Epidural abscess

Alternative names:

abscess - epidural

Definition:

A disorder characterized by inflammation and a collection of infected material (pus) between the dura (the outer membrane covering of the brain and spinal cord) and the bones of the skull or spine.

Causes, incidence, and risk factors:

An epidural abscess is caused by infection in the skull or spine, located in the area between the bones of the skull and/or spine and the meninges (the membranes covering the brain and spinal cord). The infection is usually bacterial (staphylococcus is common) but may be fungal or viral. Pus is formed by a collection of fluid, destroyed tissue cells, white blood cells, and live and dead microorganisms. The pus becomes enclosed(encapsulated) by a lining or membrane that forms at the edges of the fluid collection. There is inflammation of the tissues around the abscess in response to the infection.

General symptoms such as fever are usually present as a result of the infection. Enlargement of the abscess and swelling in conjunction with inflammation cause symptoms because of compressed tissues in the brain and spinal cord. An epidural abscess of the head usually enlarges slowly and causes gradual, progressive loss of neurologic functions (such as movement and sensation). An epidural abscess of the spine may cause sudden severe neurologic losses and may be life threatening.

The infection is commonly the result of direct extension of nearby infections or may result from microorganisms that spread from infection in distant locations. An epidural abscess of the head commonly results from disorders such as chronic sinusitis, chronic ear infection, or mastoiditis. It may also result from a head injury that penetrates the skull but leaves the meninges intact. An epidural abscess of the spine may result from the spread of infection from skin boils. An epidural abscess in either location may also result from infections in the body (the lungs and the abdomen are common sites of origin) that spread through the bloodstream. Occasionally, an epidural abscess may be a complication of infection after surgery.

The infection may spread into the bones of the spine or skull (osteomyelitis). It may spread through the membranes and cause meningitis, cerebral abscess, or spinal cord abscess.

An epidural abscess is a fairly rare disorder. It is even less common now because of the use of effective antibiotics to treat infections in the body. Chronic ear infections, chronic sinusitis, and mastoiditis are the most common disorders that increase the risk of epidural abscess.