An epidural abscess is a collection of pus (infected material) between the outer covering of the brain and spinal cord and the bones of the skull or spine. The abscess causes swelling in the area.A.D.A.M.

Causes, incidence, and risk factors

Epidural abscess is a rare disorder caused by infection in the area between the bones of the skull or spine, and the membranes covering the brain and spinal cord (meninges). This infection is called an intracranial epidural abscess if it is inside the skull area, or a spinal epidural abscess if it is found in the spine area. Most are located in the spine.

The spinal infection is usually caused by bacteria (Staphylococcus aureus is most common), but may be caused by fungus. It can be due to other infections in the body (especially a urinary tract infection), or germs that spread through the blood. However, in some patients, no other source of infection is found.

An intracranial epidural abscess (within the skull). Risk factors include:

• Chronic ear infections
• Chronic sinusitis
• Head injury
• Mastoiditis
• Recent neurosurgery

A spinal epidural abscess may be seen in patients with:

• A history of back surgery or other invasive procedures involving the spine
• Bloodstream infections
• Boils especially on the back or scalp
• Bone infections of the spine (vertebral osteomyelitis)

People who inject drugs are also at increased risk.

Symptoms

Spinal epidural abscess:

• Bowel or bladder incontinence
• Difficulty urinating (urinary retention)
• Fever and back pain

Intracranial epidural abscess:

• Fever
• Headache
• Lethargy
• Nausea and vomiting
• Pain at the site of recent surgery that gets worse (especially if fever is present)

Neurological symptoms depend on the location of the abscess and may include:

• Decreased ability to move any part of the body
• Loss of sensation in any area of the body, or abnormal changes in sensation
• Weakness

Signs and tests

The health care provider will perform an exam to look for a loss of functions such as movement or sensation.

Tests may include:

• Blood cultures
• Complete blood count (CBC)
• CT scan of head or spine
• Draining of abscess and examination of the material
• MRI of head or spine

Treatment

The goal of treatment is to cure the infection and reduce the risk of permanent damage. Treatment usually includes antibiotics and surgery. In rare cases, antibiotics alone are used.

Antibiotics are usually given through a vein (IV) for at least 4 - 6 weeks. However, some people may need to take them for a longer time, depending on the type of bacteria and severity of the disease.

Surgery is usually needed to drain or remove the abscess. In addition, surgery is often needed to reduce pressure on the spinal cord or brain, to prevent further loss of function.

Expectations (prognosis)

Early diagnosis and treatment greatly improve the chance of a good outcome. Once weakness, paralysis, or sensation changes occur, the chances of recovering lost function are reduced. Permanent nervous system damage or death may occur.

Complications

• Brain abscess
• Brain damage
• Bone infection (osteomyelitis)
• Chronic back pain
• Meningitis
• Nerve damage
• Return of infection
• Spinal cord abscess

Calling your health care provider

Call your health care provider if you have:

• Persistent back pain with fever
• Headache with fever
• Other symptoms of epidural abscess

An epidural abscess is a medical emergency.

Prevention

Treatment of certain infections, such as ear infections, sinusitis, and bloodstream infections, may decrease the risk of an epidural abscess. Early diagnosis and treatment are essential to prevent complications.

References

1. Nath A, Berger J. Brain abscess and parameningeal infections. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 421.
2. Tunkel AR. Subdural empyema, epidural abscess, and suppurative intracranial thrombophlebitis. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 89.

Review Date: 10/6/2012.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.