Epidural Abscess

How an epidural abscess develops

Bacteria reach the epidural space by three main routes:

• through the blood from an infection elsewhere, such as a skin abscess, infected injection site, urinary tract infection, or endocarditis
• direct spread from nearby infected bone (vertebral osteomyelitis) or disc
• introduced during procedures such as epidural anesthesia, spinal injections or spine surgery

Staphylococcus aureus, including MRSA, causes about two-thirds of cases. As pus accumulates, it presses on the spinal cord or nerve roots and can also block their blood supply, causing sudden irreversible damage.

Risk factors

• injection drug use
• diabetes
• recent spinal surgery, epidural or spinal injections
• bloodstream infections and indwelling catheters
• weakened immunity: cancer, HIV, steroids, chronic kidney disease or dialysis
• alcohol use disorder
• spinal trauma

Symptoms

Symptoms typically progress through stages, sometimes over days, sometimes within hours:

1. Back or neck pain at the level of the abscess, often severe and with local tenderness
2. Nerve root pain shooting around the chest, abdomen or down the limbs
3. Neurological deficits: weakness, numbness, tingling, bladder or bowel dysfunction
4. Paralysis below the level of the abscess

Fever is present in only about half of patients at first, which is why the diagnosis is often delayed. Back pain with any risk factor deserves a high level of suspicion.

Intracranial epidural abscess

An abscess between the skull and dura usually follows sinusitis, ear infection or skull surgery, and causes headache, fever, swelling of the forehead (Pott's puffy tumor) and later confusion or seizures. It may coexist with a brain abscess or subdural empyema.

Diagnosis

• MRI of the whole spine with contrast: the key test, which shows the abscess, its extent and any cord compression. Imaging the entire spine is important because abscesses can be extensive or occur at multiple levels.
• Blood tests: raised white cells, ESR and CRP; blood cultures identify the bacteria in many cases.
• CT-guided aspiration or samples at surgery when blood cultures are negative.
• CT if MRI is not possible.

Treatment

Antibiotics

Broad intravenous antibiotics covering staph (including MRSA) are started promptly, then tailored to culture results. Treatment usually lasts 6 to 8 weeks or longer, especially with associated bone infection.

Surgery

Surgical decompression and drainage is recommended for most patients, particularly those with any neurological deficit, worsening symptoms, or large abscesses. The best results come when surgery happens before or very early after weakness develops.

Selected patients with no neurological deficits may be treated with antibiotics alone, with close monitoring and repeat MRI, but surgery is performed if any deficit appears.

Rehabilitation

People with lasting weakness need physical and occupational therapy, and sometimes bladder and bowel management.

Complications

• permanent paralysis or weakness
• bladder and bowel dysfunction
• sepsis
• spinal instability or deformity from bone damage
• meningitis

Outlook

The single most important factor is the neurological condition at the time of treatment. People treated before weakness develops usually recover well. Paralysis present for more than 24 to 36 hours before surgery is often permanent. Delayed diagnosis remains common, so recognizing warning signs early is critical.

Frequently asked questions

What are the symptoms of a spinal epidural abscess?

Typical symptoms are severe back or neck pain, often with fever, followed by shooting nerve pain and then weakness, numbness and bladder or bowel problems. Not all symptoms appear at once, and fever may be absent at first.

What causes an epidural abscess?

Most are caused by bacteria, usually Staphylococcus aureus, reaching the spine through the bloodstream, spreading from nearby infected bone, or being introduced during spinal procedures. Injection drug use, diabetes and recent spine procedures increase the risk.

Is an epidural abscess an emergency?

Yes. Because it can compress the spinal cord and cause permanent paralysis, back pain with fever and any new weakness, numbness or bladder problems needs emergency evaluation and MRI.

Can you recover from an epidural abscess?

Yes, many people recover fully, especially when treated before weakness develops. Treatment involves weeks of IV antibiotics and usually surgery. People who already have significant paralysis at diagnosis are more likely to have lasting deficits.