Chapter 41 - Meningitis and encephalitis

Summary

Bacterial meningitis remains a serious disease with a high mortality. Despite antimicrobial therapy and supportive care mortality rates remain high at approximately 25%. Mortality is highest with pneumococcal infection. Intracranial hypertension is a common complication of bacterial meningitis and can lead to altered consciousness level, airway compromise and seizures. Many of the detrimental pathophysiological effects of bacterial meningitis are due to the host defence response. This has led to efforts to modify host response while ensuring bacterial eradication. Viral encephalitis can be either acute primary or post infectious. Encephalitis can produce a wide range of neurological deficits from the subtle neurological signs to coma. Meningeal irritation is classically absent but may be present in meningoencephalitis. MRI may be useful in diagnosis of encephalitis but cerebrospinal fluid (CSF) samples and viral serology are often needed to identify the organism.