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The bare essentials
Infections of the nervous system
  1. Nicholas Davies1,
  2. Guy Thwaites2
  1. 1Consultant Neurologist, Chelsea and Westminster Hospital, London, UK
  2. 2Wellcome Trust Clinical Research Fellow/Consultant in Infectious Diseases and Microbiology, Centre for Molecular Microbiology and Infection, Imperial College, South Kensington, London, UK
  1. Correspondence to Dr G E Thwaites, Centre for Molecular Microbiology and Infection, Imperial College, Exhibition Road, London SW7 2AZ, UK; guy.thwaites{at}

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Neurologists and infectious diseases physicians have much in common. There are not many of either; they share a love of the long differential diagnosis (preferably in Latin); but most importantly, both groups can suffer loss of confidence when confronted with a patient with an infected nervous system. As a result, these patients may find themselves falling between two pillars of expertise. This article aims to close the gap. We will resist temptation to present long lists of potential (but exceedingly rare and exciting) infectious agents. Instead, we will describe how to approach the infected patient, and how the common nervous system infections are recognised and treated. Readers should consult recent treatment guidelines for antibiotic doses and duration (see further reading and resources box).

General principles: how to approach an infected patient

Infectious disease practice differs from neurology in the need to consider the biology of two organisms: the bug as well as the patient. Junior physicians at the Hospital for Tropical Diseases in London are taught to ask: why did this person, from this place, get this disease, at this time? The question summarises the key considerations required to begin the diagnostic process, and is an elegant reminder that an infectious disease depends on the complex interaction between the virulence of the infectious agent, the susceptibility of the host and the nature of their shared environment (figure 1). This question can only be satisfactorily answered first by a well directed history (box 1)—whatever else, answers to the following two questions are essential:

  • is the patient particularly susceptible to some or all infectious agents?

  • what is the duration of illness?

Figure 1

The biology of nervous system infectious diseases.

Box 1 Key elements in the history: why did this person, from this place, get this disease, at this time?


  • Age

  • Occupation

  • Immune suppressed or immune competent? (eg, pregnancy, drugs, splenectomy, cancer, HIV/AIDS)

  • High risk sexual behaviour or intravenous drug use

  • Vaccination/prophylaxis (eg, against …

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  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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