: Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae. The disease occurs worldwide and is both endemic and epidemic. Spread is through droplet contact, and the disease can be transmitted as long as the respiratory tract contains the causative bacteria. Children under 5 years of age are at greatest risk. Pneumococcal meningitis is the most common form of adult meningitis.
The bacteria invade the respiratory passages and are disseminated by the bloodstream to the cerebrospinal fluid (CSF) space and the meninges of the brain and spinal cord. A growing exudate damages cranial nerves, obliterates CSF pathways, and induces vasculitis and thrombophlebitis. The exudate also generates metabolites and cytokines, which damage cell membranes, disrupt the blood-brain barrier, and cause cerebral edema and ischemic brain damage.
A prodromal respiratory illness may precede symptoms of fever, severe headache, stiff neck, and vomiting. Changes in consciousness then occur, beginning with irritability, drowsiness, and confusion and followed by stupor and coma. Seizures are common.
Complications include hydrocephalus, blindness, deafness, arthritis, myocarditis, pericarditis, and cognitive deficit.
Cultures of CSF, respiratory secretions, and blood are positive for the causative agent.
Antiinfective drugs specific for the causative agent; analgesics for muscle pain and headache; vaccine for prevention in at-risk populations; antiinfective drugs for those in close contact with an infected individual; corticosteroid use is under investigation.
Adequate hydration and balancing of electrolytes; monitoring and control of intracranial pressure; hemodynamic monitoring; ventilatory support if necessary; seizure precautions; secretion precautions to prevent spread; comfort measures for photophobia; monitoring of contacts with infected individuals.