The aim of this topic is to review the pathophysiology and pathogenesis of meningitis and encephalitis.

At the completion of this topic you should be able to:

Outline the common microorganisms that lead to meningitis and encephalitis, particularly viral, bacterial and fungal causes.
Outline the common causes of non-infectious meningeal irritation, particularly subarachnoid haemorrhage.
Describe the anatomy of the pain sensitive structures within the cranial vault, principally the blood vessels, meninges and cranial nerves.
Explain the pathophysiology of the common clinical features of meningeal irritation, particularly headache, neck stiffness, photophobia, nausea and vomiting.
Describe the route of entry of microorganisms into the central nervous system and the variety of lesions that such microbial invasion may cause, including meningitis, encephalitis and brain abscess.
Summarise the factors that would predispose an individual to develop meningitis or encephalitis.
Describe the epidemiological features of particular types of meningitis, particularly meningococcal meningitis, fungal and viral meningitis.
Discuss the role of public health measures in the prevention of epidemics of bacterial meningitis.
Describe the pathological changes that occur in the meninges during acute and chronic meningitis.
Construct a table summarising the cerebrospinal fluid abnormalities in patients with bacterial, tuberculous, viral and fungal meningitis.

Discuss the likely causes of death in meningococcal meningitis.
Compare and contrast abnormalities of the cerebrospinal fluid would you expect to find in bacterial, viral and Cryptococcal meningitis.