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A spinal epidural abscess is an accumulation of pus in the epidural space that can mechanically compress the spinal cord.

Spinal epidural abscesses usually occur in the thoracic or lumbar regions. An underlying infection is often present; it may be remote (eg, endocarditis, furuncle, dental abscess) or contiguous (eg, vertebral osteomyelitis, decubitus ulcer, retroperitoneal abscess). In about ¹/₃ of cases, the cause cannot be determined. The most common causative organism is Staphylococcus aureus, followed by Escherichia coli and mixed anaerobes. Occasionally, the cause is a tuberculous abscess of the thoracic spine (Pott's disease). Rarely, a similar abscess occurs in the subdural space.

Symptoms and Signs

Symptoms begin with local or radicular back pain and percussion tenderness, which become severe. Fever is common. Spinal cord compression may develop; compression of lumbar spinal roots may cause cauda equina syndrome, with neurologic deficits resembling those of conus medullaris syndrome (eg, leg paresis, saddle anesthesia, bladder and bowel dysfunction). Deficits progress over hours to days.

Diagnosis

• MRI

The diagnosis is suggested by characteristic neurologic deficits and by back pain worsened by recumbency, particularly in patients who have a fever or have had a recent infection. Diagnosis is by MRI; myelography followed by CT can be used if MRI is not available. Samples from blood and infectious areas are cultured. Lumbar puncture is contraindicated because it may trigger cord herniation if the abscess causes complete obstruction of CSF. Plain x-rays are not routinely indicated but may show osteomyelitis in about ¹/₃ of patients.

Treatment

• Antibiotics
• If abscess causes neurologic compromise, immediate drainage

Antibiotics with or without parenteral needle aspiration may be sufficient; however, abscesses producing neurologic compromise (eg, paresis, bowel or bladder dysfunction) are surgically drained immediately. Pus is gram-stained and cultured. Pending culture results, antibiotics to cover staphylococcus and anaerobes are given as for brain abscess (see Brain Infections: Treatment). If the abscess developed after a neurosurgical procedure, an aminoglycoside is added to cover gram-negative bacteria.

Last full review/revision January 2007 by Michael Rubin, MD

Content last modified January 2007