INTRODUCTION

A focal cerebral neurological finding in the presence of fever suggests infection or inflammation of the brain or surrounding tissues, or a cerebral complication of systemic infection. Asymmetrical motor or sensory findings, such as one-sided weakness or numbness, or language dysfunction, are more obvious findings. Perceptual deficits such as deficits in reading comprehension, visual field cuts, apraxias, ataxia, and confusion may be more subtle presentations of focal cerebral disease. Cerebral infections may be accompanied by headache and are commonly associated with the development of either focal or generalized seizures. Fever may also be absent or intermittent in infectious cerebral disease, and clinicians should have a low threshold for considering these diagnoses in the appropriate context. Focal neurological findings in the setting of suspected or known infection constitute an emergency. This chapter focuses on focal cerebral infections in immunocompetent hosts. For a discussion of causes of fever and headache, see Chapter 39, Fever and Headache. For a discussion of central nervous system infections in the immunocompromised, see Chapter 42, Altered Mental Status in HIV-Infected Patients.

GENERAL DIFFERENTIAL DIAGNOSIS

Main Diagnoses to Consider

The most common serious causes of fever and focal neurological deficit are intracranial abscess from a local or hematogenous source, and focal encephalitis with herpes simplex virus.

Historical features suggestive of intracranial abscess include:

• recent dental work

• recent ear infection, mastoiditis, sinusitis, tooth abscess, or pneumonia

• recent trauma or neurological surgery

• history of valvular disease, congenital heart disease, or endocarditis

• history of chronic infection such as osteomyelitis

• […]