Epidural Abscess

Epidural = near the dura (the outermost protective covering of the spinal cord)
Abscess = a collection of pus (infected material)

A spinal epidural abscess is an infection in the area between the bones of the spine, or on the outer covering of the spinal cord. Although it is rare, it can be fatal if left untreated. The best prognosis and lowest risk of complications are associated with early diagnosis and treatment.


A spinal epidural abscess may cause the following symptoms:

  • Loss of control of bowel or bladder function
  • Difficulty urinating (urinary retention)
  • Fever
  • Weakness in the legs
  • Back pain
  • Mental status changes (if infection is in the blood)


If a patient presents with symptoms associated with epidural abscess, the doctor may order magnetic resonance imaging (MRI). An MRI is a diagnostic procedure that uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within the body.

The doctor will draw blood to run a complete blood count (CBC) to determine if there is an infection in the body. If an infection is present, the number of white blood cells will be elevated. This is because white blood cells attack and destroy the organisms causing the infection. If so, blood cultures can determine the organism (bacteria or fungus) causing the infection.

Risk Factors

A spinal epidural abscess is usually caused by bacteria. Staphylococcus aureus is the most common organism, followed by Escherichia coli. In some cases, an abscess can be caused by a fungal infection.

The risk for developing a spinal epidural abscess is increased in the following situations:

  • Recent back surgery or recent invasive procedure involving the spine
  • An infection in the blood
  • A boil (pus-filled bump under the skin caused by an infected hair follicle), especially on the back or scalp
  • Bone infections of the spine (vertebral osteomyelitis)
  • Immunodeficiency [for example, acquired immunodeficiency syndrome (AIDS), chemotherapy, and immunosuppressive medications given to those who have undergone an organ transplant]
  • Spinal trauma


Treatment of spinal epidural abscesses typically includes surgery and antibiotics or antifungals. In some cases, treatment may include only antibiotics. Antibiotics will be given typically for 4-6 weeks.

If the abscess is placing pressure on the spinal cord, the surgeon will perform surgical decompression of the spinal cord to reduce/remove the pressure. To decompress the spinal cord, the surgeon may perform a laminectomy to remove the lamina, which is the bone that covers the spinal canal. Removing the lamina makes room for the spinal cord and allows the spinal cord to function properly. Typically a laminectomy may be required with complicated infections.

If the abscess is causing neurological symptoms such as bladder/bowel dysfunction, seen with cauda equina syndrome, the surgeon will drain the abscess immediately. When the abscess is drained, the surgeon will order a culture to ensure the medications ordered are the best to treat the specific organism causing the infection.