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Neurologic infections can be classified by clinical syndrome/localization (e.g., meningitis vs encephalitis vs myelitis vs radiculitis) and by the type of infection (e.g., viral, bacterial, tuberculous, fungal, parasitic). This chapter is organized by clinical syndrome, with each section organized into subsections by the type of infection. At the end of the chapter, the neurologic manifestations of HIV/AIDS are discussed. Table 20–1 provides a summary of the most common types of clinical syndromes caused by each pathogen or group of pathogens.

TABLE 20–1Neurologic Syndromes Caused By Infections.


Meningitis (inflammation of the meninges) can be caused by:

  • Infection: most commonly bacterial, viral, fungal, or tuberculous

  • Systemic inflammatory disease: e.g., sarcoidosis, inflammatory bowel disease, rheumatoid arthritis, granulomatosis with polyangiitis (formerly called Wegener’s granulomatosis), IgG4-related disease

  • Medications (chemical meningitis): nonsteroidal anti-inflammatory drugs (NSAIDs), intravenous immunoglobulin (IVIg), trimethoprim-sulfamethoxazole

  • Malignancy: leptomeningeal metastases (also called carcinomatous meningitis)

Most infectious meningeal processes predominantly affect the leptomeninges (arachnoid and pia), whereas most inflammatory processes predominantly affect the pachymeninges (dura mater), although there can be simultaneous involvement of both the pachymeninges and leptomeninges in both types of processes (see Figure 2–10 and accompanying discussion “Contrast-enhanced Neuroimaging” in Chapter 2). Carcinomatous meningitis typically refers to leptomeningeal metastases (see “Leptomeningeal Metastases” in Chapter 24). Dural metastases also occur (most commonly with prostate and breast cancer).

Bacterial meningitis and viral meningitis tend to be acute in onset and evolution, whereas fungal meningitis, tuberculous meningitis, inflammatory meningitis, and carcinomatous meningitis are more commonly subacute or chronic in onset and evolution.

Viral meningitis and chemical meningitis are sometimes referred to as aseptic meningitis.

Bacterial Meningitis

Bacteria can infect the meninges by spreading from sinus infections or inner ear infections, spreading hematogenously from remote sites of infection, or infecting the meninges directly in the ...

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