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Acute And Chronic Meningitis Health Article

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Clinical Features

Bacterial meningitis

Meningitis is the most likely diagnosis in patients who present with the classical triad of fever, headache and a stiff neck, which is present in at least 80% of patients. Other signs and symptoms occur less frequently (Table 22.6), and patients complaining of headache or presenting with altered mental status must be carefully examined for evidence of meningeal irritation (i.e. meningism, with Kernig's sign, Brudzinski's sign, or both).

Bacterial meningitis can be present in patients in whom the clinical diagnosis is not obvious. This is particularly true in small children and in the elderly. In children under 2 years of age, signs of meningeal inflammation are frequently absent, and the most common clinical presentations include fever and altered mental status (irritability, lethargy), which are present in over 90% of patients. Similarly, in elderly patients, fever may be minimal, and mental status changes may be the most obvious symptom. In patients who have suspected meningitis, the skin should be examined carefully for the characteristic purpuric or petechial skin rash of N. meningitidis . Other clues derived from the history and physical examination may help in the differential diagnosis of meningitis (Table 22.7).

Untreated bacterial meningitis is characterized by progressive loss of consciousness, which is commonly associated with other neurologic signs including seizures and focal deficits, leading to coma and death. The extent of mental status changes, with profound coma as the most extreme, provides a clinical indication of the severity of the disease. Patients presenting in coma have a very high mortality rate (up to 50%). Systemic complications of the infectious process include septic shock, disseminated intravascular coagulation (particularly with meningococcal infections) and acute respiratory distress syndrome.

Aseptic meningitis

The clinical manifestations of aseptic meningitis are often indistinguishable from those of bacterial meningitis. Acute onset of fever, headache, photophobia, nausea with vomiting and meningism are most common. On the other hand, severe neurologic findings, including seizures, are very uncommon in most forms of aseptic meningitis. Overall, symptoms are generally milder than those of pyogenic meningitis. Most cases of aseptic meningitis are self-limiting and do not lead to sequelae although constitutional symptoms can persist for several weeks. Depending on the causative pathogen, signs of meningeal inflammation may be associated with other clinical findings (see Table 22.3).

Chronic meningitis

Symptoms and signs of chronic meningitis evolve over several days to weeks. Most prominently, patients complain of headaches, often associated with constitutional signs of infection (fever, anorexia). Nuchal rigidity may be subtle or absent. Many forms of chronic meningitis involve the base of the brain and lead to cranial nerve palsies, often affecting eye movements and facial musculature. As the syndrome progresses, signs of brain involvement with seizures, mental status changes, confusion or hallucinations, and focal neurologic deficits develop. Hydrocephalus and increased intracranial pressure may accompany the syndrome.