The central nervous system, or CNS, comprises the brain, spinal cord and associated membranes. Under some circumstances, bacteria may enter areas of the CNS. Bacterial infection of the CNS can result in abscesses and empyemas (accumulations of pus). Abscesses have fixed boundaries, but empyemas lack definable shape and size. CNS infections are classified according to where they occur.

As pus and other material from an infection build up, pressure is exerted on the brain or spinal cord. This pressure can damage the nervous system tissue, possibly permanently. Without treatment, a CNS infection is fatal.

Symptoms

Physical symptoms, such as a fever and intense backache, or a fever, severe headache and stiff neck, raise the suspicion of a CNS infection. Blood tests may indicate the presence of an infection but do not pinpoint its location. CT or MRI scans of the brain and spine can provide definitive diagnosis.

Treatment

A two-pronged approach is taken to treat CNS infections. First, antibiotic therapy against an array of potential infectious bacteria is started. If needed, the second stage involves surgery to drain the infected site. Surgery allows immediate relief of pressure on the brain or spinal cord, as well as an opportunity to collect infectious material for bacterial identification. Once the bacterial species is identified, drug therapy can be altered to a more specific antibiotic.

There are four main causes of infections of the central nervous system: bacterial, viral, fungal and protozoal.

• Bacterial Infections

• Tuberculosis
• Leprosy
• Neurosyphilis
• Bacterial meningitis
• Late-stage Lyme disease
• Brain abscess
• Neuroborreliosis

• Viral Infections

• Viral meningitis
• Eastern equine encephalitis
• St. Louis encephalitis
• Japanese encephalitis
• West Nile encephalitis
• Herpes simplex encephalitis
• Rabies
• California encephalitis virus
• Varicella-zoster encephalitis
• La Crosse encephalitis
• Measles encephalitis
• Poliomyelitis
• Subacute sclerosing panencephalitis
• Progressive multifocal leukoencephalopathy
• Acquired immunodeficiency syndrome (AIDS)

• Fungal Infections

• Cryptococcal meningitis
• Brain abscess
• Spinal epidural infection

• Protozoal Infections

• Toxoplasmosis
• Malaria
• Primary amoebic meningoencephalitis